]> git.saurik.com Git - apple/xnu.git/blobdiff - bsd/kern/kern_event.c
xnu-6153.81.5.tar.gz
[apple/xnu.git] / bsd / kern / kern_event.c
index df25f3112263dfa04f443cbb54913a9c5bcc78f0..8f4d2207b71a4c4fecf35725c2ef6a3927c836f8 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2017 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2019 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  *
@@ -75,6 +75,7 @@
 #include <sys/socket.h>
 #include <sys/socketvar.h>
 #include <sys/stat.h>
+#include <sys/syscall.h> // SYS_* constants
 #include <sys/sysctl.h>
 #include <sys/uio.h>
 #include <sys/sysproto.h>
@@ -85,8 +86,7 @@
 #include <sys/codesign.h>
 #include <sys/pthread_shims.h>
 #include <sys/kdebug.h>
-#include <sys/reason.h>
-#include <os/reason_private.h>
+#include <os/base.h>
 #include <pexpert/pexpert.h>
 
 #include <kern/locks.h>
 #include <pthread/workqueue_syscalls.h>
 #include <pthread/workqueue_internal.h>
 #include <libkern/libkern.h>
-#include <libkern/OSAtomic.h>
 
 #include "net/net_str_id.h"
 
 #include <sys/kern_memorystatus.h>
 #endif
 
-extern thread_t        port_name_to_thread(mach_port_name_t    port_name); /* osfmk/kern/ipc_tt.h   */
 extern mach_port_name_t ipc_entry_name_mask(mach_port_name_t name); /* osfmk/ipc/ipc_entry.h */
 
 #define KEV_EVTID(code) BSDDBG_CODE(DBG_BSD_KEVENT, (code))
 
 MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system");
 
-#define        KQ_EVENT        NO_EVENT64
+#define KQ_EVENT        NO_EVENT64
 
-static int kqueue_read(struct fileproc *fp, struct uio *uio,
-               int flags, vfs_context_t ctx);
-static int kqueue_write(struct fileproc *fp, struct uio *uio,
-               int flags, vfs_context_t ctx);
-static int kqueue_ioctl(struct fileproc *fp, u_long com, caddr_t data,
-               vfs_context_t ctx);
 static int kqueue_select(struct fileproc *fp, int which, void *wq_link_id,
-               vfs_context_t ctx);
+    vfs_context_t ctx);
 static int kqueue_close(struct fileglob *fg, vfs_context_t ctx);
 static int kqueue_kqfilter(struct fileproc *fp, struct knote *kn,
-               struct kevent_internal_s *kev, vfs_context_t ctx);
+    struct kevent_qos_s *kev);
 static int kqueue_drain(struct fileproc *fp, vfs_context_t ctx);
 
 static const struct fileops kqueueops = {
-       .fo_type = DTYPE_KQUEUE,
-       .fo_read = kqueue_read,
-       .fo_write = kqueue_write,
-       .fo_ioctl = kqueue_ioctl,
-       .fo_select = kqueue_select,
-       .fo_close = kqueue_close,
+       .fo_type     = DTYPE_KQUEUE,
+       .fo_read     = fo_no_read,
+       .fo_write    = fo_no_write,
+       .fo_ioctl    = fo_no_ioctl,
+       .fo_select   = kqueue_select,
+       .fo_close    = kqueue_close,
+       .fo_drain    = kqueue_drain,
        .fo_kqfilter = kqueue_kqfilter,
-       .fo_drain = kqueue_drain,
 };
 
-static void kevent_put_kq(struct proc *p, kqueue_id_t id, struct fileproc *fp, struct kqueue *kq);
-static int kevent_internal(struct proc *p,
-                          kqueue_id_t id, kqueue_id_t *id_out,
-                          user_addr_t changelist, int nchanges,
-                          user_addr_t eventlist, int nevents,
-                          user_addr_t data_out, uint64_t data_available,
-                          unsigned int flags, user_addr_t utimeout,
-                          kqueue_continue_t continuation,
-                          int32_t *retval);
-static int kevent_copyin(user_addr_t *addrp, struct kevent_internal_s *kevp,
-                        struct proc *p, unsigned int flags);
-static int kevent_copyout(struct kevent_internal_s *kevp, user_addr_t *addrp,
-                         struct proc *p, unsigned int flags);
-char * kevent_description(struct kevent_internal_s *kevp, char *s, size_t n);
-
-static int kevent_register_wait_prepare(struct knote *kn, struct kevent_internal_s *kev);
+static inline int kevent_modern_copyout(struct kevent_qos_s *, user_addr_t *);
+static int kevent_register_wait_prepare(struct knote *kn, struct kevent_qos_s *kev, int result);
 static void kevent_register_wait_block(struct turnstile *ts, thread_t handoff_thread,
-               struct knote_lock_ctx *knlc, thread_continue_t cont,
-               struct _kevent_register *cont_args) __dead2;
+    thread_continue_t cont, struct _kevent_register *cont_args) __dead2;
 static void kevent_register_wait_return(struct _kevent_register *cont_args) __dead2;
 static void kevent_register_wait_cleanup(struct knote *kn);
-static inline void kqueue_release_last(struct proc *p, kqueue_t kqu);
-static void kqueue_interrupt(struct kqueue *kq);
-static int kevent_callback(struct kqueue *kq, struct kevent_internal_s *kevp,
-               void *data);
-static void kevent_continue(struct kqueue *kq, void *data, int error);
-static void kqueue_scan_continue(void *contp, wait_result_t wait_result);
-static int kqueue_process(struct kqueue *kq, kevent_callback_t callback, void *callback_data,
-               struct filt_process_s *process_data, int *countp);
-static int kqueue_queue_empty(struct kqueue *kq, kq_index_t qos_index);
 
 static struct kqtailq *kqueue_get_suppressed_queue(kqueue_t kq, struct knote *kn);
-static void kqueue_threadreq_initiate(struct kqueue *kq, struct kqrequest *kqr, kq_index_t qos, int flags);
+static void kqueue_threadreq_initiate(struct kqueue *kq, workq_threadreq_t, kq_index_t qos, int flags);
 
-static void kqworkq_update_override(struct kqworkq *kqwq, struct knote *kn, kq_index_t qos);
-static void kqworkq_unbind(proc_t p, struct kqrequest *kqr);
-static thread_qos_t kqworkq_unbind_locked(struct kqworkq *kqwq, struct kqrequest *kqr, thread_t thread);
-static struct kqrequest *kqworkq_get_request(struct kqworkq *kqwq, kq_index_t qos_index);
+static void kqworkq_unbind(proc_t p, workq_threadreq_t);
+static thread_qos_t kqworkq_unbind_locked(struct kqworkq *kqwq, workq_threadreq_t, thread_t thread);
+static workq_threadreq_t kqworkq_get_request(struct kqworkq *kqwq, kq_index_t qos_index);
 
-static void kqworkloop_update_override(struct kqworkloop *kqwl, kq_index_t override_index);
-static void kqworkloop_unbind(proc_t p, struct kqworkloop *kwql);
-static thread_qos_t kqworkloop_unbind_locked(struct kqworkloop *kwql, thread_t thread);
-static kq_index_t kqworkloop_owner_override(struct kqworkloop *kqwl);
+static void kqworkloop_unbind(struct kqworkloop *kwql);
+
+enum kqwl_unbind_locked_mode {
+       KQWL_OVERRIDE_DROP_IMMEDIATELY,
+       KQWL_OVERRIDE_DROP_DELAYED,
+};
+static void kqworkloop_unbind_locked(struct kqworkloop *kwql, thread_t thread,
+    enum kqwl_unbind_locked_mode how);
+static void kqworkloop_unbind_delayed_override_drop(thread_t thread);
+static kq_index_t kqworkloop_override(struct kqworkloop *kqwl);
+static void kqworkloop_set_overcommit(struct kqworkloop *kqwl);
 enum {
        KQWL_UTQ_NONE,
        /*
@@ -201,7 +175,7 @@ enum {
         *
         * This QoS is accounted for with the events override in the
         * kqr_override_index field. It is raised each time a new knote is queued at
-        * a given QoS. The kqr_wakeup_indexes field is a superset of the non empty
+        * a given QoS. The kqwl_wakeup_indexes field is a superset of the non empty
         * knote buckets and is recomputed after each event delivery.
         */
        KQWL_UTQ_UPDATE_WAKEUP_QOS,
@@ -226,40 +200,28 @@ enum {
        KQWL_UTQ_REDRIVE_EVENTS,
 };
 static void kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos);
-static void kqworkloop_request_help(struct kqworkloop *kqwl, kq_index_t qos_index);
 static int kqworkloop_end_processing(struct kqworkloop *kqwl, int flags, int kevent_flags);
 
-static int knote_process(struct knote *kn, kevent_callback_t callback, void *callback_data,
-                        struct filt_process_s *process_data);
-
-static int kq_add_knote(struct kqueue *kq, struct knote *kn,
-               struct knote_lock_ctx *knlc, struct proc *p);
-static struct knote *kq_find_knote_and_kq_lock(struct kqueue *kq, struct kevent_internal_s *kev, bool is_fd, struct proc *p);
-
-static void knote_drop(struct kqueue *kq, struct knote *kn, struct knote_lock_ctx *knlc);
 static struct knote *knote_alloc(void);
 static void knote_free(struct knote *kn);
+static int kq_add_knote(struct kqueue *kq, struct knote *kn,
+    struct knote_lock_ctx *knlc, struct proc *p);
+static struct knote *kq_find_knote_and_kq_lock(struct kqueue *kq,
+    struct kevent_qos_s *kev, bool is_fd, struct proc *p);
 
-static void knote_activate(struct knote *kn);
-static void knote_deactivate(struct knote *kn);
-
-static void knote_enable(struct knote *kn);
-static void knote_disable(struct knote *kn);
-
-static int knote_enqueue(struct knote *kn);
-static void knote_dequeue(struct knote *kn);
+static void knote_activate(kqueue_t kqu, struct knote *kn, int result);
+static void knote_dequeue(kqueue_t kqu, struct knote *kn);
 
-static void knote_suppress(struct knote *kn);
-static void knote_unsuppress(struct knote *kn);
-static void knote_wakeup(struct knote *kn);
+static void knote_apply_touch(kqueue_t kqu, struct knote *kn,
+    struct kevent_qos_s *kev, int result);
+static void knote_suppress(kqueue_t kqu, struct knote *kn);
+static void knote_unsuppress(kqueue_t kqu, struct knote *kn);
+static void knote_drop(kqueue_t kqu, struct knote *kn, struct knote_lock_ctx *knlc);
 
-static bool knote_should_apply_qos_override(struct kqueue *kq, struct knote *kn,
-               int result, thread_qos_t *qos_out);
-static void knote_apply_qos_override(struct knote *kn, kq_index_t qos_index);
+// both these functions may dequeue the knote and it is up to the caller
+// to enqueue the knote back
 static void knote_adjust_qos(struct kqueue *kq, struct knote *kn, int result);
-static void knote_reset_priority(struct knote *kn, pthread_priority_t pp);
-static kq_index_t knote_get_qos_override_index(struct knote *kn);
-static void knote_set_qos_overcommit(struct knote *kn);
+static void knote_reset_priority(kqueue_t kqu, struct knote *kn, pthread_priority_t pp);
 
 static zone_t knote_zone;
 static zone_t kqfile_zone;
@@ -288,13 +250,20 @@ kevent_debug_flags(void)
 }
 #endif
 
-#define        KN_HASH(val, mask)      (((val) ^ (val >> 8)) & (mask))
+#define KN_HASH(val, mask)      (((val) ^ (val >> 8)) & (mask))
+
+static int filt_no_attach(struct knote *kn, struct kevent_qos_s *kev);
+static void filt_no_detach(struct knote *kn);
+static int filt_bad_event(struct knote *kn, long hint);
+static int filt_bad_touch(struct knote *kn, struct kevent_qos_s *kev);
+static int filt_bad_process(struct knote *kn, struct kevent_qos_s *kev);
 
-/* placeholder for not-yet-implemented filters */
-static int filt_badattach(struct knote *kn, struct kevent_internal_s *kev);
-static int filt_badevent(struct knote *kn, long hint);
 SECURITY_READ_ONLY_EARLY(static struct filterops) bad_filtops = {
-       .f_attach = filt_badattach,
+       .f_attach  = filt_no_attach,
+       .f_detach  = filt_no_detach,
+       .f_event   = filt_bad_event,
+       .f_touch   = filt_bad_touch,
+       .f_process = filt_bad_process,
 };
 
 #if CONFIG_MEMORYSTATUS
@@ -303,6 +272,7 @@ extern const struct filterops memorystatus_filtops;
 extern const struct filterops fs_filtops;
 extern const struct filterops sig_filtops;
 extern const struct filterops machport_filtops;
+extern const struct filterops pipe_nfiltops;
 extern const struct filterops pipe_rfiltops;
 extern const struct filterops pipe_wfiltops;
 extern const struct filterops ptsd_kqops;
@@ -341,7 +311,8 @@ const static struct filterops workloop_filtops;
  * - Add a filterops to the sysfilt_ops. Private filters should be added at the end of
  *   the Private filters section of the array.
  */
-SECURITY_READ_ONLY_EARLY(static struct filterops *) sysfilt_ops[EVFILTID_MAX] = {
+static_assert(EVFILTID_MAX < UINT8_MAX, "kn_filtid expects this to be true");
+static const struct filterops * const sysfilt_ops[EVFILTID_MAX] = {
        /* Public Filters */
        [~EVFILT_READ]                  = &file_filtops,
        [~EVFILT_WRITE]                 = &file_filtops,
@@ -353,7 +324,7 @@ SECURITY_READ_ONLY_EARLY(static struct filterops *) sysfilt_ops[EVFILTID_MAX] =
        [~EVFILT_MACHPORT]              = &machport_filtops,
        [~EVFILT_FS]                    = &fs_filtops,
        [~EVFILT_USER]                  = &user_filtops,
-                                         &bad_filtops,
+       [~EVFILT_UNUSED_11]             = &bad_filtops,
        [~EVFILT_VM]                    = &bad_filtops,
        [~EVFILT_SOCK]                  = &file_filtops,
 #if CONFIG_MEMORYSTATUS
@@ -366,6 +337,7 @@ SECURITY_READ_ONLY_EARLY(static struct filterops *) sysfilt_ops[EVFILTID_MAX] =
 
        /* Private filters */
        [EVFILTID_KQREAD]               = &kqread_filtops,
+       [EVFILTID_PIPE_N]               = &pipe_nfiltops,
        [EVFILTID_PIPE_R]               = &pipe_rfiltops,
        [EVFILTID_PIPE_W]               = &pipe_wfiltops,
        [EVFILTID_PTSD]                 = &ptsd_kqops,
@@ -380,40 +352,69 @@ SECURITY_READ_ONLY_EARLY(static struct filterops *) sysfilt_ops[EVFILTID_MAX] =
        [EVFILTID_VN]                   = &vnode_filtops,
        [EVFILTID_TTY]                  = &tty_filtops,
        [EVFILTID_PTMX]                 = &ptmx_kqops,
+
+       /* fake filter for detached knotes, keep last */
+       [EVFILTID_DETACHED]             = &bad_filtops,
 };
 
 /* waitq prepost callback */
-void waitq_set__CALLING_PREPOST_HOOK__(void *kq_hook, void *knote_hook, int qos);
+void waitq_set__CALLING_PREPOST_HOOK__(waitq_set_prepost_hook_t *kq_hook);
+
+static inline bool
+kqr_thread_bound(workq_threadreq_t kqr)
+{
+       return kqr->tr_state == WORKQ_TR_STATE_BOUND;
+}
+
+static inline bool
+kqr_thread_requested_pending(workq_threadreq_t kqr)
+{
+       workq_tr_state_t tr_state = kqr->tr_state;
+       return tr_state > WORKQ_TR_STATE_IDLE && tr_state < WORKQ_TR_STATE_BOUND;
+}
+
+static inline bool
+kqr_thread_requested(workq_threadreq_t kqr)
+{
+       return kqr->tr_state != WORKQ_TR_STATE_IDLE;
+}
+
+static inline thread_t
+kqr_thread_fast(workq_threadreq_t kqr)
+{
+       assert(kqr_thread_bound(kqr));
+       return kqr->tr_thread;
+}
+
+static inline thread_t
+kqr_thread(workq_threadreq_t kqr)
+{
+       return kqr_thread_bound(kqr) ? kqr->tr_thread : THREAD_NULL;
+}
 
 static inline struct kqworkloop *
-kqr_kqworkloop(struct kqrequest *kqr)
+kqr_kqworkloop(workq_threadreq_t kqr)
 {
-       if (kqr->kqr_state & KQR_WORKLOOP) {
+       if (kqr->tr_flags & WORKQ_TR_FLAG_WORKLOOP) {
                return __container_of(kqr, struct kqworkloop, kqwl_request);
        }
        return NULL;
 }
 
 static inline kqueue_t
-kqr_kqueue(proc_t p, struct kqrequest *kqr)
+kqr_kqueue(proc_t p, workq_threadreq_t kqr)
 {
        kqueue_t kqu;
-       if (kqr->kqr_state & KQR_WORKLOOP) {
+       if (kqr->tr_flags & WORKQ_TR_FLAG_WORKLOOP) {
                kqu.kqwl = kqr_kqworkloop(kqr);
        } else {
-               kqu.kqwq = (struct kqworkq *)p->p_fd->fd_wqkqueue;
+               kqu.kqwq = p->p_fd->fd_wqkqueue;
                assert(kqr >= kqu.kqwq->kqwq_request &&
-                               kqr < kqu.kqwq->kqwq_request + KQWQ_NBUCKETS);
+                   kqr < kqu.kqwq->kqwq_request + KQWQ_NBUCKETS);
        }
        return kqu;
 }
 
-static inline boolean_t
-is_workqueue_thread(thread_t thread)
-{
-       return (thread_get_tag(thread) & THREAD_TAG_WORKQUEUE);
-}
-
 /*
  * kqueue/note lock implementations
  *
@@ -455,36 +456,56 @@ kqunlock(kqueue_t kqu)
 }
 
 static inline void
-kq_req_lock(kqueue_t kqu)
+knhash_lock(struct filedesc *fdp)
 {
-       assert(kqu.kq->kq_state & (KQ_WORKLOOP | KQ_WORKQ));
-       lck_spin_lock(&kqu.kq->kq_reqlock);
+       lck_mtx_lock(&fdp->fd_knhashlock);
 }
 
 static inline void
-kq_req_unlock(kqueue_t kqu)
+knhash_unlock(struct filedesc *fdp)
 {
-       assert(kqu.kq->kq_state & (KQ_WORKLOOP | KQ_WORKQ));
-       lck_spin_unlock(&kqu.kq->kq_reqlock);
+       lck_mtx_unlock(&fdp->fd_knhashlock);
 }
 
-static inline void
-kq_req_held(__assert_only kqueue_t kqu)
+/* wait event for knote locks */
+static inline event_t
+knote_lock_wev(struct knote *kn)
 {
-       assert(kqu.kq->kq_state & (KQ_WORKLOOP | KQ_WORKQ));
-       LCK_SPIN_ASSERT(&kqu.kq->kq_reqlock, LCK_ASSERT_OWNED);
+       return (event_t)(&kn->kn_hook);
 }
 
-static inline void
-knhash_lock(proc_t p)
+/* wait event for kevent_register_wait_* */
+static inline event64_t
+knote_filt_wev64(struct knote *kn)
 {
-       lck_mtx_lock(&p->p_fd->fd_knhashlock);
+       /* kdp_workloop_sync_wait_find_owner knows about this */
+       return CAST_EVENT64_T(kn);
 }
 
-static inline void
-knhash_unlock(proc_t p)
+/* wait event for knote_post/knote_drop */
+static inline event64_t
+knote_post_wev64(struct knote *kn)
+{
+       return CAST_EVENT64_T(&kn->kn_kevent);
+}
+
+/*!
+ * @function knote_has_qos
+ *
+ * @brief
+ * Whether the knote has a regular QoS.
+ *
+ * @discussion
+ * kn_qos_override is:
+ * - 0 on kqfiles
+ * - THREAD_QOS_LAST for special buckets (stayactive, manager)
+ *
+ * Other values mean the knote participates to QoS propagation.
+ */
+static inline bool
+knote_has_qos(struct knote *kn)
 {
-       lck_mtx_unlock(&p->p_fd->fd_knhashlock);
+       return kn->kn_qos_override > 0 && kn->kn_qos_override < THREAD_QOS_LAST;
 }
 
 #pragma mark knote locks
@@ -495,37 +516,32 @@ knhash_unlock(proc_t p)
  * KNOTE_KQ_LOCK_ALWAYS
  *   The function will always return with the kq lock held.
  *
- * KNOTE_KQ_UNLOCK_ON_SUCCESS
+ * KNOTE_KQ_LOCK_ON_SUCCESS
  *   The function will return with the kq lock held if it was successful
  *   (knote_lock() is the only function that can fail).
  *
- * KNOTE_KQ_UNLOCK_ON_FAILURE
+ * KNOTE_KQ_LOCK_ON_FAILURE
  *   The function will return with the kq lock held if it was unsuccessful
  *   (knote_lock() is the only function that can fail).
  *
  * KNOTE_KQ_UNLOCK:
  *   The function returns with the kq unlocked.
  */
-#define KNOTE_KQ_LOCK_ALWAYS      0x0
-#define KNOTE_KQ_LOCK_ON_SUCCESS  0x1
-#define KNOTE_KQ_LOCK_ON_FAILURE  0x2
-#define KNOTE_KQ_UNLOCK           0x3
-
-#if DEBUG || DEVELOPMENT
-__attribute__((noinline, not_tail_called, disable_tail_calls))
-void knote_lock_ctx_chk(struct knote_lock_ctx *knlc)
-{
-       /* evil hackery to make sure no one forgets to unlock */
-       assert(knlc->knlc_state == KNOTE_LOCK_CTX_UNLOCKED);
-}
-#endif
+enum kqlocking {
+       KNOTE_KQ_LOCK_ALWAYS,
+       KNOTE_KQ_LOCK_ON_SUCCESS,
+       KNOTE_KQ_LOCK_ON_FAILURE,
+       KNOTE_KQ_UNLOCK,
+};
 
 static struct knote_lock_ctx *
-knote_lock_ctx_find(struct kqueue *kq, struct knote *kn)
+knote_lock_ctx_find(kqueue_t kqu, struct knote *kn)
 {
        struct knote_lock_ctx *ctx;
-       LIST_FOREACH(ctx, &kq->kq_knlocks, knlc_le) {
-               if (ctx->knlc_knote == kn) return ctx;
+       LIST_FOREACH(ctx, &kqu.kq->kq_knlocks, knlc_link) {
+               if (ctx->knlc_knote == kn) {
+                       return ctx;
+               }
        }
        panic("knote lock context not found: %p", kn);
        __builtin_trap();
@@ -534,42 +550,60 @@ knote_lock_ctx_find(struct kqueue *kq, struct knote *kn)
 /* slowpath of knote_lock() */
 __attribute__((noinline))
 static bool __result_use_check
-knote_lock_slow(struct kqueue *kq, struct knote *kn,
-               struct knote_lock_ctx *knlc, int kqlocking)
+knote_lock_slow(kqueue_t kqu, struct knote *kn,
+    struct knote_lock_ctx *knlc, int kqlocking)
 {
-       kqlock_held(kq);
+       struct knote_lock_ctx *owner_lc;
+       struct uthread *uth = current_uthread();
+       wait_result_t wr;
 
-       struct knote_lock_ctx *owner_lc = knote_lock_ctx_find(kq, kn);
-       thread_t owner_thread = owner_lc->knlc_thread;
+       kqlock_held(kqu);
 
+       owner_lc = knote_lock_ctx_find(kqu, kn);
 #if DEBUG || DEVELOPMENT
        knlc->knlc_state = KNOTE_LOCK_CTX_WAITING;
 #endif
+       owner_lc->knlc_waiters++;
 
-       thread_reference(owner_thread);
-       TAILQ_INSERT_TAIL(&owner_lc->knlc_head, knlc, knlc_tqe);
-       assert_wait(&kn->kn_status, THREAD_UNINT | THREAD_WAIT_NOREPORT);
-       kqunlock(kq);
+       /*
+        * Make our lock context visible to knote_unlock()
+        */
+       uth->uu_knlock = knlc;
 
-       if (thread_handoff_deallocate(owner_thread) == THREAD_RESTART) {
-               if (kqlocking == KNOTE_KQ_LOCK_ALWAYS ||
-                               kqlocking == KNOTE_KQ_LOCK_ON_FAILURE) {
-                       kqlock(kq);
-               }
+       wr = lck_spin_sleep_with_inheritor(&kqu.kq->kq_lock, LCK_SLEEP_UNLOCK,
+           knote_lock_wev(kn), owner_lc->knlc_thread,
+           THREAD_UNINT | THREAD_WAIT_NOREPORT, TIMEOUT_WAIT_FOREVER);
+
+       if (wr == THREAD_RESTART) {
+               /*
+                * We haven't been woken up by knote_unlock() but knote_unlock_cancel.
+                * We need to cleanup the state since no one did.
+                */
+               uth->uu_knlock = NULL;
 #if DEBUG || DEVELOPMENT
                assert(knlc->knlc_state == KNOTE_LOCK_CTX_WAITING);
                knlc->knlc_state = KNOTE_LOCK_CTX_UNLOCKED;
 #endif
+
+               if (kqlocking == KNOTE_KQ_LOCK_ALWAYS ||
+                   kqlocking == KNOTE_KQ_LOCK_ON_FAILURE) {
+                       kqlock(kqu);
+               }
                return false;
-       }
+       } else {
+               if (kqlocking == KNOTE_KQ_LOCK_ALWAYS ||
+                   kqlocking == KNOTE_KQ_LOCK_ON_SUCCESS) {
+                       kqlock(kqu);
 #if DEBUG || DEVELOPMENT
-               assert(knlc->knlc_state == KNOTE_LOCK_CTX_LOCKED);
+                       /*
+                        * This state is set under the lock so we can't
+                        * really assert this unless we hold the lock.
+                        */
+                       assert(knlc->knlc_state == KNOTE_LOCK_CTX_LOCKED);
 #endif
-       if (kqlocking == KNOTE_KQ_LOCK_ALWAYS ||
-                       kqlocking == KNOTE_KQ_LOCK_ON_SUCCESS) {
-               kqlock(kq);
+               }
+               return true;
        }
-       return true;
 }
 
 /*
@@ -580,20 +614,20 @@ knote_lock_slow(struct kqueue *kq, struct knote *kn,
  * Returns true if the knote lock is acquired, false if it has been dropped
  */
 static bool __result_use_check
-knote_lock(struct kqueue *kq, struct knote *kn, struct knote_lock_ctx *knlc,
-               int kqlocking)
+knote_lock(kqueue_t kqu, struct knote *kn, struct knote_lock_ctx *knlc,
+    enum kqlocking kqlocking)
 {
-       kqlock_held(kq);
+       kqlock_held(kqu);
 
 #if DEBUG || DEVELOPMENT
        assert(knlc->knlc_state == KNOTE_LOCK_CTX_UNLOCKED);
 #endif
        knlc->knlc_knote = kn;
        knlc->knlc_thread = current_thread();
-       TAILQ_INIT(&knlc->knlc_head);
+       knlc->knlc_waiters = 0;
 
        if (__improbable(kn->kn_status & KN_LOCKED)) {
-               return knote_lock_slow(kq, kn, knlc, kqlocking);
+               return knote_lock_slow(kqu, kn, knlc, kqlocking);
        }
 
        /*
@@ -602,15 +636,15 @@ knote_lock(struct kqueue *kq, struct knote *kn, struct knote_lock_ctx *knlc,
         * hash table that references it before the lock is canceled.
         */
        assert((kn->kn_status & KN_DROPPING) == 0);
-       LIST_INSERT_HEAD(&kq->kq_knlocks, knlc, knlc_le);
+       LIST_INSERT_HEAD(&kqu.kq->kq_knlocks, knlc, knlc_link);
        kn->kn_status |= KN_LOCKED;
 #if DEBUG || DEVELOPMENT
        knlc->knlc_state = KNOTE_LOCK_CTX_LOCKED;
 #endif
 
        if (kqlocking == KNOTE_KQ_UNLOCK ||
-                       kqlocking == KNOTE_KQ_LOCK_ON_FAILURE) {
-               kqunlock(kq);
+           kqlocking == KNOTE_KQ_LOCK_ON_FAILURE) {
+               kqunlock(kqu);
        }
        return true;
 }
@@ -620,13 +654,13 @@ knote_lock(struct kqueue *kq, struct knote *kn, struct knote_lock_ctx *knlc,
  *
  * Called with the kqueue lock held.
  *
- * Returns with the kqueue lock held according to KNOTE_KQ_* flags
+ * Returns with the kqueue lock held according to KNOTE_KQ_* mode.
  */
 static void
-knote_unlock(struct kqueue *kq, struct knote *kn,
-               struct knote_lock_ctx *knlc, int flags)
+knote_unlock(kqueue_t kqu, struct knote *kn,
+    struct knote_lock_ctx *knlc, enum kqlocking kqlocking)
 {
-       kqlock_held(kq);
+       kqlock_held(kqu);
 
        assert(knlc->knlc_knote == kn);
        assert(kn->kn_status & KN_LOCKED);
@@ -634,36 +668,45 @@ knote_unlock(struct kqueue *kq, struct knote *kn,
        assert(knlc->knlc_state == KNOTE_LOCK_CTX_LOCKED);
 #endif
 
-       struct knote_lock_ctx *next_owner_lc = TAILQ_FIRST(&knlc->knlc_head);
+       LIST_REMOVE(knlc, knlc_link);
 
-       LIST_REMOVE(knlc, knlc_le);
+       if (knlc->knlc_waiters) {
+               thread_t thread = THREAD_NULL;
 
-       if (next_owner_lc) {
-               assert(next_owner_lc->knlc_knote == kn);
-               TAILQ_REMOVE(&knlc->knlc_head, next_owner_lc, knlc_tqe);
+               wakeup_one_with_inheritor(knote_lock_wev(kn), THREAD_AWAKENED,
+                   LCK_WAKE_DEFAULT, &thread);
+
+               /*
+                * knote_lock_slow() publishes the lock context of waiters
+                * in uthread::uu_knlock.
+                *
+                * Reach out and make this context the new owner.
+                */
+               struct uthread *ut = get_bsdthread_info(thread);
+               struct knote_lock_ctx *next_owner_lc = ut->uu_knlock;
 
-               assert(TAILQ_EMPTY(&next_owner_lc->knlc_head));
-               TAILQ_CONCAT(&next_owner_lc->knlc_head, &knlc->knlc_head, knlc_tqe);
-               LIST_INSERT_HEAD(&kq->kq_knlocks, next_owner_lc, knlc_le);
+               assert(next_owner_lc->knlc_knote == kn);
+               next_owner_lc->knlc_waiters = knlc->knlc_waiters - 1;
+               LIST_INSERT_HEAD(&kqu.kq->kq_knlocks, next_owner_lc, knlc_link);
 #if DEBUG || DEVELOPMENT
                next_owner_lc->knlc_state = KNOTE_LOCK_CTX_LOCKED;
 #endif
+               ut->uu_knlock = NULL;
+               thread_deallocate_safe(thread);
        } else {
                kn->kn_status &= ~KN_LOCKED;
        }
-       if (kn->kn_inuse == 0) {
+
+       if ((kn->kn_status & KN_MERGE_QOS) && !(kn->kn_status & KN_POSTING)) {
                /*
                 * No f_event() in flight anymore, we can leave QoS "Merge" mode
                 *
-                * See knote_should_apply_qos_override()
+                * See knote_adjust_qos()
                 */
                kn->kn_status &= ~KN_MERGE_QOS;
        }
-       if (flags & KNOTE_KQ_UNLOCK) {
-               kqunlock(kq);
-       }
-       if (next_owner_lc) {
-               thread_wakeup_thread(&kn->kn_status, next_owner_lc->knlc_thread);
+       if (kqlocking == KNOTE_KQ_UNLOCK) {
+               kqunlock(kqu);
        }
 #if DEBUG || DEVELOPMENT
        knlc->knlc_state = KNOTE_LOCK_CTX_UNLOCKED;
@@ -675,11 +718,11 @@ knote_unlock(struct kqueue *kq, struct knote *kn,
  *
  * Called with the kqueue lock held.
  *
- * Returns with the kqueue lock held according to KNOTE_KQ_* flags
+ * Returns with the kqueue unlocked.
  */
 static void
 knote_unlock_cancel(struct kqueue *kq, struct knote *kn,
-               struct knote_lock_ctx *knlc, int kqlocking)
+    struct knote_lock_ctx *knlc)
 {
        kqlock_held(kq);
 
@@ -687,15 +730,12 @@ knote_unlock_cancel(struct kqueue *kq, struct knote *kn,
        assert(kn->kn_status & KN_LOCKED);
        assert(kn->kn_status & KN_DROPPING);
 
-       LIST_REMOVE(knlc, knlc_le);
+       LIST_REMOVE(knlc, knlc_link);
        kn->kn_status &= ~KN_LOCKED;
+       kqunlock(kq);
 
-       if (kqlocking == KNOTE_KQ_UNLOCK ||
-                       kqlocking == KNOTE_KQ_LOCK_ON_FAILURE) {
-               kqunlock(kq);
-       }
-       if (!TAILQ_EMPTY(&knlc->knlc_head)) {
-               thread_wakeup_with_result(&kn->kn_status, THREAD_RESTART);
+       if (knlc->knlc_waiters) {
+               wakeup_all_with_inheritor(knote_lock_wev(kn), THREAD_RESTART);
        }
 #if DEBUG || DEVELOPMENT
        knlc->knlc_state = KNOTE_LOCK_CTX_UNLOCKED;
@@ -708,16 +748,23 @@ knote_unlock_cancel(struct kqueue *kq, struct knote *kn,
  * Takes a use count to protect against concurrent drops.
  */
 static void
-knote_call_filter_event(struct kqueue *kq, struct knote *kn, long hint)
+knote_post(struct knote *kn, long hint)
 {
-       int result, dropping = 0;
+       struct kqueue *kq = knote_get_kq(kn);
+       int dropping, result;
 
-       kqlock_held(kq);
+       kqlock(kq);
 
-       if (kn->kn_status & (KN_DROPPING | KN_VANISHED))
-               return;
+       if (__improbable(kn->kn_status & (KN_DROPPING | KN_VANISHED))) {
+               return kqunlock(kq);
+       }
+
+       if (__improbable(kn->kn_status & KN_POSTING)) {
+               panic("KNOTE() called concurrently on knote %p", kn);
+       }
+
+       kn->kn_status |= KN_POSTING;
 
-       kn->kn_inuse++;
        kqunlock(kq);
        result = filter_call(knote_fops(kn), f_event(kn, hint));
        kqlock(kq);
@@ -725,27 +772,26 @@ knote_call_filter_event(struct kqueue *kq, struct knote *kn, long hint)
        dropping = (kn->kn_status & KN_DROPPING);
 
        if (!dropping && (result & FILTER_ACTIVE)) {
-               if (result & FILTER_ADJUST_EVENT_QOS_BIT)
-                       knote_adjust_qos(kq, kn, result);
-               knote_activate(kn);
+               knote_activate(kq, kn, result);
        }
 
-       if (--kn->kn_inuse == 0) {
-               if ((kn->kn_status & KN_LOCKED) == 0) {
-                       /*
-                        * We're the last f_event() call and there's no other f_* call in
-                        * flight, we can leave QoS "Merge" mode.
-                        *
-                        * See knote_should_apply_qos_override()
-                        */
-                       kn->kn_status &= ~KN_MERGE_QOS;
-               }
-               if (dropping) {
-                       waitq_wakeup64_all((struct waitq *)&kq->kq_wqs,
-                                       CAST_EVENT64_T(&kn->kn_inuse),
-                                       THREAD_AWAKENED, WAITQ_ALL_PRIORITIES);
-               }
+       if ((kn->kn_status & KN_LOCKED) == 0) {
+               /*
+                * There's no other f_* call in flight, we can leave QoS "Merge" mode.
+                *
+                * See knote_adjust_qos()
+                */
+               kn->kn_status &= ~(KN_POSTING | KN_MERGE_QOS);
+       } else {
+               kn->kn_status &= ~KN_POSTING;
+       }
+
+       if (__improbable(dropping)) {
+               waitq_wakeup64_all((struct waitq *)&kq->kq_wqs, knote_post_wev64(kn),
+                   THREAD_AWAKENED, WAITQ_ALL_PRIORITIES);
        }
+
+       kqunlock(kq);
 }
 
 /*
@@ -755,7 +801,7 @@ knote_call_filter_event(struct kqueue *kq, struct knote *kn, long hint)
  *     - kq unlocked at exit
  */
 static void
-knote_wait_for_filter_events(struct kqueue *kq, struct knote *kn)
+knote_wait_for_post(struct kqueue *kq, struct knote *kn)
 {
        wait_result_t wr = THREAD_NOT_WAITING;
 
@@ -763,10 +809,10 @@ knote_wait_for_filter_events(struct kqueue *kq, struct knote *kn)
 
        assert(kn->kn_status & KN_DROPPING);
 
-       if (kn->kn_inuse) {
+       if (kn->kn_status & KN_POSTING) {
                wr = waitq_assert_wait64((struct waitq *)&kq->kq_wqs,
-                               CAST_EVENT64_T(&kn->kn_inuse),
-                               THREAD_UNINT | THREAD_WAIT_NOREPORT, TIMEOUT_WAIT_FOREVER);
+                   knote_post_wev64(kn), THREAD_UNINT | THREAD_WAIT_NOREPORT,
+                   TIMEOUT_WAIT_FOREVER);
        }
        kqunlock(kq);
        if (wr == THREAD_WAITING) {
@@ -774,12 +820,107 @@ knote_wait_for_filter_events(struct kqueue *kq, struct knote *kn)
        }
 }
 
+#pragma mark knote helpers for filters
+
+OS_ALWAYS_INLINE
+void
+knote_set_error(struct knote *kn, int error)
+{
+       kn->kn_flags |= EV_ERROR;
+       kn->kn_sdata = error;
+}
+
+OS_ALWAYS_INLINE
+int64_t
+knote_low_watermark(const struct knote *kn)
+{
+       return (kn->kn_sfflags & NOTE_LOWAT) ? kn->kn_sdata : 1;
+}
+
+/*!
+ * @function knote_fill_kevent_with_sdata
+ *
+ * @brief
+ * Fills in a kevent from the current content of a knote.
+ *
+ * @discussion
+ * This is meant to be called from filter's f_event hooks.
+ * The kevent data is filled with kn->kn_sdata.
+ *
+ * kn->kn_fflags is cleared if kn->kn_flags has EV_CLEAR set.
+ *
+ * Using knote_fill_kevent is typically preferred.
+ */
+OS_ALWAYS_INLINE
+void
+knote_fill_kevent_with_sdata(struct knote *kn, struct kevent_qos_s *kev)
+{
+#define knote_assert_aliases(name1, offs1, name2) \
+       static_assert(offsetof(struct kevent_qos_s, name1) + offs1 == \
+           offsetof(struct kevent_internal_s, name2), \
+               "kevent_qos_s::" #name1 " and kevent_internal_s::" #name2 "need to alias")
+       /*
+        * All the code makes assumptions on these aliasing,
+        * so make sure we fail the build if we ever ever ever break them.
+        */
+       knote_assert_aliases(ident, 0, kei_ident);
+#ifdef __LITTLE_ENDIAN__
+       knote_assert_aliases(filter, 0, kei_filter);  // non trivial overlap
+       knote_assert_aliases(filter, 1, kei_filtid);  // non trivial overlap
+#else
+       knote_assert_aliases(filter, 0, kei_filtid);  // non trivial overlap
+       knote_assert_aliases(filter, 1, kei_filter);  // non trivial overlap
+#endif
+       knote_assert_aliases(flags, 0, kei_flags);
+       knote_assert_aliases(qos, 0, kei_qos);
+       knote_assert_aliases(udata, 0, kei_udata);
+       knote_assert_aliases(fflags, 0, kei_fflags);
+       knote_assert_aliases(xflags, 0, kei_sfflags); // non trivial overlap
+       knote_assert_aliases(data, 0, kei_sdata);     // non trivial overlap
+       knote_assert_aliases(ext, 0, kei_ext);
+#undef knote_assert_aliases
+
+       /*
+        * Fix the differences between kevent_qos_s and kevent_internal_s:
+        * - xflags is where kn_sfflags lives, we need to zero it
+        * - fixup the high bits of `filter` where kn_filtid lives
+        */
+       *kev = *(struct kevent_qos_s *)&kn->kn_kevent;
+       kev->xflags = 0;
+       kev->filter |= 0xff00;
+       if (kn->kn_flags & EV_CLEAR) {
+               kn->kn_fflags = 0;
+       }
+}
+
+/*!
+ * @function knote_fill_kevent
+ *
+ * @brief
+ * Fills in a kevent from the current content of a knote.
+ *
+ * @discussion
+ * This is meant to be called from filter's f_event hooks.
+ * The kevent data is filled with the passed in data.
+ *
+ * kn->kn_fflags is cleared if kn->kn_flags has EV_CLEAR set.
+ */
+OS_ALWAYS_INLINE
+void
+knote_fill_kevent(struct knote *kn, struct kevent_qos_s *kev, int64_t data)
+{
+       knote_fill_kevent_with_sdata(kn, kev);
+       kev->filter = kn->kn_filter;
+       kev->data = data;
+}
+
+
 #pragma mark file_filtops
 
 static int
-filt_fileattach(struct knote *kn, struct kevent_internal_s *kev)
+filt_fileattach(struct knote *kn, struct kevent_qos_s *kev)
 {
-       return fo_kqfilter(kn->kn_fp, kn, kev, vfs_context_current());
+       return fo_kqfilter(kn->kn_fp, kn, kev);
 }
 
 SECURITY_READ_ONLY_EARLY(static struct filterops) file_filtops = {
@@ -789,9 +930,10 @@ SECURITY_READ_ONLY_EARLY(static struct filterops) file_filtops = {
 
 #pragma mark kqread_filtops
 
-#define        f_flag f_fglob->fg_flag
-#define        f_ops f_fglob->fg_ops
-#define        f_data f_fglob->fg_data
+#define f_flag f_fglob->fg_flag
+#define f_ops f_fglob->fg_ops
+#define f_data f_fglob->fg_data
+#define f_lflags f_fglob->fg_lflags
 
 static void
 filt_kqdetach(struct knote *kn)
@@ -809,39 +951,33 @@ filt_kqueue(struct knote *kn, __unused long hint)
 {
        struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
 
-       return (kq->kq_count > 0);
+       return kq->kq_count > 0;
 }
 
 static int
-filt_kqtouch(struct knote *kn, struct kevent_internal_s *kev)
+filt_kqtouch(struct knote *kn, struct kevent_qos_s *kev)
 {
 #pragma unused(kev)
        struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
        int res;
 
        kqlock(kq);
-       kn->kn_data = kq->kq_count;
-       res = (kn->kn_data > 0);
-
+       res = (kq->kq_count > 0);
        kqunlock(kq);
 
        return res;
 }
 
 static int
-filt_kqprocess(struct knote *kn, struct filt_process_s *data, struct kevent_internal_s *kev)
+filt_kqprocess(struct knote *kn, struct kevent_qos_s *kev)
 {
-#pragma unused(data)
        struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
-       int res;
+       int res = 0;
 
        kqlock(kq);
-       kn->kn_data = kq->kq_count;
-       res = (kn->kn_data > 0);
-       if (res) {
-               *kev = kn->kn_kevent;
-               if (kn->kn_flags & EV_CLEAR)
-                       kn->kn_data = 0;
+       if (kq->kq_count) {
+               knote_fill_kevent(kn, kev, kq->kq_count);
+               res = 1;
        }
        kqunlock(kq);
 
@@ -859,7 +995,7 @@ SECURITY_READ_ONLY_EARLY(static struct filterops) kqread_filtops = {
 #pragma mark proc_filtops
 
 static int
-filt_procattach(struct knote *kn, __unused struct kevent_internal_s *kev)
+filt_procattach(struct knote *kn, __unused struct kevent_qos_s *kev)
 {
        struct proc *p;
 
@@ -876,27 +1012,30 @@ filt_procattach(struct knote *kn, __unused struct kevent_internal_s *kev)
                return 0;
        }
 
-       const int NoteExitStatusBits = NOTE_EXIT | NOTE_EXITSTATUS;
+       const uint32_t NoteExitStatusBits = NOTE_EXIT | NOTE_EXITSTATUS;
 
-       if ((kn->kn_sfflags & NoteExitStatusBits) == NoteExitStatusBits)
+       if ((kn->kn_sfflags & NoteExitStatusBits) == NoteExitStatusBits) {
                do {
                        pid_t selfpid = proc_selfpid();
 
-                       if (p->p_ppid == selfpid)
-                               break;  /* parent => ok */
-
+                       if (p->p_ppid == selfpid) {
+                               break;  /* parent => ok */
+                       }
                        if ((p->p_lflag & P_LTRACED) != 0 &&
-                           (p->p_oppid == selfpid))
-                               break;  /* parent-in-waiting => ok */
-
+                           (p->p_oppid == selfpid)) {
+                               break;  /* parent-in-waiting => ok */
+                       }
                        proc_rele(p);
                        knote_set_error(kn, EACCES);
                        return 0;
                } while (0);
+       }
 
-       proc_klist_lock();
+       kn->kn_proc = p;
+       kn->kn_flags |= EV_CLEAR;       /* automatically set */
+       kn->kn_sdata = 0;               /* incoming data is ignored */
 
-       kn->kn_ptr.p_proc = p;          /* store the proc handle */
+       proc_klist_lock();
 
        KNOTE_ATTACH(&p->p_klist, kn);
 
@@ -908,7 +1047,7 @@ filt_procattach(struct knote *kn, __unused struct kevent_internal_s *kev)
         * only captures edge-triggered events after this point
         * so it can't already be fired.
         */
-       return (0);
+       return 0;
 }
 
 
@@ -924,9 +1063,9 @@ filt_procdetach(struct knote *kn)
 
        proc_klist_lock();
 
-       p = kn->kn_ptr.p_proc;
+       p = kn->kn_proc;
        if (p != PROC_NULL) {
-               kn->kn_ptr.p_proc = PROC_NULL;
+               kn->kn_proc = PROC_NULL;
                KNOTE_DETACH(&p->p_klist, kn);
        }
 
@@ -934,7 +1073,7 @@ filt_procdetach(struct knote *kn)
 }
 
 static int
-filt_proc(struct knote *kn, long hint)
+filt_procevent(struct knote *kn, long hint)
 {
        u_int event;
 
@@ -943,7 +1082,7 @@ filt_proc(struct knote *kn, long hint)
        /*
         * Note: a lot of bits in hint may be obtained from the knote
         * To free some of those bits, see <rdar://problem/12592988> Freeing up
-        * bits in hint for filt_proc
+        * bits in hint for filt_procevent
         *
         * mask off extra data
         */
@@ -958,8 +1097,8 @@ filt_proc(struct knote *kn, long hint)
         * parent and these knotes re-fired.
         */
        if (event & NOTE_EXIT) {
-               if ((kn->kn_ptr.p_proc->p_oppid != 0)
-                   && (knote_get_kq(kn)->kq_p->p_pid != kn->kn_ptr.p_proc->p_ppid)) {
+               if ((kn->kn_proc->p_oppid != 0)
+                   && (knote_get_kq(kn)->kq_p->p_pid != kn->kn_proc->p_ppid)) {
                        /*
                         * This knote is not for the current ptrace(2) parent, ignore.
                         */
@@ -970,8 +1109,9 @@ filt_proc(struct knote *kn, long hint)
        /*
         * if the user is interested in this event, record it.
         */
-       if (kn->kn_sfflags & event)
+       if (kn->kn_sfflags & event) {
                kn->kn_fflags |= event;
+       }
 
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
@@ -983,62 +1123,62 @@ filt_proc(struct knote *kn, long hint)
 
        /*
         * The kernel has a wrapper in place that returns the same data
-        * as is collected here, in kn_data.  Any changes to how
+        * as is collected here, in kn_hook32.  Any changes to how
         * NOTE_EXITSTATUS and NOTE_EXIT_DETAIL are collected
         * should also be reflected in the proc_pidnoteexit() wrapper.
         */
        if (event == NOTE_EXIT) {
-               kn->kn_data = 0;
+               kn->kn_hook32 = 0;
                if ((kn->kn_sfflags & NOTE_EXITSTATUS) != 0) {
                        kn->kn_fflags |= NOTE_EXITSTATUS;
-                       kn->kn_data |= (hint & NOTE_PDATAMASK);
+                       kn->kn_hook32 |= (hint & NOTE_PDATAMASK);
                }
                if ((kn->kn_sfflags & NOTE_EXIT_DETAIL) != 0) {
                        kn->kn_fflags |= NOTE_EXIT_DETAIL;
-                       if ((kn->kn_ptr.p_proc->p_lflag &
-                            P_LTERM_DECRYPTFAIL) != 0) {
-                               kn->kn_data |= NOTE_EXIT_DECRYPTFAIL;
+                       if ((kn->kn_proc->p_lflag &
+                           P_LTERM_DECRYPTFAIL) != 0) {
+                               kn->kn_hook32 |= NOTE_EXIT_DECRYPTFAIL;
                        }
-                       if ((kn->kn_ptr.p_proc->p_lflag &
-                            P_LTERM_JETSAM) != 0) {
-                               kn->kn_data |= NOTE_EXIT_MEMORY;
-                               switch (kn->kn_ptr.p_proc->p_lflag & P_JETSAM_MASK) {
+                       if ((kn->kn_proc->p_lflag &
+                           P_LTERM_JETSAM) != 0) {
+                               kn->kn_hook32 |= NOTE_EXIT_MEMORY;
+                               switch (kn->kn_proc->p_lflag & P_JETSAM_MASK) {
                                case P_JETSAM_VMPAGESHORTAGE:
-                                       kn->kn_data |= NOTE_EXIT_MEMORY_VMPAGESHORTAGE;
+                                       kn->kn_hook32 |= NOTE_EXIT_MEMORY_VMPAGESHORTAGE;
                                        break;
                                case P_JETSAM_VMTHRASHING:
-                                       kn->kn_data |= NOTE_EXIT_MEMORY_VMTHRASHING;
+                                       kn->kn_hook32 |= NOTE_EXIT_MEMORY_VMTHRASHING;
                                        break;
                                case P_JETSAM_FCTHRASHING:
-                                       kn->kn_data |= NOTE_EXIT_MEMORY_FCTHRASHING;
+                                       kn->kn_hook32 |= NOTE_EXIT_MEMORY_FCTHRASHING;
                                        break;
                                case P_JETSAM_VNODE:
-                                       kn->kn_data |= NOTE_EXIT_MEMORY_VNODE;
+                                       kn->kn_hook32 |= NOTE_EXIT_MEMORY_VNODE;
                                        break;
                                case P_JETSAM_HIWAT:
-                                       kn->kn_data |= NOTE_EXIT_MEMORY_HIWAT;
+                                       kn->kn_hook32 |= NOTE_EXIT_MEMORY_HIWAT;
                                        break;
                                case P_JETSAM_PID:
-                                       kn->kn_data |= NOTE_EXIT_MEMORY_PID;
+                                       kn->kn_hook32 |= NOTE_EXIT_MEMORY_PID;
                                        break;
                                case P_JETSAM_IDLEEXIT:
-                                       kn->kn_data |= NOTE_EXIT_MEMORY_IDLE;
+                                       kn->kn_hook32 |= NOTE_EXIT_MEMORY_IDLE;
                                        break;
                                }
                        }
-                       if ((kn->kn_ptr.p_proc->p_csflags &
-                            CS_KILLED) != 0) {
-                               kn->kn_data |= NOTE_EXIT_CSERROR;
+                       if ((kn->kn_proc->p_csflags &
+                           CS_KILLED) != 0) {
+                               kn->kn_hook32 |= NOTE_EXIT_CSERROR;
                        }
                }
        }
 
        /* if we have any matching state, activate the knote */
-       return (kn->kn_fflags != 0);
+       return kn->kn_fflags != 0;
 }
 
 static int
-filt_proctouch(struct knote *kn, struct kevent_internal_s *kev)
+filt_proctouch(struct knote *kn, struct kevent_qos_s *kev)
 {
        int res;
 
@@ -1062,28 +1202,25 @@ filt_proctouch(struct knote *kn, struct kevent_internal_s *kev)
 }
 
 static int
-filt_procprocess(struct knote *kn, struct filt_process_s *data, struct kevent_internal_s *kev)
+filt_procprocess(struct knote *kn, struct kevent_qos_s *kev)
 {
-#pragma unused(data)
-       int res;
+       int res = 0;
 
        proc_klist_lock();
-       res = (kn->kn_fflags != 0);
-       if (res) {
-               *kev = kn->kn_kevent;
-               kn->kn_flags |= EV_CLEAR;       /* automatically set */
-               kn->kn_fflags = 0;
-               kn->kn_data = 0;
+       if (kn->kn_fflags) {
+               knote_fill_kevent(kn, kev, kn->kn_hook32);
+               kn->kn_hook32 = 0;
+               res = 1;
        }
        proc_klist_unlock();
        return res;
 }
 
 SECURITY_READ_ONLY_EARLY(static struct filterops) proc_filtops = {
-       .f_attach = filt_procattach,
-       .f_detach = filt_procdetach,
-       .f_event = filt_proc,
-       .f_touch = filt_proctouch,
+       .f_attach  = filt_procattach,
+       .f_detach  = filt_procdetach,
+       .f_event   = filt_procevent,
+       .f_touch   = filt_proctouch,
        .f_process = filt_procprocess,
 };
 
@@ -1091,7 +1228,7 @@ SECURITY_READ_ONLY_EARLY(static struct filterops) proc_filtops = {
 
 struct filt_timer_params {
        uint64_t deadline; /* deadline in abs/cont time
-                                                 (or 0 if NOTE_ABSOLUTE and deadline is in past) */
+                           *                      (or 0 if NOTE_ABSOLUTE and deadline is in past) */
        uint64_t leeway;   /* leeway in abstime, or 0 if none */
        uint64_t interval; /* interval in abstime or 0 if non-repeating timer */
 };
@@ -1099,12 +1236,12 @@ struct filt_timer_params {
 /*
  * Values stored in the knote at rest (using Mach absolute time units)
  *
- * kn->kn_hook          where the thread_call object is stored
+ * kn->kn_thcall        where the thread_call object is stored
  * kn->kn_ext[0]        next deadline or 0 if immediate expiration
  * kn->kn_ext[1]        leeway value
  * kn->kn_sdata         interval timer: the interval
  *                      absolute/deadline timer: 0
- * kn->kn_hookid        timer state
+ * kn->kn_hook32        timer state
  *
  * TIMER_IDLE:
  *   The timer has either never been scheduled or been cancelled.
@@ -1122,7 +1259,7 @@ struct filt_timer_params {
  *   dispatched.
  */
 #define TIMER_IDLE       0x0
-#define        TIMER_ARMED      0x1
+#define TIMER_ARMED      0x1
 #define TIMER_FIRED      0x2
 #define TIMER_IMMEDIATE  0x3
 
@@ -1154,8 +1291,8 @@ filt_timer_set_params(struct knote *kn, struct filt_timer_params *params)
  * Called with timer filter lock held.
  */
 static int
-filt_timervalidate(const struct kevent_internal_s *kev,
-               struct filt_timer_params *params)
+filt_timervalidate(const struct kevent_qos_s *kev,
+    struct filt_timer_params *params)
 {
        /*
         * There are 5 knobs that need to be chosen for a timer registration:
@@ -1192,7 +1329,7 @@ filt_timervalidate(const struct kevent_internal_s *kev,
 
        boolean_t use_abstime = FALSE;
 
-       switch (kev->fflags & (NOTE_SECONDS|NOTE_USECONDS|NOTE_NSECONDS|NOTE_MACHTIME)) {
+       switch (kev->fflags & (NOTE_SECONDS | NOTE_USECONDS | NOTE_NSECONDS | NOTE_MACHTIME)) {
        case NOTE_SECONDS:
                multiplier = NSEC_PER_SEC;
                break;
@@ -1210,7 +1347,7 @@ filt_timervalidate(const struct kevent_internal_s *kev,
                multiplier = NSEC_PER_SEC / 1000;
                break;
        default:
-               return (EINVAL);
+               return EINVAL;
        }
 
        /* transform the leeway in kn_ext[1] to same time scale */
@@ -1219,10 +1356,11 @@ filt_timervalidate(const struct kevent_internal_s *kev,
 
                if (use_abstime) {
                        leeway_abs = (uint64_t)kev->ext[1];
-               } else  {
+               } else {
                        uint64_t leeway_ns;
-                       if (os_mul_overflow((uint64_t)kev->ext[1], multiplier, &leeway_ns))
-                               return (ERANGE);
+                       if (os_mul_overflow((uint64_t)kev->ext[1], multiplier, &leeway_ns)) {
+                               return ERANGE;
+                       }
 
                        nanoseconds_to_absolutetime(leeway_ns, &leeway_abs);
                }
@@ -1240,8 +1378,9 @@ filt_timervalidate(const struct kevent_internal_s *kev,
                } else {
                        uint64_t calendar_deadline_ns;
 
-                       if (os_mul_overflow((uint64_t)kev->data, multiplier, &calendar_deadline_ns))
-                               return (ERANGE);
+                       if (os_mul_overflow((uint64_t)kev->data, multiplier, &calendar_deadline_ns)) {
+                               return ERANGE;
+                       }
 
                        /* calendar_deadline_ns is in nanoseconds since the epoch */
 
@@ -1274,12 +1413,13 @@ filt_timervalidate(const struct kevent_internal_s *kev,
                                 * it does not change the calendar timebase.
                                 */
 
-                               if (kev->fflags & NOTE_MACH_CONTINUOUS_TIME)
+                               if (kev->fflags & NOTE_MACH_CONTINUOUS_TIME) {
                                        clock_continuoustime_interval_to_deadline(interval_abs,
-                                                                                 &deadline_abs);
-                               else
+                                           &deadline_abs);
+                               } else {
                                        clock_absolutetime_interval_to_deadline(interval_abs,
-                                                                               &deadline_abs);
+                                           &deadline_abs);
+                               }
                        } else {
                                deadline_abs = 0; /* cause immediate expiration */
                        }
@@ -1310,24 +1450,26 @@ filt_timervalidate(const struct kevent_internal_s *kev,
                        interval_abs = (uint64_t)kev->data;
                } else {
                        uint64_t interval_ns;
-                       if (os_mul_overflow((uint64_t)kev->data, multiplier, &interval_ns))
-                               return (ERANGE);
+                       if (os_mul_overflow((uint64_t)kev->data, multiplier, &interval_ns)) {
+                               return ERANGE;
+                       }
 
                        nanoseconds_to_absolutetime(interval_ns, &interval_abs);
                }
 
                uint64_t deadline = 0;
 
-               if (kev->fflags & NOTE_MACH_CONTINUOUS_TIME)
+               if (kev->fflags & NOTE_MACH_CONTINUOUS_TIME) {
                        clock_continuoustime_interval_to_deadline(interval_abs, &deadline);
-               else
+               } else {
                        clock_absolutetime_interval_to_deadline(interval_abs, &deadline);
+               }
 
                params->deadline = deadline;
                params->interval = interval_abs;
        }
 
-       return (0);
+       return 0;
 }
 
 /*
@@ -1339,13 +1481,13 @@ filt_timerexpire(void *knx, __unused void *spare)
        struct knote *kn = knx;
        int v;
 
-       if (os_atomic_cmpxchgv(&kn->kn_hookid, TIMER_ARMED, TIMER_FIRED,
-                       &v, relaxed)) {
+       if (os_atomic_cmpxchgv(&kn->kn_hook32, TIMER_ARMED, TIMER_FIRED,
+           &v, relaxed)) {
                // our f_event always would say FILTER_ACTIVE,
                // so be leaner and just do it.
                struct kqueue *kq = knote_get_kq(kn);
                kqlock(kq);
-               knote_activate(kn);
+               knote_activate(kq, kn, FILTER_ACTIVE);
                kqunlock(kq);
        } else {
                /*
@@ -1362,9 +1504,9 @@ filt_timerexpire(void *knx, __unused void *spare)
 static void
 filt_timercancel(struct knote *kn)
 {
-       if (os_atomic_xchg(&kn->kn_hookid, TIMER_IDLE, relaxed) == TIMER_ARMED) {
+       if (os_atomic_xchg(&kn->kn_hook32, TIMER_IDLE, relaxed) == TIMER_ARMED) {
                /* cancel the thread call and wait for any filt_timerexpire in flight */
-               thread_call_cancel_wait((thread_call_t)kn->kn_hook);
+               thread_call_cancel_wait(kn->kn_thcall);
        }
 }
 
@@ -1403,31 +1545,34 @@ filt_timerarm(struct knote *kn)
        int filter_flags = kn->kn_sfflags;
        unsigned int timer_flags = 0;
 
-       assert(os_atomic_load(&kn->kn_hookid, relaxed) == TIMER_IDLE);
+       assert(os_atomic_load(&kn->kn_hook32, relaxed) == TIMER_IDLE);
 
-       if (filter_flags & NOTE_CRITICAL)
+       if (filter_flags & NOTE_CRITICAL) {
                timer_flags |= THREAD_CALL_DELAY_USER_CRITICAL;
-       else if (filter_flags & NOTE_BACKGROUND)
+       } else if (filter_flags & NOTE_BACKGROUND) {
                timer_flags |= THREAD_CALL_DELAY_USER_BACKGROUND;
-       else
+       } else {
                timer_flags |= THREAD_CALL_DELAY_USER_NORMAL;
+       }
 
-       if (filter_flags & NOTE_LEEWAY)
+       if (filter_flags & NOTE_LEEWAY) {
                timer_flags |= THREAD_CALL_DELAY_LEEWAY;
+       }
 
-       if (filter_flags & NOTE_MACH_CONTINUOUS_TIME)
+       if (filter_flags & NOTE_MACH_CONTINUOUS_TIME) {
                timer_flags |= THREAD_CALL_CONTINUOUS;
+       }
 
-       os_atomic_store(&kn->kn_hookid, TIMER_ARMED, relaxed);
-       thread_call_enter_delayed_with_leeway((thread_call_t)kn->kn_hook, NULL,
-                       deadline, leeway, timer_flags);
+       os_atomic_store(&kn->kn_hook32, TIMER_ARMED, relaxed);
+       thread_call_enter_delayed_with_leeway(kn->kn_thcall, NULL,
+           deadline, leeway, timer_flags);
 }
 
 /*
  * Allocate a thread call for the knote's lifetime, and kick off the timer.
  */
 static int
-filt_timerattach(struct knote *kn, struct kevent_internal_s *kev)
+filt_timerattach(struct knote *kn, struct kevent_qos_s *kev)
 {
        thread_call_t callout;
        struct filt_timer_params params;
@@ -1439,8 +1584,8 @@ filt_timerattach(struct knote *kn, struct kevent_internal_s *kev)
        }
 
        callout = thread_call_allocate_with_options(filt_timerexpire,
-                       (thread_call_param_t)kn, THREAD_CALL_PRIORITY_HIGH,
-                       THREAD_CALL_OPTIONS_ONCE);
+           (thread_call_param_t)kn, THREAD_CALL_PRIORITY_HIGH,
+           THREAD_CALL_OPTIONS_ONCE);
 
        if (NULL == callout) {
                knote_set_error(kn, ENOMEM);
@@ -1448,16 +1593,17 @@ filt_timerattach(struct knote *kn, struct kevent_internal_s *kev)
        }
 
        filt_timer_set_params(kn, &params);
-       kn->kn_hook = callout;
+       kn->kn_thcall = callout;
        kn->kn_flags |= EV_CLEAR;
-       os_atomic_store(&kn->kn_hookid, TIMER_IDLE, relaxed);
+       os_atomic_store(&kn->kn_hook32, TIMER_IDLE, relaxed);
 
        /* NOTE_ABSOLUTE implies EV_ONESHOT */
-       if (kn->kn_sfflags & NOTE_ABSOLUTE)
+       if (kn->kn_sfflags & NOTE_ABSOLUTE) {
                kn->kn_flags |= EV_ONESHOT;
+       }
 
        if (filt_timer_is_ready(kn)) {
-               os_atomic_store(&kn->kn_hookid, TIMER_IMMEDIATE, relaxed);
+               os_atomic_store(&kn->kn_hook32, TIMER_IMMEDIATE, relaxed);
                return FILTER_ACTIVE;
        } else {
                filt_timerarm(kn);
@@ -1477,8 +1623,8 @@ filt_timerdetach(struct knote *kn)
         * Unconditionally cancel to make sure there can't be any filt_timerexpire()
         * running anymore.
         */
-       thread_call_cancel_wait((thread_call_t)kn->kn_hook);
-       freed = thread_call_free((thread_call_t)kn->kn_hook);
+       thread_call_cancel_wait(kn->kn_thcall);
+       freed = thread_call_free(kn->kn_thcall);
        assert(freed);
 }
 
@@ -1490,7 +1636,7 @@ filt_timerdetach(struct knote *kn)
  * pops have gone off (in kn_data).
  */
 static int
-filt_timertouch(struct knote *kn, struct kevent_internal_s *kev)
+filt_timertouch(struct knote *kn, struct kevent_qos_s *kev)
 {
        struct filt_timer_params params;
        uint32_t changed_flags = (kn->kn_sfflags ^ kev->fflags);
@@ -1514,7 +1660,7 @@ filt_timertouch(struct knote *kn, struct kevent_internal_s *kev)
        kn->kn_sfflags = kev->fflags;
 
        if (filt_timer_is_ready(kn)) {
-               os_atomic_store(&kn->kn_hookid, TIMER_IMMEDIATE, relaxed);
+               os_atomic_store(&kn->kn_hook32, TIMER_IMMEDIATE, relaxed);
                return FILTER_ACTIVE | FILTER_UPDATE_REQ_QOS;
        } else {
                filt_timerarm(kn);
@@ -1530,10 +1676,7 @@ filt_timertouch(struct knote *kn, struct kevent_internal_s *kev)
  * counters for the next time.
  */
 static int
-filt_timerprocess(
-       struct knote *kn,
-       __unused struct filt_process_s *data,
-       struct kevent_internal_s *kev)
+filt_timerprocess(struct knote *kn, struct kevent_qos_s *kev)
 {
        /*
         * filt_timerprocess is serialized with any filter routine except for
@@ -1544,7 +1687,7 @@ filt_timerprocess(
         * whether we see any of the "FIRED" state, and if we do, it is safe to
         * do simple state machine transitions.
         */
-       switch (os_atomic_load(&kn->kn_hookid, relaxed)) {
+       switch (os_atomic_load(&kn->kn_hook32, relaxed)) {
        case TIMER_IDLE:
        case TIMER_ARMED:
                /*
@@ -1554,7 +1697,7 @@ filt_timerprocess(
                return 0;
        }
 
-       os_atomic_store(&kn->kn_hookid, TIMER_IDLE, relaxed);
+       os_atomic_store(&kn->kn_hook32, TIMER_IDLE, relaxed);
 
        /*
         * Copy out the interesting kevent state,
@@ -1565,13 +1708,11 @@ filt_timerprocess(
         *      - return kn_sfflags in the fflags field so the client can know
         *        under what flags the timer fired
         */
-       *kev = kn->kn_kevent;
+       knote_fill_kevent(kn, kev, 1);
        kev->ext[0] = 0;
        /* kev->ext[1] = 0;  JMM - shouldn't we hide this too? */
 
-       if (kn->kn_sdata == 0) {
-               kev->data = 1;
-       } else {
+       if (kn->kn_sdata != 0) {
                /*
                 * This is a 'repeating' timer, so we have to emit
                 * how many intervals expired between the arm
@@ -1583,10 +1724,11 @@ filt_timerprocess(
 
                uint64_t now;
 
-               if (kn->kn_sfflags & NOTE_MACH_CONTINUOUS_TIME)
+               if (kn->kn_sfflags & NOTE_MACH_CONTINUOUS_TIME) {
                        now = mach_continuous_time();
-               else
+               } else {
                        now = mach_absolute_time();
+               }
 
                uint64_t first_deadline = kn->kn_ext[0];
                uint64_t interval_abs   = kn->kn_sdata;
@@ -1634,7 +1776,7 @@ SECURITY_READ_ONLY_EARLY(static struct filterops) timer_filtops = {
        .f_extended_codes = true,
        .f_attach   = filt_timerattach,
        .f_detach   = filt_timerdetach,
-       .f_event    = filt_badevent,
+       .f_event    = filt_bad_event,
        .f_touch    = filt_timertouch,
        .f_process  = filt_timerprocess,
 };
@@ -1642,24 +1784,18 @@ SECURITY_READ_ONLY_EARLY(static struct filterops) timer_filtops = {
 #pragma mark user_filtops
 
 static int
-filt_userattach(struct knote *kn, __unused struct kevent_internal_s *kev)
+filt_userattach(struct knote *kn, __unused struct kevent_qos_s *kev)
 {
        if (kn->kn_sfflags & NOTE_TRIGGER) {
-               kn->kn_hookid = FILTER_ACTIVE;
+               kn->kn_hook32 = FILTER_ACTIVE;
        } else {
-               kn->kn_hookid = 0;
+               kn->kn_hook32 = 0;
        }
-       return (kn->kn_hookid);
-}
-
-static void
-filt_userdetach(__unused struct knote *kn)
-{
-       /* EVFILT_USER knotes are not attached to anything in the kernel */
+       return kn->kn_hook32;
 }
 
 static int
-filt_usertouch(struct knote *kn, struct kevent_internal_s *kev)
+filt_usertouch(struct knote *kn, struct kevent_qos_s *kev)
 {
        uint32_t ffctrl;
        int fflags;
@@ -1682,27 +1818,23 @@ filt_usertouch(struct knote *kn, struct kevent_internal_s *kev)
        kn->kn_sdata = kev->data;
 
        if (kev->fflags & NOTE_TRIGGER) {
-               kn->kn_hookid = FILTER_ACTIVE;
+               kn->kn_hook32 = FILTER_ACTIVE;
        }
-       return (int)kn->kn_hookid;
+       return (int)kn->kn_hook32;
 }
 
 static int
-filt_userprocess(
-       struct knote *kn,
-       __unused struct filt_process_s *data,
-       struct kevent_internal_s *kev)
+filt_userprocess(struct knote *kn, struct kevent_qos_s *kev)
 {
-       int result = (int)kn->kn_hookid;
+       int result = (int)kn->kn_hook32;
 
        if (result) {
-               *kev = kn->kn_kevent;
+               /* EVFILT_USER returns the data that was passed in */
+               knote_fill_kevent_with_sdata(kn, kev);
                kev->fflags = kn->kn_sfflags;
-               kev->data = kn->kn_sdata;
                if (kn->kn_flags & EV_CLEAR) {
-                       kn->kn_hookid = 0;
-                       kn->kn_data = 0;
-                       kn->kn_fflags = 0;
+                       /* knote_fill_kevent cleared kn_fflags */
+                       kn->kn_hook32 = 0;
                }
        }
 
@@ -1712,24 +1844,26 @@ filt_userprocess(
 SECURITY_READ_ONLY_EARLY(static struct filterops) user_filtops = {
        .f_extended_codes = true,
        .f_attach  = filt_userattach,
-       .f_detach  = filt_userdetach,
-       .f_event   = filt_badevent,
+       .f_detach  = filt_no_detach,
+       .f_event   = filt_bad_event,
        .f_touch   = filt_usertouch,
        .f_process = filt_userprocess,
 };
 
 #pragma mark workloop_filtops
 
+#define EPREEMPTDISABLED (-1)
+
 static inline void
 filt_wllock(struct kqworkloop *kqwl)
 {
-       lck_mtx_lock(&kqwl->kqwl_statelock);
+       lck_spin_lock(&kqwl->kqwl_statelock);
 }
 
 static inline void
 filt_wlunlock(struct kqworkloop *kqwl)
 {
-       lck_mtx_unlock(&kqwl->kqwl_statelock);
+       lck_spin_unlock(&kqwl->kqwl_statelock);
 }
 
 /*
@@ -1746,17 +1880,15 @@ filt_wlunlock(struct kqworkloop *kqwl)
 static inline bool
 filt_wlturnstile_interlock_is_workq(struct kqworkloop *kqwl)
 {
-       struct kqrequest *kqr = &kqwl->kqwl_request;
-       return (kqr->kqr_state & KQR_THREQUESTED) &&
-                       (kqr->kqr_thread == THREAD_NULL);
+       return kqr_thread_requested_pending(&kqwl->kqwl_request);
 }
 
 static void
 filt_wlupdate_inheritor(struct kqworkloop *kqwl, struct turnstile *ts,
-               turnstile_update_flags_t flags)
+    turnstile_update_flags_t flags)
 {
        turnstile_inheritor_t inheritor = TURNSTILE_INHERITOR_NULL;
-       struct kqrequest *kqr = &kqwl->kqwl_request;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
 
        /*
         * binding to the workq should always happen through
@@ -1766,13 +1898,14 @@ filt_wlupdate_inheritor(struct kqworkloop *kqwl, struct turnstile *ts,
 
        if ((inheritor = kqwl->kqwl_owner)) {
                flags |= TURNSTILE_INHERITOR_THREAD;
-       } else if ((inheritor = kqr->kqr_thread)) {
+       } else if ((inheritor = kqr_thread(kqr))) {
                flags |= TURNSTILE_INHERITOR_THREAD;
        }
 
        turnstile_update_inheritor(ts, inheritor, flags);
 }
 
+#define EVFILT_WORKLOOP_EFAULT_RETRY_COUNT 100
 #define FILT_WLATTACH 0
 #define FILT_WLTOUCH  1
 #define FILT_WLDROP   2
@@ -1780,43 +1913,24 @@ filt_wlupdate_inheritor(struct kqworkloop *kqwl, struct turnstile *ts,
 __result_use_check
 static int
 filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
-               struct kevent_internal_s *kev, kq_index_t qos_index, int op)
+    struct kevent_qos_s *kev, kq_index_t qos_index, int op)
 {
        user_addr_t uaddr = CAST_USER_ADDR_T(kev->ext[EV_EXTIDX_WL_ADDR]);
-       struct kqrequest *kqr = &kqwl->kqwl_request;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
        thread_t cur_owner, new_owner, extra_thread_ref = THREAD_NULL;
-       kq_index_t cur_owner_override = THREAD_QOS_UNSPECIFIED;
+       kq_index_t cur_override = THREAD_QOS_UNSPECIFIED;
+       int efault_retry = EVFILT_WORKLOOP_EFAULT_RETRY_COUNT;
        int action = KQWL_UTQ_NONE, error = 0;
-       bool needs_wake = false, needs_wllock = false;
+       bool wl_inheritor_updated = false, needs_wake = false;
        uint64_t kdata = kev->ext[EV_EXTIDX_WL_VALUE];
        uint64_t mask = kev->ext[EV_EXTIDX_WL_MASK];
        uint64_t udata = 0;
+       struct turnstile *ts = TURNSTILE_NULL;
 
-       if (kev->fflags & (NOTE_WL_END_OWNERSHIP | NOTE_WL_DISCOVER_OWNER)) {
-               /*
-                * If we're maybe going to change the kqwl_owner,
-                * then we need to hold the filt_wllock().
-                */
-               needs_wllock = true;
-       } else if (kqr->kqr_thread == current_thread()) {
-               /*
-                * <rdar://problem/41531764> Servicer updates need to be serialized with
-                * any ownership change too, as the kqr_thread value influences the
-                * outcome of handling NOTE_WL_DISCOVER_OWNER.
-                */
-               needs_wllock = true;
-       }
+       filt_wllock(kqwl);
 
-       if (needs_wllock) {
-               filt_wllock(kqwl);
-               /*
-                * The kqwl owner is set under both the req and filter lock,
-                * meaning it's fine to look at it under any.
-                */
-               new_owner = cur_owner = kqwl->kqwl_owner;
-       } else {
-               new_owner = cur_owner = THREAD_NULL;
-       }
+again:
+       new_owner = cur_owner = kqwl->kqwl_owner;
 
        /*
         * Phase 1:
@@ -1833,8 +1947,33 @@ filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
         * Lastly decide whether we need to perform a QoS update.
         */
        if (uaddr) {
-               error = copyin_word(uaddr, &udata, sizeof(udata));
-               if (error) {
+               /*
+                * Until <rdar://problem/24999882> exists,
+                * disabling preemption copyin forces any
+                * vm_fault we encounter to fail.
+                */
+               error = copyin_atomic64(uaddr, &udata);
+
+               /*
+                * If we get EFAULT, drop locks, and retry.
+                * If we still get an error report it,
+                * else assume the memory has been faulted
+                * and attempt to copyin under lock again.
+                */
+               switch (error) {
+               case 0:
+                       break;
+               case EFAULT:
+                       if (efault_retry-- > 0) {
+                               filt_wlunlock(kqwl);
+                               error = copyin_atomic64(uaddr, &udata);
+                               filt_wllock(kqwl);
+                               if (error == 0) {
+                                       goto again;
+                               }
+                       }
+               /* FALLTHROUGH */
+               default:
                        goto out;
                }
 
@@ -1853,7 +1992,8 @@ filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
                        mach_port_name_t name = (mach_port_name_t)udata & ~0x3;
                        if (name != MACH_PORT_NULL) {
                                name = ipc_entry_name_mask(name);
-                               extra_thread_ref = port_name_to_thread(name);
+                               extra_thread_ref = port_name_to_thread(name,
+                                   PORT_TO_THREAD_IN_CURRENT_TASK);
                                if (extra_thread_ref == THREAD_NULL) {
                                        error = EOWNERDEAD;
                                        goto out;
@@ -1870,7 +2010,7 @@ filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
        if (error == 0) {
                if ((kev->fflags & NOTE_WL_THREAD_REQUEST) && (kev->flags & EV_DELETE)) {
                        action = KQWL_UTQ_SET_QOS_INDEX;
-               } else if (qos_index && kqr->kqr_qos_index != qos_index) {
+               } else if (qos_index && kqr->tr_kq_qos_index != qos_index) {
                        action = KQWL_UTQ_SET_QOS_INDEX;
                }
 
@@ -1882,19 +2022,18 @@ filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
                         */
                        kn->kn_sfflags &= ~NOTE_WL_UPDATES_MASK;
                        kn->kn_sfflags |= kev->fflags;
-                       kn->kn_sdata = kev->data;
                        if (kev->fflags & NOTE_WL_SYNC_WAKE) {
-                               needs_wake = (kn->kn_hook != THREAD_NULL);
+                               needs_wake = (kn->kn_thread != THREAD_NULL);
                        }
                } else if (op == FILT_WLDROP) {
                        if ((kn->kn_sfflags & (NOTE_WL_SYNC_WAIT | NOTE_WL_SYNC_WAKE)) ==
-                                       NOTE_WL_SYNC_WAIT) {
+                           NOTE_WL_SYNC_WAIT) {
                                /*
                                 * When deleting a SYNC_WAIT knote that hasn't been woken up
                                 * explicitly, issue a wake up.
                                 */
                                kn->kn_sfflags |= NOTE_WL_SYNC_WAKE;
-                               needs_wake = (kn->kn_hook != THREAD_NULL);
+                               needs_wake = (kn->kn_thread != THREAD_NULL);
                        }
                }
        }
@@ -1909,10 +2048,10 @@ filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
                goto out;
        }
 
-       kq_req_lock(kqwl);
+       kqlock(kqwl);
 
        /* If already tracked as servicer, don't track as owner */
-       if (new_owner == kqr->kqr_thread) {
+       if (new_owner == kqr_thread(kqr)) {
                new_owner = THREAD_NULL;
        }
 
@@ -1922,25 +2061,20 @@ filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
                        /* we just transfered this ref to kqwl_owner */
                        extra_thread_ref = THREAD_NULL;
                }
-               cur_owner_override = kqworkloop_owner_override(kqwl);
-
-               if (cur_owner) {
-                       thread_ends_owning_workloop(cur_owner);
-               }
+               cur_override = kqworkloop_override(kqwl);
 
                if (new_owner) {
                        /* override it before we drop the old */
-                       if (cur_owner_override != THREAD_QOS_UNSPECIFIED) {
-                               thread_add_ipc_override(new_owner, cur_owner_override);
+                       if (cur_override != THREAD_QOS_UNSPECIFIED) {
+                               thread_add_kevent_override(new_owner, cur_override);
                        }
-                       thread_starts_owning_workloop(new_owner);
-                       if ((kqr->kqr_state & KQR_THREQUESTED) && !kqr->kqr_thread) {
+                       if (kqr_thread_requested_pending(kqr)) {
                                if (action == KQWL_UTQ_NONE) {
                                        action = KQWL_UTQ_REDRIVE_EVENTS;
                                }
                        }
                } else {
-                       if ((kqr->kqr_state & (KQR_THREQUESTED | KQR_WAKEUP)) == KQR_WAKEUP) {
+                       if (!kqr_thread_requested(kqr) && kqr->tr_kq_wakeup) {
                                if (action == KQWL_UTQ_NONE) {
                                        action = KQWL_UTQ_REDRIVE_EVENTS;
                                }
@@ -1948,13 +2082,11 @@ filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
                }
        }
 
-       struct turnstile *ts = kqwl->kqwl_turnstile;
-       bool wl_inheritor_updated = false;
-
        if (action != KQWL_UTQ_NONE) {
                kqworkloop_update_threads_qos(kqwl, action, qos_index);
        }
 
+       ts = kqwl->kqwl_turnstile;
        if (cur_owner != new_owner && ts) {
                if (action == KQWL_UTQ_REDRIVE_EVENTS) {
                        /*
@@ -1966,7 +2098,7 @@ filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
                } else if (filt_wlturnstile_interlock_is_workq(kqwl)) {
                        workq_kern_threadreq_lock(kqwl->kqwl_p);
                        workq_kern_threadreq_update_inheritor(kqwl->kqwl_p, kqr, new_owner,
-                                       ts, TURNSTILE_IMMEDIATE_UPDATE);
+                           ts, TURNSTILE_IMMEDIATE_UPDATE);
                        workq_kern_threadreq_unlock(kqwl->kqwl_p);
                        if (!filt_wlturnstile_interlock_is_workq(kqwl)) {
                                /*
@@ -1992,16 +2124,15 @@ filt_wlupdate(struct kqworkloop *kqwl, struct knote *kn,
        }
 
        if (needs_wake && ts) {
-               waitq_wakeup64_thread(&ts->ts_waitq, CAST_EVENT64_T((event_t)kn),
-                               (thread_t)kn->kn_hook, THREAD_AWAKENED);
+               waitq_wakeup64_thread(&ts->ts_waitq, knote_filt_wev64(kn),
+                   kn->kn_thread, THREAD_AWAKENED);
+               if (op == FILT_WLATTACH || op == FILT_WLTOUCH) {
+                       disable_preemption();
+                       error = EPREEMPTDISABLED;
+               }
        }
 
-       kq_req_unlock(kqwl);
-
-       if (wl_inheritor_updated) {
-               turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
-               turnstile_deallocate(ts);
-       }
+       kqunlock(kqwl);
 
 out:
        /*
@@ -2009,14 +2140,12 @@ out:
         *
         * Unlock and cleanup various lingering references and things.
         */
-       if (needs_wllock) {
-               filt_wlunlock(kqwl);
-       }
+       filt_wlunlock(kqwl);
 
 #if CONFIG_WORKLOOP_DEBUG
        KQWL_HISTORY_WRITE_ENTRY(kqwl, {
                .updater = current_thread(),
-               .servicer = kqr->kqr_thread, /* Note: racy */
+               .servicer = kqr_thread(kqr), /* Note: racy */
                .old_owner = cur_owner,
                .new_owner = new_owner,
 
@@ -2031,15 +2160,19 @@ out:
        });
 #endif // CONFIG_WORKLOOP_DEBUG
 
+       if (wl_inheritor_updated) {
+               turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
+               turnstile_deallocate_safe(ts);
+       }
+
        if (cur_owner && new_owner != cur_owner) {
-               if (cur_owner_override != THREAD_QOS_UNSPECIFIED) {
-                       thread_drop_ipc_override(cur_owner);
+               if (cur_override != THREAD_QOS_UNSPECIFIED) {
+                       thread_drop_kevent_override(cur_owner);
                }
-               thread_deallocate(cur_owner);
+               thread_deallocate_safe(cur_owner);
        }
-
        if (extra_thread_ref) {
-               thread_deallocate(extra_thread_ref);
+               thread_deallocate_safe(extra_thread_ref);
        }
        return error;
 }
@@ -2052,62 +2185,117 @@ out:
  * - data is set to the error if any
  */
 static inline void
-filt_wlremember_last_update(struct knote *kn, struct kevent_internal_s *kev,
-               int error)
+filt_wlremember_last_update(struct knote *kn, struct kevent_qos_s *kev,
+    int error)
 {
        kn->kn_fflags = kev->fflags;
-       kn->kn_data = error;
+       kn->kn_sdata = error;
        memcpy(kn->kn_ext, kev->ext, sizeof(kev->ext));
 }
 
 static int
-filt_wlattach(struct knote *kn, struct kevent_internal_s *kev)
+filt_wlupdate_sync_ipc(struct kqworkloop *kqwl, struct knote *kn,
+    struct kevent_qos_s *kev, int op)
 {
-       struct kqueue *kq = knote_get_kq(kn);
-       struct kqworkloop *kqwl = (struct kqworkloop *)kq;
+       uint64_t uaddr = kev->ext[EV_EXTIDX_WL_ADDR];
+       uint64_t kdata = kev->ext[EV_EXTIDX_WL_VALUE];
+       uint64_t mask  = kev->ext[EV_EXTIDX_WL_MASK];
+       uint64_t udata = 0;
+       int efault_retry = EVFILT_WORKLOOP_EFAULT_RETRY_COUNT;
        int error = 0;
-       kq_index_t qos_index = 0;
 
-       if ((kq->kq_state & KQ_WORKLOOP) == 0) {
-               error = ENOTSUP;
-               goto out;
+       if (op == FILT_WLATTACH) {
+               (void)kqueue_alloc_turnstile(&kqwl->kqwl_kqueue);
+       } else if (uaddr == 0) {
+               return 0;
        }
 
-#if DEVELOPMENT || DEBUG
-       if (kev->ident == 0 && kev->udata == 0 && kev->fflags == 0) {
-               struct kqrequest *kqr = &kqwl->kqwl_request;
-
-               kq_req_lock(kqwl);
-               kev->fflags = 0;
-               if (kqr->kqr_dsync_waiters) {
-                       kev->fflags |= NOTE_WL_SYNC_WAIT;
-               }
-               if (kqr->kqr_qos_index) {
-                       kev->fflags |= NOTE_WL_THREAD_REQUEST;
-               }
-               kev->ext[0] = thread_tid(kqwl->kqwl_owner);
-               kev->ext[1] = thread_tid(kqwl->kqwl_request.kqr_thread);
-               kev->ext[2] = thread_owned_workloops_count(current_thread());
-               kev->ext[3] = kn->kn_kevent.ext[3];
-               kq_req_unlock(kqwl);
-               error = EBUSY;
-               goto out;
-       }
-#endif
+       filt_wllock(kqwl);
 
-       int command = (kn->kn_sfflags & NOTE_WL_COMMANDS_MASK);
-       switch (command) {
-       case NOTE_WL_THREAD_REQUEST:
-               if (kn->kn_id != kqwl->kqwl_dynamicid) {
-                       error = EINVAL;
+again:
+
+       /*
+        * Do the debounce thing, the lock serializing the state is the knote lock.
+        */
+       if (uaddr) {
+               /*
+                * Until <rdar://problem/24999882> exists,
+                * disabling preemption copyin forces any
+                * vm_fault we encounter to fail.
+                */
+               error = copyin_atomic64(uaddr, &udata);
+
+               /*
+                * If we get EFAULT, drop locks, and retry.
+                * If we still get an error report it,
+                * else assume the memory has been faulted
+                * and attempt to copyin under lock again.
+                */
+               switch (error) {
+               case 0:
+                       break;
+               case EFAULT:
+                       if (efault_retry-- > 0) {
+                               filt_wlunlock(kqwl);
+                               error = copyin_atomic64(uaddr, &udata);
+                               filt_wllock(kqwl);
+                               if (error == 0) {
+                                       goto again;
+                               }
+                       }
+               /* FALLTHROUGH */
+               default:
                        goto out;
                }
-               qos_index = _pthread_priority_thread_qos(kn->kn_qos);
-               if (qos_index == THREAD_QOS_UNSPECIFIED) {
-                       error = ERANGE;
-                       goto out;
+
+               kev->ext[EV_EXTIDX_WL_VALUE] = udata;
+               kn->kn_ext[EV_EXTIDX_WL_VALUE] = udata;
+
+               if ((udata & mask) != (kdata & mask)) {
+                       error = ESTALE;
+                       goto out;
+               }
+       }
+
+       if (op == FILT_WLATTACH) {
+               error = filt_wlattach_sync_ipc(kn);
+               if (error == 0) {
+                       disable_preemption();
+                       error = EPREEMPTDISABLED;
+               }
+       }
+
+out:
+       filt_wlunlock(kqwl);
+       return error;
+}
+
+static int
+filt_wlattach(struct knote *kn, struct kevent_qos_s *kev)
+{
+       struct kqueue *kq = knote_get_kq(kn);
+       struct kqworkloop *kqwl = (struct kqworkloop *)kq;
+       int error = 0, result = 0;
+       kq_index_t qos_index = 0;
+
+       if (__improbable((kq->kq_state & KQ_WORKLOOP) == 0)) {
+               error = ENOTSUP;
+               goto out;
+       }
+
+       uint32_t command = (kn->kn_sfflags & NOTE_WL_COMMANDS_MASK);
+       switch (command) {
+       case NOTE_WL_THREAD_REQUEST:
+               if (kn->kn_id != kqwl->kqwl_dynamicid) {
+                       error = EINVAL;
+                       goto out;
                }
-               if (kqwl->kqwl_request.kqr_qos_index) {
+               qos_index = _pthread_priority_thread_qos(kn->kn_qos);
+               if (qos_index == THREAD_QOS_UNSPECIFIED) {
+                       error = ERANGE;
+                       goto out;
+               }
+               if (kqwl->kqwl_request.tr_kq_qos_index) {
                        /*
                         * There already is a thread request, and well, you're only allowed
                         * one per workloop, so fail the attach.
@@ -2131,13 +2319,32 @@ filt_wlattach(struct knote *kn, struct kevent_internal_s *kev)
                        goto out;
                }
                break;
+
+       case NOTE_WL_SYNC_IPC:
+               if ((kn->kn_flags & EV_DISABLE) == 0) {
+                       error = EINVAL;
+                       goto out;
+               }
+               if (kn->kn_sfflags & (NOTE_WL_UPDATE_QOS | NOTE_WL_DISCOVER_OWNER)) {
+                       error = EINVAL;
+                       goto out;
+               }
+               break;
        default:
                error = EINVAL;
                goto out;
        }
 
-       error = filt_wlupdate(kqwl, kn, kev, qos_index, FILT_WLATTACH);
+       if (command == NOTE_WL_SYNC_IPC) {
+               error = filt_wlupdate_sync_ipc(kqwl, kn, kev, FILT_WLATTACH);
+       } else {
+               error = filt_wlupdate(kqwl, kn, kev, qos_index, FILT_WLATTACH);
+       }
 
+       if (error == EPREEMPTDISABLED) {
+               error = 0;
+               result = FILTER_THREADREQ_NODEFEER;
+       }
 out:
        if (error) {
                /* If userland wants ESTALE to be hidden, fail the attach anyway */
@@ -2145,10 +2352,10 @@ out:
                        error = 0;
                }
                knote_set_error(kn, error);
-               return 0;
+               return result;
        }
        if (command == NOTE_WL_SYNC_WAIT) {
-               return kevent_register_wait_prepare(kn, kev);
+               return kevent_register_wait_prepare(kn, kev, result);
        }
        /* Just attaching the thread request successfully will fire it */
        if (command == NOTE_WL_THREAD_REQUEST) {
@@ -2157,28 +2364,26 @@ out:
                 * so delivering an event needs to also consume it.
                 */
                kn->kn_flags |= EV_CLEAR;
-               return FILTER_ACTIVE;
+               return result | FILTER_ACTIVE;
        }
-       return 0;
+       return result;
 }
 
 static void __dead2
 filt_wlwait_continue(void *parameter, wait_result_t wr)
 {
        struct _kevent_register *cont_args = parameter;
-       struct kqworkloop *kqwl = (struct kqworkloop *)cont_args->kq;
-       struct kqrequest *kqr = &kqwl->kqwl_request;
+       struct kqworkloop *kqwl = cont_args->kqwl;
 
-       kq_req_lock(kqwl);
-       kqr->kqr_dsync_waiters--;
+       kqlock(kqwl);
        if (filt_wlturnstile_interlock_is_workq(kqwl)) {
                workq_kern_threadreq_lock(kqwl->kqwl_p);
-               turnstile_complete((uintptr_t)kqwl, &kqwl->kqwl_turnstile, NULL);
+               turnstile_complete((uintptr_t)kqwl, &kqwl->kqwl_turnstile, NULL, TURNSTILE_WORKLOOPS);
                workq_kern_threadreq_unlock(kqwl->kqwl_p);
        } else {
-               turnstile_complete((uintptr_t)kqwl, &kqwl->kqwl_turnstile, NULL);
+               turnstile_complete((uintptr_t)kqwl, &kqwl->kqwl_turnstile, NULL, TURNSTILE_WORKLOOPS);
        }
-       kq_req_unlock(kqwl);
+       kqunlock(kqwl);
 
        turnstile_cleanup();
 
@@ -2197,17 +2402,15 @@ filt_wlwait_continue(void *parameter, wait_result_t wr)
  * calls filt_wlwait_continue through a continuation.
  */
 static void __dead2
-filt_wlpost_register_wait(struct uthread *uth, struct knote_lock_ctx *knlc,
-               struct _kevent_register *cont_args)
+filt_wlpost_register_wait(struct uthread *uth, struct knote *kn,
+    struct _kevent_register *cont_args)
 {
-       struct kqworkloop *kqwl = (struct kqworkloop *)cont_args->kq;
-       struct kqrequest *kqr = &kqwl->kqwl_request;
+       struct kqworkloop *kqwl = cont_args->kqwl;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
        struct turnstile *ts;
        bool workq_locked = false;
 
-       kq_req_lock(kqwl);
-
-       kqr->kqr_dsync_waiters++;
+       kqlock_held(kqwl);
 
        if (filt_wlturnstile_interlock_is_workq(kqwl)) {
                workq_kern_threadreq_lock(kqwl->kqwl_p);
@@ -2215,12 +2418,12 @@ filt_wlpost_register_wait(struct uthread *uth, struct knote_lock_ctx *knlc,
        }
 
        ts = turnstile_prepare((uintptr_t)kqwl, &kqwl->kqwl_turnstile,
-                       TURNSTILE_NULL, TURNSTILE_WORKLOOPS);
+           TURNSTILE_NULL, TURNSTILE_WORKLOOPS);
 
        if (workq_locked) {
                workq_kern_threadreq_update_inheritor(kqwl->kqwl_p,
-                               &kqwl->kqwl_request, kqwl->kqwl_owner, ts,
-                               TURNSTILE_DELAYED_UPDATE);
+                   &kqwl->kqwl_request, kqwl->kqwl_owner, ts,
+                   TURNSTILE_DELAYED_UPDATE);
                if (!filt_wlturnstile_interlock_is_workq(kqwl)) {
                        /*
                         * if the interlock is no longer the workqueue lock,
@@ -2239,52 +2442,49 @@ filt_wlpost_register_wait(struct uthread *uth, struct knote_lock_ctx *knlc,
        }
 
        thread_set_pending_block_hint(uth->uu_thread, kThreadWaitWorkloopSyncWait);
-       waitq_assert_wait64(&ts->ts_waitq, CAST_EVENT64_T(cont_args->knote),
-                       THREAD_ABORTSAFE, TIMEOUT_WAIT_FOREVER);
+       waitq_assert_wait64(&ts->ts_waitq, knote_filt_wev64(kn),
+           THREAD_ABORTSAFE, TIMEOUT_WAIT_FOREVER);
 
        if (workq_locked) {
                workq_kern_threadreq_unlock(kqwl->kqwl_p);
        }
 
-       thread_t thread = kqwl->kqwl_owner ?: kqr->kqr_thread;
+       thread_t thread = kqwl->kqwl_owner ?: kqr_thread(kqr);
        if (thread) {
                thread_reference(thread);
        }
-       kq_req_unlock(kqwl);
 
-       kevent_register_wait_block(ts, thread, knlc, filt_wlwait_continue, cont_args);
+       kevent_register_wait_block(ts, thread, filt_wlwait_continue, cont_args);
 }
 
 /* called in stackshot context to report the thread responsible for blocking this thread */
 void
 kdp_workloop_sync_wait_find_owner(__assert_only thread_t thread,
-               event64_t event, thread_waitinfo_t *waitinfo)
+    event64_t event, thread_waitinfo_t *waitinfo)
 {
        struct knote *kn = (struct knote *)event;
        assert(kdp_is_in_zone(kn, "knote zone"));
 
-       assert(kn->kn_hook == thread);
+       assert(kn->kn_thread == thread);
 
        struct kqueue *kq = knote_get_kq(kn);
        assert(kdp_is_in_zone(kq, "kqueue workloop zone"));
        assert(kq->kq_state & KQ_WORKLOOP);
 
        struct kqworkloop *kqwl = (struct kqworkloop *)kq;
-       struct kqrequest *kqr = &kqwl->kqwl_request;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
 
        thread_t kqwl_owner = kqwl->kqwl_owner;
-       thread_t servicer = kqr->kqr_thread;
 
        if (kqwl_owner != THREAD_NULL) {
                assert(kdp_is_in_zone(kqwl_owner, "threads"));
 
                waitinfo->owner = thread_tid(kqwl->kqwl_owner);
-       } else if (servicer != THREAD_NULL) {
-               assert(kdp_is_in_zone(servicer, "threads"));
-
-               waitinfo->owner = thread_tid(servicer);
-       } else if (kqr->kqr_state & KQR_THREQUESTED) {
+       } else if (kqr_thread_requested_pending(kqr)) {
                waitinfo->owner = STACKSHOT_WAITOWNER_THREQUESTED;
+       } else if (kqr->tr_state >= WORKQ_TR_STATE_BINDING) {
+               assert(kdp_is_in_zone(kqr->tr_thread, "threads"));
+               waitinfo->owner = thread_tid(kqr->tr_thread);
        } else {
                waitinfo->owner = 0;
        }
@@ -2293,20 +2493,21 @@ kdp_workloop_sync_wait_find_owner(__assert_only thread_t thread,
 }
 
 static void
-filt_wldetach(__assert_only struct knote *kn)
+filt_wldetach(struct knote *kn)
 {
-       assert(knote_get_kq(kn)->kq_state & KQ_WORKLOOP);
-       if (kn->kn_hook) {
+       if (kn->kn_sfflags & NOTE_WL_SYNC_IPC) {
+               filt_wldetach_sync_ipc(kn);
+       } else if (kn->kn_thread) {
                kevent_register_wait_cleanup(kn);
        }
 }
 
 static int
-filt_wlvalidate_kev_flags(struct knote *kn, struct kevent_internal_s *kev,
-               thread_qos_t *qos_index)
+filt_wlvalidate_kev_flags(struct knote *kn, struct kevent_qos_s *kev,
+    thread_qos_t *qos_index)
 {
-       int new_commands = kev->fflags & NOTE_WL_COMMANDS_MASK;
-       int sav_commands = kn->kn_sfflags & NOTE_WL_COMMANDS_MASK;
+       uint32_t new_commands = kev->fflags & NOTE_WL_COMMANDS_MASK;
+       uint32_t sav_commands = kn->kn_sfflags & NOTE_WL_COMMANDS_MASK;
 
        if ((kev->fflags & NOTE_WL_DISCOVER_OWNER) && (kev->flags & EV_DELETE)) {
                return EINVAL;
@@ -2326,21 +2527,34 @@ filt_wlvalidate_kev_flags(struct knote *kn, struct kevent_internal_s *kev,
        switch (new_commands) {
        case NOTE_WL_THREAD_REQUEST:
                /* thread requests can only update themselves */
-               if (sav_commands != NOTE_WL_THREAD_REQUEST)
+               if (sav_commands != NOTE_WL_THREAD_REQUEST) {
                        return EINVAL;
+               }
                break;
 
        case NOTE_WL_SYNC_WAIT:
-               if (kev->fflags & NOTE_WL_END_OWNERSHIP)
+               if (kev->fflags & NOTE_WL_END_OWNERSHIP) {
                        return EINVAL;
+               }
                goto sync_checks;
 
        case NOTE_WL_SYNC_WAKE:
-       sync_checks:
-               if (!(sav_commands & (NOTE_WL_SYNC_WAIT | NOTE_WL_SYNC_WAKE)))
+sync_checks:
+               if (!(sav_commands & (NOTE_WL_SYNC_WAIT | NOTE_WL_SYNC_WAKE))) {
+                       return EINVAL;
+               }
+               if ((kev->flags & (EV_ENABLE | EV_DELETE)) == EV_ENABLE) {
+                       return EINVAL;
+               }
+               break;
+
+       case NOTE_WL_SYNC_IPC:
+               if (sav_commands != NOTE_WL_SYNC_IPC) {
                        return EINVAL;
-               if ((kev->flags & (EV_ENABLE | EV_DELETE)) == EV_ENABLE)
+               }
+               if ((kev->flags & (EV_ENABLE | EV_DELETE)) == EV_ENABLE) {
                        return EINVAL;
+               }
                break;
 
        default:
@@ -2350,48 +2564,54 @@ filt_wlvalidate_kev_flags(struct knote *kn, struct kevent_internal_s *kev,
 }
 
 static int
-filt_wltouch(struct knote *kn, struct kevent_internal_s *kev)
+filt_wltouch(struct knote *kn, struct kevent_qos_s *kev)
 {
        struct kqworkloop *kqwl = (struct kqworkloop *)knote_get_kq(kn);
        thread_qos_t qos_index = THREAD_QOS_UNSPECIFIED;
+       int result = 0;
 
        int error = filt_wlvalidate_kev_flags(kn, kev, &qos_index);
        if (error) {
                goto out;
        }
 
-       error = filt_wlupdate(kqwl, kn, kev, qos_index, FILT_WLTOUCH);
-       filt_wlremember_last_update(kn, kev, error);
-       if (error) {
-               goto out;
+       uint32_t command = kev->fflags & NOTE_WL_COMMANDS_MASK;
+       if (command == NOTE_WL_SYNC_IPC) {
+               error = filt_wlupdate_sync_ipc(kqwl, kn, kev, FILT_WLTOUCH);
+       } else {
+               error = filt_wlupdate(kqwl, kn, kev, qos_index, FILT_WLTOUCH);
+               filt_wlremember_last_update(kn, kev, error);
+       }
+       if (error == EPREEMPTDISABLED) {
+               error = 0;
+               result = FILTER_THREADREQ_NODEFEER;
        }
 
 out:
        if (error) {
                if (error == ESTALE && (kev->fflags & NOTE_WL_IGNORE_ESTALE)) {
                        /* If userland wants ESTALE to be hidden, do not activate */
-                       return 0;
+                       return result;
                }
                kev->flags |= EV_ERROR;
                kev->data = error;
-               return 0;
+               return result;
        }
-       int command = kev->fflags & NOTE_WL_COMMANDS_MASK;
        if (command == NOTE_WL_SYNC_WAIT && !(kn->kn_sfflags & NOTE_WL_SYNC_WAKE)) {
-               return kevent_register_wait_prepare(kn, kev);
+               return kevent_register_wait_prepare(kn, kev, result);
        }
        /* Just touching the thread request successfully will fire it */
        if (command == NOTE_WL_THREAD_REQUEST) {
                if (kev->fflags & NOTE_WL_UPDATE_QOS) {
-                       return FILTER_ACTIVE | FILTER_UPDATE_REQ_QOS;
+                       result |= FILTER_UPDATE_REQ_QOS;
                }
-               return FILTER_ACTIVE;
+               result |= FILTER_ACTIVE;
        }
-       return 0;
+       return result;
 }
 
 static bool
-filt_wlallow_drop(struct knote *kn, struct kevent_internal_s *kev)
+filt_wlallow_drop(struct knote *kn, struct kevent_qos_s *kev)
 {
        struct kqworkloop *kqwl = (struct kqworkloop *)knote_get_kq(kn);
 
@@ -2400,11 +2620,14 @@ filt_wlallow_drop(struct knote *kn, struct kevent_internal_s *kev)
                goto out;
        }
 
-       error = filt_wlupdate(kqwl, kn, kev, 0, FILT_WLDROP);
-       filt_wlremember_last_update(kn, kev, error);
-       if (error) {
-               goto out;
+       uint32_t command = (kev->fflags & NOTE_WL_COMMANDS_MASK);
+       if (command == NOTE_WL_SYNC_IPC) {
+               error = filt_wlupdate_sync_ipc(kqwl, kn, kev, FILT_WLDROP);
+       } else {
+               error = filt_wlupdate(kqwl, kn, kev, 0, FILT_WLDROP);
+               filt_wlremember_last_update(kn, kev, error);
        }
+       assert(error != EPREEMPTDISABLED);
 
 out:
        if (error) {
@@ -2419,17 +2642,14 @@ out:
 }
 
 static int
-filt_wlprocess(
-       struct knote *kn,
-       __unused struct filt_process_s *data,
-       struct kevent_internal_s *kev)
+filt_wlprocess(struct knote *kn, struct kevent_qos_s *kev)
 {
        struct kqworkloop *kqwl = (struct kqworkloop *)knote_get_kq(kn);
        int rc = 0;
 
        assert(kn->kn_sfflags & NOTE_WL_THREAD_REQUEST);
 
-       filt_wllock(kqwl);
+       kqlock(kqwl);
 
        if (kqwl->kqwl_owner) {
                /*
@@ -2440,9 +2660,7 @@ filt_wlprocess(
                 * When that happens, the automatic deactivation due to process
                 * would swallow the event, so we have to activate the knote again.
                 */
-               kqlock(kqwl);
-               knote_activate(kn);
-               kqunlock(kqwl);
+               knote_activate(kqwl, kn, FILTER_ACTIVE);
        } else {
 #if DEBUG || DEVELOPMENT
                if (kevent_debug_flags() & KEVENT_PANIC_ON_NON_ENQUEUED_PROCESS) {
@@ -2454,23 +2672,21 @@ filt_wlprocess(
                        task_t t = current_task();
                        uint64_t val;
                        if (addr && task_is_active(t) && !task_is_halting(t) &&
-                                       copyin_word(addr, &val, sizeof(val)) == 0 &&
-                                       val && (val & DISPATCH_QUEUE_ENQUEUED) == 0 &&
-                                       (val >> 48) != 0xdead && (val >> 48) != 0 && (val >> 48) != 0xffff) {
+                           copyin_atomic64(addr, &val) == 0 &&
+                           val && (val & DISPATCH_QUEUE_ENQUEUED) == 0 &&
+                           (val >> 48) != 0xdead && (val >> 48) != 0 && (val >> 48) != 0xffff) {
                                panic("kevent: workloop %#016llx is not enqueued "
-                                               "(kn:%p dq_state:%#016llx kev.dq_state:%#016llx)",
-                                               kn->kn_udata, kn, val, kn->kn_ext[EV_EXTIDX_WL_VALUE]);
+                                   "(kn:%p dq_state:%#016llx kev.dq_state:%#016llx)",
+                                   kn->kn_udata, kn, val, kn->kn_ext[EV_EXTIDX_WL_VALUE]);
                        }
                }
 #endif
-               *kev = kn->kn_kevent;
+               knote_fill_kevent(kn, kev, 0);
                kev->fflags = kn->kn_sfflags;
-               kev->data = kn->kn_sdata;
-               kev->qos = kn->kn_qos;
                rc |= FILTER_ACTIVE;
        }
 
-       filt_wlunlock(kqwl);
+       kqunlock(kqwl);
 
        if (rc & FILTER_ACTIVE) {
                workq_thread_set_max_qos(kqwl->kqwl_p, &kqwl->kqwl_request);
@@ -2482,1028 +2698,795 @@ SECURITY_READ_ONLY_EARLY(static struct filterops) workloop_filtops = {
        .f_extended_codes = true,
        .f_attach  = filt_wlattach,
        .f_detach  = filt_wldetach,
-       .f_event   = filt_badevent,
+       .f_event   = filt_bad_event,
        .f_touch   = filt_wltouch,
        .f_process = filt_wlprocess,
        .f_allow_drop = filt_wlallow_drop,
        .f_post_register_wait = filt_wlpost_register_wait,
 };
 
-#pragma mark kevent / knotes
+#pragma mark - kqueues allocation and deallocation
 
-/*
- * JMM - placeholder for not-yet-implemented filters
+/*!
+ * @enum kqworkloop_dealloc_flags_t
+ *
+ * @brief
+ * Flags that alter kqworkloop_dealloc() behavior.
+ *
+ * @const KQWL_DEALLOC_NONE
+ * Convenient name for "no flags".
+ *
+ * @const KQWL_DEALLOC_SKIP_HASH_REMOVE
+ * Do not remove the workloop fromt he hash table.
+ * This is used for process tear-down codepaths as the workloops have been
+ * removed by the caller already.
  */
-static int
-filt_badevent(struct knote *kn, long hint)
+OS_OPTIONS(kqworkloop_dealloc_flags, unsigned,
+    KQWL_DEALLOC_NONE               = 0x0000,
+    KQWL_DEALLOC_SKIP_HASH_REMOVE   = 0x0001,
+    );
+
+static void
+kqworkloop_dealloc(struct kqworkloop *, kqworkloop_dealloc_flags_t, uint32_t);
+
+OS_NOINLINE OS_COLD OS_NORETURN
+static void
+kqworkloop_retain_panic(struct kqworkloop *kqwl, uint32_t previous)
 {
-       panic("%s[%d](%p, %ld)", __func__, kn->kn_filter, kn, hint);
-       return 0;
+       if (previous == 0) {
+               panic("kq(%p) resurrection", kqwl);
+       } else {
+               panic("kq(%p) retain overflow", kqwl);
+       }
 }
 
-static int
-filt_badattach(__unused struct knote *kn, __unused struct kevent_internal_s *kev)
+OS_NOINLINE OS_COLD OS_NORETURN
+static void
+kqworkloop_release_panic(struct kqworkloop *kqwl)
 {
-       knote_set_error(kn, ENOTSUP);
-       return 0;
+       panic("kq(%p) over-release", kqwl);
 }
 
-struct kqueue *
-kqueue_alloc(struct proc *p, unsigned int flags)
+OS_ALWAYS_INLINE
+static inline bool
+kqworkloop_try_retain(struct kqworkloop *kqwl)
 {
-       struct filedesc *fdp = p->p_fd;
-       struct kqueue *kq = NULL;
-       int policy;
-       void *hook = NULL;
-
-       if (flags & KEVENT_FLAG_WORKQ) {
-               struct kqworkq *kqwq;
-               int i;
-
-               kqwq = (struct kqworkq *)zalloc(kqworkq_zone);
-               if (kqwq == NULL)
-                       return NULL;
-
-               kq = &kqwq->kqwq_kqueue;
-               bzero(kqwq, sizeof (struct kqworkq));
-
-               kqwq->kqwq_state = KQ_WORKQ;
-
-               for (i = 0; i < KQWQ_NBUCKETS; i++) {
-                       TAILQ_INIT(&kqwq->kqwq_queue[i]);
+       uint32_t old_ref, new_ref;
+       os_atomic_rmw_loop(&kqwl->kqwl_retains, old_ref, new_ref, relaxed, {
+               if (__improbable(old_ref == 0)) {
+                       os_atomic_rmw_loop_give_up(return false);
                }
-               for (i = 0; i < KQWQ_NBUCKETS; i++) {
-                       if (i != KQWQ_QOS_MANAGER) {
-                               /*
-                                * Because of how the bucketized system works, we mix overcommit
-                                * sources with not overcommit: each time we move a knote from
-                                * one bucket to the next due to overrides, we'd had to track
-                                * overcommitness, and it's really not worth it in the workloop
-                                * enabled world that track this faithfully.
-                                *
-                                * Incidentally, this behaves like the original manager-based
-                                * kqwq where event delivery always happened (hence is
-                                * "overcommit")
-                                */
-                               kqwq->kqwq_request[i].kqr_state |= KQR_THOVERCOMMIT;
-                       }
-                       kqwq->kqwq_request[i].kqr_qos_index = i;
-                       TAILQ_INIT(&kqwq->kqwq_request[i].kqr_suppressed);
+               if (__improbable(old_ref >= KQ_WORKLOOP_RETAINS_MAX)) {
+                       kqworkloop_retain_panic(kqwl, old_ref);
                }
+               new_ref = old_ref + 1;
+       });
+       return true;
+}
 
-               policy = SYNC_POLICY_FIFO;
-               hook = (void *)kqwq;
-       } else if (flags & KEVENT_FLAG_WORKLOOP) {
-               struct kqworkloop *kqwl;
-               int i;
-
-               kqwl = (struct kqworkloop *)zalloc(kqworkloop_zone);
-               if (kqwl == NULL)
-                       return NULL;
-
-               bzero(kqwl, sizeof (struct kqworkloop));
-
-               kqwl->kqwl_state = KQ_WORKLOOP | KQ_DYNAMIC;
-               kqwl->kqwl_retains = 1; /* donate a retain to creator */
-               kqwl->kqwl_request.kqr_state = KQR_WORKLOOP;
+OS_ALWAYS_INLINE
+static inline void
+kqworkloop_retain(struct kqworkloop *kqwl)
+{
+       uint32_t previous = os_atomic_inc_orig(&kqwl->kqwl_retains, relaxed);
+       if (__improbable(previous == 0 || previous >= KQ_WORKLOOP_RETAINS_MAX)) {
+               kqworkloop_retain_panic(kqwl, previous);
+       }
+}
 
-               kq = &kqwl->kqwl_kqueue;
-               for (i = 0; i < KQWL_NBUCKETS; i++) {
-                       TAILQ_INIT(&kqwl->kqwl_queue[i]);
-               }
-               TAILQ_INIT(&kqwl->kqwl_request.kqr_suppressed);
+OS_ALWAYS_INLINE
+static inline void
+kqueue_retain(kqueue_t kqu)
+{
+       if (kqu.kq->kq_state & KQ_DYNAMIC) {
+               kqworkloop_retain(kqu.kqwl);
+       }
+}
 
-               lck_mtx_init(&kqwl->kqwl_statelock, kq_lck_grp, kq_lck_attr);
+OS_ALWAYS_INLINE
+static inline void
+kqworkloop_release_live(struct kqworkloop *kqwl)
+{
+       uint32_t refs = os_atomic_dec_orig(&kqwl->kqwl_retains, relaxed);
+       if (__improbable(refs <= 1)) {
+               kqworkloop_release_panic(kqwl);
+       }
+}
 
-               policy = SYNC_POLICY_FIFO;
-               hook = (void *)kqwl;
-       } else {
-               struct kqfile *kqf;
+OS_ALWAYS_INLINE
+static inline void
+kqueue_release_live(kqueue_t kqu)
+{
+       if (kqu.kq->kq_state & KQ_DYNAMIC) {
+               kqworkloop_release_live(kqu.kqwl);
+       }
+}
 
-               kqf = (struct kqfile *)zalloc(kqfile_zone);
-               if (kqf == NULL)
-                       return NULL;
+OS_ALWAYS_INLINE
+static inline void
+kqworkloop_release(struct kqworkloop *kqwl)
+{
+       uint32_t refs = os_atomic_dec_orig(&kqwl->kqwl_retains, relaxed);
 
-               kq = &kqf->kqf_kqueue;
-               bzero(kqf, sizeof (struct kqfile));
-               TAILQ_INIT(&kqf->kqf_queue);
-               TAILQ_INIT(&kqf->kqf_suppressed);
+       if (__improbable(refs <= 1)) {
+               kqworkloop_dealloc(kqwl, KQWL_DEALLOC_NONE, refs - 1);
+       }
+}
 
-               policy = SYNC_POLICY_FIFO | SYNC_POLICY_PREPOST;
+OS_ALWAYS_INLINE
+static inline void
+kqueue_release(kqueue_t kqu)
+{
+       if (kqu.kq->kq_state & KQ_DYNAMIC) {
+               kqworkloop_release(kqu.kqwl);
        }
+}
 
-       waitq_set_init(&kq->kq_wqs, policy, NULL, hook);
-       lck_spin_init(&kq->kq_lock, kq_lck_grp, kq_lck_attr);
-       lck_spin_init(&kq->kq_reqlock, kq_lck_grp, kq_lck_attr);
-       kq->kq_p = p;
+/*!
+ * @function kqueue_destroy
+ *
+ * @brief
+ * Common part to all kqueue dealloc functions.
+ */
+OS_NOINLINE
+static void
+kqueue_destroy(kqueue_t kqu, zone_t zone)
+{
+       /*
+        * waitq_set_deinit() remove the KQ's waitq set from
+        * any select sets to which it may belong.
+        *
+        * The order of these deinits matter: before waitq_set_deinit() returns,
+        * waitq_set__CALLING_PREPOST_HOOK__ may be called and it will take the
+        * kq_lock.
+        */
+       waitq_set_deinit(&kqu.kq->kq_wqs);
+       lck_spin_destroy(&kqu.kq->kq_lock, kq_lck_grp);
 
-       if (fdp->fd_knlistsize < 0) {
-               proc_fdlock(p);
-               if (fdp->fd_knlistsize < 0)
-                       fdp->fd_knlistsize = 0; /* this process has had a kq */
-               proc_fdunlock(p);
-       }
+       zfree(zone, kqu.kq);
+}
 
-       return (kq);
+/*!
+ * @function kqueue_init
+ *
+ * @brief
+ * Common part to all kqueue alloc functions.
+ */
+static kqueue_t
+kqueue_init(kqueue_t kqu, waitq_set_prepost_hook_t *hook, int policy)
+{
+       waitq_set_init(&kqu.kq->kq_wqs, policy, NULL, hook);
+       lck_spin_init(&kqu.kq->kq_lock, kq_lck_grp, kq_lck_attr);
+       return kqu;
 }
 
-/*
- * knotes_dealloc - detach all knotes for the process and drop them
+#pragma mark kqfile allocation and deallocation
+
+/*!
+ * @function kqueue_dealloc
  *
- *             Called with proc_fdlock held.
- *             Returns with it locked.
- *             May drop it temporarily.
- *             Process is in such a state that it will not try to allocate
- *             any more knotes during this process (stopped for exit or exec).
+ * @brief
+ * Detach all knotes from a kqfile and free it.
+ *
+ * @discussion
+ * We walk each list looking for knotes referencing this
+ * this kqueue.  If we find one, we try to drop it.  But
+ * if we fail to get a drop reference, that will wait
+ * until it is dropped.  So, we can just restart again
+ * safe in the assumption that the list will eventually
+ * not contain any more references to this kqueue (either
+ * we dropped them all, or someone else did).
+ *
+ * Assumes no new events are being added to the kqueue.
+ * Nothing locked on entry or exit.
  */
 void
-knotes_dealloc(proc_t p)
+kqueue_dealloc(struct kqueue *kq)
 {
+       KNOTE_LOCK_CTX(knlc);
+       struct proc *p = kq->kq_p;
        struct filedesc *fdp = p->p_fd;
-       struct kqueue *kq;
        struct knote *kn;
-       struct  klist *kn_hash = NULL;
-       int i;
 
-       /* Close all the fd-indexed knotes up front */
-       if (fdp->fd_knlistsize > 0) {
-               for (i = 0; i < fdp->fd_knlistsize; i++) {
-                       while ((kn = SLIST_FIRST(&fdp->fd_knlist[i])) != NULL) {
-                               kq = knote_get_kq(kn);
+       assert(kq && (kq->kq_state & (KQ_WORKLOOP | KQ_WORKQ)) == 0);
+
+       proc_fdlock(p);
+       for (int i = 0; i < fdp->fd_knlistsize; i++) {
+               kn = SLIST_FIRST(&fdp->fd_knlist[i]);
+               while (kn != NULL) {
+                       if (kq == knote_get_kq(kn)) {
                                kqlock(kq);
                                proc_fdunlock(p);
-                               knote_drop(kq, kn, NULL);
+                               if (knote_lock(kq, kn, &knlc, KNOTE_KQ_LOCK_ON_SUCCESS)) {
+                                       knote_drop(kq, kn, &knlc);
+                               }
                                proc_fdlock(p);
+                               /* start over at beginning of list */
+                               kn = SLIST_FIRST(&fdp->fd_knlist[i]);
+                               continue;
                        }
+                       kn = SLIST_NEXT(kn, kn_link);
                }
-               /* free the table */
-               FREE(fdp->fd_knlist, M_KQUEUE);
-               fdp->fd_knlist = NULL;
        }
-       fdp->fd_knlistsize = -1;
 
-       knhash_lock(p);
+       knhash_lock(fdp);
        proc_fdunlock(p);
 
-       /* Clean out all the hashed knotes as well */
        if (fdp->fd_knhashmask != 0) {
-               for (i = 0; i <= (int)fdp->fd_knhashmask; i++) {
-                       while ((kn = SLIST_FIRST(&fdp->fd_knhash[i])) != NULL) {
-                               kq = knote_get_kq(kn);
-                               kqlock(kq);
-                               knhash_unlock(p);
-                               knote_drop(kq, kn, NULL);
-                               knhash_lock(p);
+               for (int i = 0; i < (int)fdp->fd_knhashmask + 1; i++) {
+                       kn = SLIST_FIRST(&fdp->fd_knhash[i]);
+                       while (kn != NULL) {
+                               if (kq == knote_get_kq(kn)) {
+                                       kqlock(kq);
+                                       knhash_unlock(fdp);
+                                       if (knote_lock(kq, kn, &knlc, KNOTE_KQ_LOCK_ON_SUCCESS)) {
+                                               knote_drop(kq, kn, &knlc);
+                                       }
+                                       knhash_lock(fdp);
+                                       /* start over at beginning of list */
+                                       kn = SLIST_FIRST(&fdp->fd_knhash[i]);
+                                       continue;
+                               }
+                               kn = SLIST_NEXT(kn, kn_link);
                        }
                }
-               kn_hash = fdp->fd_knhash;
-               fdp->fd_knhashmask = 0;
-               fdp->fd_knhash = NULL;
        }
+       knhash_unlock(fdp);
 
-       knhash_unlock(p);
-
-       /* free the kn_hash table */
-       if (kn_hash)
-               FREE(kn_hash, M_KQUEUE);
-
-       proc_fdlock(p);
+       kqueue_destroy(kq, kqfile_zone);
 }
 
-/*
- * kqworkloop_invalidate
- *
- * Invalidate ownership of a workloop.
+/*!
+ * @function kqueue_alloc
  *
- * This is meant to be used so that any remnant of overrides and ownership
- * information is dropped before a kqworkloop can no longer be found in the
- * global hash table and have ghost workloop ownership left over.
- *
- * Possibly returns a thread to deallocate in a safe context.
+ * @brief
+ * Allocate a kqfile.
  */
-static thread_t
-kqworkloop_invalidate(struct kqworkloop *kqwl)
+struct kqueue *
+kqueue_alloc(struct proc *p)
 {
-       thread_t cur_owner = kqwl->kqwl_owner;
+       struct kqfile *kqf;
 
-       assert(TAILQ_EMPTY(&kqwl->kqwl_request.kqr_suppressed));
-       if (cur_owner) {
-               /*
-                * If the kqueue had an owner that prevented the thread request to
-                * go through, then no unbind happened, and we may have lingering
-                * overrides to drop.
-                */
-               if (kqworkloop_owner_override(kqwl) != THREAD_QOS_UNSPECIFIED) {
-                       thread_drop_ipc_override(cur_owner);
-               }
-               thread_ends_owning_workloop(cur_owner);
-               kqwl->kqwl_owner = THREAD_NULL;
+       kqf = (struct kqfile *)zalloc(kqfile_zone);
+       if (__improbable(kqf == NULL)) {
+               return NULL;
        }
+       bzero(kqf, sizeof(struct kqfile));
+
+       /*
+        * kqfiles are created with kqueue() so we need to wait for
+        * the first kevent syscall to know which bit among
+        * KQ_KEV_{32,64,QOS} will be set in kqf_state
+        */
+       kqf->kqf_p = p;
+       TAILQ_INIT_AFTER_BZERO(&kqf->kqf_queue);
+       TAILQ_INIT_AFTER_BZERO(&kqf->kqf_suppressed);
 
-       return cur_owner;
+       return kqueue_init(kqf, NULL, SYNC_POLICY_FIFO | SYNC_POLICY_PREPOST).kq;
 }
 
-/*
- * kqueue_dealloc - detach all knotes from a kqueue and free it
- *
- *     We walk each list looking for knotes referencing this
- *     this kqueue.  If we find one, we try to drop it.  But
- *     if we fail to get a drop reference, that will wait
- *     until it is dropped.  So, we can just restart again
- *     safe in the assumption that the list will eventually
- *     not contain any more references to this kqueue (either
- *     we dropped them all, or someone else did).
- *
- *     Assumes no new events are being added to the kqueue.
- *     Nothing locked on entry or exit.
- *
- * Workloop kqueues cant get here unless all the knotes
- * are already gone and all requested threads have come
- * and gone (cancelled or arrived).
+/*!
+ * @function kqueue_internal
+ *
+ * @brief
+ * Core implementation for kqueue and guarded_kqueue_np()
  */
-void
-kqueue_dealloc(struct kqueue *kq)
+int
+kqueue_internal(struct proc *p, fp_allocfn_t fp_zalloc, void *cra, int32_t *retval)
 {
-       struct proc *p;
-       struct filedesc *fdp;
-       struct knote *kn;
-       int i;
+       struct kqueue *kq;
+       struct fileproc *fp;
+       int fd, error;
 
-       if (kq == NULL)
-               return;
+       error = falloc_withalloc(p, &fp, &fd, vfs_context_current(), fp_zalloc, cra);
+       if (error) {
+               return error;
+       }
 
-       p = kq->kq_p;
-       fdp = p->p_fd;
-
-       /*
-        * Workloops are refcounted by their knotes, so there's no point
-        * spending a lot of time under these locks just to deallocate one.
-        */
-       if ((kq->kq_state & KQ_WORKLOOP) == 0) {
-               KNOTE_LOCK_CTX(knlc);
-
-               proc_fdlock(p);
-               for (i = 0; i < fdp->fd_knlistsize; i++) {
-                       kn = SLIST_FIRST(&fdp->fd_knlist[i]);
-                       while (kn != NULL) {
-                               if (kq == knote_get_kq(kn)) {
-                                       kqlock(kq);
-                                       proc_fdunlock(p);
-                                       if (knote_lock(kq, kn, &knlc, KNOTE_KQ_LOCK_ON_SUCCESS)) {
-                                               knote_drop(kq, kn, &knlc);
-                                       }
-                                       proc_fdlock(p);
-                                       /* start over at beginning of list */
-                                       kn = SLIST_FIRST(&fdp->fd_knlist[i]);
-                                       continue;
-                               }
-                               kn = SLIST_NEXT(kn, kn_link);
-                       }
-               }
-
-               knhash_lock(p);
-               proc_fdunlock(p);
-
-               if (fdp->fd_knhashmask != 0) {
-                       for (i = 0; i < (int)fdp->fd_knhashmask + 1; i++) {
-                               kn = SLIST_FIRST(&fdp->fd_knhash[i]);
-                               while (kn != NULL) {
-                                       if (kq == knote_get_kq(kn)) {
-                                               kqlock(kq);
-                                               knhash_unlock(p);
-                                               if (knote_lock(kq, kn, &knlc, KNOTE_KQ_LOCK_ON_SUCCESS)) {
-                                                       knote_drop(kq, kn, &knlc);
-                                               }
-                                               knhash_lock(p);
-                                               /* start over at beginning of list */
-                                               kn = SLIST_FIRST(&fdp->fd_knhash[i]);
-                                               continue;
-                                       }
-                                       kn = SLIST_NEXT(kn, kn_link);
-                               }
-                       }
-               }
-               knhash_unlock(p);
-       }
-
-       if (kq->kq_state & KQ_WORKLOOP) {
-               struct kqworkloop *kqwl = (struct kqworkloop *)kq;
-               thread_t cur_owner = kqworkloop_invalidate(kqwl);
-
-               if (cur_owner) thread_deallocate(cur_owner);
-
-               if (kqwl->kqwl_request.kqr_state & KQR_ALLOCATED_TURNSTILE) {
-                       struct turnstile *ts;
-                       turnstile_complete((uintptr_t)kqwl, &kqwl->kqwl_turnstile, &ts);
-                       turnstile_cleanup();
-                       turnstile_deallocate(ts);
-               } else {
-                       assert(kqwl->kqwl_turnstile == NULL);
-               }
-       }
-
-       /*
-        * waitq_set_deinit() remove the KQ's waitq set from
-        * any select sets to which it may belong.
-        */
-       waitq_set_deinit(&kq->kq_wqs);
-       lck_spin_destroy(&kq->kq_lock, kq_lck_grp);
-       lck_spin_destroy(&kq->kq_reqlock, kq_lck_grp);
-
-       if (kq->kq_state & KQ_WORKQ) {
-               zfree(kqworkq_zone, (struct kqworkq *)kq);
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               struct kqworkloop *kqwl = (struct kqworkloop *)kq;
-
-               assert(kqwl->kqwl_retains == 0);
-               lck_mtx_destroy(&kqwl->kqwl_statelock, kq_lck_grp);
-               zfree(kqworkloop_zone, kqwl);
-       } else {
-               zfree(kqfile_zone, (struct kqfile *)kq);
-       }
-}
-
-static inline void
-kqueue_retain(struct kqueue *kq)
-{
-       struct kqworkloop *kqwl = (struct kqworkloop *)kq;
-       uint32_t previous;
-
-       if ((kq->kq_state & KQ_DYNAMIC) == 0)
-               return;
-
-       previous = OSIncrementAtomic(&kqwl->kqwl_retains);
-       if (previous == KQ_WORKLOOP_RETAINS_MAX)
-               panic("kq(%p) retain overflow", kq);
-
-       if (previous == 0)
-               panic("kq(%p) resurrection", kq);
-}
-
-#define KQUEUE_CANT_BE_LAST_REF  0
-#define KQUEUE_MIGHT_BE_LAST_REF 1
-
-static inline int
-kqueue_release(kqueue_t kqu, __assert_only int possibly_last)
-{
-       if ((kqu.kq->kq_state & KQ_DYNAMIC) == 0) {
-               return 0;
-       }
-
-       assert(kqu.kq->kq_state & KQ_WORKLOOP); /* for now */
-       uint32_t refs = OSDecrementAtomic(&kqu.kqwl->kqwl_retains);
-       if (__improbable(refs == 0)) {
-               panic("kq(%p) over-release", kqu.kq);
-       }
-       if (refs == 1) {
-               assert(possibly_last);
-       }
-       return refs == 1;
-}
-
-int
-kqueue_body(struct proc *p, fp_allocfn_t fp_zalloc, void *cra, int32_t *retval)
-{
-       struct kqueue *kq;
-       struct fileproc *fp;
-       int fd, error;
-
-       error = falloc_withalloc(p,
-           &fp, &fd, vfs_context_current(), fp_zalloc, cra);
-       if (error) {
-               return (error);
-       }
-
-       kq = kqueue_alloc(p, 0);
-       if (kq == NULL) {
-               fp_free(p, fd, fp);
-               return (ENOMEM);
-       }
+       kq = kqueue_alloc(p);
+       if (kq == NULL) {
+               fp_free(p, fd, fp);
+               return ENOMEM;
+       }
 
        fp->f_flag = FREAD | FWRITE;
        fp->f_ops = &kqueueops;
        fp->f_data = kq;
+       fp->f_lflags |= FG_CONFINED;
 
        proc_fdlock(p);
-       *fdflags(p, fd) |= UF_EXCLOSE;
+       *fdflags(p, fd) |= UF_EXCLOSE | UF_FORKCLOSE;
        procfdtbl_releasefd(p, fd, NULL);
        fp_drop(p, fd, fp, 1);
        proc_fdunlock(p);
 
        *retval = fd;
-       return (error);
+       return error;
 }
 
+/*!
+ * @function kqueue
+ *
+ * @brief
+ * The kqueue syscall.
+ */
 int
 kqueue(struct proc *p, __unused struct kqueue_args *uap, int32_t *retval)
 {
-       return (kqueue_body(p, fileproc_alloc_init, NULL, retval));
+       return kqueue_internal(p, fileproc_alloc_init, NULL, retval);
 }
 
-static int
-kevent_copyin(user_addr_t *addrp, struct kevent_internal_s *kevp, struct proc *p,
-               unsigned int flags)
-{
-       int advance;
-       int error;
-
-       if (flags & KEVENT_FLAG_LEGACY32) {
-               bzero(kevp, sizeof (*kevp));
-
-               if (IS_64BIT_PROCESS(p)) {
-                       struct user64_kevent kev64;
-
-                       advance = sizeof (kev64);
-                       error = copyin(*addrp, (caddr_t)&kev64, advance);
-                       if (error)
-                               return (error);
-                       kevp->ident = kev64.ident;
-                       kevp->filter = kev64.filter;
-                       kevp->flags = kev64.flags;
-                       kevp->udata = kev64.udata;
-                       kevp->fflags = kev64.fflags;
-                       kevp->data = kev64.data;
-               } else {
-                       struct user32_kevent kev32;
-
-                       advance = sizeof (kev32);
-                       error = copyin(*addrp, (caddr_t)&kev32, advance);
-                       if (error)
-                               return (error);
-                       kevp->ident = (uintptr_t)kev32.ident;
-                       kevp->filter = kev32.filter;
-                       kevp->flags = kev32.flags;
-                       kevp->udata = CAST_USER_ADDR_T(kev32.udata);
-                       kevp->fflags = kev32.fflags;
-                       kevp->data = (intptr_t)kev32.data;
-               }
-       } else if (flags & KEVENT_FLAG_LEGACY64) {
-               struct kevent64_s kev64;
-
-               bzero(kevp, sizeof (*kevp));
-
-               advance = sizeof (struct kevent64_s);
-               error = copyin(*addrp, (caddr_t)&kev64, advance);
-               if (error)
-                       return(error);
-               kevp->ident = kev64.ident;
-               kevp->filter = kev64.filter;
-               kevp->flags = kev64.flags;
-               kevp->udata = kev64.udata;
-               kevp->fflags = kev64.fflags;
-               kevp->data = kev64.data;
-               kevp->ext[0] = kev64.ext[0];
-               kevp->ext[1] = kev64.ext[1];
-
-       } else {
-               struct kevent_qos_s kevqos;
-
-               bzero(kevp, sizeof (*kevp));
-
-               advance = sizeof (struct kevent_qos_s);
-               error = copyin(*addrp, (caddr_t)&kevqos, advance);
-               if (error)
-                       return error;
-               kevp->ident = kevqos.ident;
-               kevp->filter = kevqos.filter;
-               kevp->flags = kevqos.flags;
-               kevp->qos = kevqos.qos;
-//             kevp->xflags = kevqos.xflags;
-               kevp->udata = kevqos.udata;
-               kevp->fflags = kevqos.fflags;
-               kevp->data = kevqos.data;
-               kevp->ext[0] = kevqos.ext[0];
-               kevp->ext[1] = kevqos.ext[1];
-               kevp->ext[2] = kevqos.ext[2];
-               kevp->ext[3] = kevqos.ext[3];
-       }
-       if (!error)
-               *addrp += advance;
-       return (error);
-}
+#pragma mark kqworkq allocation and deallocation
 
-static int
-kevent_copyout(struct kevent_internal_s *kevp, user_addr_t *addrp, struct proc *p,
-               unsigned int flags)
+/*!
+ * @function kqworkq_dealloc
+ *
+ * @brief
+ * Deallocates a workqueue kqueue.
+ *
+ * @discussion
+ * This only happens at process death, or for races with concurrent
+ * kevent_get_kqwq calls, hence we don't have to care about knotes referencing
+ * this kqueue, either there are none, or someone else took care of them.
+ */
+void
+kqworkq_dealloc(struct kqworkq *kqwq)
 {
-       user_addr_t addr = *addrp;
-       int advance;
-       int error;
-
-       /*
-        * fully initialize the differnt output event structure
-        * types from the internal kevent (and some universal
-        * defaults for fields not represented in the internal
-        * form).
-        */
-       if (flags & KEVENT_FLAG_LEGACY32) {
-               assert((flags & KEVENT_FLAG_STACK_EVENTS) == 0);
-
-               if (IS_64BIT_PROCESS(p)) {
-                       struct user64_kevent kev64;
-
-                       advance = sizeof (kev64);
-                       bzero(&kev64, advance);
-
-                       /*
-                        * deal with the special case of a user-supplied
-                        * value of (uintptr_t)-1.
-                        */
-                       kev64.ident = (kevp->ident == (uintptr_t)-1) ?
-                               (uint64_t)-1LL : (uint64_t)kevp->ident;
-
-                       kev64.filter = kevp->filter;
-                       kev64.flags = kevp->flags;
-                       kev64.fflags = kevp->fflags;
-                       kev64.data = (int64_t) kevp->data;
-                       kev64.udata = kevp->udata;
-                       error = copyout((caddr_t)&kev64, addr, advance);
-               } else {
-                       struct user32_kevent kev32;
-
-                       advance = sizeof (kev32);
-                       bzero(&kev32, advance);
-                       kev32.ident = (uint32_t)kevp->ident;
-                       kev32.filter = kevp->filter;
-                       kev32.flags = kevp->flags;
-                       kev32.fflags = kevp->fflags;
-                       kev32.data = (int32_t)kevp->data;
-                       kev32.udata = kevp->udata;
-                       error = copyout((caddr_t)&kev32, addr, advance);
-               }
-       } else if (flags & KEVENT_FLAG_LEGACY64) {
-               struct kevent64_s kev64;
-
-               advance = sizeof (struct kevent64_s);
-               if (flags & KEVENT_FLAG_STACK_EVENTS) {
-                       addr -= advance;
-               }
-               bzero(&kev64, advance);
-               kev64.ident = kevp->ident;
-               kev64.filter = kevp->filter;
-               kev64.flags = kevp->flags;
-               kev64.fflags = kevp->fflags;
-               kev64.data = (int64_t) kevp->data;
-               kev64.udata = kevp->udata;
-               kev64.ext[0] = kevp->ext[0];
-               kev64.ext[1] = kevp->ext[1];
-               error = copyout((caddr_t)&kev64, addr, advance);
-       } else {
-               struct kevent_qos_s kevqos;
-
-               advance = sizeof (struct kevent_qos_s);
-               if (flags & KEVENT_FLAG_STACK_EVENTS) {
-                       addr -= advance;
-               }
-               bzero(&kevqos, advance);
-               kevqos.ident = kevp->ident;
-               kevqos.filter = kevp->filter;
-               kevqos.flags = kevp->flags;
-               kevqos.qos = kevp->qos;
-               kevqos.udata = kevp->udata;
-               kevqos.fflags = kevp->fflags;
-               kevqos.xflags = 0;
-               kevqos.data = (int64_t) kevp->data;
-               kevqos.ext[0] = kevp->ext[0];
-               kevqos.ext[1] = kevp->ext[1];
-               kevqos.ext[2] = kevp->ext[2];
-               kevqos.ext[3] = kevp->ext[3];
-               error = copyout((caddr_t)&kevqos, addr, advance);
-       }
-       if (!error) {
-               if (flags & KEVENT_FLAG_STACK_EVENTS)
-                       *addrp = addr;
-               else
-                       *addrp = addr + advance;
-       }
-       return (error);
+       kqueue_destroy(kqwq, kqworkq_zone);
 }
 
-static int
-kevent_get_data_size(
-               struct proc *p,
-               uint64_t data_available,
-               unsigned int flags,
-               user_size_t *residp)
+/*!
+ * @function kqworkq_alloc
+ *
+ * @brief
+ * Allocates a workqueue kqueue.
+ *
+ * @discussion
+ * This is the slow path of kevent_get_kqwq.
+ * This takes care of making sure procs have a single workq kqueue.
+ */
+OS_NOINLINE
+static struct kqworkq *
+kqworkq_alloc(struct proc *p, unsigned int flags)
 {
-       user_size_t resid;
-       int error = 0;
+       struct kqworkq *kqwq, *tmp;
 
-       if (data_available != USER_ADDR_NULL) {
-               if (flags & KEVENT_FLAG_KERNEL) {
-                       resid = *(user_size_t *)(uintptr_t)data_available;
-               } else if (IS_64BIT_PROCESS(p)) {
-                       user64_size_t usize;
-                       error = copyin((user_addr_t)data_available, &usize, sizeof(usize));
-                       resid = (user_size_t)usize;
-               } else {
-                       user32_size_t usize;
-                       error = copyin((user_addr_t)data_available, &usize, sizeof(usize));
-                       resid = (user_size_t)usize;
-               }
-               if (error)
-                       return(error);
-       } else {
-               resid = 0;
+       kqwq = (struct kqworkq *)zalloc(kqworkq_zone);
+       if (__improbable(kqwq == NULL)) {
+               return NULL;
        }
-       *residp = resid;
-       return 0;
-}
+       bzero(kqwq, sizeof(struct kqworkq));
 
-static int
-kevent_put_data_size(
-               struct proc *p,
-               uint64_t data_available,
-               unsigned int flags,
-               user_size_t resid)
-{
-       int error = 0;
+       assert((flags & KEVENT_FLAG_LEGACY32) == 0);
+       if (flags & KEVENT_FLAG_LEGACY64) {
+               kqwq->kqwq_state = KQ_WORKQ | KQ_KEV64;
+       } else {
+               kqwq->kqwq_state = KQ_WORKQ | KQ_KEV_QOS;
+       }
+       kqwq->kqwq_p = p;
 
-       if (data_available) {
-               if (flags & KEVENT_FLAG_KERNEL) {
-                       *(user_size_t *)(uintptr_t)data_available = resid;
-               } else if (IS_64BIT_PROCESS(p)) {
-                       user64_size_t usize = (user64_size_t)resid;
-                       error = copyout(&usize, (user_addr_t)data_available, sizeof(usize));
-               } else {
-                       user32_size_t usize = (user32_size_t)resid;
-                       error = copyout(&usize, (user_addr_t)data_available, sizeof(usize));
+       for (int i = 0; i < KQWQ_NBUCKETS; i++) {
+               TAILQ_INIT_AFTER_BZERO(&kqwq->kqwq_queue[i]);
+               TAILQ_INIT_AFTER_BZERO(&kqwq->kqwq_suppressed[i]);
+       }
+       for (int i = 0; i < KQWQ_NBUCKETS; i++) {
+               /*
+                * Because of how the bucketized system works, we mix overcommit
+                * sources with not overcommit: each time we move a knote from
+                * one bucket to the next due to overrides, we'd had to track
+                * overcommitness, and it's really not worth it in the workloop
+                * enabled world that track this faithfully.
+                *
+                * Incidentally, this behaves like the original manager-based
+                * kqwq where event delivery always happened (hence is
+                * "overcommit")
+                */
+               kqwq->kqwq_request[i].tr_state = WORKQ_TR_STATE_IDLE;
+               kqwq->kqwq_request[i].tr_flags = WORKQ_TR_FLAG_KEVENT;
+               if (i != KQWQ_QOS_MANAGER) {
+                       kqwq->kqwq_request[i].tr_flags |= WORKQ_TR_FLAG_OVERCOMMIT;
                }
+               kqwq->kqwq_request[i].tr_kq_qos_index = i;
        }
-       return error;
-}
 
-/*
- * kevent_continue - continue a kevent syscall after blocking
- *
- *     assume we inherit a use count on the kq fileglob.
- */
-__attribute__((noreturn))
-static void
-kevent_continue(__unused struct kqueue *kq, void *data, int error)
-{
-       struct _kevent *cont_args;
-       struct fileproc *fp;
-       uint64_t data_available;
-       user_size_t data_size;
-       user_size_t data_resid;
-       unsigned int flags;
-       int32_t *retval;
-       int noutputs;
-       int fd;
-       struct proc *p = current_proc();
-
-       cont_args = (struct _kevent *)data;
-       data_available = cont_args->data_available;
-       flags = cont_args->process_data.fp_flags;
-       data_size = cont_args->process_data.fp_data_size;
-       data_resid = cont_args->process_data.fp_data_resid;
-       noutputs = cont_args->eventout;
-       retval = cont_args->retval;
-       fd = cont_args->fd;
-       fp = cont_args->fp;
-
-       kevent_put_kq(p, fd, fp, kq);
-
-       /* don't abandon other output just because of residual copyout failures */
-       if (error == 0 && data_available && data_resid != data_size) {
-               (void)kevent_put_data_size(p, data_available, flags, data_resid);
+       kqueue_init(kqwq, &kqwq->kqwq_waitq_hook, SYNC_POLICY_FIFO);
+
+       if (!os_atomic_cmpxchgv(&p->p_fd->fd_wqkqueue, NULL, kqwq, &tmp, release)) {
+               kqworkq_dealloc(kqwq);
+               return tmp;
        }
 
-       /* don't restart after signals... */
-       if (error == ERESTART)
-               error = EINTR;
-       else if (error == EWOULDBLOCK)
-               error = 0;
-       if (error == 0)
-               *retval = noutputs;
-       unix_syscall_return(error);
+       return kqwq;
 }
 
-/*
- * kevent - [syscall] register and wait for kernel events
- *
- */
-int
-kevent(struct proc *p, struct kevent_args *uap, int32_t *retval)
-{
-       unsigned int flags = KEVENT_FLAG_LEGACY32;
+#pragma mark kqworkloop allocation and deallocation
 
-       return kevent_internal(p,
-                              (kqueue_id_t)uap->fd, NULL,
-                              uap->changelist, uap->nchanges,
-                              uap->eventlist, uap->nevents,
-                              0ULL, 0ULL,
-                              flags,
-                              uap->timeout,
-                              kevent_continue,
-                              retval);
-}
+#define KQ_HASH(val, mask)  (((val) ^ (val >> 8)) & (mask))
+#define CONFIG_KQ_HASHSIZE  CONFIG_KN_HASHSIZE
 
-int
-kevent64(struct proc *p, struct kevent64_args *uap, int32_t *retval)
+OS_ALWAYS_INLINE
+static inline void
+kqhash_lock(struct filedesc *fdp)
 {
-       unsigned int flags;
-
-       /* restrict to user flags and set legacy64 */
-       flags = uap->flags & KEVENT_FLAG_USER;
-       flags |= KEVENT_FLAG_LEGACY64;
-
-       return kevent_internal(p,
-                              (kqueue_id_t)uap->fd, NULL,
-                              uap->changelist, uap->nchanges,
-                              uap->eventlist, uap->nevents,
-                              0ULL, 0ULL,
-                              flags,
-                              uap->timeout,
-                              kevent_continue,
-                              retval);
+       lck_mtx_lock_spin_always(&fdp->fd_kqhashlock);
 }
 
-int
-kevent_qos(struct proc *p, struct kevent_qos_args *uap, int32_t *retval)
+OS_ALWAYS_INLINE
+static inline void
+kqhash_unlock(struct filedesc *fdp)
 {
-       /* restrict to user flags */
-       uap->flags &= KEVENT_FLAG_USER;
-
-       return kevent_internal(p,
-                              (kqueue_id_t)uap->fd, NULL,
-                              uap->changelist, uap->nchanges,
-                              uap->eventlist,  uap->nevents,
-                              uap->data_out, (uint64_t)uap->data_available,
-                              uap->flags,
-                              0ULL,
-                              kevent_continue,
-                              retval);
-}
-
-int
-kevent_qos_internal(struct proc *p, int fd,
-                   user_addr_t changelist, int nchanges,
-                   user_addr_t eventlist, int nevents,
-                   user_addr_t data_out, user_size_t *data_available,
-                   unsigned int flags,
-                   int32_t *retval)
-{
-       return kevent_internal(p,
-                              (kqueue_id_t)fd, NULL,
-                              changelist, nchanges,
-                              eventlist, nevents,
-                              data_out, (uint64_t)data_available,
-                              (flags | KEVENT_FLAG_KERNEL),
-                              0ULL,
-                              NULL,
-                              retval);
+       lck_mtx_unlock(&fdp->fd_kqhashlock);
 }
 
-int
-kevent_id(struct proc *p, struct kevent_id_args *uap, int32_t *retval)
+OS_ALWAYS_INLINE
+static inline void
+kqworkloop_hash_insert_locked(struct filedesc *fdp, kqueue_id_t id,
+    struct kqworkloop *kqwl)
 {
-       /* restrict to user flags */
-       uap->flags &= KEVENT_FLAG_USER;
-
-       return kevent_internal(p,
-                              (kqueue_id_t)uap->id, NULL,
-                              uap->changelist, uap->nchanges,
-                              uap->eventlist,  uap->nevents,
-                              uap->data_out, (uint64_t)uap->data_available,
-                              (uap->flags | KEVENT_FLAG_DYNAMIC_KQUEUE),
-                              0ULL,
-                              kevent_continue,
-                              retval);
-}
-
-int
-kevent_id_internal(struct proc *p, kqueue_id_t *id,
-                   user_addr_t changelist, int nchanges,
-                   user_addr_t eventlist, int nevents,
-                   user_addr_t data_out, user_size_t *data_available,
-                   unsigned int flags,
-                   int32_t *retval)
-{
-       return kevent_internal(p,
-                              *id, id,
-                              changelist, nchanges,
-                              eventlist, nevents,
-                              data_out, (uint64_t)data_available,
-                              (flags | KEVENT_FLAG_KERNEL | KEVENT_FLAG_DYNAMIC_KQUEUE),
-                              0ULL,
-                              NULL,
-                              retval);
+       struct kqwllist *list = &fdp->fd_kqhash[KQ_HASH(id, fdp->fd_kqhashmask)];
+       LIST_INSERT_HEAD(list, kqwl, kqwl_hashlink);
 }
 
-static int
-kevent_get_timeout(struct proc *p,
-                  user_addr_t utimeout,
-                  unsigned int flags,
-                  struct timeval *atvp)
+OS_ALWAYS_INLINE
+static inline struct kqworkloop *
+kqworkloop_hash_lookup_locked(struct filedesc *fdp, kqueue_id_t id)
 {
-       struct timeval atv;
-       int error = 0;
+       struct kqwllist *list = &fdp->fd_kqhash[KQ_HASH(id, fdp->fd_kqhashmask)];
+       struct kqworkloop *kqwl;
 
-       if (flags & KEVENT_FLAG_IMMEDIATE) {
-               getmicrouptime(&atv);
-       } else if (utimeout != USER_ADDR_NULL) {
-               struct timeval rtv;
-               if (flags & KEVENT_FLAG_KERNEL) {
-                       struct timespec *tsp = (struct timespec *)utimeout;
-                       TIMESPEC_TO_TIMEVAL(&rtv, tsp);
-               } else if (IS_64BIT_PROCESS(p)) {
-                       struct user64_timespec ts;
-                       error = copyin(utimeout, &ts, sizeof(ts));
-                       if ((ts.tv_sec & 0xFFFFFFFF00000000ull) != 0)
-                               error = EINVAL;
-                       else
-                               TIMESPEC_TO_TIMEVAL(&rtv, &ts);
-               } else {
-                       struct user32_timespec ts;
-                       error = copyin(utimeout, &ts, sizeof(ts));
-                       TIMESPEC_TO_TIMEVAL(&rtv, &ts);
-               }
-               if (error)
-                       return (error);
-               if (itimerfix(&rtv))
-                       return (EINVAL);
-               getmicrouptime(&atv);
-               timevaladd(&atv, &rtv);
-       } else {
-               /* wait forever value */
-               atv.tv_sec = 0;
-               atv.tv_usec = 0;
+       LIST_FOREACH(kqwl, list, kqwl_hashlink) {
+               if (kqwl->kqwl_dynamicid == id) {
+                       return kqwl;
+               }
        }
-       *atvp = atv;
-       return 0;
+       return NULL;
 }
 
-static int
-kevent_set_kq_mode(struct kqueue *kq, unsigned int flags)
+static struct kqworkloop *
+kqworkloop_hash_lookup_and_retain(struct filedesc *fdp, kqueue_id_t kq_id)
 {
-       /* each kq should only be used for events of one type */
-       kqlock(kq);
-       if (kq->kq_state & (KQ_KEV32 | KQ_KEV64 | KQ_KEV_QOS)) {
-               if (flags & KEVENT_FLAG_LEGACY32) {
-                       if ((kq->kq_state & KQ_KEV32) == 0) {
-                               kqunlock(kq);
-                               return EINVAL;
-                       }
-               } else if (kq->kq_state & KQ_KEV32) {
-                       kqunlock(kq);
-                       return EINVAL;
+       struct kqworkloop *kqwl = NULL;
+
+       kqhash_lock(fdp);
+       if (__probable(fdp->fd_kqhash)) {
+               kqwl = kqworkloop_hash_lookup_locked(fdp, kq_id);
+               if (kqwl && !kqworkloop_try_retain(kqwl)) {
+                       kqwl = NULL;
                }
-       } else if (flags & KEVENT_FLAG_LEGACY32) {
-               kq->kq_state |= KQ_KEV32;
-       } else if (flags & KEVENT_FLAG_LEGACY64) {
-               kq->kq_state |= KQ_KEV64;
-       } else {
-               kq->kq_state |= KQ_KEV_QOS;
        }
-       kqunlock(kq);
-       return 0;
+       kqhash_unlock(fdp);
+       return kqwl;
 }
 
-#define        KQ_HASH(val, mask)  (((val) ^ (val >> 8)) & (mask))
-#define CONFIG_KQ_HASHSIZE  CONFIG_KN_HASHSIZE
-
-static inline void
-kqhash_lock(proc_t p)
+OS_NOINLINE
+static void
+kqworkloop_hash_init(struct filedesc *fdp)
 {
-       lck_mtx_lock_spin_always(&p->p_fd->fd_kqhashlock);
-}
+       struct kqwllist *alloc_hash;
+       u_long alloc_mask;
 
-static inline void
-kqhash_lock_held(__assert_only proc_t p)
-{
-       LCK_MTX_ASSERT(&p->p_fd->fd_kqhashlock, LCK_MTX_ASSERT_OWNED);
-}
+       kqhash_unlock(fdp);
+       alloc_hash = hashinit(CONFIG_KQ_HASHSIZE, M_KQUEUE, &alloc_mask);
+       kqhash_lock(fdp);
 
-static inline void
-kqhash_unlock(proc_t p)
-{
-       lck_mtx_unlock(&p->p_fd->fd_kqhashlock);
+       /* See if we won the race */
+       if (__probable(fdp->fd_kqhashmask == 0)) {
+               fdp->fd_kqhash = alloc_hash;
+               fdp->fd_kqhashmask = alloc_mask;
+       } else {
+               kqhash_unlock(fdp);
+               FREE(alloc_hash, M_KQUEUE);
+               kqhash_lock(fdp);
+       }
 }
 
+/*!
+ * @function kqworkloop_dealloc
+ *
+ * @brief
+ * Deallocates a workloop kqueue.
+ *
+ * @discussion
+ * Knotes hold references on the workloop, so we can't really reach this
+ * function unless all of these are already gone.
+ *
+ * Nothing locked on entry or exit.
+ *
+ * @param flags
+ * Unless KQWL_DEALLOC_SKIP_HASH_REMOVE is set, the workloop is removed
+ * from its hash table.
+ *
+ * @param current_ref
+ * This function is also called to undo a kqworkloop_alloc in case of
+ * allocation races, expected_ref is the current refcount that is expected
+ * on the workloop object, usually 0, and 1 when a dealloc race is resolved.
+ */
 static void
-kqueue_hash_init_if_needed(proc_t p)
+kqworkloop_dealloc(struct kqworkloop *kqwl, kqworkloop_dealloc_flags_t flags,
+    uint32_t current_ref)
 {
-       struct filedesc *fdp = p->p_fd;
-
-       kqhash_lock_held(p);
+       thread_t cur_owner;
 
-       if (__improbable(fdp->fd_kqhash == NULL)) {
-               struct kqlist *alloc_hash;
-               u_long alloc_mask;
+       if (__improbable(current_ref > 1)) {
+               kqworkloop_release_panic(kqwl);
+       }
+       assert(kqwl->kqwl_retains == current_ref);
 
-               kqhash_unlock(p);
-               alloc_hash = hashinit(CONFIG_KQ_HASHSIZE, M_KQUEUE, &alloc_mask);
-               kqhash_lock(p);
+       /* pair with kqunlock() and other kq locks */
+       os_atomic_thread_fence(acquire);
 
-               /* See if we won the race */
-               if (fdp->fd_kqhashmask == 0) {
-                       fdp->fd_kqhash = alloc_hash;
-                       fdp->fd_kqhashmask = alloc_mask;
-               } else {
-                       kqhash_unlock(p);
-                       FREE(alloc_hash, M_KQUEUE);
-                       kqhash_lock(p);
+       cur_owner = kqwl->kqwl_owner;
+       if (cur_owner) {
+               if (kqworkloop_override(kqwl) != THREAD_QOS_UNSPECIFIED) {
+                       thread_drop_kevent_override(cur_owner);
                }
+               thread_deallocate(cur_owner);
+               kqwl->kqwl_owner = THREAD_NULL;
+       }
+
+       if (kqwl->kqwl_state & KQ_HAS_TURNSTILE) {
+               struct turnstile *ts;
+               turnstile_complete((uintptr_t)kqwl, &kqwl->kqwl_turnstile,
+                   &ts, TURNSTILE_WORKLOOPS);
+               turnstile_cleanup();
+               turnstile_deallocate(ts);
+       }
+
+       if ((flags & KQWL_DEALLOC_SKIP_HASH_REMOVE) == 0) {
+               struct filedesc *fdp = kqwl->kqwl_p->p_fd;
+
+               kqhash_lock(fdp);
+               LIST_REMOVE(kqwl, kqwl_hashlink);
+               kqhash_unlock(fdp);
        }
+
+       assert(TAILQ_EMPTY(&kqwl->kqwl_suppressed));
+       assert(kqwl->kqwl_owner == THREAD_NULL);
+       assert(kqwl->kqwl_turnstile == TURNSTILE_NULL);
+
+       lck_spin_destroy(&kqwl->kqwl_statelock, kq_lck_grp);
+       kqueue_destroy(kqwl, kqworkloop_zone);
 }
 
-/*
- * Called with the kqhash_lock() held
+/*!
+ * @function kqworkloop_alloc
+ *
+ * @brief
+ * Allocates a workloop kqueue.
  */
 static void
-kqueue_hash_insert(
-       struct proc *p,
-       kqueue_id_t id,
-       struct kqueue *kq)
+kqworkloop_init(struct kqworkloop *kqwl, proc_t p,
+    kqueue_id_t id, workq_threadreq_param_t *trp)
 {
-       struct kqworkloop *kqwl = (struct kqworkloop *)kq;
-       struct filedesc *fdp = p->p_fd;
-       struct kqlist *list;
+       bzero(kqwl, sizeof(struct kqworkloop));
 
-       /* should hold the kq hash lock */
-       kqhash_lock_held(p);
+       kqwl->kqwl_state     = KQ_WORKLOOP | KQ_DYNAMIC | KQ_KEV_QOS;
+       kqwl->kqwl_retains   = 1; /* donate a retain to creator */
+       kqwl->kqwl_dynamicid = id;
+       kqwl->kqwl_p         = p;
+       if (trp) {
+               kqwl->kqwl_params = trp->trp_value;
+       }
 
-       if ((kq->kq_state & KQ_DYNAMIC) == 0) {
-               assert(kq->kq_state & KQ_DYNAMIC);
-               return;
+       workq_tr_flags_t tr_flags = WORKQ_TR_FLAG_WORKLOOP;
+       if (trp) {
+               if (trp->trp_flags & TRP_PRIORITY) {
+                       tr_flags |= WORKQ_TR_FLAG_WL_OUTSIDE_QOS;
+               }
+               if (trp->trp_flags) {
+                       tr_flags |= WORKQ_TR_FLAG_WL_PARAMS;
+               }
        }
+       kqwl->kqwl_request.tr_state = WORKQ_TR_STATE_IDLE;
+       kqwl->kqwl_request.tr_flags = tr_flags;
 
-       /* only dynamically allocate workloop kqs for now */
-       assert(kq->kq_state & KQ_WORKLOOP);
-       assert(fdp->fd_kqhash);
+       for (int i = 0; i < KQWL_NBUCKETS; i++) {
+               TAILQ_INIT_AFTER_BZERO(&kqwl->kqwl_queue[i]);
+       }
+       TAILQ_INIT_AFTER_BZERO(&kqwl->kqwl_suppressed);
 
-       kqwl->kqwl_dynamicid = id;
+       lck_spin_init(&kqwl->kqwl_statelock, kq_lck_grp, kq_lck_attr);
 
-       list = &fdp->fd_kqhash[KQ_HASH(id, fdp->fd_kqhashmask)];
-       SLIST_INSERT_HEAD(list, kqwl, kqwl_hashlink);
+       kqueue_init(kqwl, &kqwl->kqwl_waitq_hook, SYNC_POLICY_FIFO);
 }
 
-/* Called with kqhash_lock held */
-static void
-kqueue_hash_remove(
-       struct proc *p,
-       struct kqueue *kq)
+/*!
+ * @function kqworkloop_get_or_create
+ *
+ * @brief
+ * Wrapper around kqworkloop_alloc that handles the uniquing of workloops.
+ *
+ * @returns
+ * 0:      success
+ * EINVAL: invalid parameters
+ * EEXIST: KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST is set and a collision exists.
+ * ENOENT: KEVENT_FLAG_DYNAMIC_KQ_MUST_EXIST is set and the entry wasn't found.
+ * ENOMEM: allocation failed
+ */
+static int
+kqworkloop_get_or_create(struct proc *p, kqueue_id_t id,
+    workq_threadreq_param_t *trp, unsigned int flags, struct kqworkloop **kqwlp)
 {
-       struct kqworkloop *kqwl = (struct kqworkloop *)kq;
        struct filedesc *fdp = p->p_fd;
-       struct kqlist *list;
+       struct kqworkloop *alloc_kqwl = NULL;
+       struct kqworkloop *kqwl = NULL;
+       int error = 0;
 
-       /* should hold the kq hash lock */
-       kqhash_lock_held(p);
+       assert(!trp || (flags & KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST));
 
-       if ((kq->kq_state & KQ_DYNAMIC) == 0) {
-               assert(kq->kq_state & KQ_DYNAMIC);
-               return;
+       if (id == 0 || id == (kqueue_id_t)-1) {
+               return EINVAL;
        }
-       assert(kq->kq_state & KQ_WORKLOOP); /* for now */
-       list = &fdp->fd_kqhash[KQ_HASH(kqwl->kqwl_dynamicid, fdp->fd_kqhashmask)];
-       SLIST_REMOVE(list, kqwl, kqworkloop, kqwl_hashlink);
+
+       for (;;) {
+               kqhash_lock(fdp);
+               if (__improbable(fdp->fd_kqhash == NULL)) {
+                       kqworkloop_hash_init(fdp);
+               }
+
+               kqwl = kqworkloop_hash_lookup_locked(fdp, id);
+               if (kqwl) {
+                       if (__improbable(flags & KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST)) {
+                               /*
+                                * If MUST_NOT_EXIST was passed, even if we would have failed
+                                * the try_retain, it could have gone the other way, and
+                                * userspace can't tell. Let'em fix their race.
+                                */
+                               error = EEXIST;
+                               break;
+                       }
+
+                       if (__probable(kqworkloop_try_retain(kqwl))) {
+                               /*
+                                * This is a valid live workloop !
+                                */
+                               *kqwlp = kqwl;
+                               error = 0;
+                               break;
+                       }
+               }
+
+               if (__improbable(flags & KEVENT_FLAG_DYNAMIC_KQ_MUST_EXIST)) {
+                       error = ENOENT;
+                       break;
+               }
+
+               /*
+                * We didn't find what we were looking for.
+                *
+                * If this is the second time we reach this point (alloc_kqwl != NULL),
+                * then we're done.
+                *
+                * If this is the first time we reach this point (alloc_kqwl == NULL),
+                * then try to allocate one without blocking.
+                */
+               if (__probable(alloc_kqwl == NULL)) {
+                       alloc_kqwl = (struct kqworkloop *)zalloc_noblock(kqworkloop_zone);
+               }
+               if (__probable(alloc_kqwl)) {
+                       kqworkloop_init(alloc_kqwl, p, id, trp);
+                       kqworkloop_hash_insert_locked(fdp, id, alloc_kqwl);
+                       kqhash_unlock(fdp);
+                       *kqwlp = alloc_kqwl;
+                       return 0;
+               }
+
+               /*
+                * We have to block to allocate a workloop, drop the lock,
+                * allocate one, but then we need to retry lookups as someone
+                * else could race with us.
+                */
+               kqhash_unlock(fdp);
+
+               alloc_kqwl = (struct kqworkloop *)zalloc(kqworkloop_zone);
+               if (__improbable(!alloc_kqwl)) {
+                       return ENOMEM;
+               }
+       }
+
+       kqhash_unlock(fdp);
+
+       if (__improbable(alloc_kqwl)) {
+               zfree(kqworkloop_zone, alloc_kqwl);
+       }
+
+       return error;
 }
 
-/* Called with kqhash_lock held */
-static struct kqueue *
-kqueue_hash_lookup(struct proc *p, kqueue_id_t id)
+#pragma mark - knotes
+
+static int
+filt_no_attach(struct knote *kn, __unused struct kevent_qos_s *kev)
 {
-       struct filedesc *fdp = p->p_fd;
-       struct kqlist *list;
-       struct kqworkloop *kqwl;
+       knote_set_error(kn, ENOTSUP);
+       return 0;
+}
+
+static void
+filt_no_detach(__unused struct knote *kn)
+{
+}
+
+static int __dead2
+filt_bad_event(struct knote *kn, long hint)
+{
+       panic("%s[%d](%p, %ld)", __func__, kn->kn_filter, kn, hint);
+}
 
-       /* should hold the kq hash lock */
-       kqhash_lock_held(p);
+static int __dead2
+filt_bad_touch(struct knote *kn, struct kevent_qos_s *kev)
+{
+       panic("%s[%d](%p, %p)", __func__, kn->kn_filter, kn, kev);
+}
 
-       if (fdp->fd_kqhashmask == 0) return NULL;
+static int __dead2
+filt_bad_process(struct knote *kn, struct kevent_qos_s *kev)
+{
+       panic("%s[%d](%p, %p)", __func__, kn->kn_filter, kn, kev);
+}
 
-       list = &fdp->fd_kqhash[KQ_HASH(id, fdp->fd_kqhashmask)];
-       SLIST_FOREACH(kqwl, list, kqwl_hashlink) {
-               if (kqwl->kqwl_dynamicid == id) {
-                       struct kqueue *kq = (struct kqueue *)kqwl;
+/*
+ * knotes_dealloc - detach all knotes for the process and drop them
+ *
+ *             Called with proc_fdlock held.
+ *             Returns with it locked.
+ *             May drop it temporarily.
+ *             Process is in such a state that it will not try to allocate
+ *             any more knotes during this process (stopped for exit or exec).
+ */
+void
+knotes_dealloc(proc_t p)
+{
+       struct filedesc *fdp = p->p_fd;
+       struct kqueue *kq;
+       struct knote *kn;
+       struct  klist *kn_hash = NULL;
+       int i;
 
-                       assert(kq->kq_state & KQ_DYNAMIC);
-                       assert(kq->kq_state & KQ_WORKLOOP); /* for now */
-                       return kq;
+       /* Close all the fd-indexed knotes up front */
+       if (fdp->fd_knlistsize > 0) {
+               for (i = 0; i < fdp->fd_knlistsize; i++) {
+                       while ((kn = SLIST_FIRST(&fdp->fd_knlist[i])) != NULL) {
+                               kq = knote_get_kq(kn);
+                               kqlock(kq);
+                               proc_fdunlock(p);
+                               knote_drop(kq, kn, NULL);
+                               proc_fdlock(p);
+                       }
                }
+               /* free the table */
+               FREE(fdp->fd_knlist, M_KQUEUE);
+               fdp->fd_knlist = NULL;
        }
-       return NULL;
-}
+       fdp->fd_knlistsize = 0;
 
-static inline void
-kqueue_release_last(struct proc *p, kqueue_t kqu)
-{
-       struct kqueue *kq = kqu.kq;
-       if (kq->kq_state & KQ_DYNAMIC) {
-               kqhash_lock(p);
-               if (kqueue_release(kq, KQUEUE_MIGHT_BE_LAST_REF)) {
-                       thread_t cur_owner = kqworkloop_invalidate(kqu.kqwl);
-                       kqueue_hash_remove(p, kq);
-                       kqhash_unlock(p);
-                       if (cur_owner) thread_deallocate(cur_owner);
-                       kqueue_dealloc(kq);
-               } else {
-                       kqhash_unlock(p);
+       knhash_lock(fdp);
+       proc_fdunlock(p);
+
+       /* Clean out all the hashed knotes as well */
+       if (fdp->fd_knhashmask != 0) {
+               for (i = 0; i <= (int)fdp->fd_knhashmask; i++) {
+                       while ((kn = SLIST_FIRST(&fdp->fd_knhash[i])) != NULL) {
+                               kq = knote_get_kq(kn);
+                               kqlock(kq);
+                               knhash_unlock(fdp);
+                               knote_drop(kq, kn, NULL);
+                               knhash_lock(fdp);
+                       }
                }
+               kn_hash = fdp->fd_knhash;
+               fdp->fd_knhashmask = 0;
+               fdp->fd_knhash = NULL;
+       }
+
+       knhash_unlock(fdp);
+
+       /* free the kn_hash table */
+       if (kn_hash) {
+               FREE(kn_hash, M_KQUEUE);
        }
+
+       proc_fdlock(p);
 }
 
 /*
@@ -3519,732 +3502,154 @@ void
 kqworkloops_dealloc(proc_t p)
 {
        struct filedesc *fdp = p->p_fd;
-       struct kqlist *list;
        struct kqworkloop *kqwl, *kqwln;
-       struct kqlist tofree;
-       int i;
+       struct kqwllist tofree;
 
        if (!(fdp->fd_flags & FD_WORKLOOP)) {
                return;
        }
 
-       SLIST_INIT(&tofree);
+       kqhash_lock(fdp);
+
+       if (fdp->fd_kqhashmask == 0) {
+               kqhash_unlock(fdp);
+               return;
+       }
 
-       kqhash_lock(p);
-       assert(fdp->fd_kqhashmask != 0);
+       LIST_INIT(&tofree);
 
-       for (i = 0; i <= (int)fdp->fd_kqhashmask; i++) {
-               list = &fdp->fd_kqhash[i];
-               SLIST_FOREACH_SAFE(kqwl, list, kqwl_hashlink, kqwln) {
+       for (size_t i = 0; i <= fdp->fd_kqhashmask; i++) {
+               LIST_FOREACH_SAFE(kqwl, &fdp->fd_kqhash[i], kqwl_hashlink, kqwln) {
                        /*
                         * kqworkloops that have scheduling parameters have an
                         * implicit retain from kqueue_workloop_ctl that needs
                         * to be balanced on process exit.
                         */
                        assert(kqwl->kqwl_params);
-                       SLIST_REMOVE(list, kqwl, kqworkloop, kqwl_hashlink);
-                       SLIST_INSERT_HEAD(&tofree, kqwl, kqwl_hashlink);
+                       LIST_REMOVE(kqwl, kqwl_hashlink);
+                       LIST_INSERT_HEAD(&tofree, kqwl, kqwl_hashlink);
                }
        }
 
-       kqhash_unlock(p);
+       kqhash_unlock(fdp);
 
-       SLIST_FOREACH_SAFE(kqwl, &tofree, kqwl_hashlink, kqwln) {
-               struct kqueue *kq = (struct kqueue *)kqwl;
-               __assert_only bool released;
-               released = kqueue_release(kq, KQUEUE_MIGHT_BE_LAST_REF);
-               assert(released);
-               kqueue_dealloc(kq);
+       LIST_FOREACH_SAFE(kqwl, &tofree, kqwl_hashlink, kqwln) {
+               kqworkloop_dealloc(kqwl, KQWL_DEALLOC_SKIP_HASH_REMOVE, 1);
        }
 }
 
-static struct kqueue *
-kevent_get_bound_kqworkloop(thread_t thread)
-{
-       struct uthread *ut = get_bsdthread_info(thread);
-       struct kqrequest *kqr = ut->uu_kqr_bound;
-
-       return kqr ? (struct kqueue *)kqr_kqworkloop(kqr) : NULL;
-}
-
 static int
-kevent_get_kq(struct proc *p, kqueue_id_t id, workq_threadreq_param_t *trp,
-               unsigned int flags, struct fileproc **fpp, int *fdp,
-               struct kqueue **kqp)
-{
-       struct filedesc *descp = p->p_fd;
-       struct fileproc *fp = NULL;
-       struct kqueue *kq = NULL;
-       int fd = 0;
-       int error = 0;
-       thread_t th = current_thread();
-
-       assert(!trp || (flags & KEVENT_FLAG_WORKLOOP));
-
-       /* Was the workloop flag passed?  Then it is for sure only a workloop */
-       if (flags & KEVENT_FLAG_DYNAMIC_KQUEUE) {
-               assert(flags & KEVENT_FLAG_WORKLOOP);
-               assert(!trp || (flags & KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST));
-               kq = kevent_get_bound_kqworkloop(th);
+kevent_register_validate_priority(struct kqueue *kq, struct knote *kn,
+    struct kevent_qos_s *kev)
+{
+       /* We don't care about the priority of a disabled or deleted knote */
+       if (kev->flags & (EV_DISABLE | EV_DELETE)) {
+               return 0;
+       }
 
+       if (kq->kq_state & KQ_WORKLOOP) {
                /*
-                * when kevent_id_internal is called from within the
-                * kernel, and the passed 'id' value is '-1' then we
-                * look for the currently bound workloop kq.
+                * Workloops need valid priorities with a QOS (excluding manager) for
+                * any enabled knote.
+                *
+                * When it is pre-existing, just make sure it has a valid QoS as
+                * kevent_register() will not use the incoming priority (filters who do
+                * have the responsibility to validate it again, see filt_wltouch).
+                *
+                * If the knote is being made, validate the incoming priority.
                 */
-               if (id == (kqueue_id_t)-1 &&
-                   (flags & KEVENT_FLAG_KERNEL) &&
-                   (flags & KEVENT_FLAG_WORKLOOP)) {
-
-                       if (!is_workqueue_thread(th) || !kq) {
-                               return EINVAL;
-                       }
-
-                       kqueue_retain(kq);
-                       goto out;
-               }
-
-               if (id == 0 || id == (kqueue_id_t)-1) {
-                       return EINVAL;
-               }
-
-               /* try shortcut on kq lookup for bound threads */
-               if (kq != NULL && ((struct kqworkloop *)kq)->kqwl_dynamicid == id) {
-
-                       if (flags & KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST) {
-                               return EEXIST;
-                       }
-
-                       /* retain a reference while working with this kq. */
-                       assert(kq->kq_state & KQ_DYNAMIC);
-                       kqueue_retain(kq);
-                       goto out;
+               if (!_pthread_priority_thread_qos(kn ? kn->kn_qos : kev->qos)) {
+                       return ERANGE;
                }
+       }
 
-               /* look for the kq on the hash table */
-               kqhash_lock(p);
-               kq = kqueue_hash_lookup(p, id);
-               if (kq == NULL) {
-                       kqhash_unlock(p);
-
-                       if (flags & KEVENT_FLAG_DYNAMIC_KQ_MUST_EXIST) {
-                               return ENOENT;
-                       }
-
-                       struct kqueue *alloc_kq;
-                       alloc_kq = kqueue_alloc(p, flags);
-                       if (!alloc_kq) {
-                               return ENOMEM;
-                       }
-
-                       kqhash_lock(p);
-                       kqueue_hash_init_if_needed(p);
-                       kq = kqueue_hash_lookup(p, id);
-                       if (kq == NULL) {
-                               /* insert our new one */
-                               kq = alloc_kq;
-                               if (trp) {
-                                       struct kqworkloop *kqwl = (struct kqworkloop *)kq;
-                                       kqwl->kqwl_params = trp->trp_value;
-                               }
-                               kqueue_hash_insert(p, id, kq);
-                               kqhash_unlock(p);
-                       } else if (flags & KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST) {
-                               /* lost race and caller wants an error */
-                               kqhash_unlock(p);
-                               kqueue_release(alloc_kq, KQUEUE_MIGHT_BE_LAST_REF);
-                               kqueue_dealloc(alloc_kq);
-                               return EEXIST;
-                       } else {
-                               /* lost race, retain existing workloop */
-                               kqueue_retain(kq);
-                               kqhash_unlock(p);
-                               kqueue_release(alloc_kq, KQUEUE_MIGHT_BE_LAST_REF);
-                               kqueue_dealloc(alloc_kq);
-                       }
-               } else {
-
-                       if (flags & KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST) {
-                               kqhash_unlock(p);
-                               return  EEXIST;
-                       }
+       return 0;
+}
 
-                       /* retain a reference while working with this kq. */
-                       assert(kq->kq_state & KQ_DYNAMIC);
-                       kqueue_retain(kq);
-                       kqhash_unlock(p);
-               }
+/*
+ * Prepare a filter for waiting after register.
+ *
+ * The f_post_register_wait hook will be called later by kevent_register()
+ * and should call kevent_register_wait_block()
+ */
+static int
+kevent_register_wait_prepare(struct knote *kn, struct kevent_qos_s *kev, int rc)
+{
+       thread_t thread = current_thread();
 
-       } else if (flags & KEVENT_FLAG_WORKQ) {
-               /* must already exist for bound threads. */
-               if (flags & KEVENT_FLAG_KERNEL) {
-                       assert(descp->fd_wqkqueue != NULL);
-               }
+       assert(knote_fops(kn)->f_extended_codes);
 
+       if (kn->kn_thread == NULL) {
+               thread_reference(thread);
+               kn->kn_thread = thread;
+       } else if (kn->kn_thread != thread) {
                /*
-                * use the private kq associated with the proc workq.
-                * Just being a thread within the process (and not
-                * being the exit/exec thread) is enough to hold a
-                * reference on this special kq.
+                * kn_thread may be set from a previous aborted wait
+                * However, it has to be from the same thread.
                 */
-               kq = descp->fd_wqkqueue;
-               if (kq == NULL) {
-                       struct kqueue *alloc_kq = kqueue_alloc(p, KEVENT_FLAG_WORKQ);
-                       if (alloc_kq == NULL) {
-                               return ENOMEM;
-                       }
-
-                       knhash_lock(p);
-                       if (descp->fd_wqkqueue == NULL) {
-                               kq = descp->fd_wqkqueue = alloc_kq;
-                               knhash_unlock(p);
-                       } else {
-                               knhash_unlock(p);
-                               kq = descp->fd_wqkqueue;
-                               kqueue_dealloc(alloc_kq);
-                       }
-               }
-       } else {
-               /* get a usecount for the kq itself */
-               fd = (int)id;
-               if ((error = fp_getfkq(p, fd, &fp, &kq)) != 0)
-                       return (error);
-       }
-       if ((error = kevent_set_kq_mode(kq, flags)) != 0) {
-               /* drop the usecount */
-               if (fp != NULL)
-                       fp_drop(p, fd, fp, 0);
-               return error;
+               kev->flags |= EV_ERROR;
+               kev->data = EXDEV;
+               return 0;
        }
 
-out:
-       *fpp = fp;
-       *fdp = fd;
-       *kqp = kq;
-
-       return error;
+       return FILTER_REGISTER_WAIT | rc;
 }
 
+/*
+ * Cleanup a kevent_register_wait_prepare() effect for threads that have been
+ * aborted instead of properly woken up with thread_wakeup_thread().
+ */
 static void
-kevent_put_kq(
-       struct proc *p,
-       kqueue_id_t id,
-       struct fileproc *fp,
-       struct kqueue *kq)
+kevent_register_wait_cleanup(struct knote *kn)
 {
-       kqueue_release_last(p, kq);
-       if (fp != NULL) {
-               assert((kq->kq_state & KQ_WORKQ) == 0);
-               fp_drop(p, (int)id, fp, 0);
-       }
+       thread_t thread = kn->kn_thread;
+       kn->kn_thread = NULL;
+       thread_deallocate(thread);
 }
 
-static uint64_t
-kevent_workloop_serial_no_copyin(proc_t p, uint64_t workloop_id)
+/*
+ * Must be called at the end of a f_post_register_wait call from a filter.
+ */
+static void
+kevent_register_wait_block(struct turnstile *ts, thread_t thread,
+    thread_continue_t cont, struct _kevent_register *cont_args)
 {
-       uint64_t serial_no = 0;
-       user_addr_t addr;
-       int rc;
-
-       if (workloop_id == 0 || p->p_dispatchqueue_serialno_offset == 0) {
-               return 0;
-       }
-       addr = (user_addr_t)(workloop_id + p->p_dispatchqueue_serialno_offset);
-
-       if (proc_is64bit(p)) {
-               rc = copyin(addr, (caddr_t)&serial_no, sizeof(serial_no));
-       } else {
-               uint32_t serial_no32 = 0;
-               rc = copyin(addr, (caddr_t)&serial_no32, sizeof(serial_no32));
-               serial_no = serial_no32;
-       }
-       return rc == 0 ? serial_no : 0;
+       turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_HELD);
+       kqunlock(cont_args->kqwl);
+       cont_args->handoff_thread = thread;
+       thread_handoff_parameter(thread, cont, cont_args);
 }
 
-int
-kevent_exit_on_workloop_ownership_leak(thread_t thread)
+/*
+ * Called by Filters using a f_post_register_wait to return from their wait.
+ */
+static void
+kevent_register_wait_return(struct _kevent_register *cont_args)
 {
-       proc_t p = current_proc();
-       struct filedesc *fdp = p->p_fd;
-       kqueue_id_t workloop_id = 0;
-       os_reason_t reason = OS_REASON_NULL;
-       mach_vm_address_t addr;
-       uint32_t reason_size;
-
-       kqhash_lock(p);
-       if (fdp->fd_kqhashmask > 0) {
-               for (uint32_t i = 0; i < fdp->fd_kqhashmask + 1; i++) {
-                       struct kqworkloop *kqwl;
-
-                       SLIST_FOREACH(kqwl, &fdp->fd_kqhash[i], kqwl_hashlink) {
-                               struct kqueue *kq = &kqwl->kqwl_kqueue;
-                               if ((kq->kq_state & KQ_DYNAMIC) && kqwl->kqwl_owner == thread) {
-                                       workloop_id = kqwl->kqwl_dynamicid;
-                                       break;
-                               }
-                       }
-               }
-       }
-       kqhash_unlock(p);
-
-       reason = os_reason_create(OS_REASON_LIBSYSTEM,
-                       OS_REASON_LIBSYSTEM_CODE_WORKLOOP_OWNERSHIP_LEAK);
-       if (reason == OS_REASON_NULL) {
-               goto out;
-       }
+       struct kqworkloop *kqwl = cont_args->kqwl;
+       struct kevent_qos_s *kev = &cont_args->kev;
+       int error = 0;
 
-       reason->osr_flags |= OS_REASON_FLAG_GENERATE_CRASH_REPORT;
-       reason_size = 2 * sizeof(uint64_t);
-       reason_size = kcdata_estimate_required_buffer_size(2, reason_size);
-       if (os_reason_alloc_buffer(reason, reason_size) != 0) {
-               goto out;
+       if (cont_args->handoff_thread) {
+               thread_deallocate(cont_args->handoff_thread);
        }
 
-       if (workloop_id) {
-               struct kcdata_descriptor *kcd = &reason->osr_kcd_descriptor;
-
-               if (kcdata_get_memory_addr(kcd, EXIT_REASON_WORKLOOP_ID,
-                               sizeof(workloop_id), &addr) == KERN_SUCCESS) {
-                       kcdata_memcpy(kcd, addr, &workloop_id, sizeof(workloop_id));
+       if (kev->flags & (EV_ERROR | EV_RECEIPT)) {
+               if ((kev->flags & EV_ERROR) == 0) {
+                       kev->flags |= EV_ERROR;
+                       kev->data = 0;
                }
-
-               uint64_t serial_no = kevent_workloop_serial_no_copyin(p, workloop_id);
-               if (serial_no && kcdata_get_memory_addr(kcd, EXIT_REASON_DISPATCH_QUEUE_NO,
-                               sizeof(serial_no), &addr) == KERN_SUCCESS) {
-                       kcdata_memcpy(kcd, addr, &serial_no, sizeof(serial_no));
+               error = kevent_modern_copyout(kev, &cont_args->ueventlist);
+               if (error == 0) {
+                       cont_args->eventout++;
                }
        }
-out:
-#if DEVELOPMENT || DEBUG
-       if (kevent_debug_flags() & KEVENT_PANIC_ON_WORKLOOP_OWNERSHIP_LEAK) {
-               panic("thread %p in task %p is leaked workloop 0x%016llx ownership",
-                               thread, p->task, workloop_id);
+
+       kqworkloop_release(kqwl);
+       if (error == 0) {
+               *(int32_t *)&current_uthread()->uu_rval = cont_args->eventout;
        }
-       psignal_try_thread_with_reason(p, thread, SIGABRT, reason);
-       return 0;
-#else
-       return exit_with_reason(p, W_EXITCODE(0, SIGKILL), (int *)NULL,
-                       FALSE, FALSE, 0, reason);
-#endif
-}
-
-static inline boolean_t
-kevent_args_requesting_events(unsigned int flags, int nevents)
-{
-       return (!(flags & KEVENT_FLAG_ERROR_EVENTS) && nevents > 0);
-}
-
-static int
-kevent_internal(struct proc *p,
-               kqueue_id_t id, kqueue_id_t *id_out,
-               user_addr_t changelist, int nchanges,
-               user_addr_t ueventlist, int nevents,
-               user_addr_t data_out, uint64_t data_available,
-               unsigned int flags,
-               user_addr_t utimeout,
-               kqueue_continue_t continuation,
-               int32_t *retval)
-{
-       uthread_t ut;
-       struct kqueue *kq;
-       struct fileproc *fp = NULL;
-       int fd = 0;
-       struct kevent_internal_s kev;
-       int error, noutputs, register_rc;
-       bool needs_end_processing = false;
-       struct timeval atv;
-       user_size_t data_size;
-       user_size_t data_resid;
-       thread_t thread = current_thread();
-       KNOTE_LOCK_CTX(knlc);
-
-       /* Don't allow user-space threads to process output events from the workq kqs */
-       if (((flags & (KEVENT_FLAG_WORKQ | KEVENT_FLAG_KERNEL)) == KEVENT_FLAG_WORKQ) &&
-           kevent_args_requesting_events(flags, nevents))
-               return EINVAL;
-
-       if (flags & KEVENT_FLAG_PARKING) {
-               if (!kevent_args_requesting_events(flags, nevents) || id != (kqueue_id_t)-1)
-                       return EINVAL;
-       }
-
-       /* restrict dynamic kqueue allocation to workloops (for now) */
-       if ((flags & (KEVENT_FLAG_DYNAMIC_KQUEUE | KEVENT_FLAG_WORKLOOP)) == KEVENT_FLAG_DYNAMIC_KQUEUE)
-               return EINVAL;
-
-       if ((flags & (KEVENT_FLAG_WORKLOOP)) && (flags & (KEVENT_FLAG_WORKQ)))
-               return EINVAL;
-
-       if (flags & (KEVENT_FLAG_DYNAMIC_KQ_MUST_EXIST | KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST)) {
-
-               /* allowed only on workloops when calling kevent_id from user-space */
-               if (!(flags & KEVENT_FLAG_WORKLOOP) || (flags & KEVENT_FLAG_KERNEL) || !(flags & KEVENT_FLAG_DYNAMIC_KQUEUE))
-                       return EINVAL;
-       }
-
-       /* prepare to deal with stack-wise allocation of out events */
-       if (flags & KEVENT_FLAG_STACK_EVENTS) {
-               int scale = ((flags & KEVENT_FLAG_LEGACY32) ?
-                            (IS_64BIT_PROCESS(p) ? sizeof(struct user64_kevent) :
-                                                   sizeof(struct user32_kevent)) :
-                            ((flags & KEVENT_FLAG_LEGACY64) ? sizeof(struct kevent64_s) :
-                                                              sizeof(struct kevent_qos_s)));
-               ueventlist += nevents * scale;
-       }
-
-       /* convert timeout to absolute - if we have one (and not immediate) */
-       error = kevent_get_timeout(p, utimeout, flags, &atv);
-       if (error)
-               return error;
-
-       /* copyin initial value of data residual from data_available */
-       error = kevent_get_data_size(p, data_available, flags, &data_size);
-       if (error)
-               return error;
-
-       /* get the kq we are going to be working on */
-       error = kevent_get_kq(p, id, NULL, flags, &fp, &fd, &kq);
-#if CONFIG_WORKLOOP_DEBUG
-       ut = (uthread_t)get_bsdthread_info(thread);
-       UU_KEVENT_HISTORY_WRITE_ENTRY(ut, {
-               .uu_kqid = id,
-               .uu_kq = error ? NULL : kq,
-               .uu_error = error,
-               .uu_nchanges = nchanges,
-               .uu_nevents = nevents,
-               .uu_flags = flags,
-       });
-#endif // CONFIG_WORKLOOP_DEBUG
-       if (error)
-               return error;
-
-       /* only bound threads can receive events on workloops */
-       if (flags & KEVENT_FLAG_WORKLOOP) {
-               struct kqworkloop *kqwl = (struct kqworkloop *)kq;
-               struct kqrequest *kqr = &kqwl->kqwl_request;
-
-               assert(kq->kq_state & KQ_WORKLOOP);
-
-               if (kevent_args_requesting_events(flags, nevents)) {
-                       if (kq != kevent_get_bound_kqworkloop(thread)) {
-                               error = EXDEV;
-                               goto out;
-                       }
-
-                       kq_req_lock(kqwl);
-                       /*
-                        * Disable the R2K notification while doing a register, if the
-                        * caller wants events too, we don't want the AST to be set if we
-                        * will process these events soon.
-                        */
-                       kqr->kqr_state &= ~KQR_R2K_NOTIF_ARMED;
-                       needs_end_processing = true;
-                       kq_req_unlock(kq);
-               }
-
-               if (id_out) {
-                       *id_out = kqwl->kqwl_dynamicid;
-               }
-
-       }
-
-       /* register all the change requests the user provided... */
-       noutputs = 0;
-       while (nchanges > 0 && error == 0) {
-               error = kevent_copyin(&changelist, &kev, p, flags);
-               if (error)
-                       break;
-
-               /* Make sure user doesn't pass in any system flags */
-               kev.flags &= ~EV_SYSFLAGS;
-
-               register_rc = kevent_register(kq, &kev, &knlc);
-               if (register_rc & FILTER_REGISTER_WAIT) {
-                       kqlock_held(kq);
-
-                       // f_post_register_wait is meant to call a continuation and not to
-                       // return, which is why we don't support FILTER_REGISTER_WAIT if
-                       // KEVENT_FLAG_ERROR_EVENTS is not passed, or if the event that
-                       // waits isn't the last.
-                       //
-                       // It is implementable, but not used by any userspace code at the
-                       // moment, so for now return ENOTSUP if someone tries to do it.
-                       if (nchanges == 1 && nevents >= 1 && (flags & KEVENT_FLAG_ERROR_EVENTS)) {
-                               struct _kevent_register *cont_args;
-                               /* store the continuation/completion data in the uthread */
-                               ut = (uthread_t)get_bsdthread_info(thread);
-                               cont_args = &ut->uu_save.uus_kevent_register;
-                               cont_args->kev = kev;
-                               cont_args->kq = kq;
-                               cont_args->fp = fp;
-                               cont_args->fd = fd;
-                               cont_args->ueventlist = ueventlist;
-                               cont_args->flags = flags;
-                               cont_args->retval = retval;
-                               cont_args->eventcount = nevents;
-                               cont_args->eventout = noutputs;
-                               knote_fops(cont_args->knote)->f_post_register_wait(ut, &knlc, cont_args);
-                               panic("f_post_register_wait returned (kev: %p)", &kev);
-                       }
-
-                       kev.flags |= EV_ERROR;
-                       kev.data = ENOTSUP;
-                       knote_unlock(kq, knlc.knlc_knote, &knlc, KNOTE_KQ_UNLOCK);
-               }
-
-               // keep in sync with kevent_register_wait_return()
-               if (nevents > 0 && (kev.flags & (EV_ERROR|EV_RECEIPT))) {
-                       if ((kev.flags & EV_ERROR) == 0) {
-                               kev.flags |= EV_ERROR;
-                               kev.data = 0;
-                       }
-                       error = kevent_copyout(&kev, &ueventlist, p, flags);
-                       if (error == 0) {
-                               nevents--;
-                               noutputs++;
-                       }
-               } else if (kev.flags & EV_ERROR) {
-                       error = kev.data;
-               }
-               nchanges--;
-       }
-
-       /* short-circuit the scan if we only want error events */
-       if (flags & KEVENT_FLAG_ERROR_EVENTS)
-               nevents = 0;
-
-       /* process pending events */
-       if (nevents > 0 && noutputs == 0 && error == 0) {
-               struct _kevent *cont_args;
-               /* store the continuation/completion data in the uthread */
-               ut = (uthread_t)get_bsdthread_info(thread);
-               cont_args = &ut->uu_save.uus_kevent;
-               cont_args->fp = fp;
-               cont_args->fd = fd;
-               cont_args->retval = retval;
-               cont_args->eventlist = ueventlist;
-               cont_args->eventcount = nevents;
-               cont_args->eventout = noutputs;
-               cont_args->data_available = data_available;
-               cont_args->process_data.fp_fd = (int)id;
-               cont_args->process_data.fp_flags = flags;
-               cont_args->process_data.fp_data_out = data_out;
-               cont_args->process_data.fp_data_size = data_size;
-               cont_args->process_data.fp_data_resid = data_size;
-
-               /*
-                * kqworkloop_end_processing() will happen at the end of kqueue_scan()
-                */
-               needs_end_processing = false;
-
-               error = kqueue_scan(kq, kevent_callback,
-                                   continuation, cont_args,
-                                   &cont_args->process_data,
-                                   &atv, p);
-
-               /* process remaining outputs */
-               noutputs = cont_args->eventout;
-               data_resid = cont_args->process_data.fp_data_resid;
-
-               /* copyout residual data size value (if it needs to be copied out) */
-               /* don't abandon other output just because of residual copyout failures */
-               if (error == 0 && data_available && data_resid != data_size) {
-                       (void)kevent_put_data_size(p, data_available, flags, data_resid);
-               }
-       }
-
-out:
-       if (__improbable(needs_end_processing)) {
-               /*
-                * If we didn't through kqworkloop_end_processing(),
-                * we need to do it here.
-                */
-               kqlock(kq);
-               kqworkloop_end_processing((struct kqworkloop *)kq, 0, 0);
-               kqunlock(kq);
-       }
-       kevent_put_kq(p, id, fp, kq);
-
-       /* don't restart after signals... */
-       if (error == ERESTART)
-               error = EINTR;
-       else if (error == EWOULDBLOCK)
-               error = 0;
-       if (error == 0)
-               *retval = noutputs;
-       return (error);
-}
-
-
-/*
- * kevent_callback - callback for each individual event
- *
- * called with nothing locked
- * caller holds a reference on the kqueue
- */
-static int
-kevent_callback(__unused struct kqueue *kq, struct kevent_internal_s *kevp,
-               void *data)
-{
-       struct _kevent *cont_args;
-       int error;
-
-       cont_args = (struct _kevent *)data;
-       assert(cont_args->eventout < cont_args->eventcount);
-
-       /*
-        * Copy out the appropriate amount of event data for this user.
-        */
-       error = kevent_copyout(kevp, &cont_args->eventlist, current_proc(),
-                              cont_args->process_data.fp_flags);
-
-       /*
-        * If there isn't space for additional events, return
-        * a harmless error to stop the processing here
-        */
-       if (error == 0 && ++cont_args->eventout == cont_args->eventcount)
-               error = EWOULDBLOCK;
-       return (error);
-}
-
-/*
- * kevent_description - format a description of a kevent for diagnostic output
- *
- * called with a 256-byte string buffer
- */
-
-char *
-kevent_description(struct kevent_internal_s *kevp, char *s, size_t n)
-{
-       snprintf(s, n,
-           "kevent="
-           "{.ident=%#llx, .filter=%d, .flags=%#x, .udata=%#llx, .fflags=%#x, .data=%#llx, .ext[0]=%#llx, .ext[1]=%#llx}",
-           kevp->ident,
-           kevp->filter,
-           kevp->flags,
-           kevp->udata,
-           kevp->fflags,
-           kevp->data,
-           kevp->ext[0],
-           kevp->ext[1] );
-
-       return (s);
-}
-
-static int
-kevent_register_validate_priority(struct kqueue *kq, struct knote *kn,
-               struct kevent_internal_s *kev)
-{
-       /* We don't care about the priority of a disabled or deleted knote */
-       if (kev->flags & (EV_DISABLE | EV_DELETE)) {
-               return 0;
-       }
-
-       if (kq->kq_state & KQ_WORKLOOP) {
-               /*
-                * Workloops need valid priorities with a QOS (excluding manager) for
-                * any enabled knote.
-                *
-                * When it is pre-existing, just make sure it has a valid QoS as
-                * kevent_register() will not use the incoming priority (filters who do
-                * have the responsibility to validate it again, see filt_wltouch).
-                *
-                * If the knote is being made, validate the incoming priority.
-                */
-               if (!_pthread_priority_thread_qos(kn ? kn->kn_qos : kev->qos)) {
-                       return ERANGE;
-               }
-       }
-
-       return 0;
-}
-
-/*
- * Prepare a filter for waiting after register.
- *
- * The f_post_register_wait hook will be called later by kevent_register()
- * and should call kevent_register_wait_block()
- */
-static int
-kevent_register_wait_prepare(struct knote *kn, struct kevent_internal_s *kev)
-{
-       thread_t thread = current_thread();
-       struct uthread *uth = get_bsdthread_info(thread);
-
-       assert(knote_fops(kn)->f_extended_codes);
-
-       if (kn->kn_hook == NULL) {
-               thread_reference(thread);
-               kn->kn_hook = thread;
-       } else if (kn->kn_hook != thread) {
-               /*
-                * kn_hook may be set from a previous aborted wait
-                * However, it has to be from the same thread.
-                */
-               kev->flags |= EV_ERROR;
-               kev->data = EXDEV;
-               return 0;
-       }
-
-       uth->uu_save.uus_kevent_register.knote = kn;
-       return FILTER_REGISTER_WAIT;
-}
-
-/*
- * Cleanup a kevent_register_wait_prepare() effect for threads that have been
- * aborted instead of properly woken up with thread_wakeup_thread().
- */
-static void
-kevent_register_wait_cleanup(struct knote *kn)
-{
-       thread_t thread = kn->kn_hook;
-       kn->kn_hook = NULL;
-       thread_deallocate(thread);
-}
-
-/*
- * Must be called at the end of a f_post_register_wait call from a filter.
- */
-static void
-kevent_register_wait_block(struct turnstile *ts, thread_t thread,
-               struct knote_lock_ctx *knlc, thread_continue_t cont,
-               struct _kevent_register *cont_args)
-{
-       knote_unlock(cont_args->kq, cont_args->knote, knlc, KNOTE_KQ_UNLOCK);
-       turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
-       cont_args->handoff_thread = thread;
-       thread_handoff_parameter(thread, cont, cont_args);
-}
-
-/*
- * Called by Filters using a f_post_register_wait to return from their wait.
- */
-static void
-kevent_register_wait_return(struct _kevent_register *cont_args)
-{
-       struct kqueue *kq = cont_args->kq;
-       proc_t p = kq->kq_p;
-       struct kevent_internal_s *kev = &cont_args->kev;
-       int error = 0;
-
-       if (cont_args->handoff_thread) {
-               thread_deallocate(cont_args->handoff_thread);
-       }
-
-       if (kev->flags & (EV_ERROR|EV_RECEIPT)) {
-               if ((kev->flags & EV_ERROR) == 0) {
-                       kev->flags |= EV_ERROR;
-                       kev->data = 0;
-               }
-               error = kevent_copyout(kev, &cont_args->ueventlist, p, cont_args->flags);
-               if (error == 0) cont_args->eventout++;
-       }
-
-       kevent_put_kq(p, cont_args->fd, cont_args->fp, kq);
-       if (error == 0) {
-               *cont_args->retval = cont_args->eventout;
-       }
-       unix_syscall_return(error);
+       unix_syscall_return(error);
 }
 
 /*
@@ -4262,50 +3667,49 @@ kevent_register_wait_return(struct _kevent_register *cont_args)
  */
 
 int
-kevent_register(struct kqueue *kq, struct kevent_internal_s *kev,
-               struct knote_lock_ctx *knlc)
+kevent_register(struct kqueue *kq, struct kevent_qos_s *kev,
+    struct knote **kn_out)
 {
        struct proc *p = kq->kq_p;
        const struct filterops *fops;
        struct knote *kn = NULL;
        int result = 0, error = 0;
        unsigned short kev_flags = kev->flags;
+       KNOTE_LOCK_CTX(knlc);
 
-       if (kev->filter < 0) {
-               if (kev->filter + EVFILT_SYSCOUNT < 0) {
-                       error = EINVAL;
-                       goto out;
-               }
-               fops = sysfilt_ops[~kev->filter];       /* to 0-base index */
+       if (__probable(kev->filter < 0 && kev->filter + EVFILT_SYSCOUNT >= 0)) {
+               fops = sysfilt_ops[~kev->filter];       /* to 0-base index */
        } else {
                error = EINVAL;
                goto out;
        }
 
        /* restrict EV_VANISHED to adding udata-specific dispatch kevents */
-       if ((kev->flags & EV_VANISHED) &&
-                       (kev->flags & (EV_ADD | EV_DISPATCH2)) != (EV_ADD | EV_DISPATCH2)) {
+       if (__improbable((kev->flags & EV_VANISHED) &&
+           (kev->flags & (EV_ADD | EV_DISPATCH2)) != (EV_ADD | EV_DISPATCH2))) {
                error = EINVAL;
                goto out;
        }
 
        /* Simplify the flags - delete and disable overrule */
-       if (kev->flags & EV_DELETE)
+       if (kev->flags & EV_DELETE) {
                kev->flags &= ~EV_ADD;
-       if (kev->flags & EV_DISABLE)
+       }
+       if (kev->flags & EV_DISABLE) {
                kev->flags &= ~EV_ENABLE;
+       }
 
        if (kq->kq_state & KQ_WORKLOOP) {
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_REGISTER),
-                             ((struct kqworkloop *)kq)->kqwl_dynamicid,
-                             kev->udata, kev->flags, kev->filter);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_REGISTER),
+                   ((struct kqworkloop *)kq)->kqwl_dynamicid,
+                   kev->udata, kev->flags, kev->filter);
        } else if (kq->kq_state & KQ_WORKQ) {
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWQ_REGISTER),
-                             0, kev->udata, kev->flags, kev->filter);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWQ_REGISTER),
+                   0, kev->udata, kev->flags, kev->filter);
        } else {
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQ_REGISTER),
-                             VM_KERNEL_UNSLIDE_OR_PERM(kq),
-                             kev->udata, kev->flags, kev->filter);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQ_REGISTER),
+                   VM_KERNEL_UNSLIDE_OR_PERM(kq),
+                   kev->udata, kev->flags, kev->filter);
        }
 
 restart:
@@ -4323,7 +3727,7 @@ restart:
                 */
 
                if ((kev_flags & EV_ADD) && (kev_flags & EV_DELETE) &&
-                               (kq->kq_state & KQ_WORKLOOP)) {
+                   (kq->kq_state & KQ_WORKLOOP)) {
                        /*
                         * For workloops, understand EV_ADD|EV_DELETE as a "soft" delete
                         * that doesn't care about ENOENT, so just pretend the deletion
@@ -4333,7 +3737,6 @@ restart:
                        error = ENOENT;
                }
                goto out;
-
        } else if (kn == NULL) {
                /*
                 * No knote found, need to attach a new one (attach)
@@ -4351,16 +3754,16 @@ restart:
                kn = knote_alloc();
                if (kn == NULL) {
                        error = ENOMEM;
-                       if (knote_fp != NULL)
+                       if (knote_fp != NULL) {
                                fp_drop(p, kev->ident, knote_fp, 0);
+                       }
                        goto out;
                }
 
                kn->kn_fp = knote_fp;
+               kn->kn_is_fd = fops->f_isfd;
                kn->kn_kq_packed = (intptr_t)(struct kqueue *)kq;
-               kqueue_retain(kq); /* retain a kq ref */
-               kn->kn_filtid = ~kev->filter;
-               kn->kn_status = KN_ATTACHING | KN_ATTACHED;
+               kn->kn_status = 0;
 
                /* was vanish support requested */
                if (kev->flags & EV_VANISHED) {
@@ -4369,33 +3772,33 @@ restart:
                }
 
                /* snapshot matching/dispatching protcol flags into knote */
-               if (kev->flags & EV_DISPATCH)
-                       kn->kn_status |= KN_DISPATCH;
-               if (kev->flags & EV_UDATA_SPECIFIC)
-                       kn->kn_status |= KN_UDATA_SPECIFIC;
-               if (kev->flags & EV_DISABLE)
+               if (kev->flags & EV_DISABLE) {
                        kn->kn_status |= KN_DISABLED;
+               }
 
                /*
                 * copy the kevent state into knote
                 * protocol is that fflags and data
                 * are saved off, and cleared before
                 * calling the attach routine.
+                *
+                * - kn->kn_sfflags aliases with kev->xflags
+                * - kn->kn_sdata   aliases with kev->data
+                * - kn->kn_filter  is the top 8 bits of kev->filter
                 */
-               kn->kn_kevent = *kev;
+               kn->kn_kevent  = *(struct kevent_internal_s *)kev;
                kn->kn_sfflags = kev->fflags;
-               kn->kn_sdata = kev->data;
-               kn->kn_fflags = 0;
-               kn->kn_data = 0;
-               knote_reset_priority(kn, kev->qos);
+               kn->kn_filtid  = (uint8_t)~kev->filter;
+               kn->kn_fflags  = 0;
+               knote_reset_priority(kq, kn, kev->qos);
 
                /* Add the knote for lookup thru the fd table */
-               error = kq_add_knote(kq, kn, knlc, p);
+               error = kq_add_knote(kq, kn, &knlc, p);
                if (error) {
-                       (void)kqueue_release(kq, KQUEUE_CANT_BE_LAST_REF);
                        knote_free(kn);
-                       if (knote_fp != NULL)
+                       if (knote_fp != NULL) {
                                fp_drop(p, kev->ident, knote_fp, 0);
+                       }
 
                        if (error == ERESTART) {
                                goto restart;
@@ -4417,13 +3820,17 @@ restart:
 
                kqlock(kq);
 
+               if (result & FILTER_THREADREQ_NODEFEER) {
+                       enable_preemption();
+               }
+
                if (kn->kn_flags & EV_ERROR) {
                        /*
                         * Failed to attach correctly, so drop.
                         */
-                       kn->kn_status &= ~(KN_ATTACHED | KN_ATTACHING);
-                       error = kn->kn_data;
-                       knote_drop(kq, kn, knlc);
+                       kn->kn_filtid = EVFILTID_DETACHED;
+                       error = kn->kn_sdata;
+                       knote_drop(kq, kn, &knlc);
                        result = 0;
                        goto out;
                }
@@ -4436,24 +3843,17 @@ restart:
                 * If the attach routine indicated that an
                 * event is already fired, activate the knote.
                 */
-               kn->kn_status &= ~KN_ATTACHING;
-               knote_set_qos_overcommit(kn);
-
-               if (result & FILTER_ACTIVE) {
-                       if (result & FILTER_ADJUST_EVENT_QOS_BIT)
-                               knote_adjust_qos(kq, kn, result);
-                       knote_activate(kn);
+               if ((kn->kn_qos & _PTHREAD_PRIORITY_OVERCOMMIT_FLAG) &&
+                   (kq->kq_state & KQ_WORKLOOP)) {
+                       kqworkloop_set_overcommit((struct kqworkloop *)kq);
                }
-
-       } else if (!knote_lock(kq, kn, knlc, KNOTE_KQ_LOCK_ON_SUCCESS)) {
-
+       } else if (!knote_lock(kq, kn, &knlc, KNOTE_KQ_LOCK_ON_SUCCESS)) {
                /*
                 * The knote was dropped while we were waiting for the lock,
                 * we need to re-evaluate entirely
                 */
 
                goto restart;
-
        } else if (kev->flags & EV_DELETE) {
                /*
                 * Deletion of a knote (drop)
@@ -4472,20 +3872,21 @@ restart:
                        drop = knote_fops(kn)->f_allow_drop(kn, kev);
                        kqlock(kq);
 
-                       if (!drop) goto out_unlock;
+                       if (!drop) {
+                               goto out_unlock;
+                       }
                }
 
                if ((kev->flags & EV_ENABLE) == 0 &&
-                               (kn->kn_status & (KN_DISPATCH2 | KN_DISABLED)) ==
-                               (KN_DISPATCH2 | KN_DISABLED)) {
+                   (kn->kn_flags & EV_DISPATCH2) == EV_DISPATCH2 &&
+                   (kn->kn_status & KN_DISABLED) != 0) {
                        kn->kn_status |= KN_DEFERDELETE;
                        error = EINPROGRESS;
                        goto out_unlock;
                }
 
-               knote_drop(kq, kn, knlc);
+               knote_drop(kq, kn, &knlc);
                goto out;
-
        } else {
                /*
                 * Regular update of a knote (touch)
@@ -4508,49 +3909,41 @@ restart:
                        kqunlock(kq);
                        result = filter_call(knote_fops(kn), f_touch(kn, kev));
                        kqlock(kq);
+                       if (result & FILTER_THREADREQ_NODEFEER) {
+                               enable_preemption();
+                       }
                }
 
                if (kev->flags & EV_ERROR) {
                        result = 0;
-               } else {
-                       /* accept new kevent state */
-                       if ((kn->kn_status & KN_UDATA_SPECIFIC) == 0)
-                               kn->kn_udata = kev->udata;
-                       if (kev->flags & EV_DISABLE)
-                               knote_disable(kn);
-                       if (result & (FILTER_UPDATE_REQ_QOS | FILTER_ADJUST_EVENT_QOS_BIT))
-                               knote_dequeue(kn);
-                       if ((result & FILTER_UPDATE_REQ_QOS) &&
-                                       kev->qos && kev->qos != kn->kn_qos) {
-                               knote_reset_priority(kn, kev->qos);
-                       }
-                       if (result & FILTER_ACTIVE) {
-                               thread_qos_t qos;
-                               if (result & FILTER_ADJUST_EVENT_QOS_BIT) {
-                                       if (knote_should_apply_qos_override(kq, kn, result, &qos)) {
-                                               knote_apply_qos_override(kn, qos);
-                                       }
-                               }
-                               knote_activate(kn);
-                       }
-                       if (result & (FILTER_UPDATE_REQ_QOS | FILTER_ADJUST_EVENT_QOS_BIT)) {
-                               if (knote_enqueue(kn) && (kn->kn_status & KN_ACTIVE)) {
-                                       knote_wakeup(kn);
-                               }
-                       }
-                       if (kev->flags & EV_ENABLE)
-                               knote_enable(kn);
+                       goto out_unlock;
+               }
+
+               if ((kn->kn_flags & EV_UDATA_SPECIFIC) == 0 &&
+                   kn->kn_udata != kev->udata) {
+                       // this allows klist_copy_udata() not to take locks
+                       os_atomic_store_wide(&kn->kn_udata, kev->udata, relaxed);
+               }
+               if ((kev->flags & EV_DISABLE) && !(kn->kn_status & KN_DISABLED)) {
+                       kn->kn_status |= KN_DISABLED;
+                       knote_dequeue(kq, kn);
                }
        }
 
+       /* accept new kevent state */
+       knote_apply_touch(kq, kn, kev, result);
+
 out_unlock:
-       if ((result & FILTER_REGISTER_WAIT) == 0) {
-               /*
-                * When the filter asked for a post-register wait,
-                * we leave the knote and kqueue locked for kevent_register()
-                * to call the filter's f_post_register_wait hook.
-                */
-               knote_unlock(kq, kn, knlc, KNOTE_KQ_UNLOCK);
+       /*
+        * When the filter asked for a post-register wait,
+        * we leave the kqueue locked for kevent_register()
+        * to call the filter's f_post_register_wait hook.
+        */
+       if (result & FILTER_REGISTER_WAIT) {
+               knote_unlock(kq, kn, &knlc, KNOTE_KQ_LOCK_ALWAYS);
+               *kn_out = kn;
+       } else {
+               knote_unlock(kq, kn, &knlc, KNOTE_KQ_UNLOCK);
        }
 
 out:
@@ -4583,45 +3976,40 @@ out:
  *     kqueue locked on entry and exit - but may be dropped
  */
 static int
-knote_process(struct knote *kn,
-       kevent_callback_t callback,
-       void *callback_data,
-       struct filt_process_s *process_data)
+knote_process(struct knote *kn, kevent_ctx_t kectx,
+    kevent_callback_t callback)
 {
-       struct kevent_internal_s kev;
+       struct kevent_qos_s kev;
        struct kqueue *kq = knote_get_kq(kn);
        KNOTE_LOCK_CTX(knlc);
        int result = FILTER_ACTIVE;
        int error = 0;
        bool drop = false;
 
-       bzero(&kev, sizeof(kev));
-
        /*
         * Must be active or stayactive
-        * Must be queued and not disabled/suppressed
+        * Must be queued and not disabled/suppressed or dropping
         */
        assert(kn->kn_status & KN_QUEUED);
-       assert(kn->kn_status & (KN_ACTIVE|KN_STAYACTIVE));
-       assert(!(kn->kn_status & (KN_DISABLED|KN_SUPPRESSED|KN_DROPPING)));
+       assert(kn->kn_status & (KN_ACTIVE | KN_STAYACTIVE));
+       assert(!(kn->kn_status & (KN_DISABLED | KN_SUPPRESSED | KN_DROPPING)));
 
        if (kq->kq_state & KQ_WORKLOOP) {
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS),
-                             ((struct kqworkloop *)kq)->kqwl_dynamicid,
-                             kn->kn_udata, kn->kn_status | (kn->kn_id << 32),
-                             kn->kn_filtid);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS),
+                   ((struct kqworkloop *)kq)->kqwl_dynamicid,
+                   kn->kn_udata, kn->kn_status | (kn->kn_id << 32),
+                   kn->kn_filtid);
        } else if (kq->kq_state & KQ_WORKQ) {
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWQ_PROCESS),
-                             0, kn->kn_udata, kn->kn_status | (kn->kn_id << 32),
-                             kn->kn_filtid);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWQ_PROCESS),
+                   0, kn->kn_udata, kn->kn_status | (kn->kn_id << 32),
+                   kn->kn_filtid);
        } else {
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQ_PROCESS),
-                             VM_KERNEL_UNSLIDE_OR_PERM(kq), kn->kn_udata,
-                             kn->kn_status | (kn->kn_id << 32), kn->kn_filtid);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQ_PROCESS),
+                   VM_KERNEL_UNSLIDE_OR_PERM(kq), kn->kn_udata,
+                   kn->kn_status | (kn->kn_id << 32), kn->kn_filtid);
        }
 
-       if ((kn->kn_status & KN_DROPPING) ||
-                       !knote_lock(kq, kn, &knlc, KNOTE_KQ_LOCK_ALWAYS)) {
+       if (!knote_lock(kq, kn, &knlc, KNOTE_KQ_LOCK_ALWAYS)) {
                /*
                 * When the knote is dropping or has dropped,
                 * then there's nothing we want to process.
@@ -4629,6 +4017,15 @@ knote_process(struct knote *kn,
                return EJUSTRETURN;
        }
 
+       /*
+        * While waiting for the knote lock, we may have dropped the kq lock.
+        * and a touch may have disabled and dequeued the knote.
+        */
+       if (!(kn->kn_status & KN_QUEUED)) {
+               knote_unlock(kq, kn, &knlc, KNOTE_KQ_LOCK_ALWAYS);
+               return EJUSTRETURN;
+       }
+
        /*
         * For deferred-drop or vanished events, we just create a fake
         * event to acknowledge end-of-life.  Otherwise, we call the
@@ -4638,21 +4035,27 @@ knote_process(struct knote *kn,
         * suppress knotes to avoid returning the same event multiple times in
         * a single call.
         */
-       knote_suppress(kn);
+       knote_suppress(kq, kn);
 
        if (kn->kn_status & (KN_DEFERDELETE | KN_VANISHED)) {
+               int kev_flags = EV_DISPATCH2 | EV_ONESHOT;
+               if (kn->kn_status & KN_DEFERDELETE) {
+                       kev_flags |= EV_DELETE;
+               } else {
+                       kev_flags |= EV_VANISHED;
+               }
+
                /* create fake event */
-               kev.filter = kn->kn_filter;
-               kev.ident = kn->kn_id;
-               kev.flags = (kn->kn_status & KN_DEFERDELETE) ? EV_DELETE : EV_VANISHED;
-               kev.flags |= (EV_DISPATCH2 | EV_ONESHOT);
-               kev.udata = kn->kn_udata;
+               kev = (struct kevent_qos_s){
+                       .filter = kn->kn_filter,
+                       .ident  = kn->kn_id,
+                       .flags  = kev_flags,
+                       .udata  = kn->kn_udata,
+               };
        } else {
-               /* deactivate - so new activations indicate a wakeup */
-               knote_deactivate(kn);
-
                kqunlock(kq);
-               result = filter_call(knote_fops(kn), f_process(kn, process_data, &kev));
+               kev = (struct kevent_qos_s) { };
+               result = filter_call(knote_fops(kn), f_process(kn, &kev));
                kqlock(kq);
        }
 
@@ -4683,30 +4086,31 @@ knote_process(struct knote *kn,
                         * For other knotes, since we will not return an event,
                         * there's no point keeping the knote suppressed.
                         */
-                       knote_unsuppress(kn);
+                       knote_unsuppress(kq, kn);
                }
                knote_unlock(kq, kn, &knlc, KNOTE_KQ_LOCK_ALWAYS);
                return EJUSTRETURN;
        }
 
-       if (result & FILTER_ADJUST_EVENT_QOS_BIT)
+       if (result & FILTER_ADJUST_EVENT_QOS_BIT) {
                knote_adjust_qos(kq, kn, result);
+       }
        kev.qos = _pthread_priority_combine(kn->kn_qos, kn->kn_qos_override);
 
        if (kev.flags & EV_ONESHOT) {
-               if ((kn->kn_status & (KN_DISPATCH2 | KN_DEFERDELETE)) == KN_DISPATCH2) {
+               if ((kn->kn_flags & EV_DISPATCH2) == EV_DISPATCH2 &&
+                   (kn->kn_status & KN_DEFERDELETE) == 0) {
                        /* defer dropping non-delete oneshot dispatch2 events */
-                       kn->kn_status |= KN_DEFERDELETE;
-                       knote_disable(kn);
+                       kn->kn_status |= KN_DEFERDELETE | KN_DISABLED;
                } else {
                        drop = true;
                }
-       } else if (kn->kn_status & KN_DISPATCH) {
+       } else if (kn->kn_flags & EV_DISPATCH) {
                /* disable all dispatch knotes */
-               knote_disable(kn);
-       } else if ((kev.flags & EV_CLEAR) == 0) {
+               kn->kn_status |= KN_DISABLED;
+       } else if ((kn->kn_flags & EV_CLEAR) == 0) {
                /* re-activate in case there are more events */
-               knote_activate(kn);
+               knote_activate(kq, kn, FILTER_ACTIVE);
        }
 
        /*
@@ -4721,12 +4125,12 @@ knote_process(struct knote *kn,
        }
 
        if (kev.flags & EV_VANISHED) {
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KNOTE_VANISHED),
-                             kev.ident, kn->kn_udata, kn->kn_status | (kn->kn_id << 32),
-                             kn->kn_filtid);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KNOTE_VANISHED),
+                   kev.ident, kn->kn_udata, kn->kn_status | (kn->kn_id << 32),
+                   kn->kn_filtid);
        }
 
-       error = (callback)(kq, &kev, callback_data);
+       error = (callback)(&kev, kectx);
        kqlock(kq);
        return error;
 }
@@ -4738,18 +4142,19 @@ knote_process(struct knote *kn,
 #define KQWQAE_END_PROCESSING   2
 #define KQWQAE_UNBIND           3
 static int
-kqworkq_acknowledge_events(struct kqworkq *kqwq, struct kqrequest *kqr,
-               int kevent_flags, int kqwqae_op)
+kqworkq_acknowledge_events(struct kqworkq *kqwq, workq_threadreq_t kqr,
+    int kevent_flags, int kqwqae_op)
 {
        thread_qos_t old_override = THREAD_QOS_UNSPECIFIED;
-       thread_t thread = kqr->kqr_thread;
+       thread_t thread = kqr_thread_fast(kqr);
        struct knote *kn;
        int rc = 0;
-       bool seen_stayactive = false, unbind;
+       bool unbind;
+       struct kqtailq *suppressq = &kqwq->kqwq_suppressed[kqr->tr_kq_qos_index];
 
        kqlock_held(&kqwq->kqwq_kqueue);
 
-       if (!TAILQ_EMPTY(&kqr->kqr_suppressed)) {
+       if (!TAILQ_EMPTY(suppressq)) {
                /*
                 * Return suppressed knotes to their original state.
                 * For workq kqueues, suppressed ones that are still
@@ -4757,23 +4162,17 @@ kqworkq_acknowledge_events(struct kqworkq *kqwq, struct kqrequest *kqr,
                 * set flags we check below to see if anything got
                 * woken up.
                 */
-               while ((kn = TAILQ_FIRST(&kqr->kqr_suppressed)) != NULL) {
+               while ((kn = TAILQ_FIRST(suppressq)) != NULL) {
                        assert(kn->kn_status & KN_SUPPRESSED);
-                       knote_unsuppress(kn);
-                       if (kn->kn_status & KN_STAYACTIVE) {
-                               seen_stayactive = true;
-                       }
+                       knote_unsuppress(kqwq, kn);
                }
        }
 
-       kq_req_lock(kqwq);
-
 #if DEBUG || DEVELOPMENT
        thread_t self = current_thread();
        struct uthread *ut = get_bsdthread_info(self);
 
-       assert(kqr->kqr_state & KQR_THREQUESTED);
-       assert(kqr->kqr_thread == self);
+       assert(thread == self);
        assert(ut->uu_kqr_bound == kqr);
 #endif // DEBUG || DEVELOPMENT
 
@@ -4781,15 +4180,8 @@ kqworkq_acknowledge_events(struct kqworkq *kqwq, struct kqrequest *kqr,
                unbind = true;
        } else if ((kevent_flags & KEVENT_FLAG_PARKING) == 0) {
                unbind = false;
-       } else if (kqwqae_op == KQWQAE_BEGIN_PROCESSING && seen_stayactive) {
-               /*
-                * When we unsuppress stayactive knotes, for the kind that are hooked
-                * through select, we need to process once before we can assert there's
-                * no event pending. Hence we can't unbind during BEGIN PROCESSING.
-                */
-               unbind = false;
        } else {
-               unbind = ((kqr->kqr_state & KQR_WAKEUP) == 0);
+               unbind = !kqr->tr_kq_wakeup;
        }
        if (unbind) {
                old_override = kqworkq_unbind_locked(kqwq, kqr, thread);
@@ -4798,9 +4190,9 @@ kqworkq_acknowledge_events(struct kqworkq *kqwq, struct kqrequest *kqr,
                 * request a new thread if we didn't process the whole queue or real events
                 * have happened (not just putting stay-active events back).
                 */
-               if (kqr->kqr_state & KQR_WAKEUP) {
+               if (kqr->tr_kq_wakeup) {
                        kqueue_threadreq_initiate(&kqwq->kqwq_kqueue, kqr,
-                                       kqr->kqr_qos_index, 0);
+                           kqr->tr_kq_qos_index, 0);
                }
        }
 
@@ -4810,13 +4202,11 @@ kqworkq_acknowledge_events(struct kqworkq *kqwq, struct kqrequest *kqr,
                 * as we cannot rely on the bucket queue emptiness because of stay
                 * active knotes.
                 */
-               kqr->kqr_state &= ~KQR_WAKEUP;
+               kqr->tr_kq_wakeup = false;
        }
 
-       kq_req_unlock(kqwq);
-
        if (old_override) {
-               thread_drop_ipc_override(thread);
+               thread_drop_kevent_override(thread);
        }
 
        return rc;
@@ -4830,63 +4220,44 @@ kqworkq_acknowledge_events(struct kqworkq *kqwq, struct kqrequest *kqr,
  * but may drop lock temporarily.
  */
 static int
-kqworkq_begin_processing(struct kqworkq *kqwq, struct kqrequest *kqr,
-               int kevent_flags)
+kqworkq_begin_processing(struct kqworkq *kqwq, workq_threadreq_t kqr,
+    int kevent_flags)
 {
        int rc = 0;
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWQ_PROCESS_BEGIN) | DBG_FUNC_START,
-                       0, kqr->kqr_qos_index);
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWQ_PROCESS_BEGIN) | DBG_FUNC_START,
+           0, kqr->tr_kq_qos_index);
 
        rc = kqworkq_acknowledge_events(kqwq, kqr, kevent_flags,
-                       KQWQAE_BEGIN_PROCESSING);
+           KQWQAE_BEGIN_PROCESSING);
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWQ_PROCESS_BEGIN) | DBG_FUNC_END,
-                       thread_tid(kqr->kqr_thread), kqr->kqr_state);
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWQ_PROCESS_BEGIN) | DBG_FUNC_END,
+           thread_tid(kqr_thread(kqr)), kqr->tr_kq_wakeup);
 
        return rc;
 }
 
-static inline bool
-kqworkloop_is_processing_on_current_thread(struct kqworkloop *kqwl)
-{
-       struct kqueue *kq = &kqwl->kqwl_kqueue;
-
-       kqlock_held(kq);
-
-       if (kq->kq_state & KQ_PROCESSING) {
-               /*
-                * KQ_PROCESSING is unset with the kqlock held, and the kqr thread is
-                * never modified while KQ_PROCESSING is set, meaning that peeking at
-                * its value is safe from this context.
-                */
-               return kqwl->kqwl_request.kqr_thread == current_thread();
-       }
-       return false;
-}
-
 static thread_qos_t
 kqworkloop_acknowledge_events(struct kqworkloop *kqwl)
 {
-       struct kqrequest *kqr = &kqwl->kqwl_request;
        kq_index_t qos = THREAD_QOS_UNSPECIFIED;
        struct knote *kn, *tmp;
 
-       kqlock_held(&kqwl->kqwl_kqueue);
+       kqlock_held(kqwl);
 
-       TAILQ_FOREACH_SAFE(kn, &kqr->kqr_suppressed, kn_tqe, tmp) {
+       TAILQ_FOREACH_SAFE(kn, &kqwl->kqwl_suppressed, kn_tqe, tmp) {
                /*
                 * If a knote that can adjust QoS is disabled because of the automatic
                 * behavior of EV_DISPATCH, the knotes should stay suppressed so that
                 * further overrides keep pushing.
                 */
                if (knote_fops(kn)->f_adjusts_qos && (kn->kn_status & KN_DISABLED) &&
-                               (kn->kn_status & (KN_STAYACTIVE | KN_DROPPING)) == 0 &&
-                               (kn->kn_flags & (EV_DISPATCH | EV_DISABLE)) == EV_DISPATCH) {
-                       qos = MAX(qos, knote_get_qos_override_index(kn));
+                   (kn->kn_status & (KN_STAYACTIVE | KN_DROPPING)) == 0 &&
+                   (kn->kn_flags & (EV_DISPATCH | EV_DISABLE)) == EV_DISPATCH) {
+                       qos = MAX(qos, kn->kn_qos_override);
                        continue;
                }
-               knote_unsuppress(kn);
+               knote_unsuppress(kqwl, kn);
        }
 
        return qos;
@@ -4895,23 +4266,23 @@ kqworkloop_acknowledge_events(struct kqworkloop *kqwl)
 static int
 kqworkloop_begin_processing(struct kqworkloop *kqwl, unsigned int kevent_flags)
 {
-       struct kqrequest *kqr = &kqwl->kqwl_request;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
        struct kqueue *kq = &kqwl->kqwl_kqueue;
-       thread_qos_t old_override = THREAD_QOS_UNSPECIFIED, qos_override;
-       thread_t thread = kqr->kqr_thread;
+       thread_qos_t qos_override;
+       thread_t thread = kqr_thread_fast(kqr);
        int rc = 0, op = KQWL_UTQ_NONE;
 
        kqlock_held(kq);
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS_BEGIN) | DBG_FUNC_START,
-                     kqwl->kqwl_dynamicid, 0, 0);
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS_BEGIN) | DBG_FUNC_START,
+           kqwl->kqwl_dynamicid, 0, 0);
 
        /* nobody else should still be processing */
        assert((kq->kq_state & KQ_PROCESSING) == 0);
 
        kq->kq_state |= KQ_PROCESSING;
 
-       if (!TAILQ_EMPTY(&kqr->kqr_suppressed)) {
+       if (!TAILQ_EMPTY(&kqwl->kqwl_suppressed)) {
                op = KQWL_UTQ_RESET_WAKEUP_OVERRIDE;
        }
 
@@ -4926,7 +4297,7 @@ kqworkloop_begin_processing(struct kqworkloop *kqwl, unsigned int kevent_flags)
                 * workqueue subsystem whether the thread should park despite having
                 * pending events.
                 */
-               if (kqr->kqr_state & KQR_THOVERCOMMIT) {
+               if (kqr->tr_flags & WORKQ_TR_FLAG_OVERCOMMIT) {
                        op = KQWL_UTQ_PARKING;
                } else {
                        op = KQWL_UTQ_UNBINDING;
@@ -4938,27 +4309,25 @@ kqworkloop_begin_processing(struct kqworkloop *kqwl, unsigned int kevent_flags)
 
        qos_override = kqworkloop_acknowledge_events(kqwl);
 
-       kq_req_lock(kqwl);
-
        if (op == KQWL_UTQ_UNBINDING) {
-               old_override = kqworkloop_unbind_locked(kqwl, thread);
-               (void)kqueue_release(kqwl, KQUEUE_CANT_BE_LAST_REF);
+               kqworkloop_unbind_locked(kqwl, thread, KQWL_OVERRIDE_DROP_IMMEDIATELY);
+               kqworkloop_release_live(kqwl);
        }
        kqworkloop_update_threads_qos(kqwl, op, qos_override);
        if (op == KQWL_UTQ_PARKING) {
                if (!TAILQ_EMPTY(&kqwl->kqwl_queue[KQWL_BUCKET_STAYACTIVE])) {
                        /*
-                        * We cannot trust KQR_WAKEUP when looking at stay active knotes.
+                        * We cannot trust tr_kq_wakeup when looking at stay active knotes.
                         * We need to process once, and kqworkloop_end_processing will
                         * handle the unbind.
                         */
-               } else if ((kqr->kqr_state & KQR_WAKEUP) == 0 || kqwl->kqwl_owner) {
-                       old_override = kqworkloop_unbind_locked(kqwl, thread);
-                       (void)kqueue_release(kqwl, KQUEUE_CANT_BE_LAST_REF);
+               } else if (!kqr->tr_kq_wakeup || kqwl->kqwl_owner) {
+                       kqworkloop_unbind_locked(kqwl, thread, KQWL_OVERRIDE_DROP_DELAYED);
+                       kqworkloop_release_live(kqwl);
                        rc = -1;
                }
        } else if (op == KQWL_UTQ_UNBINDING) {
-               if (kqr->kqr_thread == thread) {
+               if (kqr_thread(kqr) == thread) {
                        /*
                         * The thread request fired again, passed the admission check and
                         * got bound to the current thread again.
@@ -4973,20 +4342,18 @@ kqworkloop_begin_processing(struct kqworkloop *kqwl, unsigned int kevent_flags)
                 * Reset wakeup bit to notice stay active events firing while we are
                 * processing, as we cannot rely on the stayactive bucket emptiness.
                 */
-               kqr->kqr_wakeup_indexes &= ~KQWL_STAYACTIVE_FIRED_BIT;
+               kqwl->kqwl_wakeup_indexes &= ~KQWL_STAYACTIVE_FIRED_BIT;
        } else {
                kq->kq_state &= ~KQ_PROCESSING;
        }
 
-       kq_req_unlock(kqwl);
-
-       if (old_override) {
-               thread_drop_ipc_override(thread);
+       if (rc == -1) {
+               kqworkloop_unbind_delayed_override_drop(thread);
        }
 
 done:
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS_BEGIN) | DBG_FUNC_END,
-                     kqwl->kqwl_dynamicid, 0, 0);
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS_BEGIN) | DBG_FUNC_END,
+           kqwl->kqwl_dynamicid, 0, 0);
 
        return rc;
 }
@@ -4994,39 +4361,41 @@ done:
 /*
  * Return 0 to indicate that processing should proceed,
  * -1 if there is nothing to process.
+ * EBADF if the kqueue is draining
  *
  * Called with kqueue locked and returns the same way,
  * but may drop lock temporarily.
  * May block.
  */
 static int
-kqfile_begin_processing(struct kqueue *kq)
+kqfile_begin_processing(struct kqfile *kq)
 {
        struct kqtailq *suppressq;
 
        kqlock_held(kq);
 
-       assert((kq->kq_state & (KQ_WORKQ | KQ_WORKLOOP)) == 0);
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_BEGIN) | DBG_FUNC_START,
-                     VM_KERNEL_UNSLIDE_OR_PERM(kq), 0);
+       assert((kq->kqf_state & (KQ_WORKQ | KQ_WORKLOOP)) == 0);
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_BEGIN) | DBG_FUNC_START,
+           VM_KERNEL_UNSLIDE_OR_PERM(kq), 0);
 
        /* wait to become the exclusive processing thread */
        for (;;) {
-               if (kq->kq_state & KQ_DRAIN) {
-                       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_BEGIN) | DBG_FUNC_END,
-                                     VM_KERNEL_UNSLIDE_OR_PERM(kq), 2);
-                       return -1;
+               if (kq->kqf_state & KQ_DRAIN) {
+                       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_BEGIN) | DBG_FUNC_END,
+                           VM_KERNEL_UNSLIDE_OR_PERM(kq), 2);
+                       return EBADF;
                }
 
-               if ((kq->kq_state & KQ_PROCESSING) == 0)
+               if ((kq->kqf_state & KQ_PROCESSING) == 0) {
                        break;
+               }
 
                /* if someone else is processing the queue, wait */
-               kq->kq_state |= KQ_PROCWAIT;
-               suppressq = kqueue_get_suppressed_queue(kq, NULL);
-               waitq_assert_wait64((struct waitq *)&kq->kq_wqs,
-                               CAST_EVENT64_T(suppressq), THREAD_UNINT | THREAD_WAIT_NOREPORT,
-                               TIMEOUT_WAIT_FOREVER);
+               kq->kqf_state |= KQ_PROCWAIT;
+               suppressq = &kq->kqf_suppressed;
+               waitq_assert_wait64((struct waitq *)&kq->kqf_wqs,
+                   CAST_EVENT64_T(suppressq), THREAD_UNINT | THREAD_WAIT_NOREPORT,
+                   TIMEOUT_WAIT_FOREVER);
 
                kqunlock(kq);
                thread_block(THREAD_CONTINUE_NULL);
@@ -5036,21 +4405,21 @@ kqfile_begin_processing(struct kqueue *kq)
        /* Nobody else processing */
 
        /* clear pre-posts and KQ_WAKEUP now, in case we bail early */
-       waitq_set_clear_preposts(&kq->kq_wqs);
-       kq->kq_state &= ~KQ_WAKEUP;
+       waitq_set_clear_preposts(&kq->kqf_wqs);
+       kq->kqf_state &= ~KQ_WAKEUP;
 
        /* anything left to process? */
-       if (kqueue_queue_empty(kq, QOS_INDEX_KQFILE)) {
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_BEGIN) | DBG_FUNC_END,
-                             VM_KERNEL_UNSLIDE_OR_PERM(kq), 1);
+       if (TAILQ_EMPTY(&kq->kqf_queue)) {
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_BEGIN) | DBG_FUNC_END,
+                   VM_KERNEL_UNSLIDE_OR_PERM(kq), 1);
                return -1;
        }
 
        /* convert to processing mode */
-       kq->kq_state |= KQ_PROCESSING;
+       kq->kqf_state |= KQ_PROCESSING;
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_BEGIN) | DBG_FUNC_END,
-                     VM_KERNEL_UNSLIDE_OR_PERM(kq));
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_BEGIN) | DBG_FUNC_END,
+           VM_KERNEL_UNSLIDE_OR_PERM(kq));
 
        return 0;
 }
@@ -5063,14 +4432,12 @@ kqfile_begin_processing(struct kqueue *kq)
  * processed.
  */
 static int
-kqworkq_end_processing(struct kqworkq *kqwq, struct kqrequest *kqr,
-               int kevent_flags)
+kqworkq_end_processing(struct kqworkq *kqwq, workq_threadreq_t kqr,
+    int kevent_flags)
 {
-       if (!kqueue_queue_empty(&kqwq->kqwq_kqueue, kqr->kqr_qos_index)) {
+       if (!TAILQ_EMPTY(&kqwq->kqwq_queue[kqr->tr_kq_qos_index])) {
                /* remember we didn't process everything */
-               kq_req_lock(kqwq);
-               kqr->kqr_state |= KQR_WAKEUP;
-               kq_req_unlock(kqwq);
+               kqr->tr_kq_wakeup = true;
        }
 
        if (kevent_flags & KEVENT_FLAG_PARKING) {
@@ -5079,7 +4446,7 @@ kqworkq_end_processing(struct kqworkq *kqwq, struct kqrequest *kqr,
                 * which is a failure condition for end_processing.
                 */
                int rc = kqworkq_acknowledge_events(kqwq, kqr, kevent_flags,
-                               KQWQAE_END_PROCESSING);
+                   KQWQAE_END_PROCESSING);
                if (rc == 0) {
                        return -1;
                }
@@ -5102,15 +4469,15 @@ static int
 kqworkloop_end_processing(struct kqworkloop *kqwl, int flags, int kevent_flags)
 {
        struct kqueue *kq = &kqwl->kqwl_kqueue;
-       struct kqrequest *kqr = &kqwl->kqwl_request;
-       thread_qos_t old_override = THREAD_QOS_UNSPECIFIED, qos_override;
-       thread_t thread = kqr->kqr_thread;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
+       thread_qos_t qos_override;
+       thread_t thread = kqr_thread_fast(kqr);
        int rc = 0;
 
        kqlock_held(kq);
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS_END) | DBG_FUNC_START,
-                       kqwl->kqwl_dynamicid, 0, 0);
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS_END) | DBG_FUNC_START,
+           kqwl->kqwl_dynamicid, 0, 0);
 
        if (flags & KQ_PROCESSING) {
                assert(kq->kq_state & KQ_PROCESSING);
@@ -5121,10 +4488,8 @@ kqworkloop_end_processing(struct kqworkloop *kqwl, int flags, int kevent_flags)
                 * require to have a lot of them registered and fired.
                 */
                if (!TAILQ_EMPTY(&kqwl->kqwl_queue[KQWL_BUCKET_STAYACTIVE])) {
-                       kq_req_lock(kqwl);
                        kqworkloop_update_threads_qos(kqwl, KQWL_UTQ_UPDATE_WAKEUP_QOS,
-                                       KQWL_BUCKET_STAYACTIVE);
-                       kq_req_unlock(kqwl);
+                           KQWL_BUCKET_STAYACTIVE);
                }
 
                /*
@@ -5144,86 +4509,85 @@ kqworkloop_end_processing(struct kqworkloop *kqwl, int flags, int kevent_flags)
                }
        }
 
-       kq_req_lock(kqwl);
-
        if (kevent_flags & KEVENT_FLAG_PARKING) {
                kqworkloop_update_threads_qos(kqwl, KQWL_UTQ_PARKING, qos_override);
-               if ((kqr->kqr_state & KQR_WAKEUP) && !kqwl->kqwl_owner) {
+               if (kqr->tr_kq_wakeup && !kqwl->kqwl_owner) {
                        /*
                         * Reset wakeup bit to notice stay active events firing while we are
                         * processing, as we cannot rely on the stayactive bucket emptiness.
                         */
-                       kqr->kqr_wakeup_indexes &= ~KQWL_STAYACTIVE_FIRED_BIT;
+                       kqwl->kqwl_wakeup_indexes &= ~KQWL_STAYACTIVE_FIRED_BIT;
                        rc = -1;
                } else {
-                       old_override = kqworkloop_unbind_locked(kqwl, thread);
-                       (void)kqueue_release(kqwl, KQUEUE_CANT_BE_LAST_REF);
+                       kqworkloop_unbind_locked(kqwl, thread, KQWL_OVERRIDE_DROP_DELAYED);
+                       kqworkloop_release_live(kqwl);
                        kq->kq_state &= ~flags;
                }
        } else {
                kq->kq_state &= ~flags;
-               kqr->kqr_state |= KQR_R2K_NOTIF_ARMED;
+               kq->kq_state |= KQ_R2K_ARMED;
                kqworkloop_update_threads_qos(kqwl, KQWL_UTQ_RECOMPUTE_WAKEUP_QOS, 0);
        }
 
-       kq_req_unlock(kqwl);
-
-       if (old_override) {
-               thread_drop_ipc_override(thread);
+       if ((kevent_flags & KEVENT_FLAG_PARKING) && rc == 0) {
+               kqworkloop_unbind_delayed_override_drop(thread);
        }
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS_END) | DBG_FUNC_END,
-                       kqwl->kqwl_dynamicid, 0, 0);
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_PROCESS_END) | DBG_FUNC_END,
+           kqwl->kqwl_dynamicid, 0, 0);
 
        return rc;
 }
 
 /*
  * Called with kqueue lock held.
+ *
+ * 0: no more events
+ * -1: has more events
+ * EBADF: kqueue is in draining mode
  */
-static void
-kqfile_end_processing(struct kqueue *kq)
+static int
+kqfile_end_processing(struct kqfile *kq)
 {
+       struct kqtailq *suppressq = &kq->kqf_suppressed;
        struct knote *kn;
-       struct kqtailq *suppressq;
        int procwait;
 
        kqlock_held(kq);
 
-       assert((kq->kq_state & (KQ_WORKQ|KQ_WORKLOOP)) == 0);
+       assert((kq->kqf_state & (KQ_WORKQ | KQ_WORKLOOP)) == 0);
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_END),
-                       VM_KERNEL_UNSLIDE_OR_PERM(kq), 0);
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQ_PROCESS_END),
+           VM_KERNEL_UNSLIDE_OR_PERM(kq), 0);
 
        /*
         * Return suppressed knotes to their original state.
         */
-       suppressq = kqueue_get_suppressed_queue(kq, NULL);
        while ((kn = TAILQ_FIRST(suppressq)) != NULL) {
                assert(kn->kn_status & KN_SUPPRESSED);
-               knote_unsuppress(kn);
+               knote_unsuppress(kq, kn);
        }
 
-       procwait = (kq->kq_state & KQ_PROCWAIT);
-       kq->kq_state &= ~(KQ_PROCESSING | KQ_PROCWAIT);
+       procwait = (kq->kqf_state & KQ_PROCWAIT);
+       kq->kqf_state &= ~(KQ_PROCESSING | KQ_PROCWAIT);
 
        if (procwait) {
                /* first wake up any thread already waiting to process */
-               waitq_wakeup64_all((struct waitq *)&kq->kq_wqs,
-                                  CAST_EVENT64_T(suppressq),
-                                  THREAD_AWAKENED,
-                                  WAITQ_ALL_PRIORITIES);
+               waitq_wakeup64_all((struct waitq *)&kq->kqf_wqs,
+                   CAST_EVENT64_T(suppressq), THREAD_AWAKENED, WAITQ_ALL_PRIORITIES);
+       }
+
+       if (kq->kqf_state & KQ_DRAIN) {
+               return EBADF;
        }
+       return (kq->kqf_state & KQ_WAKEUP) ? -1 : 0;
 }
 
 static int
 kqueue_workloop_ctl_internal(proc_t p, uintptr_t cmd, uint64_t __unused options,
-               struct kqueue_workloop_params *params, int *retval)
+    struct kqueue_workloop_params *params, int *retval)
 {
        int error = 0;
-       int fd;
-       struct fileproc *fp;
-       struct kqueue *kq;
        struct kqworkloop *kqwl;
        struct filedesc *fdp = p->p_fd;
        workq_threadreq_param_t trp = { };
@@ -5236,23 +4600,23 @@ kqueue_workloop_ctl_internal(proc_t p, uintptr_t cmd, uint64_t __unused options,
                }
 
                if ((params->kqwlp_flags & KQ_WORKLOOP_CREATE_SCHED_PRI) &&
-                               (params->kqwlp_sched_pri < 1 ||
-                                params->kqwlp_sched_pri > 63 /* MAXPRI_USER */)) {
+                   (params->kqwlp_sched_pri < 1 ||
+                   params->kqwlp_sched_pri > 63 /* MAXPRI_USER */)) {
                        error = EINVAL;
                        break;
                }
 
                if ((params->kqwlp_flags & KQ_WORKLOOP_CREATE_SCHED_POL) &&
-                               invalid_policy(params->kqwlp_sched_pol)) {
+                   invalid_policy(params->kqwlp_sched_pol)) {
                        error = EINVAL;
                        break;
                }
 
                if ((params->kqwlp_flags & KQ_WORKLOOP_CREATE_CPU_PERCENT) &&
-                               (params->kqwlp_cpu_percent <= 0 ||
-                                params->kqwlp_cpu_percent > 100 ||
-                                params->kqwlp_cpu_refillms <= 0 ||
-                                params->kqwlp_cpu_refillms > 0x00ffffff)) {
+                   (params->kqwlp_cpu_percent <= 0 ||
+                   params->kqwlp_cpu_percent > 100 ||
+                   params->kqwlp_cpu_refillms <= 0 ||
+                   params->kqwlp_cpu_refillms > 0x00ffffff)) {
                        error = EINVAL;
                        break;
                }
@@ -5271,9 +4635,9 @@ kqueue_workloop_ctl_internal(proc_t p, uintptr_t cmd, uint64_t __unused options,
                        trp.trp_refillms = params->kqwlp_cpu_refillms;
                }
 
-               error = kevent_get_kq(p, params->kqwlp_id, &trp,
-                               KEVENT_FLAG_DYNAMIC_KQUEUE | KEVENT_FLAG_WORKLOOP |
-                               KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST , &fp, &fd, &kq);
+               error = kqworkloop_get_or_create(p, params->kqwlp_id, &trp,
+                   KEVENT_FLAG_DYNAMIC_KQUEUE | KEVENT_FLAG_WORKLOOP |
+                   KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST, &kqwl);
                if (error) {
                        break;
                }
@@ -5289,23 +4653,23 @@ kqueue_workloop_ctl_internal(proc_t p, uintptr_t cmd, uint64_t __unused options,
                }
                break;
        case KQ_WORKLOOP_DESTROY:
-               error = kevent_get_kq(p, params->kqwlp_id, NULL,
-                               KEVENT_FLAG_DYNAMIC_KQUEUE | KEVENT_FLAG_WORKLOOP |
-                               KEVENT_FLAG_DYNAMIC_KQ_MUST_EXIST , &fp, &fd, &kq);
+               error = kqworkloop_get_or_create(p, params->kqwlp_id, NULL,
+                   KEVENT_FLAG_DYNAMIC_KQUEUE | KEVENT_FLAG_WORKLOOP |
+                   KEVENT_FLAG_DYNAMIC_KQ_MUST_EXIST, &kqwl);
                if (error) {
                        break;
                }
-               kqlock(kq);
-               kqwl = (struct kqworkloop *)kq;
+               kqlock(kqwl);
                trp.trp_value = kqwl->kqwl_params;
                if (trp.trp_flags && !(trp.trp_flags & TRP_RELEASED)) {
                        trp.trp_flags |= TRP_RELEASED;
-                       kqueue_release(kq, KQUEUE_CANT_BE_LAST_REF);
+                       kqwl->kqwl_params = trp.trp_value;
+                       kqworkloop_release_live(kqwl);
                } else {
                        error = EINVAL;
                }
-               kqunlock(kq);
-               kqueue_release_last(p, kq);
+               kqunlock(kqwl);
+               kqworkloop_release(kqwl);
                break;
        }
        *retval = 0;
@@ -5333,483 +4697,140 @@ kqueue_workloop_ctl(proc_t p, struct kqueue_workloop_ctl_args *uap, int *retval)
        }
 
        return kqueue_workloop_ctl_internal(p, uap->cmd, uap->options, &params,
-                       retval);
+                  retval);
 }
 
-/*
- * kqueue_process - process the triggered events in a kqueue
- *
- *     Walk the queued knotes and validate that they are really still triggered
- *     events by calling the filter routines (if necessary).
- *
- *     For each event that is still considered triggered, invoke the callback
- *     routine provided.
- *
- *     caller holds a reference on the kqueue.
- *     kqueue locked on entry and exit - but may be dropped
- *     kqueue list locked (held for duration of call)
- */
+/*ARGSUSED*/
 static int
-kqueue_process(struct kqueue *kq,
-               kevent_callback_t callback,
-               void *callback_data,
-               struct filt_process_s *process_data,
-               int *countp)
+kqueue_select(struct fileproc *fp, int which, void *wq_link_id,
+    __unused vfs_context_t ctx)
 {
-       struct uthread *ut = get_bsdthread_info(current_thread());
-       struct kqrequest *kqr = ut->uu_kqr_bound;
+       struct kqfile *kq = (struct kqfile *)fp->f_data;
+       struct kqtailq *suppressq = &kq->kqf_suppressed;
+       struct kqtailq *queue = &kq->kqf_queue;
        struct knote *kn;
-       unsigned int flags = process_data ? process_data->fp_flags : 0;
-       int nevents = 0, error = 0, rc = 0;
-       struct kqtailq *base_queue, *queue;
-       kqueue_t kqu = { .kq = kq };
-#if DEBUG || DEVELOPMENT
-       int retries = 64;
-#endif
-
-       if (kq->kq_state & KQ_WORKQ) {
-               if (kqr == NULL || (kqr->kqr_state & KQR_WORKLOOP)) {
-                       return EJUSTRETURN;
-               }
-               rc = kqworkq_begin_processing(kqu.kqwq, kqr, flags);
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               if (ut->uu_kqr_bound != &kqu.kqwl->kqwl_request) {
-                       return EJUSTRETURN;
-               }
-               rc = kqworkloop_begin_processing(kqu.kqwl, flags);
-       } else {
-               rc = kqfile_begin_processing(kq);
-       }
+       int retnum = 0;
 
-       if (rc == -1) {
-               /* Nothing to process */
-               *countp = 0;
+       if (which != FREAD) {
                return 0;
        }
 
+       kqlock(kq);
+
+       assert((kq->kqf_state & KQ_WORKQ) == 0);
+
        /*
-        * loop through the enqueued knotes associated with this request,
-        * processing each one. Each request may have several queues
-        * of knotes to process (depending on the type of kqueue) so we
-        * have to loop through all the queues as long as we have additional
-        * space.
+        * If this is the first pass, link the wait queue associated with the
+        * the kqueue onto the wait queue set for the select().  Normally we
+        * use selrecord() for this, but it uses the wait queue within the
+        * selinfo structure and we need to use the main one for the kqueue to
+        * catch events from KN_STAYQUEUED sources. So we do the linkage manually.
+        * (The select() call will unlink them when it ends).
         */
+       if (wq_link_id != NULL) {
+               thread_t cur_act = current_thread();
+               struct uthread * ut = get_bsdthread_info(cur_act);
 
-process_again:
-       if (kq->kq_state & KQ_WORKQ) {
-               base_queue = queue = &kqu.kqwq->kqwq_queue[kqr->kqr_qos_index];
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               base_queue = &kqu.kqwl->kqwl_queue[0];
-               queue = &kqu.kqwl->kqwl_queue[KQWL_NBUCKETS - 1];
-       } else {
-               base_queue = queue = &kq->kq_queue[QOS_INDEX_KQFILE];
-       }
-
-       do {
-               while (error == 0 && (kn = TAILQ_FIRST(queue)) != NULL) {
-                       error = knote_process(kn, callback, callback_data, process_data);
-                       if (error == EJUSTRETURN) {
-                               error = 0;
-                       } else {
-                               nevents++;
-                       }
-                       /* error is EWOULDBLOCK when the out event array is full */
-               }
+               kq->kqf_state |= KQ_SEL;
+               waitq_link((struct waitq *)&kq->kqf_wqs, ut->uu_wqset,
+                   WAITQ_SHOULD_LOCK, (uint64_t *)wq_link_id);
 
-               if (error == EWOULDBLOCK) {
-                       /* break out if no more space for additional events */
-                       error = 0;
-                       break;
-               }
-       } while (queue-- > base_queue);
+               /* always consume the reserved link object */
+               waitq_link_release(*(uint64_t *)wq_link_id);
+               *(uint64_t *)wq_link_id = 0;
 
-       *countp = nevents;
+               /*
+                * selprocess() is expecting that we send it back the waitq
+                * that was just added to the thread's waitq set. In order
+                * to not change the selrecord() API (which is exported to
+                * kexts), we pass this value back through the
+                * void *wq_link_id pointer we were passed. We need to use
+                * memcpy here because the pointer may not be properly aligned
+                * on 32-bit systems.
+                */
+               void *wqptr = &kq->kqf_wqs;
+               memcpy(wq_link_id, (void *)&wqptr, sizeof(void *));
+       }
 
-       /*
-        * If KEVENT_FLAG_PARKING is set, and no kevents have been returned,
-        * we want to unbind the kqrequest from the thread.
-        *
-        * However, because the kq locks are dropped several times during process,
-        * new knotes may have fired again, in which case, we want to fail the end
-        * processing and process again, until it converges.
-        *
-        * If we returned events however, end processing never fails.
-        */
-       if (error || nevents) flags &= ~KEVENT_FLAG_PARKING;
-       if (kq->kq_state & KQ_WORKQ) {
-               rc = kqworkq_end_processing(kqu.kqwq, kqr, flags);
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               rc = kqworkloop_end_processing(kqu.kqwl, KQ_PROCESSING, flags);
-       } else {
-               kqfile_end_processing(kq);
-               rc = 0;
+       if (kqfile_begin_processing(kq) == -1) {
+               kqunlock(kq);
+               return 0;
        }
-       if (rc == -1) {
-               assert(flags & KEVENT_FLAG_PARKING);
-#if DEBUG || DEVELOPMENT
-               if (retries-- == 0) {
-                       panic("kevent: way too many knote_process retries, kq: %p (0x%02x)",
-                                       kq, kq->kq_state);
+
+       if (!TAILQ_EMPTY(queue)) {
+               /*
+                * there is something queued - but it might be a
+                * KN_STAYACTIVE knote, which may or may not have
+                * any events pending.  Otherwise, we have to walk
+                * the list of knotes to see, and peek at the
+                * (non-vanished) stay-active ones to be really sure.
+                */
+               while ((kn = (struct knote *)TAILQ_FIRST(queue)) != NULL) {
+                       if (kn->kn_status & KN_ACTIVE) {
+                               retnum = 1;
+                               goto out;
+                       }
+                       assert(kn->kn_status & KN_STAYACTIVE);
+                       knote_suppress(kq, kn);
                }
-#endif
-               goto process_again;
-       }
-       return error;
-}
 
-static void
-kqueue_scan_continue(void *data, wait_result_t wait_result)
-{
-       thread_t self = current_thread();
-       uthread_t ut = (uthread_t)get_bsdthread_info(self);
-       struct _kqueue_scan * cont_args = &ut->uu_save.uus_kqueue_scan;
-       struct kqueue *kq = (struct kqueue *)data;
-       struct filt_process_s *process_data = cont_args->process_data;
-       int error;
-       int count;
+               /*
+                * There were no regular events on the queue, so take
+                * a deeper look at the stay-queued ones we suppressed.
+                */
+               while ((kn = (struct knote *)TAILQ_FIRST(suppressq)) != NULL) {
+                       KNOTE_LOCK_CTX(knlc);
+                       int result = 0;
 
-       /* convert the (previous) wait_result to a proper error */
-       switch (wait_result) {
-       case THREAD_AWAKENED: {
-               kqlock(kq);
-       retry:
-               error = kqueue_process(kq, cont_args->call, cont_args->data,
-                                      process_data, &count);
-               if (error == 0 && count == 0) {
-                       if (kq->kq_state & KQ_DRAIN) {
-                               kqunlock(kq);
-                               goto drain;
+                       /* If didn't vanish while suppressed - peek at it */
+                       if ((kn->kn_status & KN_DROPPING) || !knote_lock(kq, kn, &knlc,
+                           KNOTE_KQ_LOCK_ON_FAILURE)) {
+                               continue;
                        }
 
-                       if (kq->kq_state & KQ_WAKEUP)
-                               goto retry;
+                       result = filter_call(knote_fops(kn), f_peek(kn));
 
-                       waitq_assert_wait64((struct waitq *)&kq->kq_wqs,
-                                           KQ_EVENT, THREAD_ABORTSAFE,
-                                           cont_args->deadline);
-                       kq->kq_state |= KQ_SLEEP;
-                       kqunlock(kq);
-                       thread_block_parameter(kqueue_scan_continue, kq);
-                       /* NOTREACHED */
+                       kqlock(kq);
+                       knote_unlock(kq, kn, &knlc, KNOTE_KQ_LOCK_ALWAYS);
+
+                       /* unsuppress it */
+                       knote_unsuppress(kq, kn);
+
+                       /* has data or it has to report a vanish */
+                       if (result & FILTER_ACTIVE) {
+                               retnum = 1;
+                               goto out;
+                       }
                }
-               kqunlock(kq);
-               } break;
-       case THREAD_TIMED_OUT:
-               error = EWOULDBLOCK;
-               break;
-       case THREAD_INTERRUPTED:
-               error = EINTR;
-               break;
-       case THREAD_RESTART:
-       drain:
-               error = EBADF;
-               break;
-       default:
-               panic("%s: - invalid wait_result (%d)", __func__,
-                   wait_result);
-               error = 0;
        }
 
-       /* call the continuation with the results */
-       assert(cont_args->cont != NULL);
-       (cont_args->cont)(kq, cont_args->data, error);
+out:
+       kqfile_end_processing(kq);
+       kqunlock(kq);
+       return retnum;
 }
 
-
 /*
- * kqueue_scan - scan and wait for events in a kqueue
- *
- *     Process the triggered events in a kqueue.
- *
- *     If there are no events triggered arrange to
- *     wait for them. If the caller provided a
- *     continuation routine, then kevent_scan will
- *     also.
- *
- *     The callback routine must be valid.
- *     The caller must hold a use-count reference on the kq.
+ * kqueue_close -
  */
-int
-kqueue_scan(struct kqueue *kq,
-           kevent_callback_t callback,
-           kqueue_continue_t continuation,
-           void *callback_data,
-           struct filt_process_s *process_data,
-           struct timeval *atvp,
-           __unused struct proc *p)
-{
-       thread_continue_t cont = THREAD_CONTINUE_NULL;
-       unsigned int flags;
-       uint64_t deadline;
-       int error;
-       int first;
-       int fd;
-
-       assert(callback != NULL);
+/*ARGSUSED*/
+static int
+kqueue_close(struct fileglob *fg, __unused vfs_context_t ctx)
+{
+       struct kqfile *kqf = (struct kqfile *)fg->fg_data;
 
-       /*
-        * Determine which QoS index we are servicing
-        */
-       flags = (process_data) ? process_data->fp_flags : 0;
-       fd = (process_data) ? process_data->fp_fd : -1;
+       assert((kqf->kqf_state & KQ_WORKQ) == 0);
+       kqueue_dealloc(&kqf->kqf_kqueue);
+       fg->fg_data = NULL;
+       return 0;
+}
 
-       first = 1;
-       for (;;) {
-               wait_result_t wait_result;
-               int count;
-
-               /*
-                * Make a pass through the kq to find events already
-                * triggered.
-                */
-               kqlock(kq);
-               error = kqueue_process(kq, callback, callback_data,
-                                      process_data, &count);
-               if (error || count)
-                       break; /* lock still held */
-
-               /* looks like we have to consider blocking */
-               if (first) {
-                       first = 0;
-                       /* convert the timeout to a deadline once */
-                       if (atvp->tv_sec || atvp->tv_usec) {
-                               uint64_t now;
-
-                               clock_get_uptime(&now);
-                               nanoseconds_to_absolutetime((uint64_t)atvp->tv_sec * NSEC_PER_SEC +
-                                                           atvp->tv_usec * (long)NSEC_PER_USEC,
-                                                           &deadline);
-                               if (now >= deadline) {
-                                       /* non-blocking call */
-                                       error = EWOULDBLOCK;
-                                       break; /* lock still held */
-                               }
-                               deadline -= now;
-                               clock_absolutetime_interval_to_deadline(deadline, &deadline);
-                       } else {
-                               deadline = 0;   /* block forever */
-                       }
-
-                       if (continuation) {
-                               uthread_t ut = (uthread_t)get_bsdthread_info(current_thread());
-                               struct _kqueue_scan *cont_args = &ut->uu_save.uus_kqueue_scan;
-
-                               cont_args->call = callback;
-                               cont_args->cont = continuation;
-                               cont_args->deadline = deadline;
-                               cont_args->data = callback_data;
-                               cont_args->process_data = process_data;
-                               cont = kqueue_scan_continue;
-                       }
-               }
-
-               if (kq->kq_state & KQ_DRAIN) {
-                       kqunlock(kq);
-                       return EBADF;
-               }
-
-               /* If awakened during processing, try again */
-               if (kq->kq_state & KQ_WAKEUP) {
-                       kqunlock(kq);
-                       continue;
-               }
-
-               /* go ahead and wait */
-               waitq_assert_wait64_leeway((struct waitq *)&kq->kq_wqs,
-                                          KQ_EVENT, THREAD_ABORTSAFE,
-                                          TIMEOUT_URGENCY_USER_NORMAL,
-                                          deadline, TIMEOUT_NO_LEEWAY);
-               kq->kq_state |= KQ_SLEEP;
-               kqunlock(kq);
-               wait_result = thread_block_parameter(cont, kq);
-               /* NOTREACHED if (continuation != NULL) */
-
-               switch (wait_result) {
-               case THREAD_AWAKENED:
-                       continue;
-               case THREAD_TIMED_OUT:
-                       return EWOULDBLOCK;
-               case THREAD_INTERRUPTED:
-                       return EINTR;
-               case THREAD_RESTART:
-                       return EBADF;
-               default:
-                       panic("%s: - bad wait_result (%d)", __func__,
-                           wait_result);
-                       error = 0;
-               }
-       }
-       kqunlock(kq);
-       return (error);
-}
-
-
-/*
- * XXX
- * This could be expanded to call kqueue_scan, if desired.
- */
-/*ARGSUSED*/
-static int
-kqueue_read(__unused struct fileproc *fp,
-               __unused struct uio *uio,
-               __unused int flags,
-               __unused vfs_context_t ctx)
-{
-       return (ENXIO);
-}
-
-/*ARGSUSED*/
-static int
-kqueue_write(__unused struct fileproc *fp,
-               __unused struct uio *uio,
-               __unused int flags,
-               __unused vfs_context_t ctx)
-{
-       return (ENXIO);
-}
-
-/*ARGSUSED*/
-static int
-kqueue_ioctl(__unused struct fileproc *fp,
-               __unused u_long com,
-               __unused caddr_t data,
-               __unused vfs_context_t ctx)
-{
-       return (ENOTTY);
-}
-
-/*ARGSUSED*/
-static int
-kqueue_select(struct fileproc *fp, int which, void *wq_link_id,
-               __unused vfs_context_t ctx)
-{
-       struct kqueue *kq = (struct kqueue *)fp->f_data;
-       struct kqtailq *queue;
-       struct kqtailq *suppressq;
-       struct knote *kn;
-       int retnum = 0;
-
-       if (which != FREAD)
-               return (0);
-
-       kqlock(kq);
-
-       assert((kq->kq_state & KQ_WORKQ) == 0);
-
-       /*
-        * If this is the first pass, link the wait queue associated with the
-        * the kqueue onto the wait queue set for the select().  Normally we
-        * use selrecord() for this, but it uses the wait queue within the
-        * selinfo structure and we need to use the main one for the kqueue to
-        * catch events from KN_STAYQUEUED sources. So we do the linkage manually.
-        * (The select() call will unlink them when it ends).
-        */
-       if (wq_link_id != NULL) {
-               thread_t cur_act = current_thread();
-               struct uthread * ut = get_bsdthread_info(cur_act);
-
-               kq->kq_state |= KQ_SEL;
-               waitq_link((struct waitq *)&kq->kq_wqs, ut->uu_wqset,
-                          WAITQ_SHOULD_LOCK, (uint64_t *)wq_link_id);
-
-               /* always consume the reserved link object */
-               waitq_link_release(*(uint64_t *)wq_link_id);
-               *(uint64_t *)wq_link_id = 0;
-
-               /*
-                * selprocess() is expecting that we send it back the waitq
-                * that was just added to the thread's waitq set. In order
-                * to not change the selrecord() API (which is exported to
-                * kexts), we pass this value back through the
-                * void *wq_link_id pointer we were passed. We need to use
-                * memcpy here because the pointer may not be properly aligned
-                * on 32-bit systems.
-                */
-               void *wqptr = &kq->kq_wqs;
-               memcpy(wq_link_id, (void *)&wqptr, sizeof(void *));
-       }
-
-       if (kqfile_begin_processing(kq) == -1) {
-               kqunlock(kq);
-               return (0);
-       }
-
-       queue = &kq->kq_queue[QOS_INDEX_KQFILE];
-       if (!TAILQ_EMPTY(queue)) {
-               /*
-                * there is something queued - but it might be a
-                * KN_STAYACTIVE knote, which may or may not have
-                * any events pending.  Otherwise, we have to walk
-                * the list of knotes to see, and peek at the
-                * (non-vanished) stay-active ones to be really sure.
-                */
-               while ((kn = (struct knote *)TAILQ_FIRST(queue)) != NULL) {
-                       if (kn->kn_status & KN_ACTIVE) {
-                               retnum = 1;
-                               goto out;
-                       }
-                       assert(kn->kn_status & KN_STAYACTIVE);
-                       knote_suppress(kn);
-               }
-
-               /*
-                * There were no regular events on the queue, so take
-                * a deeper look at the stay-queued ones we suppressed.
-                */
-               suppressq = kqueue_get_suppressed_queue(kq, NULL);
-               while ((kn = (struct knote *)TAILQ_FIRST(suppressq)) != NULL) {
-                       KNOTE_LOCK_CTX(knlc);
-                       int result = 0;
-
-                       /* If didn't vanish while suppressed - peek at it */
-                       if ((kn->kn_status & KN_DROPPING) || !knote_lock(kq, kn, &knlc,
-                                       KNOTE_KQ_LOCK_ON_FAILURE)) {
-                               continue;
-                       }
-
-                       result = filter_call(knote_fops(kn), f_peek(kn));
-
-                       kqlock(kq);
-                       knote_unlock(kq, kn, &knlc, KNOTE_KQ_LOCK_ALWAYS);
-
-                       /* unsuppress it */
-                       knote_unsuppress(kn);
-
-                       /* has data or it has to report a vanish */
-                       if (result & FILTER_ACTIVE) {
-                               retnum = 1;
-                               goto out;
-                       }
-               }
-       }
-
-out:
-       kqfile_end_processing(kq);
-       kqunlock(kq);
-       return (retnum);
-}
-
-/*
- * kqueue_close -
- */
-/*ARGSUSED*/
-static int
-kqueue_close(struct fileglob *fg, __unused vfs_context_t ctx)
-{
-       struct kqfile *kqf = (struct kqfile *)fg->fg_data;
-
-       assert((kqf->kqf_state & KQ_WORKQ) == 0);
-       kqueue_dealloc(&kqf->kqf_kqueue);
-       fg->fg_data = NULL;
-       return (0);
-}
-
-/*
- * Max depth of the nested kq path that can be created.
- * Note that this has to be less than the size of kq_level
- * to avoid wrapping around and mislabeling the level.
- */
-#define MAX_NESTED_KQ 1000
+/*
+ * Max depth of the nested kq path that can be created.
+ * Note that this has to be less than the size of kq_level
+ * to avoid wrapping around and mislabeling the level.
+ */
+#define MAX_NESTED_KQ 1000
 
 /*ARGSUSED*/
 /*
@@ -5818,13 +4839,12 @@ kqueue_close(struct fileglob *fg, __unused vfs_context_t ctx)
  * that relationship is torn down.
  */
 static int
-kqueue_kqfilter(__unused struct fileproc *fp, struct knote *kn,
-               __unused struct kevent_internal_s *kev, __unused vfs_context_t ctx)
+kqueue_kqfilter(struct fileproc *fp, struct knote *kn,
+    __unused struct kevent_qos_s *kev)
 {
-       struct kqfile *kqf = (struct kqfile *)kn->kn_fp->f_data;
+       struct kqfile *kqf = (struct kqfile *)fp->f_data;
        struct kqueue *kq = &kqf->kqf_kqueue;
        struct kqueue *parentkq = knote_get_kq(kn);
-       uint16_t plevel = 0;
 
        assert((kqf->kqf_state & KQ_WORKQ) == 0);
 
@@ -5844,18 +4864,23 @@ kqueue_kqfilter(__unused struct fileproc *fp, struct knote *kn,
         * passes, we just mark the nesting levels accordingly.
         *
         * Only up to MAX_NESTED_KQ can be nested.
+        *
+        * Note: kqworkq and kqworkloop cannot be nested and have reused their
+        *       kq_level field, so ignore these as parent.
         */
 
        kqlock(parentkq);
-       if (parentkq->kq_level > 0 &&
-           parentkq->kq_level < kq->kq_level)
-       {
-               kqunlock(parentkq);
-               knote_set_error(kn, EINVAL);
-               return 0;
-       } else {
+
+       if ((parentkq->kq_state & (KQ_WORKQ | KQ_WORKLOOP)) == 0) {
+               if (parentkq->kq_level > 0 &&
+                   parentkq->kq_level < kq->kq_level) {
+                       kqunlock(parentkq);
+                       knote_set_error(kn, EINVAL);
+                       return 0;
+               }
+
                /* set parent level appropriately */
-               plevel = (parentkq->kq_level == 0)? 2: parentkq->kq_level;
+               uint16_t plevel = (parentkq->kq_level == 0)? 2: parentkq->kq_level;
                if (plevel < kq->kq_level + 1) {
                        if (kq->kq_level + 1 > MAX_NESTED_KQ) {
                                kqunlock(parentkq);
@@ -5866,19 +4891,21 @@ kqueue_kqfilter(__unused struct fileproc *fp, struct knote *kn,
                }
 
                parentkq->kq_level = plevel;
-               kqunlock(parentkq);
+       }
 
-               kn->kn_filtid = EVFILTID_KQREAD;
-               kqlock(kq);
-               KNOTE_ATTACH(&kqf->kqf_sel.si_note, kn);
-               /* indicate nesting in child, if needed */
-               if (kq->kq_level == 0)
-                       kq->kq_level = 1;
+       kqunlock(parentkq);
 
-               int count = kq->kq_count;
-               kqunlock(kq);
-               return (count > 0);
+       kn->kn_filtid = EVFILTID_KQREAD;
+       kqlock(kq);
+       KNOTE_ATTACH(&kqf->kqf_sel.si_note, kn);
+       /* indicate nesting in child, if needed */
+       if (kq->kq_level == 0) {
+               kq->kq_level = 1;
        }
+
+       int count = kq->kq_count;
+       kqunlock(kq);
+       return count > 0;
 }
 
 /*
@@ -5888,15 +4915,34 @@ kqueue_kqfilter(__unused struct fileproc *fp, struct knote *kn,
 static int
 kqueue_drain(struct fileproc *fp, __unused vfs_context_t ctx)
 {
-       struct kqueue *kq = (struct kqueue *)fp->f_fglob->fg_data;
+       struct kqfile *kqf = (struct kqfile *)fp->f_fglob->fg_data;
 
-       assert((kq->kq_state & KQ_WORKQ) == 0);
+       assert((kqf->kqf_state & KQ_WORKQ) == 0);
 
-       kqlock(kq);
-       kq->kq_state |= KQ_DRAIN;
-       kqueue_interrupt(kq);
-       kqunlock(kq);
-       return (0);
+       kqlock(kqf);
+       kqf->kqf_state |= KQ_DRAIN;
+
+       /* wakeup sleeping threads */
+       if ((kqf->kqf_state & (KQ_SLEEP | KQ_SEL)) != 0) {
+               kqf->kqf_state &= ~(KQ_SLEEP | KQ_SEL);
+               (void)waitq_wakeup64_all((struct waitq *)&kqf->kqf_wqs,
+                   KQ_EVENT,
+                   THREAD_RESTART,
+                   WAITQ_ALL_PRIORITIES);
+       }
+
+       /* wakeup threads waiting their turn to process */
+       if (kqf->kqf_state & KQ_PROCWAIT) {
+               assert(kqf->kqf_state & KQ_PROCESSING);
+
+               kqf->kqf_state &= ~KQ_PROCWAIT;
+               (void)waitq_wakeup64_all((struct waitq *)&kqf->kqf_wqs,
+                   CAST_EVENT64_T(&kqf->kqf_suppressed),
+                   THREAD_RESTART, WAITQ_ALL_PRIORITIES);
+       }
+
+       kqunlock(kqf);
+       return 0;
 }
 
 /*ARGSUSED*/
@@ -5911,32 +4957,65 @@ kqueue_stat(struct kqueue *kq, void *ub, int isstat64, proc_t p)
 
                bzero((void *)sb64, sizeof(*sb64));
                sb64->st_size = kq->kq_count;
-               if (kq->kq_state & KQ_KEV_QOS)
+               if (kq->kq_state & KQ_KEV_QOS) {
                        sb64->st_blksize = sizeof(struct kevent_qos_s);
-               else if (kq->kq_state & KQ_KEV64)
+               } else if (kq->kq_state & KQ_KEV64) {
                        sb64->st_blksize = sizeof(struct kevent64_s);
-               else if (IS_64BIT_PROCESS(p))
+               } else if (IS_64BIT_PROCESS(p)) {
                        sb64->st_blksize = sizeof(struct user64_kevent);
-               else
+               } else {
                        sb64->st_blksize = sizeof(struct user32_kevent);
+               }
                sb64->st_mode = S_IFIFO;
        } else {
                struct stat *sb = (struct stat *)ub;
 
                bzero((void *)sb, sizeof(*sb));
                sb->st_size = kq->kq_count;
-               if (kq->kq_state & KQ_KEV_QOS)
+               if (kq->kq_state & KQ_KEV_QOS) {
                        sb->st_blksize = sizeof(struct kevent_qos_s);
-               else if (kq->kq_state & KQ_KEV64)
+               } else if (kq->kq_state & KQ_KEV64) {
                        sb->st_blksize = sizeof(struct kevent64_s);
-               else if (IS_64BIT_PROCESS(p))
+               } else if (IS_64BIT_PROCESS(p)) {
                        sb->st_blksize = sizeof(struct user64_kevent);
-               else
+               } else {
                        sb->st_blksize = sizeof(struct user32_kevent);
+               }
                sb->st_mode = S_IFIFO;
        }
        kqunlock(kq);
-       return (0);
+       return 0;
+}
+
+static inline bool
+kqueue_threadreq_can_use_ast(struct kqueue *kq)
+{
+       if (current_proc() == kq->kq_p) {
+               /*
+                * Setting an AST from a non BSD syscall is unsafe: mach_msg_trap() can
+                * do combined send/receive and in the case of self-IPC, the AST may bet
+                * set on a thread that will not return to userspace and needs the
+                * thread the AST would create to unblock itself.
+                *
+                * At this time, we really want to target:
+                *
+                * - kevent variants that can cause thread creations, and dispatch
+                *   really only uses kevent_qos and kevent_id,
+                *
+                * - workq_kernreturn (directly about thread creations)
+                *
+                * - bsdthread_ctl which is used for qos changes and has direct impact
+                *   on the creator thread scheduling decisions.
+                */
+               switch (current_uthread()->syscall_code) {
+               case SYS_kevent_qos:
+               case SYS_kevent_id:
+               case SYS_workq_kernreturn:
+               case SYS_bsdthread_ctl:
+                       return true;
+               }
+       }
+       return false;
 }
 
 /*
@@ -5949,44 +5028,41 @@ kqueue_stat(struct kqueue *kq, void *ub, int isstat64, proc_t p)
  *   so cannot do anything that could recurse on that.
  */
 static void
-kqueue_threadreq_initiate(struct kqueue *kq, struct kqrequest *kqr,
-               kq_index_t qos, int flags)
+kqueue_threadreq_initiate(struct kqueue *kq, workq_threadreq_t kqr,
+    kq_index_t qos, int flags)
 {
-       assert(kqr->kqr_state & KQR_WAKEUP);
-       assert(kqr->kqr_thread == THREAD_NULL);
-       assert((kqr->kqr_state & KQR_THREQUESTED) == 0);
+       assert(kqr->tr_kq_wakeup);
+       assert(kqr_thread(kqr) == THREAD_NULL);
+       assert(!kqr_thread_requested(kqr));
        struct turnstile *ts = TURNSTILE_NULL;
 
        if (workq_is_exiting(kq->kq_p)) {
                return;
        }
 
-       /* Add a thread request reference on the kqueue. */
-       kqueue_retain(kq);
-
-       kq_req_held(kq);
+       kqlock_held(kq);
 
        if (kq->kq_state & KQ_WORKLOOP) {
                __assert_only struct kqworkloop *kqwl = (struct kqworkloop *)kq;
 
                assert(kqwl->kqwl_owner == THREAD_NULL);
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_THREQUEST),
-                               kqwl->kqwl_dynamicid, 0, qos, kqr->kqr_state);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_THREQUEST),
+                   kqwl->kqwl_dynamicid, 0, qos, kqr->tr_kq_wakeup);
                ts = kqwl->kqwl_turnstile;
+               /* Add a thread request reference on the kqueue. */
+               kqworkloop_retain(kqwl);
        } else {
                assert(kq->kq_state & KQ_WORKQ);
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWQ_THREQUEST),
-                               -1, 0, qos, kqr->kqr_state);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWQ_THREQUEST),
+                   -1, 0, qos, kqr->tr_kq_wakeup);
        }
 
-       kqr->kqr_state |= KQR_THREQUESTED;
-
        /*
         * New-style thread request supported.
         * Provide the pthread kext a pointer to a workq_threadreq_s structure for
         * its use until a corresponding kqueue_threadreq_bind callback.
         */
-       if ((kq->kq_state & KQ_WORKLOOP) && current_proc() == kq->kq_p) {
+       if (kqueue_threadreq_can_use_ast(kq)) {
                flags |= WORKQ_THREADREQ_SET_AST_ON_FAILURE;
        }
        if (qos == KQWQ_QOS_MANAGER) {
@@ -5999,8 +5075,8 @@ kqueue_threadreq_initiate(struct kqueue *kq, struct kqrequest *kqr,
                 * soon. Forget we even asked for a thread -
                 * and make sure we don't ask for more.
                 */
-               kqr->kqr_state &= ~(KQR_THREQUESTED | KQR_R2K_NOTIF_ARMED);
-               kqueue_release(kq, KQUEUE_CANT_BE_LAST_REF);
+               kq->kq_state &= ~KQ_R2K_ARMED;
+               kqueue_release_live(kq);
        }
 }
 
@@ -6009,28 +5085,14 @@ kqueue_threadreq_initiate(struct kqueue *kq, struct kqrequest *kqr,
  *
  * This is used when kqueue_threadreq_bind may cause a lock inversion.
  */
+__attribute__((always_inline))
 void
-kqueue_threadreq_bind_prepost(struct proc *p __unused, workq_threadreq_t req,
-               thread_t thread)
+kqueue_threadreq_bind_prepost(struct proc *p __unused, workq_threadreq_t kqr,
+    struct uthread *ut)
 {
-       struct kqrequest *kqr = __container_of(req, struct kqrequest, kqr_req);
-       struct uthread *ut = get_bsdthread_info(thread);
-
-       req->tr_binding_thread = thread;
        ut->uu_kqr_bound = kqr;
-       req->tr_state = TR_STATE_BINDING;
-
-       struct kqworkloop *kqwl = kqr_kqworkloop(kqr);
-       if (kqwl && kqwl->kqwl_turnstile) {
-               struct turnstile *ts = kqwl->kqwl_turnstile;
-               /*
-                * While a thread request is in flight, the workqueue
-                * is the interlock for the turnstile and can update the inheritor.
-                */
-               turnstile_update_inheritor(ts, thread, TURNSTILE_IMMEDIATE_UPDATE |
-                               TURNSTILE_INHERITOR_THREAD);
-               turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_HELD);
-       }
+       kqr->tr_thread = ut->uu_thread;
+       kqr->tr_state = WORKQ_TR_STATE_BINDING;
 }
 
 /*
@@ -6043,29 +5105,28 @@ void
 kqueue_threadreq_bind_commit(struct proc *p, thread_t thread)
 {
        struct uthread *ut = get_bsdthread_info(thread);
-       struct kqrequest *kqr = ut->uu_kqr_bound;
+       workq_threadreq_t kqr = ut->uu_kqr_bound;
        kqueue_t kqu = kqr_kqueue(p, kqr);
 
-       kq_req_lock(kqu);
-       if (kqr->kqr_req.tr_state == TR_STATE_BINDING) {
-               kqueue_threadreq_bind(p, &kqr->kqr_req, thread, 0);
+       kqlock(kqu);
+       if (kqr->tr_state == WORKQ_TR_STATE_BINDING) {
+               kqueue_threadreq_bind(p, kqr, thread, 0);
        }
-       kq_req_unlock(kqu);
+       kqunlock(kqu);
 }
 
 static void
-kqueue_threadreq_modify(struct kqueue *kq, struct kqrequest *kqr, kq_index_t qos)
+kqueue_threadreq_modify(kqueue_t kqu, workq_threadreq_t kqr, kq_index_t qos,
+    workq_kern_threadreq_flags_t flags)
 {
-       assert(kqr->kqr_state & KQR_THREQUESTED);
-       assert(kqr->kqr_thread == THREAD_NULL);
+       assert(kqr_thread_requested_pending(kqr));
 
-       kq_req_held(kq);
+       kqlock_held(kqu);
 
-       int flags = 0;
-       if ((kq->kq_state & KQ_WORKLOOP) && kq->kq_p == current_proc()) {
+       if (kqueue_threadreq_can_use_ast(kqu.kq)) {
                flags |= WORKQ_THREADREQ_SET_AST_ON_FAILURE;
        }
-       workq_kern_threadreq_modify(kq->kq_p, kqr, qos, flags);
+       workq_kern_threadreq_modify(kqu.kq->kq_p, kqr, qos, flags);
 }
 
 /*
@@ -6076,30 +5137,28 @@ kqueue_threadreq_modify(struct kqueue *kq, struct kqrequest *kqr, kq_index_t qos
  * the thread to eventually arrive.
  */
 void
-kqueue_threadreq_bind(struct proc *p, workq_threadreq_t req, thread_t thread,
-               unsigned int flags)
+kqueue_threadreq_bind(struct proc *p, workq_threadreq_t kqr, thread_t thread,
+    unsigned int flags)
 {
-       struct kqrequest *kqr = __container_of(req, struct kqrequest, kqr_req);
        kqueue_t kqu = kqr_kqueue(p, kqr);
        struct uthread *ut = get_bsdthread_info(thread);
 
-       kq_req_held(kqu);
+       kqlock_held(kqu);
 
-       assert(kqr->kqr_state & KQR_THREQUESTED);
-       assert(kqr->kqr_thread == THREAD_NULL);
        assert(ut->uu_kqueue_override == 0);
 
-       if (kqr->kqr_req.tr_state == TR_STATE_BINDING) {
+       if (kqr->tr_state == WORKQ_TR_STATE_BINDING) {
                assert(ut->uu_kqr_bound == kqr);
-               assert(kqr->kqr_req.tr_binding_thread == thread);
-               kqr->kqr_req.tr_state = TR_STATE_IDLE;
-               kqr->kqr_req.tr_binding_thread = NULL;
+               assert(kqr->tr_thread == thread);
        } else {
+               assert(kqr_thread_requested_pending(kqr));
+               assert(kqr->tr_thread == THREAD_NULL);
                assert(ut->uu_kqr_bound == NULL);
+               ut->uu_kqr_bound = kqr;
+               kqr->tr_thread = thread;
        }
 
-       ut->uu_kqr_bound = kqr;
-       kqr->kqr_thread = thread;
+       kqr->tr_state = WORKQ_TR_STATE_BOUND;
 
        if (kqu.kq->kq_state & KQ_WORKLOOP) {
                struct turnstile *ts = kqu.kqwl->kqwl_turnstile;
@@ -6120,10 +5179,9 @@ kqueue_threadreq_bind(struct proc *p, workq_threadreq_t req, thread_t thread,
                         * owners and everything would basically go downhill from here.
                         */
                        kqu.kqwl->kqwl_owner = THREAD_NULL;
-                       if (kqworkloop_owner_override(kqu.kqwl)) {
-                               thread_drop_ipc_override(thread);
+                       if (kqworkloop_override(kqu.kqwl)) {
+                               thread_drop_kevent_override(thread);
                        }
-                       thread_ends_owning_workloop(thread);
                }
 
                if (ts && (flags & KQUEUE_THREADERQ_BIND_NO_INHERITOR_UPDATE) == 0) {
@@ -6135,20 +5193,20 @@ kqueue_threadreq_bind(struct proc *p, workq_threadreq_t req, thread_t thread,
                        turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_HELD);
                }
 
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_BIND), kqu.kqwl->kqwl_dynamicid,
-                               thread_tid(thread), kqr->kqr_qos_index,
-                               (kqr->kqr_override_index << 16) | kqr->kqr_state);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_BIND), kqu.kqwl->kqwl_dynamicid,
+                   thread_tid(thread), kqr->tr_kq_qos_index,
+                   (kqr->tr_kq_override_index << 16) | kqr->tr_kq_wakeup);
 
-               ut->uu_kqueue_override = kqr->kqr_override_index;
-               if (kqr->kqr_override_index) {
-                       thread_add_ipc_override(thread, kqr->kqr_override_index);
+               ut->uu_kqueue_override = kqr->tr_kq_override_index;
+               if (kqr->tr_kq_override_index) {
+                       thread_add_servicer_override(thread, kqr->tr_kq_override_index);
                }
        } else {
-               assert(kqr->kqr_override_index == 0);
+               assert(kqr->tr_kq_override_index == 0);
 
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWQ_BIND), -1,
-                               thread_tid(thread), kqr->kqr_qos_index,
-                               (kqr->kqr_override_index << 16) | kqr->kqr_state);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWQ_BIND), -1,
+                   thread_tid(thread), kqr->tr_kq_qos_index,
+                   (kqr->tr_kq_override_index << 16) | kqr->tr_kq_wakeup);
        }
 }
 
@@ -6158,30 +5216,18 @@ kqueue_threadreq_bind(struct proc *p, workq_threadreq_t req, thread_t thread,
  * Called when exiting/exec'ing. Forget our pending request.
  */
 void
-kqueue_threadreq_cancel(struct proc *p, workq_threadreq_t req)
+kqueue_threadreq_cancel(struct proc *p, workq_threadreq_t kqr)
 {
-       struct kqrequest *kqr = __container_of(req, struct kqrequest, kqr_req);
-       kqueue_t kqu = kqr_kqueue(p, kqr);
-
-       kq_req_lock(kqu);
-
-       assert(kqr->kqr_thread == THREAD_NULL);
-       assert(kqr->kqr_state & KQR_THREQUESTED);
-       kqr->kqr_state &= ~(KQR_THREQUESTED | KQR_R2K_NOTIF_ARMED);
-
-       kq_req_unlock(kqu);
-
-       kqueue_release_last(p, kqu); /* may dealloc kqu */
+       kqueue_release(kqr_kqueue(p, kqr));
 }
 
 workq_threadreq_param_t
-kqueue_threadreq_workloop_param(workq_threadreq_t req)
+kqueue_threadreq_workloop_param(workq_threadreq_t kqr)
 {
-       struct kqrequest *kqr = __container_of(req, struct kqrequest, kqr_req);
        struct kqworkloop *kqwl;
        workq_threadreq_param_t trp;
 
-       assert(kqr->kqr_state & KQR_WORKLOOP);
+       assert(kqr->tr_flags & WORKQ_TR_FLAG_WORKLOOP);
        kqwl = __container_of(kqr, struct kqworkloop, kqwl_request);
        trp.trp_value = kqwl->kqwl_params;
        return trp;
@@ -6196,10 +5242,10 @@ kqueue_threadreq_workloop_param(workq_threadreq_t req)
  *     caller holds a reference on the kqueue.
  */
 void
-kqueue_threadreq_unbind(struct proc *p, struct kqrequest *kqr)
+kqueue_threadreq_unbind(struct proc *p, workq_threadreq_t kqr)
 {
-       if (kqr->kqr_state & KQR_WORKLOOP) {
-               kqworkloop_unbind(p, kqr_kqworkloop(kqr));
+       if (kqr->tr_flags & WORKQ_TR_FLAG_WORKLOOP) {
+               kqworkloop_unbind(kqr_kqworkloop(kqr));
        } else {
                kqworkq_unbind(p, kqr);
        }
@@ -6215,63 +5261,62 @@ kqueue_threadreq_unbind(struct proc *p, struct kqrequest *kqr)
  *   so cannot do anything that could recurse on that.
  */
 static void
-kqworkq_request_help(struct kqworkq *kqwq, kq_index_t qos_index)
+kqworkq_wakeup(struct kqworkq *kqwq, kq_index_t qos_index)
 {
-       struct kqrequest *kqr;
+       workq_threadreq_t kqr = kqworkq_get_request(kqwq, qos_index);
 
        /* convert to thread qos value */
        assert(qos_index < KQWQ_NBUCKETS);
 
-       kq_req_lock(kqwq);
-       kqr = kqworkq_get_request(kqwq, qos_index);
-
-       if ((kqr->kqr_state & KQR_WAKEUP) == 0) {
-               kqr->kqr_state |= KQR_WAKEUP;
-               if ((kqr->kqr_state & KQR_THREQUESTED) == 0) {
+       if (!kqr->tr_kq_wakeup) {
+               kqr->tr_kq_wakeup = true;
+               if (!kqr_thread_requested(kqr)) {
                        kqueue_threadreq_initiate(&kqwq->kqwq_kqueue, kqr, qos_index, 0);
                }
        }
-       kq_req_unlock(kqwq);
 }
 
+/*
+ * This represent the asynchronous QoS a given workloop contributes,
+ * hence is the max of the current active knotes (override index)
+ * and the workloop max qos (userspace async qos).
+ */
 static kq_index_t
-kqworkloop_owner_override(struct kqworkloop *kqwl)
+kqworkloop_override(struct kqworkloop *kqwl)
 {
-       struct kqrequest *kqr = &kqwl->kqwl_request;
-       return MAX(kqr->kqr_qos_index, kqr->kqr_override_index);
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
+       return MAX(kqr->tr_kq_qos_index, kqr->tr_kq_override_index);
 }
 
 static inline void
 kqworkloop_request_fire_r2k_notification(struct kqworkloop *kqwl)
 {
-       struct kqrequest *kqr = &kqwl->kqwl_request;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
 
-       kq_req_held(kqwl);
+       kqlock_held(kqwl);
 
-       if (kqr->kqr_state & KQR_R2K_NOTIF_ARMED) {
-               assert(kqr->kqr_thread);
-               kqr->kqr_state &= ~KQR_R2K_NOTIF_ARMED;
-               act_set_astkevent(kqr->kqr_thread, AST_KEVENT_RETURN_TO_KERNEL);
+       if (kqwl->kqwl_state & KQ_R2K_ARMED) {
+               kqwl->kqwl_state &= ~KQ_R2K_ARMED;
+               act_set_astkevent(kqr_thread_fast(kqr), AST_KEVENT_RETURN_TO_KERNEL);
        }
 }
 
 static void
 kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
 {
-       struct kqrequest *kqr = &kqwl->kqwl_request;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
        struct kqueue *kq = &kqwl->kqwl_kqueue;
-       kq_index_t old_owner_override = kqworkloop_owner_override(kqwl);
+       kq_index_t old_override = kqworkloop_override(kqwl);
        kq_index_t i;
 
-       /* must hold the kqr lock */
-       kq_req_held(kqwl);
+       kqlock_held(kqwl);
 
        switch (op) {
        case KQWL_UTQ_UPDATE_WAKEUP_QOS:
                if (qos == KQWL_BUCKET_STAYACTIVE) {
                        /*
                         * the KQWL_BUCKET_STAYACTIVE is not a QoS bucket, we only remember
-                        * a high watermark (kqr_stayactive_qos) of any stay active knote
+                        * a high watermark (kqwl_stayactive_qos) of any stay active knote
                         * that was ever registered with this workloop.
                         *
                         * When waitq_set__CALLING_PREPOST_HOOK__() wakes up any stay active
@@ -6280,27 +5325,27 @@ kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
                         * there is at least one stay active knote fired until the next full
                         * processing of this bucket.
                         */
-                       kqr->kqr_wakeup_indexes |= KQWL_STAYACTIVE_FIRED_BIT;
-                       qos = kqr->kqr_stayactive_qos;
+                       kqwl->kqwl_wakeup_indexes |= KQWL_STAYACTIVE_FIRED_BIT;
+                       qos = kqwl->kqwl_stayactive_qos;
                        assert(qos);
                }
-               if (kqr->kqr_wakeup_indexes & (1 << qos)) {
-                       assert(kqr->kqr_state & KQR_WAKEUP);
+               if (kqwl->kqwl_wakeup_indexes & (1 << qos)) {
+                       assert(kqr->tr_kq_wakeup);
                        break;
                }
 
-               kqr->kqr_wakeup_indexes |= (1 << qos);
-               kqr->kqr_state |= KQR_WAKEUP;
+               kqwl->kqwl_wakeup_indexes |= (1 << qos);
+               kqr->tr_kq_wakeup = true;
                kqworkloop_request_fire_r2k_notification(kqwl);
                goto recompute;
 
        case KQWL_UTQ_UPDATE_STAYACTIVE_QOS:
                assert(qos);
-               if (kqr->kqr_stayactive_qos < qos) {
-                       kqr->kqr_stayactive_qos = qos;
-                       if (kqr->kqr_wakeup_indexes & KQWL_STAYACTIVE_FIRED_BIT) {
-                               assert(kqr->kqr_state & KQR_WAKEUP);
-                               kqr->kqr_wakeup_indexes |= (1 << qos);
+               if (kqwl->kqwl_stayactive_qos < qos) {
+                       kqwl->kqwl_stayactive_qos = qos;
+                       if (kqwl->kqwl_wakeup_indexes & KQWL_STAYACTIVE_FIRED_BIT) {
+                               assert(kqr->tr_kq_wakeup);
+                               kqwl->kqwl_wakeup_indexes |= (1 << qos);
                                goto recompute;
                        }
                }
@@ -6308,49 +5353,48 @@ kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
 
        case KQWL_UTQ_PARKING:
        case KQWL_UTQ_UNBINDING:
-               kqr->kqr_override_index = qos;
-               /* FALLTHROUGH */
+               kqr->tr_kq_override_index = qos;
+       /* FALLTHROUGH */
        case KQWL_UTQ_RECOMPUTE_WAKEUP_QOS:
                if (op == KQWL_UTQ_RECOMPUTE_WAKEUP_QOS) {
                        assert(qos == THREAD_QOS_UNSPECIFIED);
                }
-               kqlock_held(kqwl); // to look at kq_queues
                i = KQWL_BUCKET_STAYACTIVE;
-               if (TAILQ_EMPTY(&kqr->kqr_suppressed)) {
-                       kqr->kqr_override_index = THREAD_QOS_UNSPECIFIED;
+               if (TAILQ_EMPTY(&kqwl->kqwl_suppressed)) {
+                       kqr->tr_kq_override_index = THREAD_QOS_UNSPECIFIED;
                }
                if (!TAILQ_EMPTY(&kqwl->kqwl_queue[i]) &&
-                               (kqr->kqr_wakeup_indexes & KQWL_STAYACTIVE_FIRED_BIT)) {
+                   (kqwl->kqwl_wakeup_indexes & KQWL_STAYACTIVE_FIRED_BIT)) {
                        /*
                         * If the KQWL_STAYACTIVE_FIRED_BIT is set, it means a stay active
-                        * knote may have fired, so we need to merge in kqr_stayactive_qos.
+                        * knote may have fired, so we need to merge in kqwl_stayactive_qos.
                         *
                         * Unlike other buckets, this one is never empty but could be idle.
                         */
-                       kqr->kqr_wakeup_indexes &= KQWL_STAYACTIVE_FIRED_BIT;
-                       kqr->kqr_wakeup_indexes |= (1 << kqr->kqr_stayactive_qos);
+                       kqwl->kqwl_wakeup_indexes &= KQWL_STAYACTIVE_FIRED_BIT;
+                       kqwl->kqwl_wakeup_indexes |= (1 << kqwl->kqwl_stayactive_qos);
                } else {
-                       kqr->kqr_wakeup_indexes = 0;
+                       kqwl->kqwl_wakeup_indexes = 0;
                }
                for (i = THREAD_QOS_UNSPECIFIED + 1; i < KQWL_BUCKET_STAYACTIVE; i++) {
                        if (!TAILQ_EMPTY(&kqwl->kqwl_queue[i])) {
-                               kqr->kqr_wakeup_indexes |= (1 << i);
+                               kqwl->kqwl_wakeup_indexes |= (1 << i);
                        }
                }
-               if (kqr->kqr_wakeup_indexes) {
-                       kqr->kqr_state |= KQR_WAKEUP;
+               if (kqwl->kqwl_wakeup_indexes) {
+                       kqr->tr_kq_wakeup = true;
                        kqworkloop_request_fire_r2k_notification(kqwl);
                } else {
-                       kqr->kqr_state &= ~KQR_WAKEUP;
+                       kqr->tr_kq_wakeup = false;
                }
                goto recompute;
 
        case KQWL_UTQ_RESET_WAKEUP_OVERRIDE:
-               kqr->kqr_override_index = qos;
+               kqr->tr_kq_override_index = qos;
                goto recompute;
 
        case KQWL_UTQ_UPDATE_WAKEUP_OVERRIDE:
-       recompute:
+recompute:
                /*
                 * When modifying the wakeup QoS or the override QoS, we always need to
                 * maintain our invariant that kqr_override_index is at least as large
@@ -6359,11 +5403,11 @@ kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
                 * However this override index can be larger when there is an overriden
                 * suppressed knote pushing on the kqueue.
                 */
-               if (kqr->kqr_wakeup_indexes > (1 << qos)) {
-                       qos = fls(kqr->kqr_wakeup_indexes) - 1; /* fls is 1-based */
+               if (kqwl->kqwl_wakeup_indexes > (1 << qos)) {
+                       qos = fls(kqwl->kqwl_wakeup_indexes) - 1; /* fls is 1-based */
                }
-               if (kqr->kqr_override_index < qos) {
-                       kqr->kqr_override_index = qos;
+               if (kqr->tr_kq_override_index < qos) {
+                       kqr->tr_kq_override_index = qos;
                }
                break;
 
@@ -6371,7 +5415,7 @@ kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
                break;
 
        case KQWL_UTQ_SET_QOS_INDEX:
-               kqr->kqr_qos_index = qos;
+               kqr->tr_kq_qos_index = qos;
                break;
 
        default:
@@ -6379,9 +5423,9 @@ kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
        }
 
        thread_t kqwl_owner = kqwl->kqwl_owner;
-       thread_t servicer = kqr->kqr_thread;
+       thread_t servicer = kqr_thread(kqr);
        boolean_t qos_changed = FALSE;
-       kq_index_t new_owner_override = kqworkloop_owner_override(kqwl);
+       kq_index_t new_override = kqworkloop_override(kqwl);
 
        /*
         * Apply the diffs to the owner if applicable
@@ -6389,25 +5433,25 @@ kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
        if (kqwl_owner) {
 #if 0
                /* JMM - need new trace hooks for owner overrides */
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_THADJUST),
-                               kqwl->kqwl_dynamicid, thread_tid(kqwl_owner), kqr->kqr_qos_index,
-                               (kqr->kqr_override_index << 16) | kqr->kqr_state);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_THADJUST),
+                   kqwl->kqwl_dynamicid, thread_tid(kqwl_owner), kqr->tr_kq_qos_index,
+                   (kqr->tr_kq_override_index << 16) | kqr->tr_kq_wakeup);
 #endif
-               if (new_owner_override == old_owner_override) {
+               if (new_override == old_override) {
                        // nothing to do
-               } else if (old_owner_override == THREAD_QOS_UNSPECIFIED) {
-                       thread_add_ipc_override(kqwl_owner, new_owner_override);
-               } else if (new_owner_override == THREAD_QOS_UNSPECIFIED) {
-                       thread_drop_ipc_override(kqwl_owner);
-               } else /*  old_owner_override != new_owner_override */ {
-                       thread_update_ipc_override(kqwl_owner, new_owner_override);
+               } else if (old_override == THREAD_QOS_UNSPECIFIED) {
+                       thread_add_kevent_override(kqwl_owner, new_override);
+               } else if (new_override == THREAD_QOS_UNSPECIFIED) {
+                       thread_drop_kevent_override(kqwl_owner);
+               } else { /*  old_override != new_override */
+                       thread_update_kevent_override(kqwl_owner, new_override);
                }
        }
 
        /*
         * apply the diffs to the servicer
         */
-       if ((kqr->kqr_state & KQR_THREQUESTED) == 0) {
+       if (!kqr_thread_requested(kqr)) {
                /*
                 * No servicer, nor thread-request
                 *
@@ -6416,13 +5460,12 @@ kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
                 * first place.
                 */
 
-               if (kqwl_owner == NULL && (kqr->kqr_state & KQR_WAKEUP)) {
+               if (kqwl_owner == NULL && kqr->tr_kq_wakeup) {
                        int initiate_flags = 0;
                        if (op == KQWL_UTQ_UNBINDING) {
                                initiate_flags = WORKQ_THREADREQ_ATTEMPT_REBIND;
                        }
-                       kqueue_threadreq_initiate(kq, kqr, new_owner_override,
-                                       initiate_flags);
+                       kqueue_threadreq_initiate(kq, kqr, new_override, initiate_flags);
                }
        } else if (servicer) {
                /*
@@ -6431,18 +5474,18 @@ kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
                 * Just apply the diff to the servicer
                 */
                struct uthread *ut = get_bsdthread_info(servicer);
-               if (ut->uu_kqueue_override != kqr->kqr_override_index) {
+               if (ut->uu_kqueue_override != new_override) {
                        if (ut->uu_kqueue_override == THREAD_QOS_UNSPECIFIED) {
-                               thread_add_ipc_override(servicer, kqr->kqr_override_index);
-                       } else if (kqr->kqr_override_index == THREAD_QOS_UNSPECIFIED) {
-                               thread_drop_ipc_override(servicer);
-                       } else /* ut->uu_kqueue_override != kqr->kqr_override_index */ {
-                               thread_update_ipc_override(servicer, kqr->kqr_override_index);
+                               thread_add_servicer_override(servicer, new_override);
+                       } else if (new_override == THREAD_QOS_UNSPECIFIED) {
+                               thread_drop_servicer_override(servicer);
+                       } else { /* ut->uu_kqueue_override != new_override */
+                               thread_update_servicer_override(servicer, new_override);
                        }
-                       ut->uu_kqueue_override = kqr->kqr_override_index;
+                       ut->uu_kqueue_override = new_override;
                        qos_changed = TRUE;
                }
-       } else if (new_owner_override == THREAD_QOS_UNSPECIFIED) {
+       } else if (new_override == THREAD_QOS_UNSPECIFIED) {
                /*
                 * No events to deliver anymore.
                 *
@@ -6450,216 +5493,165 @@ kqworkloop_update_threads_qos(struct kqworkloop *kqwl, int op, kq_index_t qos)
                 * the request isn't useful will be discovered by the servicer himself
                 * later on.
                 */
-       } else if (old_owner_override != new_owner_override) {
+       } else if (old_override != new_override) {
                /*
                 * Request is in flight
                 *
                 * Apply the diff to the thread request
                 */
-               kqueue_threadreq_modify(kq, kqr, new_owner_override);
+               kqueue_threadreq_modify(kq, kqr, new_override, WORKQ_THREADREQ_NONE);
                qos_changed = TRUE;
        }
 
        if (qos_changed) {
-               KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_THADJUST), kqwl->kqwl_dynamicid,
-                               thread_tid(kqr->kqr_thread), kqr->kqr_qos_index,
-                               (kqr->kqr_override_index << 16) | kqr->kqr_state);
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_THADJUST), kqwl->kqwl_dynamicid,
+                   thread_tid(servicer), kqr->tr_kq_qos_index,
+                   (kqr->tr_kq_override_index << 16) | kqr->tr_kq_wakeup);
        }
 }
 
 static void
-kqworkloop_request_help(struct kqworkloop *kqwl, kq_index_t qos_index)
+kqworkloop_wakeup(struct kqworkloop *kqwl, kq_index_t qos)
 {
-       /* convert to thread qos value */
-       assert(qos_index < KQWL_NBUCKETS);
+       if ((kqwl->kqwl_state & KQ_PROCESSING) &&
+           kqr_thread(&kqwl->kqwl_request) == current_thread()) {
+               /*
+                * kqworkloop_end_processing() will perform the required QoS
+                * computations when it unsets the processing mode.
+                */
+               return;
+       }
 
-       kq_req_lock(kqwl);
-       kqworkloop_update_threads_qos(kqwl, KQWL_UTQ_UPDATE_WAKEUP_QOS, qos_index);
-       kq_req_unlock(kqwl);
+       kqworkloop_update_threads_qos(kqwl, KQWL_UTQ_UPDATE_WAKEUP_QOS, qos);
 }
 
 static struct kqtailq *
-kqueue_get_queue(struct kqueue *kq, kq_index_t qos_index)
+kqueue_get_suppressed_queue(kqueue_t kq, struct knote *kn)
 {
-       if (kq->kq_state & KQ_WORKQ) {
-               assert(qos_index < KQWQ_NBUCKETS);
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               assert(qos_index < KQWL_NBUCKETS);
+       if (kq.kq->kq_state & KQ_WORKLOOP) {
+               return &kq.kqwl->kqwl_suppressed;
+       } else if (kq.kq->kq_state & KQ_WORKQ) {
+               return &kq.kqwq->kqwq_suppressed[kn->kn_qos_index];
        } else {
-               assert(qos_index == QOS_INDEX_KQFILE);
+               return &kq.kqf->kqf_suppressed;
        }
-       static_assert(offsetof(struct kqueue, kq_queue) == sizeof(struct kqueue),
-                       "struct kqueue::kq_queue must be exactly at the end");
-       return &kq->kq_queue[qos_index];
 }
 
-static int
-kqueue_queue_empty(struct kqueue *kq, kq_index_t qos_index)
+struct turnstile *
+kqueue_alloc_turnstile(kqueue_t kqu)
 {
-       return TAILQ_EMPTY(kqueue_get_queue(kq, qos_index));
-}
+       struct kqworkloop *kqwl = kqu.kqwl;
+       kq_state_t kq_state;
 
-static struct kqtailq *
-kqueue_get_suppressed_queue(kqueue_t kq, struct knote *kn)
-{
-       if (kq.kq->kq_state & KQ_WORKQ) {
-               return &kqworkq_get_request(kq.kqwq, kn->kn_qos_index)->kqr_suppressed;
-       } else if (kq.kq->kq_state & KQ_WORKLOOP) {
-               return &kq.kqwl->kqwl_request.kqr_suppressed;
-       } else {
-               return &kq.kqf->kqf_suppressed;
-       }
-}
-
-static struct turnstile *
-kqueue_get_turnstile(kqueue_t kqu, bool can_alloc)
-{
-       uint8_t kqr_state;
-
-       if ((kqu.kq->kq_state & KQ_WORKLOOP) == 0) {
-               return TURNSTILE_NULL;
-       }
-
-       kqr_state = os_atomic_load(&kqu.kqwl->kqwl_request.kqr_state, relaxed);
-       if (kqr_state & KQR_ALLOCATED_TURNSTILE) {
+       kq_state = os_atomic_load(&kqu.kq->kq_state, dependency);
+       if (kq_state & KQ_HAS_TURNSTILE) {
                /* force a dependency to pair with the atomic or with release below */
-               return os_atomic_load_with_dependency_on(&kqu.kqwl->kqwl_turnstile,
-                               kqr_state);
+               return os_atomic_load_with_dependency_on(&kqwl->kqwl_turnstile,
+                          (uintptr_t)kq_state);
        }
 
-       if (!can_alloc) {
+       if (!(kq_state & KQ_WORKLOOP)) {
                return TURNSTILE_NULL;
        }
 
        struct turnstile *ts = turnstile_alloc(), *free_ts = TURNSTILE_NULL;
+       bool workq_locked = false;
+
+       kqlock(kqu);
 
-       kq_req_lock(kqu);
-       if (filt_wlturnstile_interlock_is_workq(kqu.kqwl)) {
-               workq_kern_threadreq_lock(kqu.kqwl->kqwl_p);
+       if (filt_wlturnstile_interlock_is_workq(kqwl)) {
+               workq_locked = true;
+               workq_kern_threadreq_lock(kqwl->kqwl_p);
        }
 
-       if (kqu.kqwl->kqwl_request.kqr_state & KQR_ALLOCATED_TURNSTILE) {
+       if (kqwl->kqwl_state & KQ_HAS_TURNSTILE) {
                free_ts = ts;
-               ts = kqu.kqwl->kqwl_turnstile;
+               ts = kqwl->kqwl_turnstile;
        } else {
-               ts = turnstile_prepare((uintptr_t)kqu.kqwl, &kqu.kqwl->kqwl_turnstile,
-                               ts, TURNSTILE_WORKLOOPS);
+               ts = turnstile_prepare((uintptr_t)kqwl, &kqwl->kqwl_turnstile,
+                   ts, TURNSTILE_WORKLOOPS);
 
                /* release-barrier to pair with the unlocked load of kqwl_turnstile above */
-               os_atomic_or(&kqu.kqwl->kqwl_request.kqr_state,
-                               KQR_ALLOCATED_TURNSTILE, release);
+               os_atomic_or(&kqwl->kqwl_state, KQ_HAS_TURNSTILE, release);
+
+               if (filt_wlturnstile_interlock_is_workq(kqwl)) {
+                       workq_kern_threadreq_update_inheritor(kqwl->kqwl_p,
+                           &kqwl->kqwl_request, kqwl->kqwl_owner,
+                           ts, TURNSTILE_IMMEDIATE_UPDATE);
+                       /*
+                        * The workq may no longer be the interlock after this.
+                        * In which case the inheritor wasn't updated.
+                        */
+               }
+               if (!filt_wlturnstile_interlock_is_workq(kqwl)) {
+                       filt_wlupdate_inheritor(kqwl, ts, TURNSTILE_IMMEDIATE_UPDATE);
+               }
        }
 
-       if (filt_wlturnstile_interlock_is_workq(kqu.kqwl)) {
-               workq_kern_threadreq_unlock(kqu.kqwl->kqwl_p);
+       if (workq_locked) {
+               workq_kern_threadreq_unlock(kqwl->kqwl_p);
        }
-       kq_req_unlock(kqu.kqwl);
+
+       kqunlock(kqu);
 
        if (free_ts) {
                turnstile_deallocate(free_ts);
+       } else {
+               turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
        }
        return ts;
 }
 
+__attribute__((always_inline))
 struct turnstile *
-kqueue_turnstile(struct kqueue *kq)
+kqueue_turnstile(kqueue_t kqu)
 {
-       return kqueue_get_turnstile(kq, false);
+       kq_state_t kq_state = os_atomic_load(&kqu.kq->kq_state, relaxed);
+       if (kq_state & KQ_WORKLOOP) {
+               return os_atomic_load(&kqu.kqwl->kqwl_turnstile, relaxed);
+       }
+       return TURNSTILE_NULL;
 }
 
+__attribute__((always_inline))
 struct turnstile *
-kqueue_alloc_turnstile(struct kqueue *kq)
-{
-       return kqueue_get_turnstile(kq, true);
-}
-
-static struct kqtailq *
-knote_get_queue(struct knote *kn)
-{
-       return kqueue_get_queue(knote_get_kq(kn), kn->kn_qos_index);
-}
-
-static void
-knote_reset_priority(struct knote *kn, pthread_priority_t pp)
+kqueue_threadreq_get_turnstile(workq_threadreq_t kqr)
 {
-       struct kqueue *kq = knote_get_kq(kn);
-       kq_index_t qos = _pthread_priority_thread_qos(pp);
-
-       assert((kn->kn_status & KN_QUEUED) == 0);
-
-       if (kq->kq_state & KQ_WORKQ) {
-               if (qos == THREAD_QOS_UNSPECIFIED) {
-                       /* On workqueues, outside of QoS means MANAGER */
-                       qos = KQWQ_QOS_MANAGER;
-                       pp = _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG;
-               } else {
-                       pp = _pthread_priority_normalize(pp);
-               }
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               assert((pp & _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG) == 0);
-               pp = _pthread_priority_normalize(pp);
-       } else {
-               pp = _pthread_unspecified_priority();
-               qos = THREAD_QOS_UNSPECIFIED;
-       }
-
-       kn->kn_qos = pp;
-       kn->kn_req_index = qos;
-
-       if ((kn->kn_status & KN_MERGE_QOS) == 0 || qos > kn->kn_qos_override) {
-               /* Never lower QoS when in "Merge" mode */
-               kn->kn_qos_override = qos;
-       }
-
-       /* only adjust in-use qos index when not suppressed */
-       if ((kn->kn_status & KN_SUPPRESSED) == 0) {
-               kn->kn_qos_index = qos;
-       } else if (kq->kq_state & KQ_WORKQ) {
-               kqworkq_update_override((struct kqworkq *)kq, kn, qos);
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               kqworkloop_update_override((struct kqworkloop *)kq, qos);
+       struct kqworkloop *kqwl = kqr_kqworkloop(kqr);
+       if (kqwl) {
+               return os_atomic_load(&kqwl->kqwl_turnstile, relaxed);
        }
+       return TURNSTILE_NULL;
 }
 
 static void
-knote_set_qos_overcommit(struct knote *kn)
+kqworkloop_set_overcommit(struct kqworkloop *kqwl)
 {
-       struct kqueue *kq = knote_get_kq(kn);
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
 
-       /* turn overcommit on for the appropriate thread request? */
-       if ((kn->kn_qos & _PTHREAD_PRIORITY_OVERCOMMIT_FLAG) &&
-                       (kq->kq_state & KQ_WORKLOOP)) {
-               struct kqworkloop *kqwl = (struct kqworkloop *)kq;
-               struct kqrequest *kqr = &kqwl->kqwl_request;
+       /*
+        * This test is racy, but since we never remove this bit,
+        * it allows us to avoid taking a lock.
+        */
+       if (kqr->tr_flags & WORKQ_TR_FLAG_OVERCOMMIT) {
+               return;
+       }
 
-               /*
-                * This test is racy, but since we never remove this bit,
-                * it allows us to avoid taking a lock.
-                */
-               if (kqr->kqr_state & KQR_THOVERCOMMIT) {
-                       return;
-               }
+       kqlock_held(kqwl);
 
-               kq_req_lock(kqwl);
-               kqr->kqr_state |= KQR_THOVERCOMMIT;
-               if (!kqr->kqr_thread && (kqr->kqr_state & KQR_THREQUESTED)) {
-                       kqueue_threadreq_modify(kq, kqr, kqr->kqr_req.tr_qos);
-               }
-               kq_req_unlock(kqwl);
+       if (kqr_thread_requested_pending(kqr)) {
+               kqueue_threadreq_modify(kqwl, kqr, kqr->tr_qos,
+                   WORKQ_THREADREQ_MAKE_OVERCOMMIT);
+       } else {
+               kqr->tr_flags |= WORKQ_TR_FLAG_OVERCOMMIT;
        }
 }
 
-static kq_index_t
-knote_get_qos_override_index(struct knote *kn)
-{
-       return kn->kn_qos_override;
-}
-
 static void
 kqworkq_update_override(struct kqworkq *kqwq, struct knote *kn,
-               kq_index_t override_index)
+    kq_index_t override_index)
 {
-       struct kqrequest *kqr;
+       workq_threadreq_t kqr;
        kq_index_t old_override_index;
        kq_index_t queue_index = kn->kn_qos_index;
 
@@ -6669,56 +5661,76 @@ kqworkq_update_override(struct kqworkq *kqwq, struct knote *kn,
 
        kqr = kqworkq_get_request(kqwq, queue_index);
 
-       kq_req_lock(kqwq);
-       old_override_index = kqr->kqr_override_index;
-       if (override_index > MAX(kqr->kqr_qos_index, old_override_index)) {
-               kqr->kqr_override_index = override_index;
+       kqlock_held(kqwq);
+
+       old_override_index = kqr->tr_kq_override_index;
+       if (override_index > MAX(kqr->tr_kq_qos_index, old_override_index)) {
+               thread_t servicer = kqr_thread(kqr);
+               kqr->tr_kq_override_index = override_index;
 
                /* apply the override to [incoming?] servicing thread */
-               if (kqr->kqr_thread) {
-                       if (old_override_index)
-                               thread_update_ipc_override(kqr->kqr_thread, override_index);
-                       else
-                               thread_add_ipc_override(kqr->kqr_thread, override_index);
+               if (servicer) {
+                       if (old_override_index) {
+                               thread_update_kevent_override(servicer, override_index);
+                       } else {
+                               thread_add_kevent_override(servicer, override_index);
+                       }
                }
        }
-       kq_req_unlock(kqwq);
 }
 
 static void
-kqworkloop_update_override(struct kqworkloop *kqwl, kq_index_t override_index)
+kqueue_update_override(kqueue_t kqu, struct knote *kn, thread_qos_t qos)
 {
-       kq_req_lock(kqwl);
-       kqworkloop_update_threads_qos(kqwl, KQWL_UTQ_UPDATE_WAKEUP_OVERRIDE,
-                       override_index);
-       kq_req_unlock(kqwl);
+       if (kqu.kq->kq_state & KQ_WORKLOOP) {
+               kqworkloop_update_threads_qos(kqu.kqwl, KQWL_UTQ_UPDATE_WAKEUP_OVERRIDE,
+                   qos);
+       } else {
+               kqworkq_update_override(kqu.kqwq, kn, qos);
+       }
 }
 
-static thread_qos_t
-kqworkloop_unbind_locked(struct kqworkloop *kqwl, thread_t thread)
+static void
+kqworkloop_unbind_locked(struct kqworkloop *kqwl, thread_t thread,
+    enum kqwl_unbind_locked_mode how)
 {
        struct uthread *ut = get_bsdthread_info(thread);
-       struct kqrequest *kqr = &kqwl->kqwl_request;
-       kq_index_t ipc_override = ut->uu_kqueue_override;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
+
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWL_UNBIND), kqwl->kqwl_dynamicid,
+           thread_tid(thread), 0, 0);
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWL_UNBIND), kqwl->kqwl_dynamicid,
-                       thread_tid(thread), 0, 0);
+       kqlock_held(kqwl);
 
-       kq_req_held(kqwl);
        assert(ut->uu_kqr_bound == kqr);
        ut->uu_kqr_bound = NULL;
-       ut->uu_kqueue_override = THREAD_QOS_UNSPECIFIED;
+       if (how == KQWL_OVERRIDE_DROP_IMMEDIATELY &&
+           ut->uu_kqueue_override != THREAD_QOS_UNSPECIFIED) {
+               thread_drop_servicer_override(thread);
+               ut->uu_kqueue_override = THREAD_QOS_UNSPECIFIED;
+       }
 
        if (kqwl->kqwl_owner == NULL && kqwl->kqwl_turnstile) {
                turnstile_update_inheritor(kqwl->kqwl_turnstile,
-                               TURNSTILE_INHERITOR_NULL, TURNSTILE_IMMEDIATE_UPDATE);
+                   TURNSTILE_INHERITOR_NULL, TURNSTILE_IMMEDIATE_UPDATE);
                turnstile_update_inheritor_complete(kqwl->kqwl_turnstile,
-                               TURNSTILE_INTERLOCK_HELD);
+                   TURNSTILE_INTERLOCK_HELD);
        }
 
-       kqr->kqr_thread = NULL;
-       kqr->kqr_state &= ~(KQR_THREQUESTED | KQR_R2K_NOTIF_ARMED);
-       return ipc_override;
+       kqr->tr_thread = THREAD_NULL;
+       kqr->tr_state = WORKQ_TR_STATE_IDLE;
+       kqwl->kqwl_state &= ~KQ_R2K_ARMED;
+}
+
+static void
+kqworkloop_unbind_delayed_override_drop(thread_t thread)
+{
+       struct uthread *ut = get_bsdthread_info(thread);
+       assert(ut->uu_kqr_bound == NULL);
+       if (ut->uu_kqueue_override != THREAD_QOS_UNSPECIFIED) {
+               thread_drop_servicer_override(thread);
+               ut->uu_kqueue_override = THREAD_QOS_UNSPECIFIED;
+       }
 }
 
 /*
@@ -6732,13 +5744,13 @@ kqworkloop_unbind_locked(struct kqworkloop *kqwl, thread_t thread)
  *     Called with kqueue lock held.
  */
 static void
-kqworkloop_unbind(proc_t p, struct kqworkloop *kqwl)
+kqworkloop_unbind(struct kqworkloop *kqwl)
 {
        struct kqueue *kq = &kqwl->kqwl_kqueue;
-       struct kqrequest *kqr = &kqwl->kqwl_request;
-       thread_t thread = kqr->kqr_thread;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
+       thread_t thread = kqr_thread_fast(kqr);
        int op = KQWL_UTQ_PARKING;
-       kq_index_t ipc_override, qos_override = THREAD_QOS_UNSPECIFIED;
+       kq_index_t qos_override = THREAD_QOS_UNSPECIFIED;
 
        assert(thread == current_thread());
 
@@ -6750,49 +5762,45 @@ kqworkloop_unbind(proc_t p, struct kqworkloop *kqwl)
         * kqworkloop_update_threads_qos() below.
         */
        assert((kq->kq_state & KQ_PROCESSING) == 0);
-       if (!TAILQ_EMPTY(&kqr->kqr_suppressed)) {
+       if (!TAILQ_EMPTY(&kqwl->kqwl_suppressed)) {
                kq->kq_state |= KQ_PROCESSING;
                qos_override = kqworkloop_acknowledge_events(kqwl);
                kq->kq_state &= ~KQ_PROCESSING;
        }
 
-       kq_req_lock(kqwl);
-
-       ipc_override = kqworkloop_unbind_locked(kqwl, thread);
+       kqworkloop_unbind_locked(kqwl, thread, KQWL_OVERRIDE_DROP_DELAYED);
        kqworkloop_update_threads_qos(kqwl, op, qos_override);
 
-       kq_req_unlock(kqwl);
-
        kqunlock(kqwl);
 
        /*
         * Drop the override on the current thread last, after the call to
         * kqworkloop_update_threads_qos above.
         */
-       if (ipc_override) {
-               thread_drop_ipc_override(thread);
-       }
+       kqworkloop_unbind_delayed_override_drop(thread);
 
        /* If last reference, dealloc the workloop kq */
-       kqueue_release_last(p, kqwl);
+       kqworkloop_release(kqwl);
 }
 
 static thread_qos_t
-kqworkq_unbind_locked(__assert_only struct kqworkq *kqwq,
-               struct kqrequest *kqr, thread_t thread)
+kqworkq_unbind_locked(struct kqworkq *kqwq,
+    workq_threadreq_t kqr, thread_t thread)
 {
        struct uthread *ut = get_bsdthread_info(thread);
-       kq_index_t old_override = kqr->kqr_override_index;
+       kq_index_t old_override = kqr->tr_kq_override_index;
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KQWQ_UNBIND), -1,
-                       thread_tid(kqr->kqr_thread), kqr->kqr_qos_index, 0);
+       KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KQWQ_UNBIND), -1,
+           thread_tid(kqr_thread(kqr)), kqr->tr_kq_qos_index, 0);
+
+       kqlock_held(kqwq);
 
-       kq_req_held(kqwq);
        assert(ut->uu_kqr_bound == kqr);
        ut->uu_kqr_bound = NULL;
-       kqr->kqr_thread = NULL;
-       kqr->kqr_state &= ~(KQR_THREQUESTED | KQR_R2K_NOTIF_ARMED);
-       kqr->kqr_override_index = THREAD_QOS_UNSPECIFIED;
+       kqr->tr_thread = THREAD_NULL;
+       kqr->tr_state = WORKQ_TR_STATE_IDLE;
+       kqr->tr_kq_override_index = THREAD_QOS_UNSPECIFIED;
+       kqwq->kqwq_state &= ~KQ_R2K_ARMED;
 
        return old_override;
 }
@@ -6807,7 +5815,7 @@ kqworkq_unbind_locked(__assert_only struct kqworkq *kqwq,
  *     - we pended wakeups while processing (or unsuppressing)
  */
 static void
-kqworkq_unbind(proc_t p, struct kqrequest *kqr)
+kqworkq_unbind(proc_t p, workq_threadreq_t kqr)
 {
        struct kqworkq *kqwq = (struct kqworkq *)p->p_fd->fd_wqkqueue;
        __assert_only int rc;
@@ -6818,7 +5826,7 @@ kqworkq_unbind(proc_t p, struct kqrequest *kqr)
        kqunlock(kqwq);
 }
 
-struct kqrequest *
+workq_threadreq_t
 kqworkq_get_request(struct kqworkq *kqwq, kq_index_t qos_index)
 {
        assert(qos_index < KQWQ_NBUCKETS);
@@ -6826,35 +5834,44 @@ kqworkq_get_request(struct kqworkq *kqwq, kq_index_t qos_index)
 }
 
 static void
-knote_apply_qos_override(struct knote *kn, kq_index_t qos_index)
+knote_reset_priority(kqueue_t kqu, struct knote *kn, pthread_priority_t pp)
 {
-       assert((kn->kn_status & KN_QUEUED) == 0);
-
-       kn->kn_qos_override = qos_index;
+       kq_index_t qos = _pthread_priority_thread_qos(pp);
 
-       if (kn->kn_status & KN_SUPPRESSED) {
-               struct kqueue *kq = knote_get_kq(kn);
-               /*
-                * For suppressed events, the kn_qos_index field cannot be touched as it
-                * allows us to know on which supress queue the knote is for a kqworkq.
-                *
-                * Also, there's no natural push applied on the kqueues when this field
-                * changes anyway. We hence need to apply manual overrides in this case,
-                * which will be cleared when the events are later acknowledged.
-                */
-               if (kq->kq_state & KQ_WORKQ) {
-                       kqworkq_update_override((struct kqworkq *)kq, kn, qos_index);
+       if (kqu.kq->kq_state & KQ_WORKLOOP) {
+               assert((pp & _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG) == 0);
+               pp = _pthread_priority_normalize(pp);
+       } else if (kqu.kq->kq_state & KQ_WORKQ) {
+               if (qos == THREAD_QOS_UNSPECIFIED) {
+                       /* On workqueues, outside of QoS means MANAGER */
+                       qos = KQWQ_QOS_MANAGER;
+                       pp = _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG;
                } else {
-                       kqworkloop_update_override((struct kqworkloop *)kq, qos_index);
+                       pp = _pthread_priority_normalize(pp);
                }
        } else {
-               kn->kn_qos_index = qos_index;
+               pp = _pthread_unspecified_priority();
+               qos = THREAD_QOS_UNSPECIFIED;
+       }
+
+       kn->kn_qos = pp;
+
+       if ((kn->kn_status & KN_MERGE_QOS) == 0 || qos > kn->kn_qos_override) {
+               /* Never lower QoS when in "Merge" mode */
+               kn->kn_qos_override = qos;
+       }
+
+       /* only adjust in-use qos index when not suppressed */
+       if (kn->kn_status & KN_SUPPRESSED) {
+               kqueue_update_override(kqu, kn, qos);
+       } else if (kn->kn_qos_index != qos) {
+               knote_dequeue(kqu, kn);
+               kn->kn_qos_index = qos;
        }
 }
 
-static bool
-knote_should_apply_qos_override(struct kqueue *kq, struct knote *kn, int result,
-               thread_qos_t *qos_out)
+static void
+knote_adjust_qos(struct kqueue *kq, struct knote *kn, int result)
 {
        thread_qos_t qos_index = (result >> FILTER_ADJUST_EVENT_QOS_SHIFT) & 7;
 
@@ -6865,42 +5882,33 @@ knote_should_apply_qos_override(struct kqueue *kq, struct knote *kn, int result,
 
        /*
         * Early exit for knotes that should not change QoS
-        *
-        * It is safe to test kn_req_index against MANAGER / STAYACTIVE because
-        * knotes with such kn_req_index values never change for their entire
-        * lifetime.
         */
        if (__improbable(!knote_fops(kn)->f_adjusts_qos)) {
                panic("filter %d cannot change QoS", kn->kn_filtid);
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               if (kn->kn_req_index == KQWL_BUCKET_STAYACTIVE) {
-                       return false;
-               }
-       } else if (kq->kq_state & KQ_WORKQ) {
-               if (kn->kn_req_index == KQWQ_QOS_MANAGER) {
-                       return false;
-               }
-       } else {
-               return false;
+       } else if (__improbable(!knote_has_qos(kn))) {
+               return;
        }
 
        /*
         * knotes with the FALLBACK flag will only use their registration QoS if the
         * incoming event has no QoS, else, the registration QoS acts as a floor.
         */
+       thread_qos_t req_qos = _pthread_priority_thread_qos_fast(kn->kn_qos);
        if (kn->kn_qos & _PTHREAD_PRIORITY_FALLBACK_FLAG) {
-               if (qos_index == THREAD_QOS_UNSPECIFIED)
-                       qos_index = kn->kn_req_index;
+               if (qos_index == THREAD_QOS_UNSPECIFIED) {
+                       qos_index = req_qos;
+               }
        } else {
-               if (qos_index < kn->kn_req_index)
-                       qos_index = kn->kn_req_index;
+               if (qos_index < req_qos) {
+                       qos_index = req_qos;
+               }
        }
        if ((kn->kn_status & KN_MERGE_QOS) && (qos_index < kn->kn_qos_override)) {
                /* Never lower QoS when in "Merge" mode */
-               return false;
+               return;
        }
 
-       if ((kn->kn_status & KN_LOCKED) && kn->kn_inuse) {
+       if ((kn->kn_status & KN_LOCKED) && (kn->kn_status & KN_POSTING)) {
                /*
                 * When we're trying to update the QoS override and that both an
                 * f_event() and other f_* calls are running concurrently, any of these
@@ -6911,132 +5919,62 @@ knote_should_apply_qos_override(struct kqueue *kq, struct knote *kn, int result,
                 * mode which causes subsequent override requests to saturate the
                 * override instead of replacing its value.
                 *
-                * This mode is left when knote_unlock() or knote_call_filter_event()
+                * This mode is left when knote_unlock() or knote_post()
                 * observe that no other f_* routine is in flight.
                 */
                kn->kn_status |= KN_MERGE_QOS;
        }
 
-       if (kn->kn_qos_override == qos_index) {
-               return false;
-       }
-
-       *qos_out = qos_index;
-       return true;
-}
+       /*
+        * Now apply the override if it changed.
+        */
 
-static void
-knote_adjust_qos(struct kqueue *kq, struct knote *kn, int result)
-{
-       thread_qos_t qos;
-       if (knote_should_apply_qos_override(kq, kn, result, &qos)) {
-               knote_dequeue(kn);
-               knote_apply_qos_override(kn, qos);
-               if (knote_enqueue(kn) && (kn->kn_status & KN_ACTIVE)) {
-                       knote_wakeup(kn);
-               }
+       if (kn->kn_qos_override == qos_index) {
+               return;
        }
-}
-
-static void
-knote_wakeup(struct knote *kn)
-{
-       struct kqueue *kq = knote_get_kq(kn);
-
-       kqlock_held(kq);
-
-       if (kq->kq_state & KQ_WORKQ) {
-               struct kqworkq *kqwq = (struct kqworkq *)kq;
 
-               kqworkq_request_help(kqwq, kn->kn_qos_index);
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               struct kqworkloop *kqwl = (struct kqworkloop *)kq;
+       kn->kn_qos_override = qos_index;
 
+       if (kn->kn_status & KN_SUPPRESSED) {
                /*
-                * kqworkloop_end_processing() will perform the required QoS
-                * computations when it unsets the processing mode.
+                * For suppressed events, the kn_qos_index field cannot be touched as it
+                * allows us to know on which supress queue the knote is for a kqworkq.
+                *
+                * Also, there's no natural push applied on the kqueues when this field
+                * changes anyway. We hence need to apply manual overrides in this case,
+                * which will be cleared when the events are later acknowledged.
                 */
-               if (!kqworkloop_is_processing_on_current_thread(kqwl)) {
-                       kqworkloop_request_help(kqwl, kn->kn_qos_index);
-               }
-       } else {
-               struct kqfile *kqf = (struct kqfile *)kq;
-
-               /* flag wakeups during processing */
-               if (kq->kq_state & KQ_PROCESSING)
-                       kq->kq_state |= KQ_WAKEUP;
-
-               /* wakeup a thread waiting on this queue */
-               if (kq->kq_state & (KQ_SLEEP | KQ_SEL)) {
-                       kq->kq_state &= ~(KQ_SLEEP | KQ_SEL);
-                       waitq_wakeup64_all((struct waitq *)&kq->kq_wqs, KQ_EVENT,
-                                       THREAD_AWAKENED, WAITQ_ALL_PRIORITIES);
-               }
-
-               /* wakeup other kqueues/select sets we're inside */
-               KNOTE(&kqf->kqf_sel.si_note, 0);
-       }
-}
-
-/*
- * Called with the kqueue locked
- */
-static void
-kqueue_interrupt(struct kqueue *kq)
-{
-       assert((kq->kq_state & KQ_WORKQ) == 0);
-
-       /* wakeup sleeping threads */
-       if ((kq->kq_state & (KQ_SLEEP | KQ_SEL)) != 0) {
-               kq->kq_state &= ~(KQ_SLEEP | KQ_SEL);
-               (void)waitq_wakeup64_all((struct waitq *)&kq->kq_wqs,
-                                        KQ_EVENT,
-                                        THREAD_RESTART,
-                                        WAITQ_ALL_PRIORITIES);
-       }
-
-       /* wakeup threads waiting their turn to process */
-       if (kq->kq_state & KQ_PROCWAIT) {
-               struct kqtailq *suppressq;
-
-               assert(kq->kq_state & KQ_PROCESSING);
-
-               kq->kq_state &= ~KQ_PROCWAIT;
-               suppressq = kqueue_get_suppressed_queue(kq, NULL);
-               (void)waitq_wakeup64_all((struct waitq *)&kq->kq_wqs,
-                                        CAST_EVENT64_T(suppressq),
-                                        THREAD_RESTART,
-                                        WAITQ_ALL_PRIORITIES);
+               kqueue_update_override(kq, kn, qos_index);
+       } else if (kn->kn_qos_index != qos_index) {
+               knote_dequeue(kq, kn);
+               kn->kn_qos_index = qos_index;
        }
 }
 
 /*
  * Called back from waitq code when no threads waiting and the hook was set.
  *
- * Interrupts are likely disabled and spin locks are held - minimal work
- * can be done in this context!!!
- *
- * JMM - in the future, this will try to determine which knotes match the
- * wait queue wakeup and apply these wakeups against those knotes themselves.
- * For now, all the events dispatched this way are dispatch-manager handled,
- * so hard-code that for now.
+ * Preemption is disabled - minimal work can be done in this context!!!
  */
 void
-waitq_set__CALLING_PREPOST_HOOK__(void *kq_hook, void *knote_hook, int qos)
+waitq_set__CALLING_PREPOST_HOOK__(waitq_set_prepost_hook_t *kq_hook)
 {
-#pragma unused(knote_hook, qos)
-
-       struct kqueue *kq = (struct kqueue *)kq_hook;
+       kqueue_t kqu;
 
-       if (kq->kq_state & KQ_WORKQ) {
-               struct kqworkq *kqwq = (struct kqworkq *)kq;
+       kqu.kq = __container_of(kq_hook, struct kqueue, kq_waitq_hook);
+       assert(kqu.kq->kq_state & (KQ_WORKQ | KQ_WORKLOOP));
 
-               kqworkq_request_help(kqwq, KQWQ_QOS_MANAGER);
-       } else if (kq->kq_state & KQ_WORKLOOP) {
-               struct kqworkloop *kqwl = (struct kqworkloop *)kq;
+       kqlock(kqu);
 
-               kqworkloop_request_help(kqwl, KQWL_BUCKET_STAYACTIVE);
+       if (kqu.kq->kq_count > 0) {
+               if (kqu.kq->kq_state & KQ_WORKLOOP) {
+                       kqworkloop_wakeup(kqu.kqwl, KQWL_BUCKET_STAYACTIVE);
+               } else {
+                       kqworkq_wakeup(kqu.kqwq, KQWQ_QOS_MANAGER);
+               }
        }
+
+       kqunlock(kqu);
 }
 
 void
@@ -7063,10 +6001,7 @@ knote(struct klist *list, long hint)
        struct knote *kn;
 
        SLIST_FOREACH(kn, list, kn_selnext) {
-               struct kqueue *kq = knote_get_kq(kn);
-               kqlock(kq);
-               knote_call_filter_event(kq, kn, hint);
-               kqunlock(kq);
+               knote_post(kn, hint);
        }
 }
 
@@ -7079,7 +6014,7 @@ knote_attach(struct klist *list, struct knote *kn)
 {
        int ret = SLIST_EMPTY(list);
        SLIST_INSERT_HEAD(list, kn, kn_selnext);
-       return (ret);
+       return ret;
 }
 
 /*
@@ -7090,7 +6025,7 @@ int
 knote_detach(struct klist *list, struct knote *kn)
 {
        SLIST_REMOVE(list, kn, knote, kn_selnext);
-       return (SLIST_EMPTY(list));
+       return SLIST_EMPTY(list);
 }
 
 /*
@@ -7109,7 +6044,7 @@ knote_detach(struct klist *list, struct knote *kn)
  * recursively - which likely is not supported.
  */
 void
-knote_vanish(struct klist *list)
+knote_vanish(struct klist *list, bool make_active)
 {
        struct knote *kn;
        struct knote *kn_next;
@@ -7118,12 +6053,26 @@ knote_vanish(struct klist *list)
                struct kqueue *kq = knote_get_kq(kn);
 
                kqlock(kq);
-               if (kn->kn_status & KN_REQVANISH) {
-                       /* If EV_VANISH supported - prepare to deliver one */
+               if (__probable(kn->kn_status & KN_REQVANISH)) {
+                       /*
+                        * If EV_VANISH supported - prepare to deliver one
+                        */
                        kn->kn_status |= KN_VANISHED;
-                       knote_activate(kn);
                } else {
-                       knote_call_filter_event(kq, kn, NOTE_REVOKE);
+                       /*
+                        * Handle the legacy way to indicate that the port/portset was
+                        * deallocated or left the current Mach portspace (modern technique
+                        * is with an EV_VANISHED protocol).
+                        *
+                        * Deliver an EV_EOF event for these changes (hopefully it will get
+                        * delivered before the port name recycles to the same generation
+                        * count and someone tries to re-register a kevent for it or the
+                        * events are udata-specific - avoiding a conflict).
+                        */
+                       kn->kn_flags |= EV_EOF | EV_ONESHOT;
+               }
+               if (make_active) {
+                       knote_activate(kq, kn, FILTER_ACTIVE);
                }
                kqunlock(kq);
        }
@@ -7176,9 +6125,9 @@ knote_link_waitq(struct knote *kn, struct waitq *wq, uint64_t *reserved_link)
        kr = waitq_link(wq, &kq->kq_wqs, WAITQ_ALREADY_LOCKED, reserved_link);
        if (kr == KERN_SUCCESS) {
                knote_markstayactive(kn);
-               return (0);
+               return 0;
        } else {
-               return (EINVAL);
+               return EINVAL;
        }
 }
 
@@ -7199,7 +6148,7 @@ knote_unlink_waitq(struct knote *kn, struct waitq *wq)
 
        kr = waitq_unlink(wq, &kq->kq_wqs);
        knote_clearstayactive(kn);
-       return ((kr != KERN_SUCCESS) ? EINVAL : 0);
+       return (kr != KERN_SUCCESS) ? EINVAL : 0;
 }
 
 /*
@@ -7222,9 +6171,10 @@ restart:
 
                kqlock(kq);
 
-               if (kq->kq_p != p)
+               if (kq->kq_p != p) {
                        panic("%s: proc mismatch (kq->kq_p=%p != p=%p)",
                            __func__, kq->kq_p, p);
+               }
 
                /*
                 * If the knote supports EV_VANISHED delivery,
@@ -7241,15 +6191,16 @@ restart:
                        /* the knote was dropped by someone, nothing to do */
                } else if (kn->kn_status & KN_REQVANISH) {
                        kn->kn_status |= KN_VANISHED;
-                       kn->kn_status &= ~KN_ATTACHED;
 
                        kqunlock(kq);
                        knote_fops(kn)->f_detach(kn);
-                       if (knote_fops(kn)->f_isfd)
+                       if (kn->kn_is_fd) {
                                fp_drop(p, kn->kn_id, kn->kn_fp, 0);
+                       }
+                       kn->kn_filtid = EVFILTID_DETACHED;
                        kqlock(kq);
 
-                       knote_activate(kn);
+                       knote_activate(kq, kn, FILTER_ACTIVE);
                        knote_unlock(kq, kn, &knlc, KNOTE_KQ_UNLOCK);
                } else {
                        knote_drop(kq, kn, &knlc);
@@ -7275,9 +6226,9 @@ restart:
  */
 static struct knote *
 knote_fdfind(struct kqueue *kq,
-               struct kevent_internal_s *kev,
-               bool is_fd,
-               struct proc *p)
+    const struct kevent_internal_s *kev,
+    bool is_fd,
+    struct proc *p)
 {
        struct filedesc *fdp = p->p_fd;
        struct klist *list = NULL;
@@ -7288,12 +6239,12 @@ knote_fdfind(struct kqueue *kq,
         */
        if (is_fd) {
                /* fd-based knotes are linked off the fd table */
-               if (kev->ident < (u_int)fdp->fd_knlistsize) {
-                       list = &fdp->fd_knlist[kev->ident];
+               if (kev->kei_ident < (u_int)fdp->fd_knlistsize) {
+                       list = &fdp->fd_knlist[kev->kei_ident];
                }
        } else if (fdp->fd_knhashmask != 0) {
                /* hash non-fd knotes here too */
-               list = &fdp->fd_knhash[KN_HASH((u_long)kev->ident, fdp->fd_knhashmask)];
+               list = &fdp->fd_knhash[KN_HASH((u_long)kev->kei_ident, fdp->fd_knhashmask)];
        }
 
        /*
@@ -7302,14 +6253,14 @@ knote_fdfind(struct kqueue *kq,
        if (list != NULL) {
                SLIST_FOREACH(kn, list, kn_link) {
                        if (kq == knote_get_kq(kn) &&
-                           kev->ident == kn->kn_id &&
-                           kev->filter == kn->kn_filter) {
-                               if (kev->flags & EV_UDATA_SPECIFIC) {
-                                       if ((kn->kn_status & KN_UDATA_SPECIFIC) &&
-                                           kev->udata == kn->kn_udata) {
+                           kev->kei_ident == kn->kn_id &&
+                           kev->kei_filter == kn->kn_filter) {
+                               if (kev->kei_flags & EV_UDATA_SPECIFIC) {
+                                       if ((kn->kn_flags & EV_UDATA_SPECIFIC) &&
+                                           kev->kei_udata == kn->kn_udata) {
                                                break; /* matching udata-specific knote */
                                        }
-                               } else if ((kn->kn_status & KN_UDATA_SPECIFIC) == 0) {
+                               } else if ((kn->kn_flags & EV_UDATA_SPECIFIC) == 0) {
                                        break; /* matching non-udata-specific knote */
                                }
                        }
@@ -7334,17 +6285,18 @@ knote_fdfind(struct kqueue *kq,
  */
 static int
 kq_add_knote(struct kqueue *kq, struct knote *kn, struct knote_lock_ctx *knlc,
-               struct proc *p)
+    struct proc *p)
 {
        struct filedesc *fdp = p->p_fd;
        struct klist *list = NULL;
        int ret = 0;
-       bool is_fd = knote_fops(kn)->f_isfd;
+       bool is_fd = kn->kn_is_fd;
 
-       if (is_fd)
+       if (is_fd) {
                proc_fdlock(p);
-       else
-               knhash_lock(p);
+       } else {
+               knhash_lock(fdp);
+       }
 
        if (knote_fdfind(kq, &kn->kn_kevent, is_fd, p) != NULL) {
                /* found an existing knote: we can't add this one */
@@ -7371,7 +6323,6 @@ kq_add_knote(struct kqueue *kq, struct knote *kn, struct knote_lock_ctx *knlc,
                SLIST_INSERT_HEAD(list, kn, kn_link);
                ret = 0;
                goto out_locked;
-
        } else {
                /* knote is fd based */
 
@@ -7385,10 +6336,11 @@ kq_add_knote(struct kqueue *kq, struct knote *kn, struct knote_lock_ctx *knlc,
                        }
                        /* have to grow the fd_knlist */
                        size = fdp->fd_knlistsize;
-                       while (size <= kn->kn_id)
+                       while (size <= kn->kn_id) {
                                size += KQEXTENT;
+                       }
 
-                       if (size >= (UINT_MAX/sizeof(struct klist *))) {
+                       if (size >= (UINT_MAX / sizeof(struct klist *))) {
                                ret = EINVAL;
                                goto out_locked;
                        }
@@ -7414,7 +6366,6 @@ kq_add_knote(struct kqueue *kq, struct knote *kn, struct knote_lock_ctx *knlc,
                SLIST_INSERT_HEAD(list, kn, kn_link);
                ret = 0;
                goto out_locked;
-
        }
 
 out_locked:
@@ -7422,11 +6373,13 @@ out_locked:
                kqlock(kq);
                assert((kn->kn_status & KN_LOCKED) == 0);
                (void)knote_lock(kq, kn, knlc, KNOTE_KQ_UNLOCK);
+               kqueue_retain(kq); /* retain a kq ref */
        }
-       if (is_fd)
+       if (is_fd) {
                proc_fdunlock(p);
-       else
-               knhash_unlock(p);
+       } else {
+               knhash_unlock(fdp);
+       }
 
        return ret;
 }
@@ -7441,22 +6394,21 @@ out_locked:
  */
 static void
 kq_remove_knote(struct kqueue *kq, struct knote *kn, struct proc *p,
-               struct knote_lock_ctx *knlc)
+    struct knote_lock_ctx *knlc)
 {
        struct filedesc *fdp = p->p_fd;
        struct klist *list = NULL;
        uint16_t kq_state;
-       bool is_fd;
-
-       is_fd = knote_fops(kn)->f_isfd;
+       bool is_fd = kn->kn_is_fd;
 
-       if (is_fd)
+       if (is_fd) {
                proc_fdlock(p);
-       else
-               knhash_lock(p);
+       } else {
+               knhash_lock(fdp);
+       }
 
        if (is_fd) {
-               assert ((u_int)fdp->fd_knlistsize > kn->kn_id);
+               assert((u_int)fdp->fd_knlistsize > kn->kn_id);
                list = &fdp->fd_knlist[kn->kn_id];
        } else {
                list = &fdp->fd_knhash[KN_HASH(kn->kn_id, fdp->fd_knhashmask)];
@@ -7466,17 +6418,19 @@ kq_remove_knote(struct kqueue *kq, struct knote *kn, struct proc *p,
        kqlock(kq);
        kq_state = kq->kq_state;
        if (knlc) {
-               knote_unlock_cancel(kq, kn, knlc, KNOTE_KQ_UNLOCK);
+               knote_unlock_cancel(kq, kn, knlc);
        } else {
                kqunlock(kq);
        }
-       if (is_fd)
+       if (is_fd) {
                proc_fdunlock(p);
-       else
-               knhash_unlock(p);
+       } else {
+               knhash_unlock(fdp);
+       }
 
-       if (kq_state & KQ_DYNAMIC)
-               kqueue_release_last(p, kq);
+       if (kq_state & KQ_DYNAMIC) {
+               kqworkloop_release((struct kqworkloop *)kq);
+       }
 }
 
 /*
@@ -7487,29 +6441,276 @@ kq_remove_knote(struct kqueue *kq, struct knote *kn, struct proc *p,
  */
 
 static struct knote *
-kq_find_knote_and_kq_lock(struct kqueue *kq, struct kevent_internal_s *kev,
-               bool is_fd, struct proc *p)
+kq_find_knote_and_kq_lock(struct kqueue *kq, struct kevent_qos_s *kev,
+    bool is_fd, struct proc *p)
 {
-       struct knote * ret;
+       struct filedesc *fdp = p->p_fd;
+       struct knote *kn;
 
-       if (is_fd)
+       if (is_fd) {
                proc_fdlock(p);
-       else
-               knhash_lock(p);
+       } else {
+               knhash_lock(fdp);
+       }
 
-       ret = knote_fdfind(kq, kev, is_fd, p);
+       /*
+        * Temporary horrible hack:
+        * this cast is gross and will go away in a future change.
+        * It is OK to do because we don't look at xflags/s_fflags,
+        * and that when we cast down the kev this way,
+        * the truncated filter field works.
+        */
+       kn = knote_fdfind(kq, (struct kevent_internal_s *)kev, is_fd, p);
 
-       if (ret) {
+       if (kn) {
                kqlock(kq);
+               assert(knote_get_kq(kn) == kq);
        }
 
-       if (is_fd)
+       if (is_fd) {
                proc_fdunlock(p);
-       else
-               knhash_unlock(p);
+       } else {
+               knhash_unlock(fdp);
+       }
 
-       return ret;
+       return kn;
+}
+
+__attribute__((noinline))
+static void
+kqfile_wakeup(struct kqfile *kqf, __unused kq_index_t qos)
+{
+       /* flag wakeups during processing */
+       if (kqf->kqf_state & KQ_PROCESSING) {
+               kqf->kqf_state |= KQ_WAKEUP;
+       }
+
+       /* wakeup a thread waiting on this queue */
+       if (kqf->kqf_state & (KQ_SLEEP | KQ_SEL)) {
+               kqf->kqf_state &= ~(KQ_SLEEP | KQ_SEL);
+               waitq_wakeup64_all((struct waitq *)&kqf->kqf_wqs, KQ_EVENT,
+                   THREAD_AWAKENED, WAITQ_ALL_PRIORITIES);
+       }
+
+       /* wakeup other kqueues/select sets we're inside */
+       KNOTE(&kqf->kqf_sel.si_note, 0);
+}
+
+static struct kqtailq *
+knote_get_tailq(kqueue_t kqu, struct knote *kn)
+{
+       kq_index_t qos_index = kn->kn_qos_index;
+
+       if (kqu.kq->kq_state & KQ_WORKLOOP) {
+               assert(qos_index < KQWL_NBUCKETS);
+       } else if (kqu.kq->kq_state & KQ_WORKQ) {
+               assert(qos_index < KQWQ_NBUCKETS);
+       } else {
+               assert(qos_index == QOS_INDEX_KQFILE);
+       }
+       static_assert(offsetof(struct kqueue, kq_queue) == sizeof(struct kqueue),
+           "struct kqueue::kq_queue must be exactly at the end");
+       return &kqu.kq->kq_queue[qos_index];
+}
+
+static void
+knote_enqueue(kqueue_t kqu, struct knote *kn, kn_status_t wakeup_mask)
+{
+       kqlock_held(kqu);
+
+       if ((kn->kn_status & (KN_ACTIVE | KN_STAYACTIVE)) == 0) {
+               return;
+       }
+
+       if (kn->kn_status & (KN_DISABLED | KN_SUPPRESSED | KN_DROPPING)) {
+               return;
+       }
+
+       if ((kn->kn_status & KN_QUEUED) == 0) {
+               struct kqtailq *queue = knote_get_tailq(kqu, kn);
+
+               TAILQ_INSERT_TAIL(queue, kn, kn_tqe);
+               kn->kn_status |= KN_QUEUED;
+               kqu.kq->kq_count++;
+       } else if ((kn->kn_status & KN_STAYACTIVE) == 0) {
+               return;
+       }
+
+       if (kn->kn_status & wakeup_mask) {
+               if (kqu.kq->kq_state & KQ_WORKLOOP) {
+                       kqworkloop_wakeup(kqu.kqwl, kn->kn_qos_index);
+               } else if (kqu.kq->kq_state & KQ_WORKQ) {
+                       kqworkq_wakeup(kqu.kqwq, kn->kn_qos_index);
+               } else {
+                       kqfile_wakeup(kqu.kqf, kn->kn_qos_index);
+               }
+       }
+}
+
+__attribute__((always_inline))
+static inline void
+knote_dequeue(kqueue_t kqu, struct knote *kn)
+{
+       if (kn->kn_status & KN_QUEUED) {
+               struct kqtailq *queue = knote_get_tailq(kqu, kn);
+
+               // attaching the knote calls knote_reset_priority() without
+               // the kqlock which is fine, so we can't call kqlock_held()
+               // if we're not queued.
+               kqlock_held(kqu);
+
+               TAILQ_REMOVE(queue, kn, kn_tqe);
+               kn->kn_status &= ~KN_QUEUED;
+               kqu.kq->kq_count--;
+       }
+}
+
+/* called with kqueue lock held */
+static void
+knote_suppress(kqueue_t kqu, struct knote *kn)
+{
+       struct kqtailq *suppressq;
+
+       kqlock_held(kqu);
+
+       assert((kn->kn_status & KN_SUPPRESSED) == 0);
+       assert(kn->kn_status & KN_QUEUED);
+
+       knote_dequeue(kqu, kn);
+       /* deactivate - so new activations indicate a wakeup */
+       kn->kn_status &= ~KN_ACTIVE;
+       kn->kn_status |= KN_SUPPRESSED;
+       suppressq = kqueue_get_suppressed_queue(kqu, kn);
+       TAILQ_INSERT_TAIL(suppressq, kn, kn_tqe);
+}
+
+__attribute__((always_inline))
+static inline void
+knote_unsuppress_noqueue(kqueue_t kqu, struct knote *kn)
+{
+       struct kqtailq *suppressq;
+
+       kqlock_held(kqu);
+
+       assert(kn->kn_status & KN_SUPPRESSED);
+
+       kn->kn_status &= ~KN_SUPPRESSED;
+       suppressq = kqueue_get_suppressed_queue(kqu, kn);
+       TAILQ_REMOVE(suppressq, kn, kn_tqe);
+
+       /*
+        * If the knote is no longer active, reset its push,
+        * and resynchronize kn_qos_index with kn_qos_override
+        * for knotes with a real qos.
+        */
+       if ((kn->kn_status & KN_ACTIVE) == 0 && knote_has_qos(kn)) {
+               kn->kn_qos_override = _pthread_priority_thread_qos_fast(kn->kn_qos);
+       }
+       kn->kn_qos_index = kn->kn_qos_override;
+}
+
+/* called with kqueue lock held */
+static void
+knote_unsuppress(kqueue_t kqu, struct knote *kn)
+{
+       if (kn->kn_status & KN_SUPPRESSED) {
+               knote_unsuppress_noqueue(kqu, kn);
+
+               /* don't wakeup if unsuppressing just a stay-active knote */
+               knote_enqueue(kqu, kn, KN_ACTIVE);
+       }
+}
+
+__attribute__((always_inline))
+static inline void
+knote_mark_active(struct knote *kn)
+{
+       if ((kn->kn_status & KN_ACTIVE) == 0) {
+               KDBG_DEBUG(KEV_EVTID(BSD_KEVENT_KNOTE_ACTIVATE),
+                   kn->kn_udata, kn->kn_status | (kn->kn_id << 32),
+                   kn->kn_filtid);
+       }
+
+       kn->kn_status |= KN_ACTIVE;
+}
+
+/* called with kqueue lock held */
+static void
+knote_activate(kqueue_t kqu, struct knote *kn, int result)
+{
+       assert(result & FILTER_ACTIVE);
+       if (result & FILTER_ADJUST_EVENT_QOS_BIT) {
+               // may dequeue the knote
+               knote_adjust_qos(kqu.kq, kn, result);
+       }
+       knote_mark_active(kn);
+       knote_enqueue(kqu, kn, KN_ACTIVE | KN_STAYACTIVE);
+}
+
+/*
+ * This function applies changes requested by f_attach or f_touch for
+ * a given filter. It proceeds in a carefully chosen order to help
+ * every single transition do the minimal amount of work possible.
+ */
+static void
+knote_apply_touch(kqueue_t kqu, struct knote *kn, struct kevent_qos_s *kev,
+    int result)
+{
+       kn_status_t wakeup_mask = KN_ACTIVE;
+
+       if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) {
+               /*
+                * When a stayactive knote is reenabled, we may have missed wakeups
+                * while it was disabled, so we need to poll it. To do so, ask
+                * knote_enqueue() below to reenqueue it.
+                */
+               wakeup_mask |= KN_STAYACTIVE;
+               kn->kn_status &= ~KN_DISABLED;
+
+               /*
+                * it is possible for userland to have knotes registered for a given
+                * workloop `wl_orig` but really handled on another workloop `wl_new`.
+                *
+                * In that case, rearming will happen from the servicer thread of
+                * `wl_new` which if `wl_orig` is no longer being serviced, would cause
+                * this knote to stay suppressed forever if we only relied on
+                * kqworkloop_acknowledge_events to be called by `wl_orig`.
+                *
+                * However if we see the KQ_PROCESSING bit on `wl_orig` set, we can't
+                * unsuppress because that would mess with the processing phase of
+                * `wl_orig`, however it also means kqworkloop_acknowledge_events()
+                * will be called.
+                */
+               if (__improbable(kn->kn_status & KN_SUPPRESSED)) {
+                       if ((kqu.kq->kq_state & KQ_PROCESSING) == 0) {
+                               knote_unsuppress_noqueue(kqu, kn);
+                       }
+               }
+       }
+
+       if ((result & FILTER_UPDATE_REQ_QOS) && kev->qos && kev->qos != kn->kn_qos) {
+               // may dequeue the knote
+               knote_reset_priority(kqu, kn, kev->qos);
+       }
+
+       /*
+        * When we unsuppress above, or because of knote_reset_priority(),
+        * the knote may have been dequeued, we need to restore the invariant
+        * that if the knote is active it needs to be queued now that
+        * we're done applying changes.
+        */
+       if (result & FILTER_ACTIVE) {
+               knote_activate(kqu, kn, result);
+       } else {
+               knote_enqueue(kqu, kn, wakeup_mask);
+       }
+
+       if ((result & FILTER_THREADREQ_NODEFEER) &&
+           act_clear_astkevent(current_thread(), AST_KEVENT_REDRIVE_THREADREQ)) {
+               workq_kern_threadreq_redrive(kqu.kq->kq_p, WORKQ_THREADREQ_NONE);
+       }
 }
+
 /*
  * knote_drop - disconnect and drop the knote
  *
@@ -7533,249 +6734,1323 @@ knote_drop(struct kqueue *kq, struct knote *kn, struct knote_lock_ctx *knlc)
        }
        kn->kn_status |= KN_DROPPING;
 
-       knote_unsuppress(kn);
-       knote_dequeue(kn);
-       knote_wait_for_filter_events(kq, kn);
-
-       /* If we are attached, disconnect from the source first */
-       if (kn->kn_status & KN_ATTACHED) {
-               knote_fops(kn)->f_detach(kn);
+       if (kn->kn_status & KN_SUPPRESSED) {
+               knote_unsuppress_noqueue(kq, kn);
+       } else {
+               knote_dequeue(kq, kn);
        }
+       knote_wait_for_post(kq, kn);
+
+       knote_fops(kn)->f_detach(kn);
 
        /* kq may be freed when kq_remove_knote() returns */
        kq_remove_knote(kq, kn, p, knlc);
-       if (knote_fops(kn)->f_isfd && ((kn->kn_status & KN_VANISHED) == 0))
+       if (kn->kn_is_fd && ((kn->kn_status & KN_VANISHED) == 0)) {
                fp_drop(p, kn->kn_id, kn->kn_fp, 0);
+       }
 
        knote_free(kn);
 }
 
-/* called with kqueue lock held */
-static void
-knote_activate(struct knote *kn)
+void
+knote_init(void)
 {
-       if (kn->kn_status & KN_ACTIVE)
-               return;
+       knote_zone = zinit(sizeof(struct knote), 8192 * sizeof(struct knote),
+           8192, "knote zone");
+       zone_change(knote_zone, Z_CACHING_ENABLED, TRUE);
 
-       KDBG_FILTERED(KEV_EVTID(BSD_KEVENT_KNOTE_ACTIVATE),
-                     kn->kn_udata, kn->kn_status | (kn->kn_id << 32),
-                     kn->kn_filtid);
+       kqfile_zone = zinit(sizeof(struct kqfile), 8192 * sizeof(struct kqfile),
+           8192, "kqueue file zone");
 
-       kn->kn_status |= KN_ACTIVE;
-       if (knote_enqueue(kn))
-               knote_wakeup(kn);
+       kqworkq_zone = zinit(sizeof(struct kqworkq), 8192 * sizeof(struct kqworkq),
+           8192, "kqueue workq zone");
+
+       kqworkloop_zone = zinit(sizeof(struct kqworkloop), 8192 * sizeof(struct kqworkloop),
+           8192, "kqueue workloop zone");
+       zone_change(kqworkloop_zone, Z_CACHING_ENABLED, TRUE);
+
+       /* allocate kq lock group attribute and group */
+       kq_lck_grp_attr = lck_grp_attr_alloc_init();
+
+       kq_lck_grp = lck_grp_alloc_init("kqueue", kq_lck_grp_attr);
+
+       /* Allocate kq lock attribute */
+       kq_lck_attr = lck_attr_alloc_init();
+
+#if CONFIG_MEMORYSTATUS
+       /* Initialize the memorystatus list lock */
+       memorystatus_kevent_init(kq_lck_grp, kq_lck_attr);
+#endif
 }
+SYSINIT(knote, SI_SUB_PSEUDO, SI_ORDER_ANY, knote_init, NULL);
 
-/* called with kqueue lock held */
-static void
-knote_deactivate(struct knote *kn)
+const struct filterops *
+knote_fops(struct knote *kn)
 {
-       kn->kn_status &= ~KN_ACTIVE;
-       if ((kn->kn_status & KN_STAYACTIVE) == 0)
-               knote_dequeue(kn);
+       return sysfilt_ops[kn->kn_filtid];
+}
+
+static struct knote *
+knote_alloc(void)
+{
+       struct knote *kn = ((struct knote *)zalloc(knote_zone));
+       bzero(kn, sizeof(struct knote));
+       return kn;
 }
 
-/* called with kqueue lock held */
 static void
-knote_enable(struct knote *kn)
+knote_free(struct knote *kn)
 {
-       if ((kn->kn_status & KN_DISABLED) == 0)
-               return;
+       assert((kn->kn_status & (KN_LOCKED | KN_POSTING)) == 0);
+       zfree(knote_zone, kn);
+}
 
-       kn->kn_status &= ~KN_DISABLED;
+#pragma mark - syscalls: kevent, kevent64, kevent_qos, kevent_id
 
-       if (kn->kn_status & KN_SUPPRESSED) {
-               /*
-                * it is possible for userland to have knotes registered for a given
-                * workloop `wl_orig` but really handled on another workloop `wl_new`.
-                *
-                * In that case, rearming will happen from the servicer thread of
-                * `wl_new` which if `wl_orig` is no longer being serviced, would cause
-                * this knote to stay suppressed forever if we only relied on
-                * kqworkloop_acknowledge_events to be called by `wl_orig`.
-                *
-                * However if we see the KQ_PROCESSING bit on `wl_orig` set, we can't
-                * unsuppress because that would mess with the processing phase of
-                * `wl_orig`, however it also means kqworkloop_acknowledge_events()
-                * will be called.
-                */
-               struct kqueue *kq = knote_get_kq(kn);
-               if ((kq->kq_state & KQ_PROCESSING) == 0) {
-                       knote_unsuppress(kn);
+kevent_ctx_t
+kevent_get_context(thread_t thread)
+{
+       uthread_t ut = get_bsdthread_info(thread);
+       return &ut->uu_save.uus_kevent;
+}
+
+static inline bool
+kevent_args_requesting_events(unsigned int flags, int nevents)
+{
+       return !(flags & KEVENT_FLAG_ERROR_EVENTS) && nevents > 0;
+}
+
+static inline int
+kevent_adjust_flags_for_proc(proc_t p, int flags)
+{
+       __builtin_assume(p);
+       return flags | (IS_64BIT_PROCESS(p) ? KEVENT_FLAG_PROC64 : 0);
+}
+
+/*!
+ * @function kevent_get_kqfile
+ *
+ * @brief
+ * Lookup a kqfile by fd.
+ *
+ * @discussion
+ * Callers: kevent, kevent64, kevent_qos
+ *
+ * This is not assumed to be a fastpath (kqfile interfaces are legacy)
+ */
+OS_NOINLINE
+static int
+kevent_get_kqfile(struct proc *p, int fd, int flags,
+    struct fileproc **fp, struct kqueue **kqp)
+{
+       int error = 0;
+       struct kqueue *kq;
+
+       error = fp_getfkq(p, fd, fp, &kq);
+       if (__improbable(error)) {
+               return error;
+       }
+
+       uint16_t kq_state = os_atomic_load(&kq->kq_state, relaxed);
+       if (__improbable((kq_state & (KQ_KEV32 | KQ_KEV64 | KQ_KEV_QOS)) == 0)) {
+               kqlock(kq);
+               kq_state = kq->kq_state;
+               if (!(kq_state & (KQ_KEV32 | KQ_KEV64 | KQ_KEV_QOS))) {
+                       if (flags & KEVENT_FLAG_LEGACY32) {
+                               kq_state |= KQ_KEV32;
+                       } else if (flags & KEVENT_FLAG_LEGACY64) {
+                               kq_state |= KQ_KEV64;
+                       } else {
+                               kq_state |= KQ_KEV_QOS;
+                       }
+                       kq->kq_state = kq_state;
+               }
+               kqunlock(kq);
+       }
+
+       /*
+        * kqfiles can't be used through the legacy kevent()
+        * and other interfaces at the same time.
+        */
+       if (__improbable((bool)(flags & KEVENT_FLAG_LEGACY32) !=
+           (bool)(kq_state & KQ_KEV32))) {
+               fp_drop(p, fd, *fp, 0);
+               return EINVAL;
+       }
+
+       *kqp = kq;
+       return 0;
+}
+
+/*!
+ * @function kevent_get_kqwq
+ *
+ * @brief
+ * Lookup or create the process kqwq (faspath).
+ *
+ * @discussion
+ * Callers: kevent64, kevent_qos
+ */
+OS_ALWAYS_INLINE
+static int
+kevent_get_kqwq(proc_t p, int flags, int nevents, struct kqueue **kqp)
+{
+       struct kqworkq *kqwq = p->p_fd->fd_wqkqueue;
+
+       if (__improbable(kevent_args_requesting_events(flags, nevents))) {
+               return EINVAL;
+       }
+       if (__improbable(kqwq == NULL)) {
+               kqwq = kqworkq_alloc(p, flags);
+               if (__improbable(kqwq == NULL)) {
+                       return ENOMEM;
                }
-       } else if (knote_enqueue(kn)) {
-               knote_wakeup(kn);
        }
-}
-
-/* called with kqueue lock held */
-static void
-knote_disable(struct knote *kn)
-{
-       if (kn->kn_status & KN_DISABLED)
-               return;
 
-       kn->kn_status |= KN_DISABLED;
-       knote_dequeue(kn);
+       *kqp = &kqwq->kqwq_kqueue;
+       return 0;
+}
+
+#pragma mark kevent copyio
+
+/*!
+ * @function kevent_get_data_size
+ *
+ * @brief
+ * Copies in the extra data size from user-space.
+ */
+static int
+kevent_get_data_size(int flags, user_addr_t data_avail, user_addr_t data_out,
+    kevent_ctx_t kectx)
+{
+       if (!data_avail || !data_out) {
+               kectx->kec_data_size  = 0;
+               kectx->kec_data_resid = 0;
+       } else if (flags & KEVENT_FLAG_PROC64) {
+               user64_size_t usize = 0;
+               int error = copyin((user_addr_t)data_avail, &usize, sizeof(usize));
+               if (__improbable(error)) {
+                       return error;
+               }
+               kectx->kec_data_resid = kectx->kec_data_size = (user_size_t)usize;
+       } else {
+               user32_size_t usize = 0;
+               int error = copyin((user_addr_t)data_avail, &usize, sizeof(usize));
+               if (__improbable(error)) {
+                       return error;
+               }
+               kectx->kec_data_avail = data_avail;
+               kectx->kec_data_resid = kectx->kec_data_size = (user_size_t)usize;
+       }
+       kectx->kec_data_out   = data_out;
+       kectx->kec_data_avail = data_avail;
+       return 0;
+}
+
+/*!
+ * @function kevent_put_data_size
+ *
+ * @brief
+ * Copies out the residual data size to user-space if any has been used.
+ */
+static int
+kevent_put_data_size(unsigned int flags, kevent_ctx_t kectx)
+{
+       if (kectx->kec_data_resid == kectx->kec_data_size) {
+               return 0;
+       }
+       if (flags & KEVENT_FLAG_KERNEL) {
+               *(user_size_t *)(uintptr_t)kectx->kec_data_avail = kectx->kec_data_resid;
+               return 0;
+       }
+       if (flags & KEVENT_FLAG_PROC64) {
+               user64_size_t usize = (user64_size_t)kectx->kec_data_resid;
+               return copyout(&usize, (user_addr_t)kectx->kec_data_avail, sizeof(usize));
+       } else {
+               user32_size_t usize = (user32_size_t)kectx->kec_data_resid;
+               return copyout(&usize, (user_addr_t)kectx->kec_data_avail, sizeof(usize));
+       }
+}
+
+/*!
+ * @function kevent_legacy_copyin
+ *
+ * @brief
+ * Handles the copyin of a kevent/kevent64 event.
+ */
+static int
+kevent_legacy_copyin(user_addr_t *addrp, struct kevent_qos_s *kevp, unsigned int flags)
+{
+       int error;
+
+       assert((flags & (KEVENT_FLAG_LEGACY32 | KEVENT_FLAG_LEGACY64)) != 0);
+
+       if (flags & KEVENT_FLAG_LEGACY64) {
+               struct kevent64_s kev64;
+
+               error = copyin(*addrp, (caddr_t)&kev64, sizeof(kev64));
+               if (__improbable(error)) {
+                       return error;
+               }
+               *addrp += sizeof(kev64);
+               *kevp = (struct kevent_qos_s){
+                       .ident  = kev64.ident,
+                       .filter = kev64.filter,
+                       /* Make sure user doesn't pass in any system flags */
+                       .flags  = kev64.flags & ~EV_SYSFLAGS,
+                       .udata  = kev64.udata,
+                       .fflags = kev64.fflags,
+                       .data   = kev64.data,
+                       .ext[0] = kev64.ext[0],
+                       .ext[1] = kev64.ext[1],
+               };
+       } else if (flags & KEVENT_FLAG_PROC64) {
+               struct user64_kevent kev64;
+
+               error = copyin(*addrp, (caddr_t)&kev64, sizeof(kev64));
+               if (__improbable(error)) {
+                       return error;
+               }
+               *addrp += sizeof(kev64);
+               *kevp = (struct kevent_qos_s){
+                       .ident  = kev64.ident,
+                       .filter = kev64.filter,
+                       /* Make sure user doesn't pass in any system flags */
+                       .flags  = kev64.flags & ~EV_SYSFLAGS,
+                       .udata  = kev64.udata,
+                       .fflags = kev64.fflags,
+                       .data   = kev64.data,
+               };
+       } else {
+               struct user32_kevent kev32;
+
+               error = copyin(*addrp, (caddr_t)&kev32, sizeof(kev32));
+               if (__improbable(error)) {
+                       return error;
+               }
+               *addrp += sizeof(kev32);
+               *kevp = (struct kevent_qos_s){
+                       .ident  = (uintptr_t)kev32.ident,
+                       .filter = kev32.filter,
+                       /* Make sure user doesn't pass in any system flags */
+                       .flags  = kev32.flags & ~EV_SYSFLAGS,
+                       .udata  = CAST_USER_ADDR_T(kev32.udata),
+                       .fflags = kev32.fflags,
+                       .data   = (intptr_t)kev32.data,
+               };
+       }
+
+       return 0;
+}
+
+/*!
+ * @function kevent_modern_copyin
+ *
+ * @brief
+ * Handles the copyin of a kevent_qos/kevent_id event.
+ */
+static int
+kevent_modern_copyin(user_addr_t *addrp, struct kevent_qos_s *kevp)
+{
+       int error = copyin(*addrp, (caddr_t)kevp, sizeof(struct kevent_qos_s));
+       if (__probable(!error)) {
+               /* Make sure user doesn't pass in any system flags */
+               *addrp += sizeof(struct kevent_qos_s);
+               kevp->flags &= ~EV_SYSFLAGS;
+       }
+       return error;
+}
+
+/*!
+ * @function kevent_legacy_copyout
+ *
+ * @brief
+ * Handles the copyout of a kevent/kevent64 event.
+ */
+static int
+kevent_legacy_copyout(struct kevent_qos_s *kevp, user_addr_t *addrp, unsigned int flags)
+{
+       int advance;
+       int error;
+
+       assert((flags & (KEVENT_FLAG_LEGACY32 | KEVENT_FLAG_LEGACY64)) != 0);
+
+       /*
+        * fully initialize the differnt output event structure
+        * types from the internal kevent (and some universal
+        * defaults for fields not represented in the internal
+        * form).
+        *
+        * Note: these structures have no padding hence the C99
+        *       initializers below do not leak kernel info.
+        */
+       if (flags & KEVENT_FLAG_LEGACY64) {
+               struct kevent64_s kev64 = {
+                       .ident  = kevp->ident,
+                       .filter = kevp->filter,
+                       .flags  = kevp->flags,
+                       .fflags = kevp->fflags,
+                       .data   = (int64_t)kevp->data,
+                       .udata  = kevp->udata,
+                       .ext[0] = kevp->ext[0],
+                       .ext[1] = kevp->ext[1],
+               };
+               advance = sizeof(struct kevent64_s);
+               error = copyout((caddr_t)&kev64, *addrp, advance);
+       } else if (flags & KEVENT_FLAG_PROC64) {
+               /*
+                * deal with the special case of a user-supplied
+                * value of (uintptr_t)-1.
+                */
+               uint64_t ident = (kevp->ident == (uintptr_t)-1) ?
+                   (uint64_t)-1LL : (uint64_t)kevp->ident;
+               struct user64_kevent kev64 = {
+                       .ident  = ident,
+                       .filter = kevp->filter,
+                       .flags  = kevp->flags,
+                       .fflags = kevp->fflags,
+                       .data   = (int64_t) kevp->data,
+                       .udata  = kevp->udata,
+               };
+               advance = sizeof(kev64);
+               error = copyout((caddr_t)&kev64, *addrp, advance);
+       } else {
+               struct user32_kevent kev32 = {
+                       .ident  = (uint32_t)kevp->ident,
+                       .filter = kevp->filter,
+                       .flags  = kevp->flags,
+                       .fflags = kevp->fflags,
+                       .data   = (int32_t)kevp->data,
+                       .udata  = kevp->udata,
+               };
+               advance = sizeof(kev32);
+               error = copyout((caddr_t)&kev32, *addrp, advance);
+       }
+       if (__probable(!error)) {
+               *addrp += advance;
+       }
+       return error;
+}
+
+/*!
+ * @function kevent_modern_copyout
+ *
+ * @brief
+ * Handles the copyout of a kevent_qos/kevent_id event.
+ */
+OS_ALWAYS_INLINE
+static inline int
+kevent_modern_copyout(struct kevent_qos_s *kevp, user_addr_t *addrp)
+{
+       int error = copyout((caddr_t)kevp, *addrp, sizeof(struct kevent_qos_s));
+       if (__probable(!error)) {
+               *addrp += sizeof(struct kevent_qos_s);
+       }
+       return error;
+}
+
+#pragma mark kevent core implementation
+
+/*!
+ * @function kevent_callback_inline
+ *
+ * @brief
+ * Callback for each individual event
+ *
+ * @discussion
+ * This is meant to be inlined in kevent_modern_callback and
+ * kevent_legacy_callback.
+ */
+OS_ALWAYS_INLINE
+static inline int
+kevent_callback_inline(struct kevent_qos_s *kevp, kevent_ctx_t kectx, bool legacy)
+{
+       int error;
+
+       assert(kectx->kec_process_noutputs < kectx->kec_process_nevents);
+
+       /*
+        * Copy out the appropriate amount of event data for this user.
+        */
+       if (legacy) {
+               error = kevent_legacy_copyout(kevp, &kectx->kec_process_eventlist,
+                   kectx->kec_process_flags);
+       } else {
+               error = kevent_modern_copyout(kevp, &kectx->kec_process_eventlist);
+       }
+
+       /*
+        * If there isn't space for additional events, return
+        * a harmless error to stop the processing here
+        */
+       if (error == 0 && ++kectx->kec_process_noutputs == kectx->kec_process_nevents) {
+               error = EWOULDBLOCK;
+       }
+       return error;
+}
+
+/*!
+ * @function kevent_modern_callback
+ *
+ * @brief
+ * Callback for each individual modern event.
+ *
+ * @discussion
+ * This callback handles kevent_qos/kevent_id events.
+ */
+static int
+kevent_modern_callback(struct kevent_qos_s *kevp, kevent_ctx_t kectx)
+{
+       return kevent_callback_inline(kevp, kectx, /*legacy*/ false);
+}
+
+/*!
+ * @function kevent_legacy_callback
+ *
+ * @brief
+ * Callback for each individual legacy event.
+ *
+ * @discussion
+ * This callback handles kevent/kevent64 events.
+ */
+static int
+kevent_legacy_callback(struct kevent_qos_s *kevp, kevent_ctx_t kectx)
+{
+       return kevent_callback_inline(kevp, kectx, /*legacy*/ true);
+}
+
+/*!
+ * @function kevent_cleanup
+ *
+ * @brief
+ * Handles the cleanup returning from a kevent call.
+ *
+ * @discussion
+ * kevent entry points will take a reference on workloops,
+ * and a usecount on the fileglob of kqfiles.
+ *
+ * This function undoes this on the exit paths of kevents.
+ *
+ * @returns
+ * The error to return to userspace.
+ */
+static int
+kevent_cleanup(kqueue_t kqu, int flags, int error, kevent_ctx_t kectx)
+{
+       // poll should not call any codepath leading to this
+       assert((flags & KEVENT_FLAG_POLL) == 0);
+
+       if (flags & KEVENT_FLAG_WORKLOOP) {
+               kqworkloop_release(kqu.kqwl);
+       } else if (flags & KEVENT_FLAG_WORKQ) {
+               /* nothing held */
+       } else {
+               fp_drop(kqu.kqf->kqf_p, kectx->kec_fd, kectx->kec_fp, 0);
+       }
+
+       /* don't restart after signals... */
+       if (error == ERESTART) {
+               error = EINTR;
+       } else if (error == 0) {
+               /* don't abandon other output just because of residual copyout failures */
+               (void)kevent_put_data_size(flags, kectx);
+       }
+
+       if (flags & KEVENT_FLAG_PARKING) {
+               thread_t th = current_thread();
+               struct uthread *uth = get_bsdthread_info(th);
+               if (uth->uu_kqr_bound) {
+                       thread_unfreeze_base_pri(th);
+               }
+       }
+       return error;
+}
+
+/*!
+ * @function kqueue_process
+ *
+ * @brief
+ * Process the triggered events in a kqueue.
+ *
+ * @discussion
+ * Walk the queued knotes and validate that they are really still triggered
+ * events by calling the filter routines (if necessary).
+ *
+ * For each event that is still considered triggered, invoke the callback
+ * routine provided.
+ *
+ * caller holds a reference on the kqueue.
+ * kqueue locked on entry and exit - but may be dropped
+ * kqueue list locked (held for duration of call)
+ *
+ * This is only called by kqueue_scan() so that the compiler can inline it.
+ *
+ * @returns
+ * - 0:            no event was returned, no other error occured
+ * - EBADF:        the kqueue is being destroyed (KQ_DRAIN is set)
+ * - EWOULDBLOCK:  (not an error) events have been found and we should return
+ * - EFAULT:       copyout failed
+ * - filter specific errors
+ */
+static int
+kqueue_process(kqueue_t kqu, int flags, kevent_ctx_t kectx,
+    kevent_callback_t callback)
+{
+       workq_threadreq_t kqr = current_uthread()->uu_kqr_bound;
+       struct knote *kn;
+       int error = 0, rc = 0;
+       struct kqtailq *base_queue, *queue;
+#if DEBUG || DEVELOPMENT
+       int retries = 64;
+#endif
+       uint16_t kq_type = (kqu.kq->kq_state & (KQ_WORKQ | KQ_WORKLOOP));
+
+       if (kq_type & KQ_WORKQ) {
+               rc = kqworkq_begin_processing(kqu.kqwq, kqr, flags);
+       } else if (kq_type & KQ_WORKLOOP) {
+               rc = kqworkloop_begin_processing(kqu.kqwl, flags);
+       } else {
+kqfile_retry:
+               rc = kqfile_begin_processing(kqu.kqf);
+               if (rc == EBADF) {
+                       return EBADF;
+               }
+       }
+
+       if (rc == -1) {
+               /* Nothing to process */
+               return 0;
+       }
+
+       /*
+        * loop through the enqueued knotes associated with this request,
+        * processing each one. Each request may have several queues
+        * of knotes to process (depending on the type of kqueue) so we
+        * have to loop through all the queues as long as we have additional
+        * space.
+        */
+
+process_again:
+       if (kq_type & KQ_WORKQ) {
+               base_queue = queue = &kqu.kqwq->kqwq_queue[kqr->tr_kq_qos_index];
+       } else if (kq_type & KQ_WORKLOOP) {
+               base_queue = &kqu.kqwl->kqwl_queue[0];
+               queue = &kqu.kqwl->kqwl_queue[KQWL_NBUCKETS - 1];
+       } else {
+               base_queue = queue = &kqu.kqf->kqf_queue;
+       }
+
+       do {
+               while ((kn = TAILQ_FIRST(queue)) != NULL) {
+                       error = knote_process(kn, kectx, callback);
+                       if (error == EJUSTRETURN) {
+                               error = 0;
+                       } else if (__improbable(error)) {
+                               /* error is EWOULDBLOCK when the out event array is full */
+                               goto stop_processing;
+                       }
+               }
+       } while (queue-- > base_queue);
+
+       if (kectx->kec_process_noutputs) {
+               /* callers will transform this into no error */
+               error = EWOULDBLOCK;
+       }
+
+stop_processing:
+       /*
+        * If KEVENT_FLAG_PARKING is set, and no kevents have been returned,
+        * we want to unbind the kqrequest from the thread.
+        *
+        * However, because the kq locks are dropped several times during process,
+        * new knotes may have fired again, in which case, we want to fail the end
+        * processing and process again, until it converges.
+        *
+        * If we have an error or returned events, end processing never fails.
+        */
+       if (error) {
+               flags &= ~KEVENT_FLAG_PARKING;
+       }
+       if (kq_type & KQ_WORKQ) {
+               rc = kqworkq_end_processing(kqu.kqwq, kqr, flags);
+       } else if (kq_type & KQ_WORKLOOP) {
+               rc = kqworkloop_end_processing(kqu.kqwl, KQ_PROCESSING, flags);
+       } else {
+               rc = kqfile_end_processing(kqu.kqf);
+       }
+
+       if (__probable(error)) {
+               return error;
+       }
+
+       if (__probable(rc >= 0)) {
+               assert(rc == 0 || rc == EBADF);
+               return rc;
+       }
+
+#if DEBUG || DEVELOPMENT
+       if (retries-- == 0) {
+               panic("kevent: way too many knote_process retries, kq: %p (0x%04x)",
+                   kqu.kq, kqu.kq->kq_state);
+       }
+#endif
+       if (kq_type & (KQ_WORKQ | KQ_WORKLOOP)) {
+               assert(flags & KEVENT_FLAG_PARKING);
+               goto process_again;
+       } else {
+               goto kqfile_retry;
+       }
+}
+
+/*!
+ * @function kqueue_scan_continue
+ *
+ * @brief
+ * The continuation used by kqueue_scan for kevent entry points.
+ *
+ * @discussion
+ * Assumes we inherit a use/ref count on the kq or its fileglob.
+ *
+ * This is called by kqueue_scan if neither KEVENT_FLAG_POLL nor
+ * KEVENT_FLAG_KERNEL was set, and the caller had to wait.
+ */
+OS_NORETURN OS_NOINLINE
+static void
+kqueue_scan_continue(void *data, wait_result_t wait_result)
+{
+       uthread_t ut = current_uthread();
+       kevent_ctx_t kectx = &ut->uu_save.uus_kevent;
+       int error = 0, flags = kectx->kec_process_flags;
+       struct kqueue *kq = data;
+
+       /*
+        * only kevent variants call in here, so we know the callback is
+        * kevent_legacy_callback or kevent_modern_callback.
+        */
+       assert((flags & (KEVENT_FLAG_POLL | KEVENT_FLAG_KERNEL)) == 0);
+
+       switch (wait_result) {
+       case THREAD_AWAKENED:
+               if (__improbable(flags & (KEVENT_FLAG_LEGACY32 | KEVENT_FLAG_LEGACY64))) {
+                       error = kqueue_scan(kq, flags, kectx, kevent_legacy_callback);
+               } else {
+                       error = kqueue_scan(kq, flags, kectx, kevent_modern_callback);
+               }
+               break;
+       case THREAD_TIMED_OUT:
+               error = 0;
+               break;
+       case THREAD_INTERRUPTED:
+               error = EINTR;
+               break;
+       case THREAD_RESTART:
+               error = EBADF;
+               break;
+       default:
+               panic("%s: - invalid wait_result (%d)", __func__, wait_result);
+       }
+
+
+       error = kevent_cleanup(kq, flags, error, kectx);
+       *(int32_t *)&ut->uu_rval = kectx->kec_process_noutputs;
+       unix_syscall_return(error);
+}
+
+/*!
+ * @function kqueue_scan
+ *
+ * @brief
+ * Scan and wait for events in a kqueue (used by poll & kevent).
+ *
+ * @discussion
+ * Process the triggered events in a kqueue.
+ *
+ * If there are no events triggered arrange to wait for them:
+ * - unless KEVENT_FLAG_IMMEDIATE is set in kectx->kec_process_flags
+ * - possibly until kectx->kec_deadline expires
+ *
+ * When it waits, and that neither KEVENT_FLAG_POLL nor KEVENT_FLAG_KERNEL
+ * are set, then it will wait in the kqueue_scan_continue continuation.
+ *
+ * poll() will block in place, and KEVENT_FLAG_KERNEL calls
+ * all pass KEVENT_FLAG_IMMEDIATE and will not wait.
+ *
+ * @param kq
+ * The kqueue being scanned.
+ *
+ * @param flags
+ * The KEVENT_FLAG_* flags for this call.
+ *
+ * @param kectx
+ * The context used for this scan.
+ * The uthread_t::uu_save.uus_kevent storage is used for this purpose.
+ *
+ * @param callback
+ * The callback to be called on events sucessfully processed.
+ * (Either kevent_legacy_callback, kevent_modern_callback or poll_callback)
+ */
+int
+kqueue_scan(struct kqueue *kq, int flags, kevent_ctx_t kectx,
+    kevent_callback_t callback)
+{
+       int error;
+
+       for (;;) {
+               kqlock(kq);
+               error = kqueue_process(kq, flags, kectx, callback);
+
+               /*
+                * If we got an error, events returned (EWOULDBLOCK)
+                * or blocking was disallowed (KEVENT_FLAG_IMMEDIATE),
+                * just return.
+                */
+               if (__probable(error || (flags & KEVENT_FLAG_IMMEDIATE))) {
+                       kqunlock(kq);
+                       return error == EWOULDBLOCK ? 0 : error;
+               }
+
+               waitq_assert_wait64_leeway((struct waitq *)&kq->kq_wqs,
+                   KQ_EVENT, THREAD_ABORTSAFE, TIMEOUT_URGENCY_USER_NORMAL,
+                   kectx->kec_deadline, TIMEOUT_NO_LEEWAY);
+               kq->kq_state |= KQ_SLEEP;
+
+               kqunlock(kq);
+
+               if (__probable((flags & (KEVENT_FLAG_POLL | KEVENT_FLAG_KERNEL)) == 0)) {
+                       thread_block_parameter(kqueue_scan_continue, kq);
+                       __builtin_unreachable();
+               }
+
+               wait_result_t wr = thread_block(THREAD_CONTINUE_NULL);
+               switch (wr) {
+               case THREAD_AWAKENED:
+                       break;
+               case THREAD_TIMED_OUT:
+                       return 0;
+               case THREAD_INTERRUPTED:
+                       return EINTR;
+               case THREAD_RESTART:
+                       return EBADF;
+               default:
+                       panic("%s: - bad wait_result (%d)", __func__, wr);
+               }
+       }
+}
+
+/*!
+ * @function kevent_internal
+ *
+ * @brief
+ * Common kevent code.
+ *
+ * @discussion
+ * Needs to be inlined to specialize for legacy or modern and
+ * eliminate dead code.
+ *
+ * This is the core logic of kevent entry points, that will:
+ * - register kevents
+ * - optionally scan the kqueue for events
+ *
+ * The caller is giving kevent_internal a reference on the kqueue
+ * or its fileproc that needs to be cleaned up by kevent_cleanup().
+ */
+OS_ALWAYS_INLINE
+static inline int
+kevent_internal(kqueue_t kqu,
+    user_addr_t changelist, int nchanges,
+    user_addr_t ueventlist, int nevents,
+    int flags, kevent_ctx_t kectx, int32_t *retval,
+    bool legacy)
+{
+       int error = 0, noutputs = 0, register_rc;
+
+       /* only bound threads can receive events on workloops */
+       if (!legacy && (flags & KEVENT_FLAG_WORKLOOP)) {
+#if CONFIG_WORKLOOP_DEBUG
+               UU_KEVENT_HISTORY_WRITE_ENTRY(current_uthread(), {
+                       .uu_kqid = kqu.kqwl->kqwl_dynamicid,
+                       .uu_kq = error ? NULL : kqu.kq,
+                       .uu_error = error,
+                       .uu_nchanges = nchanges,
+                       .uu_nevents = nevents,
+                       .uu_flags = flags,
+               });
+#endif // CONFIG_WORKLOOP_DEBUG
+
+               if (flags & KEVENT_FLAG_KERNEL) {
+                       /* see kevent_workq_internal */
+                       error = copyout(&kqu.kqwl->kqwl_dynamicid,
+                           ueventlist - sizeof(kqueue_id_t), sizeof(kqueue_id_t));
+                       kectx->kec_data_resid -= sizeof(kqueue_id_t);
+                       if (__improbable(error)) {
+                               goto out;
+                       }
+               }
+
+               if (kevent_args_requesting_events(flags, nevents)) {
+                       /*
+                        * Disable the R2K notification while doing a register, if the
+                        * caller wants events too, we don't want the AST to be set if we
+                        * will process these events soon.
+                        */
+                       kqlock(kqu);
+                       kqu.kq->kq_state &= ~KQ_R2K_ARMED;
+                       kqunlock(kqu);
+                       flags |= KEVENT_FLAG_NEEDS_END_PROCESSING;
+               }
+       }
+
+       /* register all the change requests the user provided... */
+       while (nchanges > 0 && error == 0) {
+               struct kevent_qos_s kev;
+               struct knote *kn = NULL;
+
+               if (legacy) {
+                       error = kevent_legacy_copyin(&changelist, &kev, flags);
+               } else {
+                       error = kevent_modern_copyin(&changelist, &kev);
+               }
+               if (error) {
+                       break;
+               }
+
+               register_rc = kevent_register(kqu.kq, &kev, &kn);
+               if (__improbable(!legacy && (register_rc & FILTER_REGISTER_WAIT))) {
+                       thread_t thread = current_thread();
+
+                       kqlock_held(kqu);
+
+                       if (act_clear_astkevent(thread, AST_KEVENT_REDRIVE_THREADREQ)) {
+                               workq_kern_threadreq_redrive(kqu.kq->kq_p, WORKQ_THREADREQ_NONE);
+                       }
+
+                       // f_post_register_wait is meant to call a continuation and not to
+                       // return, which is why we don't support FILTER_REGISTER_WAIT if
+                       // KEVENT_FLAG_ERROR_EVENTS is not passed, or if the event that
+                       // waits isn't the last.
+                       //
+                       // It is implementable, but not used by any userspace code at the
+                       // moment, so for now return ENOTSUP if someone tries to do it.
+                       if (nchanges == 1 && noutputs < nevents &&
+                           (flags & KEVENT_FLAG_KERNEL) == 0 &&
+                           (flags & KEVENT_FLAG_PARKING) == 0 &&
+                           (flags & KEVENT_FLAG_ERROR_EVENTS) &&
+                           (flags & KEVENT_FLAG_WORKLOOP)) {
+                               uthread_t ut = get_bsdthread_info(thread);
+
+                               /*
+                                * store the continuation/completion data in the uthread
+                                *
+                                * Note: the kectx aliases with this,
+                                * and is destroyed in the process.
+                                */
+                               ut->uu_save.uus_kevent_register = (struct _kevent_register){
+                                       .kev        = kev,
+                                       .kqwl       = kqu.kqwl,
+                                       .eventout   = noutputs,
+                                       .ueventlist = ueventlist,
+                               };
+                               knote_fops(kn)->f_post_register_wait(ut, kn,
+                                   &ut->uu_save.uus_kevent_register);
+                               __builtin_unreachable();
+                       }
+                       kqunlock(kqu);
+
+                       kev.flags |= EV_ERROR;
+                       kev.data = ENOTSUP;
+               } else {
+                       assert((register_rc & FILTER_REGISTER_WAIT) == 0);
+               }
+
+               // keep in sync with kevent_register_wait_return()
+               if (noutputs < nevents && (kev.flags & (EV_ERROR | EV_RECEIPT))) {
+                       if ((kev.flags & EV_ERROR) == 0) {
+                               kev.flags |= EV_ERROR;
+                               kev.data = 0;
+                       }
+                       if (legacy) {
+                               error = kevent_legacy_copyout(&kev, &ueventlist, flags);
+                       } else {
+                               error = kevent_modern_copyout(&kev, &ueventlist);
+                       }
+                       if (error == 0) {
+                               noutputs++;
+                       }
+               } else if (kev.flags & EV_ERROR) {
+                       error = kev.data;
+               }
+               nchanges--;
+       }
+
+       if ((flags & KEVENT_FLAG_ERROR_EVENTS) == 0 &&
+           nevents > 0 && noutputs == 0 && error == 0) {
+               kectx->kec_process_flags = flags;
+               kectx->kec_process_nevents = nevents;
+               kectx->kec_process_noutputs = 0;
+               kectx->kec_process_eventlist = ueventlist;
+
+               if (legacy) {
+                       error = kqueue_scan(kqu.kq, flags, kectx, kevent_legacy_callback);
+               } else {
+                       error = kqueue_scan(kqu.kq, flags, kectx, kevent_modern_callback);
+               }
+
+               noutputs = kectx->kec_process_noutputs;
+       } else if (!legacy && (flags & KEVENT_FLAG_NEEDS_END_PROCESSING)) {
+               /*
+                * If we didn't through kqworkloop_end_processing(),
+                * we need to do it here.
+                *
+                * kqueue_scan will call kqworkloop_end_processing(),
+                * so we only need to do it if we didn't scan.
+                */
+               kqlock(kqu);
+               kqworkloop_end_processing(kqu.kqwl, 0, 0);
+               kqunlock(kqu);
+       }
+
+       *retval = noutputs;
+out:
+       return kevent_cleanup(kqu.kq, flags, error, kectx);
 }
 
-/* called with kqueue lock held */
-static void
-knote_suppress(struct knote *kn)
-{
-       struct kqtailq *suppressq;
-       struct kqueue *kq = knote_get_kq(kn);
-
-       kqlock_held(kq);
-
-       if (kn->kn_status & KN_SUPPRESSED)
-               return;
+#pragma mark modern syscalls: kevent_qos, kevent_id, kevent_workq_internal
 
-       knote_dequeue(kn);
-       kn->kn_status |= KN_SUPPRESSED;
-       suppressq = kqueue_get_suppressed_queue(kq, kn);
-       TAILQ_INSERT_TAIL(suppressq, kn, kn_tqe);
+/*!
+ * @function kevent_modern_internal
+ *
+ * @brief
+ * The backend of the kevent_id and kevent_workq_internal entry points.
+ *
+ * @discussion
+ * Needs to be inline due to the number of arguments.
+ */
+OS_NOINLINE
+static int
+kevent_modern_internal(kqueue_t kqu,
+    user_addr_t changelist, int nchanges,
+    user_addr_t ueventlist, int nevents,
+    int flags, kevent_ctx_t kectx, int32_t *retval)
+{
+       return kevent_internal(kqu.kq, changelist, nchanges,
+                  ueventlist, nevents, flags, kectx, retval, /*legacy*/ false);
 }
 
-/* called with kqueue lock held */
-static void
-knote_unsuppress(struct knote *kn)
+/*!
+ * @function kevent_id
+ *
+ * @brief
+ * The kevent_id() syscall.
+ */
+int
+kevent_id(struct proc *p, struct kevent_id_args *uap, int32_t *retval)
 {
-       struct kqtailq *suppressq;
-       struct kqueue *kq = knote_get_kq(kn);
+       int error, flags = uap->flags & KEVENT_FLAG_USER;
+       uthread_t uth = current_uthread();
+       workq_threadreq_t kqr = uth->uu_kqr_bound;
+       kevent_ctx_t kectx = &uth->uu_save.uus_kevent;
+       kqueue_t kqu;
 
-       kqlock_held(kq);
+       flags = kevent_adjust_flags_for_proc(p, flags);
+       flags |= KEVENT_FLAG_DYNAMIC_KQUEUE;
 
-       if ((kn->kn_status & KN_SUPPRESSED) == 0)
-               return;
+       if (__improbable((flags & (KEVENT_FLAG_WORKQ | KEVENT_FLAG_WORKLOOP)) !=
+           KEVENT_FLAG_WORKLOOP)) {
+               return EINVAL;
+       }
 
-       kn->kn_status &= ~KN_SUPPRESSED;
-       suppressq = kqueue_get_suppressed_queue(kq, kn);
-       TAILQ_REMOVE(suppressq, kn, kn_tqe);
+       error = kevent_get_data_size(flags, uap->data_available, uap->data_out, kectx);
+       if (__improbable(error)) {
+               return error;
+       }
+
+       kectx->kec_deadline = 0;
+       kectx->kec_fp       = NULL;
+       kectx->kec_fd       = -1;
+       /* the kec_process_* fields are filled if kqueue_scann is called only */
 
        /*
-        * If the knote is no longer active, reset its push,
-        * and resynchronize kn_qos_index with kn_qos_override
+        * Get the kq we are going to be working on
+        * As a fastpath, look at the currently bound workloop.
         */
-       if ((kn->kn_status & KN_ACTIVE) == 0) {
-               kn->kn_qos_override = kn->kn_req_index;
+       kqu.kqwl = kqr ? kqr_kqworkloop(kqr) : NULL;
+       if (kqu.kqwl && kqu.kqwl->kqwl_dynamicid == uap->id) {
+               if (__improbable(flags & KEVENT_FLAG_DYNAMIC_KQ_MUST_NOT_EXIST)) {
+                       return EEXIST;
+               }
+               kqworkloop_retain(kqu.kqwl);
+       } else if (__improbable(kevent_args_requesting_events(flags, uap->nevents))) {
+               return EXDEV;
+       } else {
+               error = kqworkloop_get_or_create(p, uap->id, NULL, flags, &kqu.kqwl);
+               if (__improbable(error)) {
+                       return error;
+               }
        }
-       kn->kn_qos_index = kn->kn_qos_override;
 
-       /* don't wakeup if unsuppressing just a stay-active knote */
-       if (knote_enqueue(kn) && (kn->kn_status & KN_ACTIVE)) {
-               knote_wakeup(kn);
-       }
+       return kevent_modern_internal(kqu, uap->changelist, uap->nchanges,
+                  uap->eventlist, uap->nevents, flags, kectx, retval);
+}
 
-       if ((kq->kq_state & KQ_WORKLOOP) && TAILQ_EMPTY(suppressq)) {
-               struct kqworkloop *kqwl = (struct kqworkloop *)kq;
+/**!
+ * @function kevent_workq_internal
+ *
+ * @discussion
+ * This function is exported for the sake of the workqueue subsystem.
+ *
+ * It is called in two ways:
+ * - when a thread is about to go to userspace to ask for pending event
+ * - when a thread is returning from userspace with events back
+ *
+ * the workqueue subsystem will only use the following flags:
+ * - KEVENT_FLAG_STACK_DATA (always)
+ * - KEVENT_FLAG_IMMEDIATE (always)
+ * - KEVENT_FLAG_PARKING (depending on whether it is going to or returning from
+ *   userspace).
+ *
+ * It implicitly acts on the bound kqueue, and for the case of workloops
+ * will copyout the kqueue ID before anything else.
+ *
+ *
+ * Pthread will have setup the various arguments to fit this stack layout:
+ *
+ * +-------....----+--------------+-----------+--------------------+
+ * |  user stack   |  data avail  |  nevents  |   pthread_self()   |
+ * +-------....----+--------------+-----------+--------------------+
+ *                 ^              ^
+ *             data_out       eventlist
+ *
+ * When a workloop is used, the workloop ID is copied out right before
+ * the eventlist and is taken from the data buffer.
+ *
+ * @warning
+ * This function is carefuly tailored to not make any call except the final tail
+ * call into kevent_modern_internal. (LTO inlines current_uthread()).
+ *
+ * This function is performance sensitive due to the workq subsystem.
+ */
+int
+kevent_workq_internal(struct proc *p,
+    user_addr_t changelist, int nchanges,
+    user_addr_t eventlist, int nevents,
+    user_addr_t data_out, user_size_t *data_available,
+    unsigned int flags, int32_t *retval)
+{
+       uthread_t uth = current_uthread();
+       workq_threadreq_t kqr = uth->uu_kqr_bound;
+       kevent_ctx_t kectx = &uth->uu_save.uus_kevent;
+       kqueue_t kqu;
 
-               if (kqworkloop_is_processing_on_current_thread(kqwl)) {
-                       /*
-                        * kqworkloop_end_processing() or kqworkloop_begin_processing()
-                        * will perform the required QoS computations when it unsets the
-                        * processing mode.
-                        */
-               } else {
-                       kq_req_lock(kqwl);
-                       kqworkloop_update_threads_qos(kqwl, KQWL_UTQ_RESET_WAKEUP_OVERRIDE, 0);
-                       kq_req_unlock(kqwl);
-               }
+       assert(flags == (KEVENT_FLAG_STACK_DATA | KEVENT_FLAG_IMMEDIATE) ||
+           flags == (KEVENT_FLAG_STACK_DATA | KEVENT_FLAG_IMMEDIATE | KEVENT_FLAG_PARKING));
+
+       kectx->kec_data_out   = data_out;
+       kectx->kec_data_avail = (uint64_t)data_available;
+       kectx->kec_data_size  = *data_available;
+       kectx->kec_data_resid = *data_available;
+       kectx->kec_deadline   = 0;
+       kectx->kec_fp         = NULL;
+       kectx->kec_fd         = -1;
+       /* the kec_process_* fields are filled if kqueue_scann is called only */
+
+       flags = kevent_adjust_flags_for_proc(p, flags);
+
+       if (kqr->tr_flags & WORKQ_TR_FLAG_WORKLOOP) {
+               kqu.kqwl = __container_of(kqr, struct kqworkloop, kqwl_request);
+               kqworkloop_retain(kqu.kqwl);
+
+               flags |= KEVENT_FLAG_WORKLOOP | KEVENT_FLAG_DYNAMIC_KQUEUE |
+                   KEVENT_FLAG_KERNEL;
+       } else {
+               kqu.kqwq = p->p_fd->fd_wqkqueue;
+
+               flags |= KEVENT_FLAG_WORKQ | KEVENT_FLAG_KERNEL;
        }
+
+       return kevent_modern_internal(kqu, changelist, nchanges,
+                  eventlist, nevents, flags, kectx, retval);
 }
 
-/* called with kqueue lock held */
-static int
-knote_enqueue(struct knote *kn)
+/*!
+ * @function kevent_qos
+ *
+ * @brief
+ * The kevent_qos() syscall.
+ */
+int
+kevent_qos(struct proc *p, struct kevent_qos_args *uap, int32_t *retval)
 {
-       if ((kn->kn_status & (KN_ACTIVE | KN_STAYACTIVE)) == 0 ||
-           (kn->kn_status & (KN_DISABLED | KN_SUPPRESSED | KN_DROPPING)))
-               return 0;
+       uthread_t uth = current_uthread();
+       kevent_ctx_t kectx = &uth->uu_save.uus_kevent;
+       int error, flags = uap->flags & KEVENT_FLAG_USER;
+       struct kqueue *kq;
 
-       if ((kn->kn_status & KN_QUEUED) == 0) {
-               struct kqtailq *queue = knote_get_queue(kn);
-               struct kqueue *kq = knote_get_kq(kn);
+       if (__improbable(flags & KEVENT_ID_FLAG_USER)) {
+               return EINVAL;
+       }
 
-               kqlock_held(kq);
-               TAILQ_INSERT_TAIL(queue, kn, kn_tqe);
-               kn->kn_status |= KN_QUEUED;
-               kq->kq_count++;
-               return 1;
+       flags = kevent_adjust_flags_for_proc(p, flags);
+
+       error = kevent_get_data_size(flags, uap->data_available, uap->data_out, kectx);
+       if (__improbable(error)) {
+               return error;
+       }
+
+       kectx->kec_deadline = 0;
+       kectx->kec_fp       = NULL;
+       kectx->kec_fd       = uap->fd;
+       /* the kec_process_* fields are filled if kqueue_scann is called only */
+
+       /* get the kq we are going to be working on */
+       if (__probable(flags & KEVENT_FLAG_WORKQ)) {
+               error = kevent_get_kqwq(p, flags, uap->nevents, &kq);
+       } else {
+               error = kevent_get_kqfile(p, uap->fd, flags, &kectx->kec_fp, &kq);
        }
-       return ((kn->kn_status & KN_STAYACTIVE) != 0);
+       if (__improbable(error)) {
+               return error;
+       }
+
+       return kevent_modern_internal(kq, uap->changelist, uap->nchanges,
+                  uap->eventlist, uap->nevents, flags, kectx, retval);
 }
 
+#pragma mark legacy syscalls: kevent, kevent64
 
-/* called with kqueue lock held */
-static void
-knote_dequeue(struct knote *kn)
+/*!
+ * @function kevent_legacy_get_deadline
+ *
+ * @brief
+ * Compute the deadline for the legacy kevent syscalls.
+ *
+ * @discussion
+ * This is not necessary if KEVENT_FLAG_IMMEDIATE is specified,
+ * as this takes precedence over the deadline.
+ *
+ * This function will fail if utimeout is USER_ADDR_NULL
+ * (the caller should check).
+ */
+static int
+kevent_legacy_get_deadline(int flags, user_addr_t utimeout, uint64_t *deadline)
 {
-       struct kqueue *kq = knote_get_kq(kn);
-       struct kqtailq *queue;
-
-       kqlock_held(kq);
+       struct timespec ts;
 
-       if ((kn->kn_status & KN_QUEUED) == 0)
-               return;
+       if (flags & KEVENT_FLAG_PROC64) {
+               struct user64_timespec ts64;
+               int error = copyin(utimeout, &ts64, sizeof(ts64));
+               if (__improbable(error)) {
+                       return error;
+               }
+               ts.tv_sec = ts64.tv_sec;
+               ts.tv_nsec = ts64.tv_nsec;
+       } else {
+               struct user32_timespec ts32;
+               int error = copyin(utimeout, &ts32, sizeof(ts32));
+               if (__improbable(error)) {
+                       return error;
+               }
+               ts.tv_sec = ts32.tv_sec;
+               ts.tv_nsec = ts32.tv_nsec;
+       }
+       if (!timespec_is_valid(&ts)) {
+               return EINVAL;
+       }
 
-       queue = knote_get_queue(kn);
-       TAILQ_REMOVE(queue, kn, kn_tqe);
-       kn->kn_status &= ~KN_QUEUED;
-       kq->kq_count--;
+       clock_absolutetime_interval_to_deadline(tstoabstime(&ts), deadline);
+       return 0;
 }
 
-void
-knote_init(void)
+/*!
+ * @function kevent_legacy_internal
+ *
+ * @brief
+ * The core implementation for kevent and kevent64
+ */
+OS_NOINLINE
+static int
+kevent_legacy_internal(struct proc *p, struct kevent64_args *uap,
+    int32_t *retval, int flags)
 {
-       knote_zone = zinit(sizeof(struct knote), 8192*sizeof(struct knote),
-                          8192, "knote zone");
-
-       kqfile_zone = zinit(sizeof(struct kqfile), 8192*sizeof(struct kqfile),
-                           8192, "kqueue file zone");
+       uthread_t uth = current_uthread();
+       kevent_ctx_t kectx = &uth->uu_save.uus_kevent;
+       struct kqueue *kq;
+       int error;
 
-       kqworkq_zone = zinit(sizeof(struct kqworkq), 8192*sizeof(struct kqworkq),
-                           8192, "kqueue workq zone");
+       if (__improbable(uap->flags & KEVENT_ID_FLAG_USER)) {
+               return EINVAL;
+       }
 
-       kqworkloop_zone = zinit(sizeof(struct kqworkloop), 8192*sizeof(struct kqworkloop),
-                           8192, "kqueue workloop zone");
+       flags = kevent_adjust_flags_for_proc(p, flags);
 
-       /* allocate kq lock group attribute and group */
-       kq_lck_grp_attr = lck_grp_attr_alloc_init();
+       kectx->kec_data_out   = 0;
+       kectx->kec_data_avail = 0;
+       kectx->kec_data_size  = 0;
+       kectx->kec_data_resid = 0;
+       kectx->kec_deadline   = 0;
+       kectx->kec_fp         = NULL;
+       kectx->kec_fd         = uap->fd;
+       /* the kec_process_* fields are filled if kqueue_scann is called only */
 
-       kq_lck_grp = lck_grp_alloc_init("kqueue",  kq_lck_grp_attr);
+       /* convert timeout to absolute - if we have one (and not immediate) */
+       if (__improbable(uap->timeout && !(flags & KEVENT_FLAG_IMMEDIATE))) {
+               error = kevent_legacy_get_deadline(flags, uap->timeout,
+                   &kectx->kec_deadline);
+               if (__improbable(error)) {
+                       return error;
+               }
+       }
 
-       /* Allocate kq lock attribute */
-       kq_lck_attr = lck_attr_alloc_init();
+       /* get the kq we are going to be working on */
+       if (flags & KEVENT_FLAG_WORKQ) {
+               error = kevent_get_kqwq(p, flags, uap->nevents, &kq);
+       } else {
+               error = kevent_get_kqfile(p, uap->fd, flags, &kectx->kec_fp, &kq);
+       }
+       if (__improbable(error)) {
+               return error;
+       }
 
-#if CONFIG_MEMORYSTATUS
-       /* Initialize the memorystatus list lock */
-       memorystatus_kevent_init(kq_lck_grp, kq_lck_attr);
-#endif
+       return kevent_internal(kq, uap->changelist, uap->nchanges,
+                  uap->eventlist, uap->nevents, flags, kectx, retval,
+                  /*legacy*/ true);
 }
-SYSINIT(knote, SI_SUB_PSEUDO, SI_ORDER_ANY, knote_init, NULL)
 
-const struct filterops *
-knote_fops(struct knote *kn)
+/*!
+ * @function kevent
+ *
+ * @brief
+ * The legacy kevent() syscall.
+ */
+int
+kevent(struct proc *p, struct kevent_args *uap, int32_t *retval)
 {
-       return sysfilt_ops[kn->kn_filtid];
-}
+       struct kevent64_args args = {
+               .fd         = uap->fd,
+               .changelist = uap->changelist,
+               .nchanges   = uap->nchanges,
+               .eventlist  = uap->eventlist,
+               .nevents    = uap->nevents,
+               .timeout    = uap->timeout,
+       };
 
-static struct knote *
-knote_alloc(void)
-{
-       struct knote *kn = ((struct knote *)zalloc(knote_zone));
-       bzero(kn, sizeof(struct knote));
-       return kn;
+       return kevent_legacy_internal(p, &args, retval, KEVENT_FLAG_LEGACY32);
 }
 
-static void
-knote_free(struct knote *kn)
+/*!
+ * @function kevent64
+ *
+ * @brief
+ * The legacy kevent64() syscall.
+ */
+int
+kevent64(struct proc *p, struct kevent64_args *uap, int32_t *retval)
 {
-       assert(kn->kn_inuse == 0);
-       assert((kn->kn_status & KN_LOCKED) == 0);
-       zfree(knote_zone, kn);
+       int flags = (uap->flags & KEVENT_FLAG_USER) | KEVENT_FLAG_LEGACY64;
+       return kevent_legacy_internal(p, uap, retval, flags);
 }
 
+#pragma mark - socket interface
+
 #if SOCKETS
 #include <sys/param.h>
 #include <sys/socket.h>
@@ -7788,23 +8063,23 @@ knote_free(struct knote *kn)
 #include <sys/syslog.h>
 
 #ifndef ROUNDUP64
-#define        ROUNDUP64(x) P2ROUNDUP((x), sizeof (u_int64_t))
+#define ROUNDUP64(x) P2ROUNDUP((x), sizeof (u_int64_t))
 #endif
 
 #ifndef ADVANCE64
-#define        ADVANCE64(p, n) (void*)((char *)(p) + ROUNDUP64(n))
+#define ADVANCE64(p, n) (void*)((char *)(p) + ROUNDUP64(n))
 #endif
 
 static lck_grp_attr_t *kev_lck_grp_attr;
 static lck_attr_t *kev_lck_attr;
 static lck_grp_t *kev_lck_grp;
-static decl_lck_rw_data(,kev_lck_data);
+static decl_lck_rw_data(, kev_lck_data);
 static lck_rw_t *kev_rwlock = &kev_lck_data;
 
 static int kev_attach(struct socket *so, int proto, struct proc *p);
 static int kev_detach(struct socket *so);
 static int kev_control(struct socket *so, u_long cmd, caddr_t data,
-               struct ifnet *ifp, struct proc *p);
+    struct ifnet *ifp, struct proc *p);
 static lck_mtx_t * event_getlock(struct socket *, int);
 static int event_lock(struct socket *, int, void *);
 static int event_unlock(struct socket *, int, void *);
@@ -7813,38 +8088,38 @@ static int event_sofreelastref(struct socket *);
 static void kev_delete(struct kern_event_pcb *);
 
 static struct pr_usrreqs event_usrreqs = {
-       .pru_attach =           kev_attach,
-       .pru_control =          kev_control,
-       .pru_detach =           kev_detach,
-       .pru_soreceive =        soreceive,
+       .pru_attach =           kev_attach,
+       .pru_control =          kev_control,
+       .pru_detach =           kev_detach,
+       .pru_soreceive =        soreceive,
 };
 
 static struct protosw eventsw[] = {
-{
-       .pr_type =              SOCK_RAW,
-       .pr_protocol =          SYSPROTO_EVENT,
-       .pr_flags =             PR_ATOMIC,
-       .pr_usrreqs =           &event_usrreqs,
-       .pr_lock =              event_lock,
-       .pr_unlock =            event_unlock,
-       .pr_getlock =           event_getlock,
-}
+       {
+               .pr_type =              SOCK_RAW,
+               .pr_protocol =          SYSPROTO_EVENT,
+               .pr_flags =             PR_ATOMIC,
+               .pr_usrreqs =           &event_usrreqs,
+               .pr_lock =              event_lock,
+               .pr_unlock =            event_unlock,
+               .pr_getlock =           event_getlock,
+       }
 };
 
 __private_extern__ int kevt_getstat SYSCTL_HANDLER_ARGS;
 __private_extern__ int kevt_pcblist SYSCTL_HANDLER_ARGS;
 
 SYSCTL_NODE(_net_systm, OID_AUTO, kevt,
-       CTLFLAG_RW|CTLFLAG_LOCKED, 0, "Kernel event family");
+    CTLFLAG_RW | CTLFLAG_LOCKED, 0, "Kernel event family");
 
 struct kevtstat kevtstat;
 SYSCTL_PROC(_net_systm_kevt, OID_AUTO, stats,
-               CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
-               kevt_getstat, "S,kevtstat", "");
+    CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
+    kevt_getstat, "S,kevtstat", "");
 
 SYSCTL_PROC(_net_systm_kevt, OID_AUTO, pcblist,
-       CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
-       kevt_pcblist, "S,xkevtpcb", "");
+    CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
+    kevt_pcblist, "S,xkevtpcb", "");
 
 static lck_mtx_t *
 event_getlock(struct socket *so, int flags)
@@ -7852,17 +8127,18 @@ event_getlock(struct socket *so, int flags)
 #pragma unused(flags)
        struct kern_event_pcb *ev_pcb = (struct kern_event_pcb *)so->so_pcb;
 
-       if (so->so_pcb != NULL)  {
-               if (so->so_usecount < 0)
+       if (so->so_pcb != NULL) {
+               if (so->so_usecount < 0) {
                        panic("%s: so=%p usecount=%d lrh= %s\n", __func__,
                            so, so->so_usecount, solockhistory_nr(so));
-                       /* NOTREACHED */
+               }
+               /* NOTREACHED */
        } else {
                panic("%s: so=%p NULL NO so_pcb %s\n", __func__,
                    so, solockhistory_nr(so));
                /* NOTREACHED */
        }
-       return (&ev_pcb->evp_mtx);
+       return &ev_pcb->evp_mtx;
 }
 
 static int
@@ -7870,14 +8146,15 @@ event_lock(struct socket *so, int refcount, void *lr)
 {
        void *lr_saved;
 
-       if (lr == NULL)
+       if (lr == NULL) {
                lr_saved = __builtin_return_address(0);
-       else
+       } else {
                lr_saved = lr;
+       }
 
        if (so->so_pcb != NULL) {
                lck_mtx_lock(&((struct kern_event_pcb *)so->so_pcb)->evp_mtx);
-       } else  {
+       } else {
                panic("%s: so=%p NO PCB! lr=%p lrh= %s\n", __func__,
                    so, lr_saved, solockhistory_nr(so));
                /* NOTREACHED */
@@ -7890,12 +8167,13 @@ event_lock(struct socket *so, int refcount, void *lr)
                /* NOTREACHED */
        }
 
-       if (refcount)
+       if (refcount) {
                so->so_usecount++;
+       }
 
        so->lock_lr[so->next_lock_lr] = lr_saved;
-       so->next_lock_lr = (so->next_lock_lr+1) % SO_LCKDBG_MAX;
-       return (0);
+       so->next_lock_lr = (so->next_lock_lr + 1) % SO_LCKDBG_MAX;
+       return 0;
 }
 
 static int
@@ -7904,10 +8182,11 @@ event_unlock(struct socket *so, int refcount, void *lr)
        void *lr_saved;
        lck_mtx_t *mutex_held;
 
-       if (lr == NULL)
+       if (lr == NULL) {
                lr_saved = __builtin_return_address(0);
-       else
+       } else {
                lr_saved = lr;
+       }
 
        if (refcount) {
                so->so_usecount--;
@@ -7927,7 +8206,7 @@ event_unlock(struct socket *so, int refcount, void *lr)
 
        LCK_MTX_ASSERT(mutex_held, LCK_MTX_ASSERT_OWNED);
        so->unlock_lr[so->next_unlock_lr] = lr_saved;
-       so->next_unlock_lr = (so->next_unlock_lr+1) % SO_LCKDBG_MAX;
+       so->next_unlock_lr = (so->next_unlock_lr + 1) % SO_LCKDBG_MAX;
 
        if (so->so_usecount == 0) {
                VERIFY(so->so_flags & SOF_PCBCLEARING);
@@ -7936,7 +8215,7 @@ event_unlock(struct socket *so, int refcount, void *lr)
                lck_mtx_unlock(mutex_held);
        }
 
-       return (0);
+       return 0;
 }
 
 static int
@@ -7967,18 +8246,18 @@ event_sofreelastref(struct socket *so)
        kev_delete(ev_pcb);
 
        sofreelastref(so, 1);
-       return (0);
+       return 0;
 }
 
-static int event_proto_count = (sizeof (eventsw) / sizeof (struct protosw));
+static int event_proto_count = (sizeof(eventsw) / sizeof(struct protosw));
 
 static
 struct kern_event_head kern_event_head;
 
 static u_int32_t static_event_id = 0;
 
-#define        EVPCB_ZONE_MAX          65536
-#define        EVPCB_ZONE_NAME         "kerneventpcb"
+#define EVPCB_ZONE_MAX          65536
+#define EVPCB_ZONE_NAME         "kerneventpcb"
 static struct zone *ev_pcb_zone;
 
 /*
@@ -8018,8 +8297,9 @@ kern_event_init(struct domain *dp)
                /* NOTREACHED */
        }
 
-       for (i = 0, pr = &eventsw[0]; i < event_proto_count; i++, pr++)
+       for (i = 0, pr = &eventsw[0]; i < event_proto_count; i++, pr++) {
                net_add_proto(pr, dp, 1);
+       }
 
        ev_pcb_zone = zinit(sizeof(struct kern_event_pcb),
            EVPCB_ZONE_MAX * sizeof(struct kern_event_pcb), 0, EVPCB_ZONE_NAME);
@@ -8038,11 +8318,12 @@ kev_attach(struct socket *so, __unused int proto, __unused struct proc *p)
        struct kern_event_pcb *ev_pcb;
 
        error = soreserve(so, KEV_SNDSPACE, KEV_RECVSPACE);
-       if (error != 0)
-               return (error);
+       if (error != 0) {
+               return error;
+       }
 
        if ((ev_pcb = (struct kern_event_pcb *)zalloc(ev_pcb_zone)) == NULL) {
-               return (ENOBUFS);
+               return ENOBUFS;
        }
        bzero(ev_pcb, sizeof(struct kern_event_pcb));
        lck_mtx_init(&ev_pcb->evp_mtx, kev_lck_grp, kev_lck_attr);
@@ -8057,7 +8338,7 @@ kev_attach(struct socket *so, __unused int proto, __unused struct proc *p)
        kevtstat.kes_gencnt++;
        lck_rw_done(kev_rwlock);
 
-       return (error);
+       return error;
 }
 
 static void
@@ -8078,22 +8359,23 @@ kev_detach(struct socket *so)
                so->so_flags |= SOF_PCBCLEARING;
        }
 
-       return (0);
+       return 0;
 }
 
 /*
  * For now, kev_vendor_code and mbuf_tags use the same
  * mechanism.
  */
-errno_t kev_vendor_code_find(
-       const char      *string,
-       u_int32_t       *out_vendor_code)
+errno_t
+kev_vendor_code_find(
+       const char      *string,
+       u_int32_t       *out_vendor_code)
 {
        if (strlen(string) >= KEV_VENDOR_CODE_MAX_STR_LEN) {
-               return (EINVAL);
+               return EINVAL;
        }
-       return (net_str_id_find_internal(string, out_vendor_code,
-           NSI_VENDOR_CODE, 1));
+       return net_str_id_find_internal(string, out_vendor_code,
+                  NSI_VENDOR_CODE, 1);
 }
 
 errno_t
@@ -8103,8 +8385,9 @@ kev_msg_post(struct kev_msg *event_msg)
 
        net_str_id_first_last(&min_vendor, &max_vendor, NSI_VENDOR_CODE);
 
-       if (event_msg == NULL)
-               return (EINVAL);
+       if (event_msg == NULL) {
+               return EINVAL;
+       }
 
        /*
         * Limit third parties to posting events for registered vendor codes
@@ -8112,10 +8395,10 @@ kev_msg_post(struct kev_msg *event_msg)
         */
        if (event_msg->vendor_code < min_vendor ||
            event_msg->vendor_code > max_vendor) {
-               OSIncrementAtomic64((SInt64 *)&kevtstat.kes_badvendor);
-               return (EINVAL);
+               os_atomic_inc(&kevtstat.kes_badvendor, relaxed);
+               return EINVAL;
        }
-       return (kev_post_msg(event_msg));
+       return kev_post_msg(event_msg);
 }
 
 int
@@ -8132,28 +8415,30 @@ kev_post_msg(struct kev_msg *event_msg)
        total_size = KEV_MSG_HEADER_SIZE;
 
        for (i = 0; i < 5; i++) {
-               if (event_msg->dv[i].data_length == 0)
+               if (event_msg->dv[i].data_length == 0) {
                        break;
+               }
                total_size += event_msg->dv[i].data_length;
        }
 
        if (total_size > MLEN) {
-               OSIncrementAtomic64((SInt64 *)&kevtstat.kes_toobig);
-               return (EMSGSIZE);
+               os_atomic_inc(&kevtstat.kes_toobig, relaxed);
+               return EMSGSIZE;
        }
 
        m = m_get(M_WAIT, MT_DATA);
        if (m == 0) {
-               OSIncrementAtomic64((SInt64 *)&kevtstat.kes_nomem);
-               return (ENOMEM);
+               os_atomic_inc(&kevtstat.kes_nomem, relaxed);
+               return ENOMEM;
        }
        ev = mtod(m, struct kern_event_msg *);
        total_size = KEV_MSG_HEADER_SIZE;
 
        tmp = (char *) &ev->event_data[0];
        for (i = 0; i < 5; i++) {
-               if (event_msg->dv[i].data_length == 0)
+               if (event_msg->dv[i].data_length == 0) {
                        break;
+               }
 
                total_size += event_msg->dv[i].data_length;
                bcopy(event_msg->dv[i].data_ptr, tmp,
@@ -8202,11 +8487,11 @@ kev_post_msg(struct kev_msg *event_msg)
 
                m2 = m_copym(m, 0, m->m_len, M_WAIT);
                if (m2 == 0) {
-                       OSIncrementAtomic64((SInt64 *)&kevtstat.kes_nomem);
+                       os_atomic_inc(&kevtstat.kes_nomem, relaxed);
                        m_free(m);
                        lck_mtx_unlock(&ev_pcb->evp_mtx);
                        lck_rw_done(kev_rwlock);
-                       return (ENOMEM);
+                       return ENOMEM;
                }
                if (sbappendrecord(&ev_pcb->evp_socket->so_rcv, m2)) {
                        /*
@@ -8217,24 +8502,24 @@ kev_post_msg(struct kev_msg *event_msg)
                            1, m->m_len, MBUF_TC_BE);
 
                        sorwakeup(ev_pcb->evp_socket);
-                       OSIncrementAtomic64((SInt64 *)&kevtstat.kes_posted);
+                       os_atomic_inc(&kevtstat.kes_posted, relaxed);
                } else {
-                       OSIncrementAtomic64((SInt64 *)&kevtstat.kes_fullsock);
+                       os_atomic_inc(&kevtstat.kes_fullsock, relaxed);
                }
                lck_mtx_unlock(&ev_pcb->evp_mtx);
        }
        m_free(m);
        lck_rw_done(kev_rwlock);
 
-       return (0);
+       return 0;
 }
 
 static int
 kev_control(struct socket *so,
-               u_long cmd,
-               caddr_t data,
-               __unused struct ifnet *ifp,
-               __unused struct proc *p)
+    u_long cmd,
+    caddr_t data,
+    __unused struct ifnet *ifp,
+    __unused struct proc *p)
 {
        struct kev_request *kev_req = (struct kev_request *) data;
        struct kern_event_pcb  *ev_pcb;
@@ -8242,32 +8527,32 @@ kev_control(struct socket *so,
        u_int32_t  *id_value = (u_int32_t *) data;
 
        switch (cmd) {
-               case SIOCGKEVID:
-                       *id_value = static_event_id;
-                       break;
-               case SIOCSKEVFILT:
-                       ev_pcb = (struct kern_event_pcb *) so->so_pcb;
-                       ev_pcb->evp_vendor_code_filter = kev_req->vendor_code;
-                       ev_pcb->evp_class_filter = kev_req->kev_class;
-                       ev_pcb->evp_subclass_filter  = kev_req->kev_subclass;
-                       break;
-               case SIOCGKEVFILT:
-                       ev_pcb = (struct kern_event_pcb *) so->so_pcb;
-                       kev_req->vendor_code = ev_pcb->evp_vendor_code_filter;
-                       kev_req->kev_class   = ev_pcb->evp_class_filter;
-                       kev_req->kev_subclass = ev_pcb->evp_subclass_filter;
-                       break;
-               case SIOCGKEVVENDOR:
-                       kev_vendor = (struct kev_vendor_code *)data;
-                       /* Make sure string is NULL terminated */
-                       kev_vendor->vendor_string[KEV_VENDOR_CODE_MAX_STR_LEN-1] = 0;
-                       return (net_str_id_find_internal(kev_vendor->vendor_string,
-                           &kev_vendor->vendor_code, NSI_VENDOR_CODE, 0));
-               default:
-                       return (ENOTSUP);
+       case SIOCGKEVID:
+               *id_value = static_event_id;
+               break;
+       case SIOCSKEVFILT:
+               ev_pcb = (struct kern_event_pcb *) so->so_pcb;
+               ev_pcb->evp_vendor_code_filter = kev_req->vendor_code;
+               ev_pcb->evp_class_filter = kev_req->kev_class;
+               ev_pcb->evp_subclass_filter  = kev_req->kev_subclass;
+               break;
+       case SIOCGKEVFILT:
+               ev_pcb = (struct kern_event_pcb *) so->so_pcb;
+               kev_req->vendor_code = ev_pcb->evp_vendor_code_filter;
+               kev_req->kev_class   = ev_pcb->evp_class_filter;
+               kev_req->kev_subclass = ev_pcb->evp_subclass_filter;
+               break;
+       case SIOCGKEVVENDOR:
+               kev_vendor = (struct kev_vendor_code *)data;
+               /* Make sure string is NULL terminated */
+               kev_vendor->vendor_string[KEV_VENDOR_CODE_MAX_STR_LEN - 1] = 0;
+               return net_str_id_find_internal(kev_vendor->vendor_string,
+                          &kev_vendor->vendor_code, NSI_VENDOR_CODE, 0);
+       default:
+               return ENOTSUP;
        }
 
-       return (0);
+       return 0;
 }
 
 int
@@ -8292,7 +8577,7 @@ kevt_getstat SYSCTL_HANDLER_ARGS
 done:
        lck_rw_done(kev_rwlock);
 
-       return (error);
+       return error;
 }
 
 __private_extern__ int
@@ -8303,34 +8588,35 @@ kevt_pcblist SYSCTL_HANDLER_ARGS
        int n, i;
        struct xsystmgen xsg;
        void *buf = NULL;
-       size_t item_size = ROUNDUP64(sizeof (struct xkevtpcb)) +
-               ROUNDUP64(sizeof (struct xsocket_n)) +
-               2 * ROUNDUP64(sizeof (struct xsockbuf_n)) +
-               ROUNDUP64(sizeof (struct xsockstat_n));
+       size_t item_size = ROUNDUP64(sizeof(struct xkevtpcb)) +
+           ROUNDUP64(sizeof(struct xsocket_n)) +
+           2 * ROUNDUP64(sizeof(struct xsockbuf_n)) +
+           ROUNDUP64(sizeof(struct xsockstat_n));
        struct kern_event_pcb  *ev_pcb;
 
        buf = _MALLOC(item_size, M_TEMP, M_WAITOK | M_ZERO);
-       if (buf == NULL)
-               return (ENOMEM);
+       if (buf == NULL) {
+               return ENOMEM;
+       }
 
        lck_rw_lock_shared(kev_rwlock);
 
        n = kevtstat.kes_pcbcount;
 
        if (req->oldptr == USER_ADDR_NULL) {
-               req->oldidx = (n + n/8) * item_size;
+               req->oldidx = (n + n / 8) * item_size;
                goto done;
        }
        if (req->newptr != USER_ADDR_NULL) {
                error = EPERM;
                goto done;
        }
-       bzero(&xsg, sizeof (xsg));
-       xsg.xg_len = sizeof (xsg);
+       bzero(&xsg, sizeof(xsg));
+       xsg.xg_len = sizeof(xsg);
        xsg.xg_count = n;
        xsg.xg_gen = kevtstat.kes_gencnt;
        xsg.xg_sogen = so_gencnt;
-       error = SYSCTL_OUT(req, &xsg, sizeof (xsg));
+       error = SYSCTL_OUT(req, &xsg, sizeof(xsg));
        if (error) {
                goto done;
        }
@@ -8347,13 +8633,13 @@ kevt_pcblist SYSCTL_HANDLER_ARGS
            i++, ev_pcb = LIST_NEXT(ev_pcb, evp_link)) {
                struct xkevtpcb *xk = (struct xkevtpcb *)buf;
                struct xsocket_n *xso = (struct xsocket_n *)
-                       ADVANCE64(xk, sizeof (*xk));
+                   ADVANCE64(xk, sizeof(*xk));
                struct xsockbuf_n *xsbrcv = (struct xsockbuf_n *)
-                       ADVANCE64(xso, sizeof (*xso));
+                   ADVANCE64(xso, sizeof(*xso));
                struct xsockbuf_n *xsbsnd = (struct xsockbuf_n *)
-                       ADVANCE64(xsbrcv, sizeof (*xsbrcv));
+                   ADVANCE64(xsbrcv, sizeof(*xsbrcv));
                struct xsockstat_n *xsostats = (struct xsockstat_n *)
-                       ADVANCE64(xsbsnd, sizeof (*xsbsnd));
+                   ADVANCE64(xsbsnd, sizeof(*xsbsnd));
 
                bzero(buf, item_size);
 
@@ -8368,9 +8654,9 @@ kevt_pcblist SYSCTL_HANDLER_ARGS
 
                sotoxsocket_n(ev_pcb->evp_socket, xso);
                sbtoxsockbuf_n(ev_pcb->evp_socket ?
-                       &ev_pcb->evp_socket->so_rcv : NULL, xsbrcv);
+                   &ev_pcb->evp_socket->so_rcv : NULL, xsbrcv);
                sbtoxsockbuf_n(ev_pcb->evp_socket ?
-                       &ev_pcb->evp_socket->so_snd : NULL, xsbsnd);
+                   &ev_pcb->evp_socket->so_snd : NULL, xsbsnd);
                sbtoxsockstat_n(ev_pcb->evp_socket, xsostats);
 
                lck_mtx_unlock(&ev_pcb->evp_mtx);
@@ -8386,12 +8672,12 @@ kevt_pcblist SYSCTL_HANDLER_ARGS
                 * while we were processing this request, and it
                 * might be necessary to retry.
                 */
-               bzero(&xsg, sizeof (xsg));
-               xsg.xg_len = sizeof (xsg);
+               bzero(&xsg, sizeof(xsg));
+               xsg.xg_len = sizeof(xsg);
                xsg.xg_count = n;
                xsg.xg_gen = kevtstat.kes_gencnt;
                xsg.xg_sogen = so_gencnt;
-               error = SYSCTL_OUT(req, &xsg, sizeof (xsg));
+               error = SYSCTL_OUT(req, &xsg, sizeof(xsg));
                if (error) {
                        goto done;
                }
@@ -8400,7 +8686,7 @@ kevt_pcblist SYSCTL_HANDLER_ARGS
 done:
        lck_rw_done(kev_rwlock);
 
-       return (error);
+       return error;
 }
 
 #endif /* SOCKETS */
@@ -8414,66 +8700,69 @@ fill_kqueueinfo(struct kqueue *kq, struct kqueue_info * kinfo)
        st = &kinfo->kq_stat;
 
        st->vst_size = kq->kq_count;
-       if (kq->kq_state & KQ_KEV_QOS)
+       if (kq->kq_state & KQ_KEV_QOS) {
                st->vst_blksize = sizeof(struct kevent_qos_s);
-       else if (kq->kq_state & KQ_KEV64)
+       } else if (kq->kq_state & KQ_KEV64) {
                st->vst_blksize = sizeof(struct kevent64_s);
-       else
+       } else {
                st->vst_blksize = sizeof(struct kevent);
+       }
        st->vst_mode = S_IFIFO;
        st->vst_ino = (kq->kq_state & KQ_DYNAMIC) ?
-               ((struct kqworkloop *)kq)->kqwl_dynamicid : 0;
+           ((struct kqworkloop *)kq)->kqwl_dynamicid : 0;
 
        /* flags exported to libproc as PROC_KQUEUE_* (sys/proc_info.h) */
 #define PROC_KQUEUE_MASK (KQ_SEL|KQ_SLEEP|KQ_KEV32|KQ_KEV64|KQ_KEV_QOS|KQ_WORKQ|KQ_WORKLOOP)
        kinfo->kq_state = kq->kq_state & PROC_KQUEUE_MASK;
 
-       return (0);
+       return 0;
 }
 
 static int
-fill_kqueue_dyninfo(struct kqueue *kq, struct kqueue_dyninfo *kqdi)
+fill_kqueue_dyninfo(struct kqworkloop *kqwl, struct kqueue_dyninfo *kqdi)
 {
-       struct kqworkloop *kqwl = (struct kqworkloop *)kq;
-       struct kqrequest *kqr = &kqwl->kqwl_request;
+       workq_threadreq_t kqr = &kqwl->kqwl_request;
        workq_threadreq_param_t trp = {};
        int err;
 
-       if ((kq->kq_state & KQ_WORKLOOP) == 0) {
+       if ((kqwl->kqwl_state & KQ_WORKLOOP) == 0) {
                return EINVAL;
        }
 
-       if ((err = fill_kqueueinfo(kq, &kqdi->kqdi_info))) {
+       if ((err = fill_kqueueinfo(&kqwl->kqwl_kqueue, &kqdi->kqdi_info))) {
                return err;
        }
 
-       kq_req_lock(kqwl);
+       kqlock(kqwl);
 
-       kqdi->kqdi_servicer = thread_tid(kqr->kqr_thread);
+       kqdi->kqdi_servicer = thread_tid(kqr_thread(kqr));
        kqdi->kqdi_owner = thread_tid(kqwl->kqwl_owner);
-       kqdi->kqdi_request_state = kqr->kqr_state;
-       kqdi->kqdi_async_qos = kqr->kqr_qos_index;
-       kqdi->kqdi_events_qos = kqr->kqr_override_index;
-       kqdi->kqdi_sync_waiters = kqr->kqr_dsync_waiters;
+       kqdi->kqdi_request_state = kqr->tr_state;
+       kqdi->kqdi_async_qos = kqr->tr_kq_qos_index;
+       kqdi->kqdi_events_qos = kqr->tr_kq_override_index;
+       kqdi->kqdi_sync_waiters = 0;
        kqdi->kqdi_sync_waiter_qos = 0;
 
        trp.trp_value = kqwl->kqwl_params;
-       if (trp.trp_flags & TRP_PRIORITY)
+       if (trp.trp_flags & TRP_PRIORITY) {
                kqdi->kqdi_pri = trp.trp_pri;
-       else
+       } else {
                kqdi->kqdi_pri = 0;
+       }
 
-       if (trp.trp_flags & TRP_POLICY)
+       if (trp.trp_flags & TRP_POLICY) {
                kqdi->kqdi_pol = trp.trp_pol;
-       else
+       } else {
                kqdi->kqdi_pol = 0;
+       }
 
-       if (trp.trp_flags & TRP_CPUPERCENT)
+       if (trp.trp_flags & TRP_CPUPERCENT) {
                kqdi->kqdi_cpupercent = trp.trp_cpupercent;
-       else
+       } else {
                kqdi->kqdi_cpupercent = 0;
+       }
 
-       kq_req_unlock(kqwl);
+       kqunlock(kqwl);
 
        return 0;
 }
@@ -8492,70 +8781,63 @@ knote_markstayactive(struct knote *kn)
         * Making a knote stay active is a property of the knote that must be
         * established before it is fully attached.
         */
-       assert(kn->kn_status & KN_ATTACHING);
        assert((kn->kn_status & (KN_QUEUED | KN_SUPPRESSED)) == 0);
 
        /* handle all stayactive knotes on the (appropriate) manager */
-       if (kq->kq_state & KQ_WORKQ) {
-               qos = KQWQ_QOS_MANAGER;
-       } else if (kq->kq_state & KQ_WORKLOOP) {
+       if (kq->kq_state & KQ_WORKLOOP) {
                struct kqworkloop *kqwl = (struct kqworkloop *)kq;
 
                qos = _pthread_priority_thread_qos(kn->kn_qos);
                assert(qos && qos < THREAD_QOS_LAST);
-               kq_req_lock(kq);
                kqworkloop_update_threads_qos(kqwl, KQWL_UTQ_UPDATE_STAYACTIVE_QOS, qos);
-               kq_req_unlock(kq);
                qos = KQWL_BUCKET_STAYACTIVE;
+       } else if (kq->kq_state & KQ_WORKQ) {
+               qos = KQWQ_QOS_MANAGER;
        } else {
                qos = THREAD_QOS_UNSPECIFIED;
        }
 
-       kn->kn_req_index = qos;
        kn->kn_qos_override = qos;
        kn->kn_qos_index = qos;
 
-       knote_activate(kn);
+       knote_activate(kq, kn, FILTER_ACTIVE);
        kqunlock(kq);
 }
 
 void
 knote_clearstayactive(struct knote *kn)
 {
-       kqlock(knote_get_kq(kn));
-       kn->kn_status &= ~KN_STAYACTIVE;
-       knote_deactivate(kn);
-       kqunlock(knote_get_kq(kn));
+       struct kqueue *kq = knote_get_kq(kn);
+       kqlock(kq);
+       kn->kn_status &= ~(KN_STAYACTIVE | KN_ACTIVE);
+       knote_dequeue(kq, kn);
+       kqunlock(kq);
 }
 
 static unsigned long
 kevent_extinfo_emit(struct kqueue *kq, struct knote *kn, struct kevent_extinfo *buf,
-               unsigned long buflen, unsigned long nknotes)
+    unsigned long buflen, unsigned long nknotes)
 {
        for (; kn; kn = SLIST_NEXT(kn, kn_link)) {
                if (kq == knote_get_kq(kn)) {
                        if (nknotes < buflen) {
                                struct kevent_extinfo *info = &buf[nknotes];
-                               struct kevent_internal_s *kevp = &kn->kn_kevent;
 
                                kqlock(kq);
 
-                               info->kqext_kev = (struct kevent_qos_s){
-                                       .ident = kevp->ident,
-                                       .filter = kevp->filter,
-                                       .flags = kevp->flags,
-                                       .fflags = kevp->fflags,
-                                       .data = (int64_t)kevp->data,
-                                       .udata = kevp->udata,
-                                       .ext[0] = kevp->ext[0],
-                                       .ext[1] = kevp->ext[1],
-                                       .ext[2] = kevp->ext[2],
-                                       .ext[3] = kevp->ext[3],
-                                       .qos = kn->kn_req_index,
-                               };
-                               info->kqext_sdata = kn->kn_sdata;
-                               info->kqext_status = kn->kn_status;
-                               info->kqext_sfflags = kn->kn_sfflags;
+                               info->kqext_kev         = *(struct kevent_qos_s *)&kn->kn_kevent;
+                               if (knote_has_qos(kn)) {
+                                       info->kqext_kev.qos =
+                                           _pthread_priority_thread_qos_fast(kn->kn_qos);
+                               } else {
+                                       info->kqext_kev.qos = kn->kn_qos_override;
+                               }
+                               info->kqext_kev.filter |= 0xff00; /* sign extend filter */
+                               info->kqext_kev.xflags  = 0; /* this is where sfflags lives */
+                               info->kqext_kev.data    = 0; /* this is where sdata lives */
+                               info->kqext_sdata       = kn->kn_sdata;
+                               info->kqext_status      = kn->kn_status;
+                               info->kqext_sfflags     = kn->kn_sfflags;
 
                                kqunlock(kq);
                        }
@@ -8570,7 +8852,7 @@ kevent_extinfo_emit(struct kqueue *kq, struct knote *kn, struct kevent_extinfo *
 
 int
 kevent_copyout_proc_dynkqids(void *proc, user_addr_t ubuf, uint32_t ubufsize,
-               int32_t *nkqueues_out)
+    int32_t *nkqueues_out)
 {
        proc_t p = (proc_t)proc;
        struct filedesc *fdp = p->p_fd;
@@ -8602,13 +8884,13 @@ kevent_copyout_proc_dynkqids(void *proc, user_addr_t ubuf, uint32_t ubufsize,
                bzero(kq_ids, bufsize);
        }
 
-       kqhash_lock(p);
+       kqhash_lock(fdp);
 
        if (fdp->fd_kqhashmask > 0) {
                for (uint32_t i = 0; i < fdp->fd_kqhashmask + 1; i++) {
                        struct kqworkloop *kqwl;
 
-                       SLIST_FOREACH(kqwl, &fdp->fd_kqhash[i], kqwl_hashlink) {
+                       LIST_FOREACH(kqwl, &fdp->fd_kqhash[i], kqwl_hashlink) {
                                /* report the number of kqueues, even if they don't all fit */
                                if (nkqueues < buflen) {
                                        kq_ids[nkqueues] = kqwl->kqwl_dynamicid;
@@ -8618,7 +8900,7 @@ kevent_copyout_proc_dynkqids(void *proc, user_addr_t ubuf, uint32_t ubufsize,
                }
        }
 
-       kqhash_unlock(p);
+       kqhash_unlock(fdp);
 
        if (kq_ids) {
                size_t copysize;
@@ -8644,10 +8926,10 @@ out:
 
 int
 kevent_copyout_dynkqinfo(void *proc, kqueue_id_t kq_id, user_addr_t ubuf,
-               uint32_t ubufsize, int32_t *size_out)
+    uint32_t ubufsize, int32_t *size_out)
 {
        proc_t p = (proc_t)proc;
-       struct kqueue *kq;
+       struct kqworkloop *kqwl;
        int err = 0;
        struct kqueue_dyninfo kqdi = { };
 
@@ -8657,14 +8939,10 @@ kevent_copyout_dynkqinfo(void *proc, kqueue_id_t kq_id, user_addr_t ubuf,
                return ENOBUFS;
        }
 
-       kqhash_lock(p);
-       kq = kqueue_hash_lookup(p, kq_id);
-       if (!kq) {
-               kqhash_unlock(p);
+       kqwl = kqworkloop_hash_lookup_and_retain(p->p_fd, kq_id);
+       if (!kqwl) {
                return ESRCH;
        }
-       kqueue_retain(kq);
-       kqhash_unlock(p);
 
        /*
         * backward compatibility: allow the argument to this call to only be
@@ -8672,45 +8950,39 @@ kevent_copyout_dynkqinfo(void *proc, kqueue_id_t kq_id, user_addr_t ubuf,
         */
        if (ubufsize >= sizeof(struct kqueue_dyninfo)) {
                ubufsize = sizeof(struct kqueue_dyninfo);
-               err = fill_kqueue_dyninfo(kq, &kqdi);
+               err = fill_kqueue_dyninfo(kqwl, &kqdi);
        } else {
                ubufsize = sizeof(struct kqueue_info);
-               err = fill_kqueueinfo(kq, &kqdi.kqdi_info);
+               err = fill_kqueueinfo(&kqwl->kqwl_kqueue, &kqdi.kqdi_info);
        }
        if (err == 0 && (err = copyout(&kqdi, ubuf, ubufsize)) == 0) {
                *size_out = ubufsize;
        }
-       kqueue_release_last(p, kq);
+       kqworkloop_release(kqwl);
        return err;
 }
 
 int
 kevent_copyout_dynkqextinfo(void *proc, kqueue_id_t kq_id, user_addr_t ubuf,
-               uint32_t ubufsize, int32_t *nknotes_out)
+    uint32_t ubufsize, int32_t *nknotes_out)
 {
        proc_t p = (proc_t)proc;
-       struct kqueue *kq;
+       struct kqworkloop *kqwl;
        int err;
 
-       assert(p != NULL);
-
-       kqhash_lock(p);
-       kq = kqueue_hash_lookup(p, kq_id);
-       if (!kq) {
-               kqhash_unlock(p);
+       kqwl = kqworkloop_hash_lookup_and_retain(p->p_fd, kq_id);
+       if (!kqwl) {
                return ESRCH;
        }
-       kqueue_retain(kq);
-       kqhash_unlock(p);
 
-       err = pid_kqueue_extinfo(p, kq, ubuf, ubufsize, nknotes_out);
-       kqueue_release_last(p, kq);
+       err = pid_kqueue_extinfo(p, &kqwl->kqwl_kqueue, ubuf, ubufsize, nknotes_out);
+       kqworkloop_release(kqwl);
        return err;
 }
 
 int
 pid_kqueue_extinfo(proc_t p, struct kqueue *kq, user_addr_t ubuf,
-               uint32_t bufsize, int32_t *retval)
+    uint32_t bufsize, int32_t *retval)
 {
        struct knote *kn;
        int i;
@@ -8739,10 +9011,10 @@ pid_kqueue_extinfo(proc_t p, struct kqueue *kq, user_addr_t ubuf,
 
        if (fdp->fd_knhashmask != 0) {
                for (i = 0; i < (int)fdp->fd_knhashmask + 1; i++) {
-                       kqhash_lock(p);
+                       knhash_lock(fdp);
                        kn = SLIST_FIRST(&fdp->fd_knhash[i]);
                        nknotes = kevent_extinfo_emit(kq, kn, kqext, buflen, nknotes);
-                       kqhash_unlock(p);
+                       knhash_unlock(fdp);
                }
        }
 
@@ -8763,17 +9035,16 @@ out:
 
 static unsigned int
 klist_copy_udata(struct klist *list, uint64_t *buf,
-               unsigned int buflen, unsigned int nknotes)
+    unsigned int buflen, unsigned int nknotes)
 {
-       struct kevent_internal_s *kev;
        struct knote *kn;
        SLIST_FOREACH(kn, list, kn_link) {
                if (nknotes < buflen) {
-                       struct kqueue *kq = knote_get_kq(kn);
-                       kqlock(kq);
-                       kev = &(kn->kn_kevent);
-                       buf[nknotes] = kev->udata;
-                       kqunlock(kq);
+                       /*
+                        * kevent_register will always set kn_udata atomically
+                        * so that we don't have to take any kqlock here.
+                        */
+                       buf[nknotes] = os_atomic_load_wide(&kn->kn_udata, relaxed);
                }
                /* we return total number of knotes, which may be more than requested */
                nknotes++;
@@ -8782,21 +9053,6 @@ klist_copy_udata(struct klist *list, uint64_t *buf,
        return nknotes;
 }
 
-static unsigned int
-kqlist_copy_dynamicids(__assert_only proc_t p, struct kqlist *list,
-               uint64_t *buf, unsigned int buflen, unsigned int nids)
-{
-       kqhash_lock_held(p);
-       struct kqworkloop *kqwl;
-       SLIST_FOREACH(kqwl, list, kqwl_hashlink) {
-               if (nids < buflen) {
-                       buf[nids] = kqwl->kqwl_dynamicid;
-               }
-               nids++;
-       }
-       return nids;
-}
-
 int
 kevent_proc_copy_uptrs(void *proc, uint64_t *buf, int bufsize)
 {
@@ -8804,6 +9060,7 @@ kevent_proc_copy_uptrs(void *proc, uint64_t *buf, int bufsize)
        struct filedesc *fdp = p->p_fd;
        unsigned int nuptrs = 0;
        unsigned long buflen = bufsize / sizeof(uint64_t);
+       struct kqworkloop *kqwl;
 
        if (buflen > 0) {
                assert(buf != NULL);
@@ -8813,23 +9070,28 @@ kevent_proc_copy_uptrs(void *proc, uint64_t *buf, int bufsize)
        for (int i = 0; i < fdp->fd_knlistsize; i++) {
                nuptrs = klist_copy_udata(&fdp->fd_knlist[i], buf, buflen, nuptrs);
        }
-       knhash_lock(p);
        proc_fdunlock(p);
+
+       knhash_lock(fdp);
        if (fdp->fd_knhashmask != 0) {
-               for (int i = 0; i < (int)fdp->fd_knhashmask + 1; i++) {
+               for (size_t i = 0; i < fdp->fd_knhashmask + 1; i++) {
                        nuptrs = klist_copy_udata(&fdp->fd_knhash[i], buf, buflen, nuptrs);
                }
        }
-       knhash_unlock(p);
+       knhash_unlock(fdp);
 
-       kqhash_lock(p);
+       kqhash_lock(fdp);
        if (fdp->fd_kqhashmask != 0) {
-               for (int i = 0; i < (int)fdp->fd_kqhashmask + 1; i++) {
-                       nuptrs = kqlist_copy_dynamicids(p, &fdp->fd_kqhash[i], buf, buflen,
-                                       nuptrs);
+               for (size_t i = 0; i < fdp->fd_kqhashmask + 1; i++) {
+                       LIST_FOREACH(kqwl, &fdp->fd_kqhash[i], kqwl_hashlink) {
+                               if (nuptrs < buflen) {
+                                       buf[nuptrs] = kqwl->kqwl_dynamicid;
+                               }
+                               nuptrs++;
+                       }
                }
        }
-       kqhash_unlock(p);
+       kqhash_unlock(fdp);
 
        return (int)nuptrs;
 }
@@ -8863,10 +9125,10 @@ kevent_set_return_to_kernel_user_tsd(proc_t p, thread_t thread)
        }
 
        if (copyout((proc_is_64bit ? (void *)&ast_flags64 : (void *)&ast_flags32),
-                   (user_addr_t)ast_addr,
-                   user_addr_size) != 0) {
+           (user_addr_t)ast_addr,
+           user_addr_size) != 0) {
                printf("pid %d (tid:%llu): copyout of return_to_kernel ast flags failed with "
-                      "ast_addr = %llu\n", p->p_pid, thread_tid(current_thread()), ast_addr);
+                   "ast_addr = %llu\n", p->p_pid, thread_tid(current_thread()), ast_addr);
        }
 }
 
@@ -8907,9 +9169,9 @@ kevent_sysctl SYSCTL_HANDLER_ARGS
                return EFAULT;
        }
 
-       struct kqrequest *kqr = ut->uu_kqr_bound;
+       workq_threadreq_t kqr = ut->uu_kqr_bound;
        if (kqr) {
-               if (kqr->kqr_state & KQR_WORKLOOP) {
+               if (kqr->tr_flags & WORKQ_TR_FLAG_WORKLOOP) {
                        bound_id = kqr_kqworkloop(kqr)->kqwl_dynamicid;
                } else {
                        bound_id = -1;
@@ -8920,12 +9182,12 @@ kevent_sysctl SYSCTL_HANDLER_ARGS
 }
 
 SYSCTL_NODE(_kern, OID_AUTO, kevent, CTLFLAG_RW | CTLFLAG_LOCKED, 0,
-               "kevent information");
+    "kevent information");
 
 SYSCTL_PROC(_kern_kevent, OID_AUTO, bound_id,
-               CTLTYPE_QUAD | CTLFLAG_RD | CTLFLAG_LOCKED | CTLFLAG_MASKED,
-               (void *)KEVENT_SYSCTL_BOUND_ID,
-               sizeof(kqueue_id_t), kevent_sysctl, "Q",
-               "get the ID of the bound kqueue");
+    CTLTYPE_QUAD | CTLFLAG_RD | CTLFLAG_LOCKED | CTLFLAG_MASKED,
+    (void *)KEVENT_SYSCTL_BOUND_ID,
+    sizeof(kqueue_id_t), kevent_sysctl, "Q",
+    "get the ID of the bound kqueue");
 
 #endif /* DEVELOPMENT || DEBUG */