/*
- * Copyright (c) 2000-2016 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2019 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* the rights to redistribute these changes.
*/
-#define ATOMIC_PRIVATE 1
#define LOCK_PRIVATE 1
#include <mach_ldebug.h>
#define ALIGN_TEST(p, t) do{}while(0)
#endif
-/* Silence the volatile to _Atomic cast warning */
-#define ATOMIC_CAST(t, p) ((_Atomic t*)(uintptr_t)(p))
-
-/* Enforce program order of loads and stores. */
-#define ordered_load(target, type) \
- __c11_atomic_load((_Atomic type *)(target), memory_order_relaxed)
-#define ordered_store(target, type, value) \
- __c11_atomic_store((_Atomic type *)(target), value, memory_order_relaxed)
-
-#define ordered_load_hw(lock) ordered_load(&(lock)->lock_data, uintptr_t)
-#define ordered_store_hw(lock, value) ordered_store(&(lock)->lock_data, uintptr_t, (value))
-
#define NOINLINE __attribute__((noinline))
+#define ordered_load_hw(lock) os_atomic_load(&(lock)->lock_data, compiler_acq_rel)
+#define ordered_store_hw(lock, value) os_atomic_store(&(lock)->lock_data, (value), compiler_acq_rel)
+
queue_head_t lck_grp_queue;
unsigned int lck_grp_cnt;
-decl_lck_mtx_data(, lck_grp_lock)
+decl_lck_mtx_data(, lck_grp_lock);
static lck_mtx_ext_t lck_grp_lock_ext;
SECURITY_READ_ONLY_LATE(boolean_t) spinlock_timeout_panic = TRUE;
LockCompatGroup.lck_grp_attr |= LCK_GRP_ATTR_TIME_STAT;
}
- LockCompatGroup.lck_grp_refcnt = 1;
+ os_ref_init(&LockCompatGroup.lck_grp_refcnt, NULL);
enqueue_tail(&lck_grp_queue, (queue_entry_t)&LockCompatGroup);
lck_grp_cnt = 1;
lck_grp_attr_setstat(
lck_grp_attr_t *attr)
{
- (void)hw_atomic_or(&attr->grp_attr_val, LCK_GRP_ATTR_STAT);
+ os_atomic_or(&attr->grp_attr_val, LCK_GRP_ATTR_STAT, relaxed);
}
#endif /* LOCK_STATS */
}
- grp->lck_grp_refcnt = 1;
+ os_ref_init(&grp->lck_grp_refcnt, NULL);
lck_mtx_lock(&lck_grp_lock);
enqueue_tail(&lck_grp_queue, (queue_entry_t)grp);
lck_grp_reference(
lck_grp_t *grp)
{
- (void)hw_atomic_add(&grp->lck_grp_refcnt, 1);
+ os_ref_retain(&grp->lck_grp_refcnt);
}
lck_grp_deallocate(
lck_grp_t *grp)
{
- if (hw_atomic_sub(&grp->lck_grp_refcnt, 1) == 0) {
- kfree(grp, sizeof(lck_grp_t));
+ if (os_ref_release(&grp->lck_grp_refcnt) != 0) {
+ return;
}
+
+ kfree(grp, sizeof(lck_grp_t));
}
/*
return panic("lck_grp_lckcnt_incr(): invalid lock type: %d\n", lck_type);
}
- (void)hw_atomic_add(lckcnt, 1);
+ os_atomic_inc(lckcnt, relaxed);
}
/*
return;
}
- updated = (int)hw_atomic_sub(lckcnt, 1);
+ updated = os_atomic_dec(lckcnt, relaxed);
assert(updated >= 0);
}
lck_attr_setdebug(
lck_attr_t *attr)
{
- (void)hw_atomic_or(&attr->lck_attr_val, LCK_ATTR_DEBUG);
+ os_atomic_or(&attr->lck_attr_val, LCK_ATTR_DEBUG, relaxed);
}
/*
lck_attr_cleardebug(
lck_attr_t *attr)
{
- (void)hw_atomic_and(&attr->lck_attr_val, ~LCK_ATTR_DEBUG);
+ os_atomic_andnot(&attr->lck_attr_val, LCK_ATTR_DEBUG, relaxed);
}
lck_attr_rw_shared_priority(
lck_attr_t *attr)
{
- (void)hw_atomic_or(&attr->lck_attr_val, LCK_ATTR_RW_SHARED_PRIORITY);
+ os_atomic_or(&attr->lck_attr_val, LCK_ATTR_RW_SHARED_PRIORITY, relaxed);
}
ordered_store_hw(lock, 0);
}
+#if __SMP__
+static inline bool
+hw_lock_trylock_contended(hw_lock_t lock, uintptr_t newval)
+{
+#if OS_ATOMIC_USE_LLSC
+ uintptr_t oldval;
+ os_atomic_rmw_loop(&lock->lock_data, oldval, newval, acquire, {
+ if (oldval != 0) {
+ wait_for_event(); // clears the monitor so we don't need give_up()
+ return false;
+ }
+ });
+ return true;
+#else // !OS_ATOMIC_USE_LLSC
+#if OS_ATOMIC_HAS_LLSC
+ uintptr_t oldval = os_atomic_load_exclusive(&lock->lock_data, relaxed);
+ if (oldval != 0) {
+ wait_for_event(); // clears the monitor so we don't need give_up()
+ return false;
+ }
+#endif // OS_ATOMIC_HAS_LLSC
+ return os_atomic_cmpxchg(&lock->lock_data, 0, newval, acquire);
+#endif // !OS_ATOMIC_USE_LLSC
+}
+
/*
* Routine: hw_lock_lock_contended
*
* timeout is in mach_absolute_time ticks. Called with
* preemption disabled.
*/
-
-#if __SMP__
static unsigned int NOINLINE
hw_lock_lock_contended(hw_lock_t lock, uintptr_t data, uint64_t timeout, boolean_t do_panic LCK_GRP_ARG(lck_grp_t *grp))
{
continue;
}
#endif
- if (atomic_compare_exchange(&lock->lock_data, 0, data,
- memory_order_acquire_smp, TRUE)) {
+ if (hw_lock_trylock_contended(lock, data)) {
#if CONFIG_DTRACE || LOCK_STATS
if (__improbable(stat_enabled)) {
lck_grp_spin_update_spin(lock LCK_GRP_ARG(grp), mach_absolute_time() - begin);
}
#endif // __SMP__
+void *
+hw_wait_while_equals(void **address, void *current)
+{
+#if __SMP__
+ void *v;
+ uint64_t end = 0;
+
+ for (;;) {
+ for (int i = 0; i < LOCK_SNOOP_SPINS; i++) {
+ cpu_pause();
+#if OS_ATOMIC_HAS_LLSC
+ v = os_atomic_load_exclusive(address, relaxed);
+ if (__probable(v != current)) {
+ os_atomic_clear_exclusive();
+ return v;
+ }
+ wait_for_event();
+#else
+ v = os_atomic_load(address, relaxed);
+ if (__probable(v != current)) {
+ return v;
+ }
+#endif // OS_ATOMIC_HAS_LLSC
+ }
+ if (end == 0) {
+ end = ml_get_timebase() + LOCK_PANIC_TIMEOUT;
+ } else if (ml_get_timebase() >= end) {
+ panic("Wait while equals timeout @ *%p == %p", address, v);
+ }
+ }
+#else // !__SMP__
+ panic("Value at %p is %p", address, current);
+ __builtin_unreachable();
+#endif // !__SMP__
+}
+
static inline void
hw_lock_lock_internal(hw_lock_t lock, thread_t thread LCK_GRP_ARG(lck_grp_t *grp))
{
state = LCK_MTX_THREAD_TO_STATE(thread) | PLATFORM_LCK_ILOCK;
#if __SMP__
-
#if LOCK_PRETEST
if (ordered_load_hw(lock)) {
goto contended;
}
#endif // LOCK_PRETEST
- if (atomic_compare_exchange(&lock->lock_data, 0, state,
- memory_order_acquire_smp, TRUE)) {
+ if (hw_lock_trylock_contended(lock, state)) {
goto end;
}
#if LOCK_PRETEST
disable_preemption_for_thread(thread);
state = LCK_MTX_THREAD_TO_STATE(thread) | PLATFORM_LCK_ILOCK;
#if __SMP__
-
#if LOCK_PRETEST
if (ordered_load_hw(lock)) {
goto contended;
}
#endif // LOCK_PRETEST
- if (atomic_compare_exchange(&lock->lock_data, 0, state,
- memory_order_acquire_smp, TRUE)) {
+ if (hw_lock_trylock_contended(lock, state)) {
success = 1;
goto end;
}
goto failed;
}
#endif // LOCK_PRETEST
- success = atomic_compare_exchange(&lock->lock_data, 0, LCK_MTX_THREAD_TO_STATE(thread) | PLATFORM_LCK_ILOCK,
- memory_order_acquire_smp, FALSE);
+ success = os_atomic_cmpxchg(&lock->lock_data, 0,
+ LCK_MTX_THREAD_TO_STATE(thread) | PLATFORM_LCK_ILOCK, acquire);
#else
if (lock->lock_data == 0) {
lock->lock_data = LCK_MTX_THREAD_TO_STATE(thread) | PLATFORM_LCK_ILOCK;
static inline void
hw_lock_unlock_internal(hw_lock_t lock)
{
- __c11_atomic_store((_Atomic uintptr_t *)&lock->lock_data, 0, memory_order_release_smp);
+ os_atomic_store(&lock->lock_data, 0, release);
#if __arm__ || __arm64__
// ARM tests are only for open-source exclusion
set_event();
return ordered_load_hw(lock) != 0;
}
+#if __SMP__
+static unsigned int
+hw_lock_bit_to_contended(hw_lock_bit_t *lock, uint32_t mask, uint32_t timeout LCK_GRP_ARG(lck_grp_t *grp));
+#endif
+
+static inline unsigned int
+hw_lock_bit_to_internal(hw_lock_bit_t *lock, unsigned int bit, uint32_t timeout LCK_GRP_ARG(lck_grp_t *grp))
+{
+ unsigned int success = 0;
+ uint32_t mask = (1 << bit);
+#if !__SMP__
+ uint32_t state;
+#endif
+
+#if __SMP__
+ if (__improbable(!hw_atomic_test_and_set32(lock, mask, mask, memory_order_acquire, FALSE))) {
+ success = hw_lock_bit_to_contended(lock, mask, timeout LCK_GRP_ARG(grp));
+ } else {
+ success = 1;
+ }
+#else // __SMP__
+ (void)timeout;
+ state = ordered_load_bit(lock);
+ if (!(mask & state)) {
+ ordered_store_bit(lock, state | mask);
+ success = 1;
+ }
+#endif // __SMP__
+
+ if (success) {
+ lck_grp_spin_update_held(lock LCK_GRP_ARG(grp));
+ }
+
+ return success;
+}
+
+unsigned
+int
+(hw_lock_bit_to)(hw_lock_bit_t * lock, unsigned int bit, uint32_t timeout LCK_GRP_ARG(lck_grp_t *grp))
+{
+ _disable_preemption();
+ return hw_lock_bit_to_internal(lock, bit, timeout LCK_GRP_ARG(grp));
+}
+
+#if __SMP__
+static unsigned int NOINLINE
+hw_lock_bit_to_contended(hw_lock_bit_t *lock, uint32_t mask, uint32_t timeout LCK_GRP_ARG(lck_grp_t *grp))
+{
+ uint64_t end = 0;
+ int i;
+#if CONFIG_DTRACE || LOCK_STATS
+ uint64_t begin = 0;
+ boolean_t stat_enabled = lck_grp_spin_spin_enabled(lock LCK_GRP_ARG(grp));
+#endif /* CONFIG_DTRACE || LOCK_STATS */
+
+#if LOCK_STATS || CONFIG_DTRACE
+ if (__improbable(stat_enabled)) {
+ begin = mach_absolute_time();
+ }
+#endif /* LOCK_STATS || CONFIG_DTRACE */
+ for (;;) {
+ for (i = 0; i < LOCK_SNOOP_SPINS; i++) {
+ // Always load-exclusive before wfe
+ // This grabs the monitor and wakes up on a release event
+ if (hw_atomic_test_and_set32(lock, mask, mask, memory_order_acquire, TRUE)) {
+ goto end;
+ }
+ }
+ if (end == 0) {
+ end = ml_get_timebase() + timeout;
+ } else if (ml_get_timebase() >= end) {
+ break;
+ }
+ }
+ return 0;
+end:
+#if CONFIG_DTRACE || LOCK_STATS
+ if (__improbable(stat_enabled)) {
+ lck_grp_spin_update_spin(lock LCK_GRP_ARG(grp), mach_absolute_time() - begin);
+ }
+ lck_grp_spin_update_miss(lock LCK_GRP_ARG(grp));
+#endif /* CONFIG_DTRACE || LCK_GRP_STAT */
+
+ return 1;
+}
+#endif // __SMP__
+
+void
+(hw_lock_bit)(hw_lock_bit_t * lock, unsigned int bit LCK_GRP_ARG(lck_grp_t *grp))
+{
+ if (hw_lock_bit_to(lock, bit, LOCK_PANIC_TIMEOUT, LCK_GRP_PROBEARG(grp))) {
+ return;
+ }
+#if __SMP__
+ panic("hw_lock_bit(): timed out (%p)", lock);
+#else
+ panic("hw_lock_bit(): interlock held (%p)", lock);
+#endif
+}
+
+void
+(hw_lock_bit_nopreempt)(hw_lock_bit_t * lock, unsigned int bit LCK_GRP_ARG(lck_grp_t *grp))
+{
+ if (__improbable(get_preemption_level() == 0)) {
+ panic("Attempt to take no-preempt bitlock %p in preemptible context", lock);
+ }
+ if (hw_lock_bit_to_internal(lock, bit, LOCK_PANIC_TIMEOUT LCK_GRP_ARG(grp))) {
+ return;
+ }
+#if __SMP__
+ panic("hw_lock_bit_nopreempt(): timed out (%p)", lock);
+#else
+ panic("hw_lock_bit_nopreempt(): interlock held (%p)", lock);
+#endif
+}
+
+unsigned
+int
+(hw_lock_bit_try)(hw_lock_bit_t * lock, unsigned int bit LCK_GRP_ARG(lck_grp_t *grp))
+{
+ uint32_t mask = (1 << bit);
+#if !__SMP__
+ uint32_t state;
+#endif
+ boolean_t success = FALSE;
+
+ _disable_preemption();
+#if __SMP__
+ // TODO: consider weak (non-looping) atomic test-and-set
+ success = hw_atomic_test_and_set32(lock, mask, mask, memory_order_acquire, FALSE);
+#else
+ state = ordered_load_bit(lock);
+ if (!(mask & state)) {
+ ordered_store_bit(lock, state | mask);
+ success = TRUE;
+ }
+#endif // __SMP__
+ if (!success) {
+ _enable_preemption();
+ }
+
+ if (success) {
+ lck_grp_spin_update_held(lock LCK_GRP_ARG(grp));
+ }
+
+ return success;
+}
+
+static inline void
+hw_unlock_bit_internal(hw_lock_bit_t *lock, unsigned int bit)
+{
+ uint32_t mask = (1 << bit);
+#if !__SMP__
+ uint32_t state;
+#endif
+
+#if __SMP__
+ os_atomic_andnot(lock, mask, release);
+#if __arm__
+ set_event();
+#endif
+#else // __SMP__
+ state = ordered_load_bit(lock);
+ ordered_store_bit(lock, state & ~mask);
+#endif // __SMP__
+#if CONFIG_DTRACE
+ LOCKSTAT_RECORD(LS_LCK_SPIN_UNLOCK_RELEASE, lock, bit);
+#endif
+}
+
+/*
+ * Routine: hw_unlock_bit
+ *
+ * Release spin-lock. The second parameter is the bit number to test and set.
+ * Decrement the preemption level.
+ */
+void
+hw_unlock_bit(hw_lock_bit_t * lock, unsigned int bit)
+{
+ hw_unlock_bit_internal(lock, bit);
+ _enable_preemption();
+}
+
+void
+hw_unlock_bit_nopreempt(hw_lock_bit_t * lock, unsigned int bit)
+{
+ if (__improbable(get_preemption_level() == 0)) {
+ panic("Attempt to release no-preempt bitlock %p in preemptible context", lock);
+ }
+ hw_unlock_bit_internal(lock, bit);
+}
+
/*
* Routine: lck_spin_sleep
*/
* The lock owner is always promoted to the max priority of all its waiters.
* Max priority is capped at MAXPRI_PROMOTE.
*
- * lck_mtx_pri being set implies that the lock owner is promoted to at least lck_mtx_pri
- * This prevents the thread from dropping in priority while holding a mutex
- * (note: Intel locks currently don't do this, to avoid thread lock churn)
- *
- * thread->promotions has a +1 for every mutex currently promoting the thread
- * and 1 for was_promoted_on_wakeup being set.
- * TH_SFLAG_PROMOTED is set on a thread whenever it has any promotions
- * from any mutex (i.e. thread->promotions != 0)
- *
- * was_promoted_on_wakeup is set on a thread which is woken up by a mutex when
- * it raises the priority of the woken thread to match lck_mtx_pri.
- * It can be set for multiple iterations of wait, fail to acquire, re-wait, etc
- * was_promoted_on_wakeup being set always implies a +1 promotions count.
- *
* The last waiter is not given a promotion when it wakes up or acquires the lock.
* When the last waiter is waking up, a new contender can always come in and
* steal the lock without having to wait for the last waiter to make forward progress.
- *
- * lck_mtx_waiters has a +1 for every waiter currently between wait and acquire
- * This prevents us from asserting that every wakeup wakes up a thread.
- * This also causes excess thread_wakeup calls in the unlock path.
- * It can only be fooled into thinking there are more waiters than are
- * actually blocked, not less.
- * It does allows us to reduce the complexity of the lock state.
- *
- * This also means that a starved bg thread as the last waiter could end up
- * keeping the lock in the contended state for a long period of time, which
- * may keep lck_mtx_pri artificially high for a very long time even though
- * it is not participating or blocking anyone else.
- * Intel locks don't have this problem because they can go uncontended
- * as soon as there are no blocked threads involved.
*/
/*
void
lck_mtx_lock_wait(
lck_mtx_t *lck,
- thread_t holder)
+ thread_t holder,
+ struct turnstile **ts)
{
- thread_t self = current_thread();
+ thread_t thread = current_thread();
lck_mtx_t *mutex;
__kdebug_only uintptr_t trace_lck = unslide_for_kdebug(lck);
KERNEL_DEBUG(MACHDBG_CODE(DBG_MACH_LOCKS, LCK_MTX_LCK_WAIT_CODE) | DBG_FUNC_START,
trace_lck, (uintptr_t)thread_tid(thread), 0, 0, 0);
- spl_t s = splsched();
- thread_lock(holder);
-
- assert_promotions_invariant(holder);
-
- if ((holder->sched_flags & TH_SFLAG_DEPRESS) == 0) {
- assert(holder->sched_pri >= mutex->lck_mtx_pri);
- }
-
- integer_t priority = self->sched_pri;
- priority = MAX(priority, self->base_pri);
- priority = MAX(priority, BASEPRI_DEFAULT);
- priority = MIN(priority, MAXPRI_PROMOTE);
-
- if (mutex->lck_mtx_pri == 0) {
- /* This is the first promotion for this mutex */
- if (holder->promotions++ == 0) {
- /* This is the first promotion for holder */
- sched_thread_promote_to_pri(holder, priority, trace_lck);
- } else {
- /* Holder was previously promoted due to a different mutex, raise to match this one */
- sched_thread_update_promotion_to_pri(holder, priority, trace_lck);
- }
- } else {
- /* Holder was previously promoted due to this mutex, check if the pri needs to go up */
- sched_thread_update_promotion_to_pri(holder, priority, trace_lck);
- }
-
- assert(holder->promotions > 0);
- assert(holder->promotion_priority >= priority);
-
- if ((holder->sched_flags & TH_SFLAG_DEPRESS) == 0) {
- assert(holder->sched_pri >= mutex->lck_mtx_pri);
- }
-
- assert_promotions_invariant(holder);
-
- thread_unlock(holder);
- splx(s);
+ assert(thread->waiting_for_mutex == NULL);
+ thread->waiting_for_mutex = mutex;
+ mutex->lck_mtx_waiters++;
- if (mutex->lck_mtx_pri < priority) {
- mutex->lck_mtx_pri = priority;
+ if (*ts == NULL) {
+ *ts = turnstile_prepare((uintptr_t)mutex, NULL, TURNSTILE_NULL, TURNSTILE_KERNEL_MUTEX);
}
- if (self->waiting_for_mutex == NULL) {
- self->waiting_for_mutex = mutex;
- mutex->lck_mtx_waiters++;
- }
+ struct turnstile *turnstile = *ts;
+ thread_set_pending_block_hint(thread, kThreadWaitKernelMutex);
+ turnstile_update_inheritor(turnstile, holder, (TURNSTILE_DELAYED_UPDATE | TURNSTILE_INHERITOR_THREAD));
- assert(self->waiting_for_mutex == mutex);
+ waitq_assert_wait64(&turnstile->ts_waitq, CAST_EVENT64_T(LCK_MTX_EVENT(mutex)), THREAD_UNINT | THREAD_WAIT_NOREPORT_USER, TIMEOUT_WAIT_FOREVER);
- thread_set_pending_block_hint(self, kThreadWaitKernelMutex);
- assert_wait(LCK_MTX_EVENT(mutex), THREAD_UNINT | THREAD_WAIT_NOREPORT_USER);
lck_mtx_ilk_unlock(mutex);
+ turnstile_update_inheritor_complete(turnstile, TURNSTILE_INTERLOCK_NOT_HELD);
+
thread_block(THREAD_CONTINUE_NULL);
- assert(mutex->lck_mtx_waiters > 0);
+ thread->waiting_for_mutex = NULL;
KERNEL_DEBUG(MACHDBG_CODE(DBG_MACH_LOCKS, LCK_MTX_LCK_WAIT_CODE) | DBG_FUNC_END, 0, 0, 0, 0, 0);
#if CONFIG_DTRACE
*/
int
lck_mtx_lock_acquire(
- lck_mtx_t *lck)
+ lck_mtx_t *lck,
+ struct turnstile *ts)
{
thread_t thread = current_thread();
lck_mtx_t *mutex;
- integer_t priority;
if (lck->lck_mtx_tag != LCK_MTX_TAG_INDIRECT) {
mutex = lck;
mutex = &lck->lck_mtx_ptr->lck_mtx;
}
- /*
- * If waiting_for_mutex is set, then this thread was previously blocked waiting on this lock
- * If it's un-set, then this thread stole the lock from another waiter.
- */
- if (thread->waiting_for_mutex == mutex) {
- assert(mutex->lck_mtx_waiters > 0);
-
- thread->waiting_for_mutex = NULL;
- mutex->lck_mtx_waiters--;
- }
-
assert(thread->waiting_for_mutex == NULL);
if (mutex->lck_mtx_waiters > 0) {
- priority = mutex->lck_mtx_pri;
- } else {
- /* I was the last waiter, so the mutex is no longer promoted or contended */
- mutex->lck_mtx_pri = 0;
- priority = 0;
- }
-
- if (priority || thread->was_promoted_on_wakeup) {
- __kdebug_only uintptr_t trace_lck = unslide_for_kdebug(lck);
-
- /*
- * Note: was_promoted_on_wakeup can happen for multiple wakeups in a row without
- * an intervening acquire if a thread keeps failing to acquire the lock
- *
- * If priority is true but not promoted on wakeup,
- * then this is a lock steal of a promoted mutex, so it needs a ++ of promotions.
- *
- * If promoted on wakeup is true, but priority is not,
- * then this is the last owner, and the last owner does not need a promotion.
- */
-
- spl_t s = splsched();
- thread_lock(thread);
-
- assert_promotions_invariant(thread);
-
- if (thread->was_promoted_on_wakeup) {
- assert(thread->promotions > 0);
+ if (ts == NULL) {
+ ts = turnstile_prepare((uintptr_t)mutex, NULL, TURNSTILE_NULL, TURNSTILE_KERNEL_MUTEX);
}
- if (priority) {
- if (thread->promotions++ == 0) {
- /* This is the first promotion for holder */
- sched_thread_promote_to_pri(thread, priority, trace_lck);
- } else {
- /*
- * Holder was previously promoted due to a different mutex, raise to match this one
- * Or, this thread was promoted on wakeup but someone else later contended on mutex
- * at higher priority before we got here
- */
- sched_thread_update_promotion_to_pri(thread, priority, trace_lck);
- }
- }
-
- if (thread->was_promoted_on_wakeup) {
- thread->was_promoted_on_wakeup = 0;
- if (--thread->promotions == 0) {
- sched_thread_unpromote(thread, trace_lck);
- }
- }
-
- assert_promotions_invariant(thread);
-
- if (priority && (thread->sched_flags & TH_SFLAG_DEPRESS) == 0) {
- assert(thread->sched_pri >= priority);
- }
+ turnstile_update_inheritor(ts, thread, (TURNSTILE_IMMEDIATE_UPDATE | TURNSTILE_INHERITOR_THREAD));
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_HELD);
+ }
- thread_unlock(thread);
- splx(s);
+ if (ts != NULL) {
+ turnstile_complete((uintptr_t)mutex, NULL, NULL, TURNSTILE_KERNEL_MUTEX);
}
return mutex->lck_mtx_waiters;
*
* Called with the interlock locked.
*
- * TODO: the 'waiters' flag does not indicate waiters exist on the waitqueue,
- * it indicates waiters exist between wait and acquire.
- * This means that here we may do extra unneeded wakeups.
+ * NOTE: callers should call turnstile_clenup after
+ * dropping the interlock.
*/
-void
+boolean_t
lck_mtx_unlock_wakeup(
lck_mtx_t *lck,
thread_t holder)
thread_t thread = current_thread();
lck_mtx_t *mutex;
__kdebug_only uintptr_t trace_lck = unslide_for_kdebug(lck);
+ struct turnstile *ts;
+ kern_return_t did_wake;
if (lck->lck_mtx_tag != LCK_MTX_TAG_INDIRECT) {
mutex = lck;
trace_lck, (uintptr_t)thread_tid(thread), 0, 0, 0);
assert(mutex->lck_mtx_waiters > 0);
- assert(thread->was_promoted_on_wakeup == 0);
assert(thread->waiting_for_mutex == NULL);
- /*
- * The waiters count does not precisely match the number of threads on the waitqueue,
- * therefore we cannot assert that we actually wake up a thread here
- */
+ ts = turnstile_prepare((uintptr_t)mutex, NULL, TURNSTILE_NULL, TURNSTILE_KERNEL_MUTEX);
+
if (mutex->lck_mtx_waiters > 1) {
- thread_wakeup_one_with_pri(LCK_MTX_EVENT(lck), lck->lck_mtx_pri);
+ /* WAITQ_PROMOTE_ON_WAKE will call turnstile_update_inheritor on the wokenup thread */
+ did_wake = waitq_wakeup64_one(&ts->ts_waitq, CAST_EVENT64_T(LCK_MTX_EVENT(mutex)), THREAD_AWAKENED, WAITQ_PROMOTE_ON_WAKE);
} else {
- thread_wakeup_one(LCK_MTX_EVENT(lck));
+ did_wake = waitq_wakeup64_one(&ts->ts_waitq, CAST_EVENT64_T(LCK_MTX_EVENT(mutex)), THREAD_AWAKENED, WAITQ_ALL_PRIORITIES);
+ turnstile_update_inheritor(ts, NULL, TURNSTILE_IMMEDIATE_UPDATE);
}
+ assert(did_wake == KERN_SUCCESS);
- /* When mutex->lck_mtx_pri is set, it means means I as the owner have a promotion. */
- if (mutex->lck_mtx_pri) {
- spl_t s = splsched();
- thread_lock(thread);
-
- assert(thread->promotions > 0);
-
- assert_promotions_invariant(thread);
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_HELD);
+ turnstile_complete((uintptr_t)mutex, NULL, NULL, TURNSTILE_KERNEL_MUTEX);
- if (--thread->promotions == 0) {
- sched_thread_unpromote(thread, trace_lck);
- }
-
- assert_promotions_invariant(thread);
-
- thread_unlock(thread);
- splx(s);
- }
+ mutex->lck_mtx_waiters--;
KERNEL_DEBUG(MACHDBG_CODE(DBG_MACH_LOCKS, LCK_MTX_UNLCK_WAKEUP_CODE) | DBG_FUNC_END, 0, 0, 0, 0, 0);
-}
-
-/*
- * Callout from the waitqueue code from inside thread_wakeup_one_with_pri
- * At splsched, thread is pulled from waitq, still locked, not on runqueue yet
- *
- * We always make sure to set the promotion flag, even if the thread is already at this priority,
- * so that it doesn't go down.
- */
-void
-lck_mtx_wakeup_adjust_pri(thread_t thread, integer_t priority)
-{
- assert(priority <= MAXPRI_PROMOTE);
- assert(thread->waiting_for_mutex != NULL);
-
- __kdebug_only uintptr_t trace_lck = unslide_for_kdebug(thread->waiting_for_mutex);
-
- assert_promotions_invariant(thread);
-
- if (thread->was_promoted_on_wakeup) {
- /* Thread was previously promoted, but contended again */
- sched_thread_update_promotion_to_pri(thread, priority, trace_lck);
- return;
- }
-
- if (thread->promotions > 0 && priority <= thread->promotion_priority) {
- /*
- * Thread is already promoted to the right level, no need to do more
- * I can draft off of another promotion here, which is OK
- * because I know the thread will soon run acquire to get its own promotion
- */
- assert((thread->sched_flags & TH_SFLAG_PROMOTED) == TH_SFLAG_PROMOTED);
- return;
- }
-
- thread->was_promoted_on_wakeup = 1;
-
- if (thread->promotions++ == 0) {
- /* This is the first promotion for this thread */
- sched_thread_promote_to_pri(thread, priority, trace_lck);
- } else {
- /* Holder was previously promoted due to a different mutex, raise to match this one */
- sched_thread_update_promotion_to_pri(thread, priority, trace_lck);
- }
- assert_promotions_invariant(thread);
+ return mutex->lck_mtx_waiters > 0;
}
-
/*
* Routine: mutex_pause
*
}
/*
- * Atomic primitives, prototyped in kern/simple_lock.h
- * Noret versions are more efficient on some architectures
+ * sleep_with_inheritor and wakeup_with_inheritor KPI
+ *
+ * Functions that allow to sleep on an event and use turnstile to propagate the priority of the sleeping threads to
+ * the latest thread specified as inheritor.
+ *
+ * The inheritor management is delegated to the caller, the caller needs to store a thread identifier to provide to this functions to specified upon whom
+ * direct the push. The inheritor cannot run in user space while holding a push from an event. Therefore is the caller responsibility to call a
+ * wakeup_with_inheritor from inheritor before running in userspace or specify another inheritor before letting the old inheritor run in userspace.
+ *
+ * sleep_with_inheritor requires to hold a locking primitive while invoked, but wakeup_with_inheritor and change_sleep_inheritor don't require it.
+ *
+ * Turnstile requires a non blocking primitive as interlock to synchronize the turnstile data structure manipulation, threfore sleep_with_inheritor, change_sleep_inheritor and
+ * wakeup_with_inheritor will require the same interlock to manipulate turnstiles.
+ * If sleep_with_inheritor is associated with a locking primitive that can block (like lck_mtx_t or lck_rw_t), an handoff to a non blocking primitive is required before
+ * invoking any turnstile operation.
+ *
+ * All functions will save the turnstile associated with the event on the turnstile kernel hash table and will use the the turnstile kernel hash table bucket
+ * spinlock as the turnstile interlock. Because we do not want to hold interrupt disabled while holding the bucket interlock a new turnstile kernel hash table
+ * is instantiated for this KPI to manage the hash without interrupt disabled.
+ * Also:
+ * - all events on the system that hash on the same bucket will contend on the same spinlock.
+ * - every event will have a dedicated wait_queue.
+ *
+ * Different locking primitives can be associated with sleep_with_inheritor as long as the primitive_lock() and primitive_unlock() functions are provided to
+ * sleep_with_inheritor_turnstile to perform the handoff with the bucket spinlock.
*/
-uint32_t
-hw_atomic_add(volatile uint32_t *dest, uint32_t delt)
+kern_return_t
+wakeup_with_inheritor_and_turnstile_type(event_t event, turnstile_type_t type, wait_result_t result, bool wake_one, lck_wake_action_t action, thread_t *thread_wokenup)
{
- ALIGN_TEST(dest, uint32_t);
- return __c11_atomic_fetch_add(ATOMIC_CAST(uint32_t, dest), delt, memory_order_relaxed) + delt;
-}
+ uint32_t index;
+ struct turnstile *ts = NULL;
+ kern_return_t ret = KERN_NOT_WAITING;
+ int priority;
+ thread_t wokeup;
-uint32_t
-hw_atomic_sub(volatile uint32_t *dest, uint32_t delt)
-{
- ALIGN_TEST(dest, uint32_t);
- return __c11_atomic_fetch_sub(ATOMIC_CAST(uint32_t, dest), delt, memory_order_relaxed) - delt;
-}
+ /*
+ * the hash bucket spinlock is used as turnstile interlock
+ */
+ turnstile_hash_bucket_lock((uintptr_t)event, &index, type);
-uint32_t
-hw_atomic_or(volatile uint32_t *dest, uint32_t mask)
-{
- ALIGN_TEST(dest, uint32_t);
- return __c11_atomic_fetch_or(ATOMIC_CAST(uint32_t, dest), mask, memory_order_relaxed) | mask;
-}
+ ts = turnstile_prepare((uintptr_t)event, NULL, TURNSTILE_NULL, type);
+ if (wake_one) {
+ if (action == LCK_WAKE_DEFAULT) {
+ priority = WAITQ_PROMOTE_ON_WAKE;
+ } else {
+ assert(action == LCK_WAKE_DO_NOT_TRANSFER_PUSH);
+ priority = WAITQ_ALL_PRIORITIES;
+ }
+
+ /*
+ * WAITQ_PROMOTE_ON_WAKE will call turnstile_update_inheritor
+ * if it finds a thread
+ */
+ wokeup = waitq_wakeup64_identify(&ts->ts_waitq, CAST_EVENT64_T(event), result, priority);
+ if (wokeup != NULL) {
+ if (thread_wokenup != NULL) {
+ *thread_wokenup = wokeup;
+ } else {
+ thread_deallocate_safe(wokeup);
+ }
+ ret = KERN_SUCCESS;
+ if (action == LCK_WAKE_DO_NOT_TRANSFER_PUSH) {
+ goto complete;
+ }
+ } else {
+ if (thread_wokenup != NULL) {
+ *thread_wokenup = NULL;
+ }
+ turnstile_update_inheritor(ts, TURNSTILE_INHERITOR_NULL, TURNSTILE_IMMEDIATE_UPDATE);
+ ret = KERN_NOT_WAITING;
+ }
+ } else {
+ ret = waitq_wakeup64_all(&ts->ts_waitq, CAST_EVENT64_T(event), result, WAITQ_ALL_PRIORITIES);
+ turnstile_update_inheritor(ts, TURNSTILE_INHERITOR_NULL, TURNSTILE_IMMEDIATE_UPDATE);
+ }
+
+ /*
+ * turnstile_update_inheritor_complete could be called while holding the interlock.
+ * In this case the new inheritor or is null, or is a thread that is just been woken up
+ * and have not blocked because it is racing with the same interlock used here
+ * after the wait.
+ * So there is no chain to update for the new inheritor.
+ *
+ * However unless the current thread is the old inheritor,
+ * old inheritor can be blocked and requires a chain update.
+ *
+ * The chain should be short because kernel turnstiles cannot have user turnstiles
+ * chained after them.
+ *
+ * We can anyway optimize this by asking turnstile to tell us
+ * if old inheritor needs an update and drop the lock
+ * just in that case.
+ */
+ turnstile_hash_bucket_unlock((uintptr_t)NULL, &index, type, 0);
+
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
+
+ turnstile_hash_bucket_lock((uintptr_t)NULL, &index, type);
+
+complete:
+ turnstile_complete((uintptr_t)event, NULL, NULL, type);
+
+ turnstile_hash_bucket_unlock((uintptr_t)NULL, &index, type, 0);
+
+ turnstile_cleanup();
+
+ return ret;
+}
+
+static wait_result_t
+sleep_with_inheritor_and_turnstile_type(event_t event,
+ thread_t inheritor,
+ wait_interrupt_t interruptible,
+ uint64_t deadline,
+ turnstile_type_t type,
+ void (^primitive_lock)(void),
+ void (^primitive_unlock)(void))
+{
+ wait_result_t ret;
+ uint32_t index;
+ struct turnstile *ts = NULL;
+
+ /*
+ * the hash bucket spinlock is used as turnstile interlock,
+ * lock it before releasing the primitive lock
+ */
+ turnstile_hash_bucket_lock((uintptr_t)event, &index, type);
+
+ primitive_unlock();
+
+ ts = turnstile_prepare((uintptr_t)event, NULL, TURNSTILE_NULL, type);
+
+ thread_set_pending_block_hint(current_thread(), kThreadWaitSleepWithInheritor);
+ /*
+ * We need TURNSTILE_DELAYED_UPDATE because we will call
+ * waitq_assert_wait64 after.
+ */
+ turnstile_update_inheritor(ts, inheritor, (TURNSTILE_DELAYED_UPDATE | TURNSTILE_INHERITOR_THREAD));
+
+ ret = waitq_assert_wait64(&ts->ts_waitq, CAST_EVENT64_T(event), interruptible, deadline);
+
+ turnstile_hash_bucket_unlock((uintptr_t)NULL, &index, type, 0);
+
+ /*
+ * Update new and old inheritor chains outside the interlock;
+ */
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
+
+ if (ret == THREAD_WAITING) {
+ ret = thread_block(THREAD_CONTINUE_NULL);
+ }
+
+ turnstile_hash_bucket_lock((uintptr_t)NULL, &index, type);
+
+ turnstile_complete((uintptr_t)event, NULL, NULL, type);
+
+ turnstile_hash_bucket_unlock((uintptr_t)NULL, &index, type, 0);
+
+ turnstile_cleanup();
+
+ primitive_lock();
+
+ return ret;
+}
+
+kern_return_t
+change_sleep_inheritor_and_turnstile_type(event_t event,
+ thread_t inheritor,
+ turnstile_type_t type)
+{
+ uint32_t index;
+ struct turnstile *ts = NULL;
+ kern_return_t ret = KERN_SUCCESS;
+ /*
+ * the hash bucket spinlock is used as turnstile interlock
+ */
+ turnstile_hash_bucket_lock((uintptr_t)event, &index, type);
+
+ ts = turnstile_prepare((uintptr_t)event, NULL, TURNSTILE_NULL, type);
+
+ if (!turnstile_has_waiters(ts)) {
+ ret = KERN_NOT_WAITING;
+ }
+
+ /*
+ * We will not call an assert_wait later so use TURNSTILE_IMMEDIATE_UPDATE
+ */
+ turnstile_update_inheritor(ts, inheritor, (TURNSTILE_IMMEDIATE_UPDATE | TURNSTILE_INHERITOR_THREAD));
+
+ turnstile_hash_bucket_unlock((uintptr_t)NULL, &index, type, 0);
+
+ /*
+ * update the chains outside the interlock
+ */
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
+
+ turnstile_hash_bucket_lock((uintptr_t)NULL, &index, type);
+
+ turnstile_complete((uintptr_t)event, NULL, NULL, type);
+
+ turnstile_hash_bucket_unlock((uintptr_t)NULL, &index, type, 0);
+
+ turnstile_cleanup();
+
+ return ret;
+}
+
+typedef void (^void_block_void)(void);
+
+/*
+ * sleep_with_inheritor functions with lck_mtx_t as locking primitive.
+ */
+
+wait_result_t
+lck_mtx_sleep_with_inheritor_and_turnstile_type(lck_mtx_t *lock, lck_sleep_action_t lck_sleep_action, event_t event, thread_t inheritor, wait_interrupt_t interruptible, uint64_t deadline, turnstile_type_t type)
+{
+ LCK_MTX_ASSERT(lock, LCK_MTX_ASSERT_OWNED);
+
+ if (lck_sleep_action & LCK_SLEEP_UNLOCK) {
+ return sleep_with_inheritor_and_turnstile_type(event,
+ inheritor,
+ interruptible,
+ deadline,
+ type,
+ ^{;},
+ ^{lck_mtx_unlock(lock);});
+ } else if (lck_sleep_action & LCK_SLEEP_SPIN) {
+ return sleep_with_inheritor_and_turnstile_type(event,
+ inheritor,
+ interruptible,
+ deadline,
+ type,
+ ^{lck_mtx_lock_spin(lock);},
+ ^{lck_mtx_unlock(lock);});
+ } else if (lck_sleep_action & LCK_SLEEP_SPIN_ALWAYS) {
+ return sleep_with_inheritor_and_turnstile_type(event,
+ inheritor,
+ interruptible,
+ deadline,
+ type,
+ ^{lck_mtx_lock_spin_always(lock);},
+ ^{lck_mtx_unlock(lock);});
+ } else {
+ return sleep_with_inheritor_and_turnstile_type(event,
+ inheritor,
+ interruptible,
+ deadline,
+ type,
+ ^{lck_mtx_lock(lock);},
+ ^{lck_mtx_unlock(lock);});
+ }
+}
+
+/*
+ * Name: lck_spin_sleep_with_inheritor
+ *
+ * Description: deschedule the current thread and wait on the waitq associated with event to be woken up.
+ * While waiting, the sched priority of the waiting thread will contribute to the push of the event that will
+ * be directed to the inheritor specified.
+ * An interruptible mode and deadline can be specified to return earlier from the wait.
+ *
+ * Args:
+ * Arg1: lck_spin_t lock used to protect the sleep. The lock will be dropped while sleeping and reaquired before returning according to the sleep action specified.
+ * Arg2: sleep action. LCK_SLEEP_DEFAULT, LCK_SLEEP_UNLOCK.
+ * Arg3: event to wait on.
+ * Arg4: thread to propagate the event push to.
+ * Arg5: interruptible flag for wait.
+ * Arg6: deadline for wait.
+ *
+ * Conditions: Lock must be held. Returns with the lock held according to the sleep action specified.
+ * Lock will be dropped while waiting.
+ * The inheritor specified cannot run in user space until another inheritor is specified for the event or a
+ * wakeup for the event is called.
+ *
+ * Returns: result of the wait.
+ */
+wait_result_t
+lck_spin_sleep_with_inheritor(
+ lck_spin_t *lock,
+ lck_sleep_action_t lck_sleep_action,
+ event_t event,
+ thread_t inheritor,
+ wait_interrupt_t interruptible,
+ uint64_t deadline)
+{
+ if (lck_sleep_action & LCK_SLEEP_UNLOCK) {
+ return sleep_with_inheritor_and_turnstile_type(event, inheritor,
+ interruptible, deadline, TURNSTILE_SLEEP_INHERITOR,
+ ^{}, ^{ lck_spin_unlock(lock); });
+ } else {
+ return sleep_with_inheritor_and_turnstile_type(event, inheritor,
+ interruptible, deadline, TURNSTILE_SLEEP_INHERITOR,
+ ^{ lck_spin_lock(lock); }, ^{ lck_spin_unlock(lock); });
+ }
+}
+
+/*
+ * Name: lck_mtx_sleep_with_inheritor
+ *
+ * Description: deschedule the current thread and wait on the waitq associated with event to be woken up.
+ * While waiting, the sched priority of the waiting thread will contribute to the push of the event that will
+ * be directed to the inheritor specified.
+ * An interruptible mode and deadline can be specified to return earlier from the wait.
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the sleep. The lock will be dropped while sleeping and reaquired before returning according to the sleep action specified.
+ * Arg2: sleep action. LCK_SLEEP_DEFAULT, LCK_SLEEP_UNLOCK, LCK_SLEEP_SPIN, LCK_SLEEP_SPIN_ALWAYS.
+ * Arg3: event to wait on.
+ * Arg4: thread to propagate the event push to.
+ * Arg5: interruptible flag for wait.
+ * Arg6: deadline for wait.
+ *
+ * Conditions: Lock must be held. Returns with the lock held according to the sleep action specified.
+ * Lock will be dropped while waiting.
+ * The inheritor specified cannot run in user space until another inheritor is specified for the event or a
+ * wakeup for the event is called.
+ *
+ * Returns: result of the wait.
+ */
+wait_result_t
+lck_mtx_sleep_with_inheritor(lck_mtx_t *lock, lck_sleep_action_t lck_sleep_action, event_t event, thread_t inheritor, wait_interrupt_t interruptible, uint64_t deadline)
+{
+ return lck_mtx_sleep_with_inheritor_and_turnstile_type(lock, lck_sleep_action, event, inheritor, interruptible, deadline, TURNSTILE_SLEEP_INHERITOR);
+}
+
+/*
+ * sleep_with_inheritor functions with lck_rw_t as locking primitive.
+ */
+
+wait_result_t
+lck_rw_sleep_with_inheritor_and_turnstile_type(lck_rw_t *lock, lck_sleep_action_t lck_sleep_action, event_t event, thread_t inheritor, wait_interrupt_t interruptible, uint64_t deadline, turnstile_type_t type)
+{
+ __block lck_rw_type_t lck_rw_type = LCK_RW_TYPE_EXCLUSIVE;
+
+ LCK_RW_ASSERT(lock, LCK_RW_ASSERT_HELD);
+
+ if (lck_sleep_action & LCK_SLEEP_UNLOCK) {
+ return sleep_with_inheritor_and_turnstile_type(event,
+ inheritor,
+ interruptible,
+ deadline,
+ type,
+ ^{;},
+ ^{lck_rw_type = lck_rw_done(lock);});
+ } else if (!(lck_sleep_action & (LCK_SLEEP_SHARED | LCK_SLEEP_EXCLUSIVE))) {
+ return sleep_with_inheritor_and_turnstile_type(event,
+ inheritor,
+ interruptible,
+ deadline,
+ type,
+ ^{lck_rw_lock(lock, lck_rw_type);},
+ ^{lck_rw_type = lck_rw_done(lock);});
+ } else if (lck_sleep_action & LCK_SLEEP_EXCLUSIVE) {
+ return sleep_with_inheritor_and_turnstile_type(event,
+ inheritor,
+ interruptible,
+ deadline,
+ type,
+ ^{lck_rw_lock_exclusive(lock);},
+ ^{lck_rw_type = lck_rw_done(lock);});
+ } else {
+ return sleep_with_inheritor_and_turnstile_type(event,
+ inheritor,
+ interruptible,
+ deadline,
+ type,
+ ^{lck_rw_lock_shared(lock);},
+ ^{lck_rw_type = lck_rw_done(lock);});
+ }
+}
+
+/*
+ * Name: lck_rw_sleep_with_inheritor
+ *
+ * Description: deschedule the current thread and wait on the waitq associated with event to be woken up.
+ * While waiting, the sched priority of the waiting thread will contribute to the push of the event that will
+ * be directed to the inheritor specified.
+ * An interruptible mode and deadline can be specified to return earlier from the wait.
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the sleep. The lock will be dropped while sleeping and reaquired before returning according to the sleep action specified.
+ * Arg2: sleep action. LCK_SLEEP_DEFAULT, LCK_SLEEP_SHARED, LCK_SLEEP_EXCLUSIVE.
+ * Arg3: event to wait on.
+ * Arg4: thread to propagate the event push to.
+ * Arg5: interruptible flag for wait.
+ * Arg6: deadline for wait.
+ *
+ * Conditions: Lock must be held. Returns with the lock held according to the sleep action specified.
+ * Lock will be dropped while waiting.
+ * The inheritor specified cannot run in user space until another inheritor is specified for the event or a
+ * wakeup for the event is called.
+ *
+ * Returns: result of the wait.
+ */
+wait_result_t
+lck_rw_sleep_with_inheritor(lck_rw_t *lock, lck_sleep_action_t lck_sleep_action, event_t event, thread_t inheritor, wait_interrupt_t interruptible, uint64_t deadline)
+{
+ return lck_rw_sleep_with_inheritor_and_turnstile_type(lock, lck_sleep_action, event, inheritor, interruptible, deadline, TURNSTILE_SLEEP_INHERITOR);
+}
+
+/*
+ * wakeup_with_inheritor functions are independent from the locking primitive.
+ */
+
+/*
+ * Name: wakeup_one_with_inheritor
+ *
+ * Description: wake up one waiter for event if any. The thread woken up will be the one with the higher sched priority waiting on event.
+ * The push for the event will be transferred from the last inheritor to the woken up thread if LCK_WAKE_DEFAULT is specified.
+ * If LCK_WAKE_DO_NOT_TRANSFER_PUSH is specified the push will not be transferred.
+ *
+ * Args:
+ * Arg1: event to wake from.
+ * Arg2: wait result to pass to the woken up thread.
+ * Arg3: wake flag. LCK_WAKE_DEFAULT or LCK_WAKE_DO_NOT_TRANSFER_PUSH.
+ * Arg4: pointer for storing the thread wokenup.
+ *
+ * Returns: KERN_NOT_WAITING if no threads were waiting, KERN_SUCCESS otherwise.
+ *
+ * Conditions: The new inheritor wokenup cannot run in user space until another inheritor is specified for the event or a
+ * wakeup for the event is called.
+ * A reference for the wokenup thread is acquired.
+ * NOTE: this cannot be called from interrupt context.
+ */
+kern_return_t
+wakeup_one_with_inheritor(event_t event, wait_result_t result, lck_wake_action_t action, thread_t *thread_wokenup)
+{
+ return wakeup_with_inheritor_and_turnstile_type(event,
+ TURNSTILE_SLEEP_INHERITOR,
+ result,
+ TRUE,
+ action,
+ thread_wokenup);
+}
+
+/*
+ * Name: wakeup_all_with_inheritor
+ *
+ * Description: wake up all waiters waiting for event. The old inheritor will lose the push.
+ *
+ * Args:
+ * Arg1: event to wake from.
+ * Arg2: wait result to pass to the woken up threads.
+ *
+ * Returns: KERN_NOT_WAITING if no threads were waiting, KERN_SUCCESS otherwise.
+ *
+ * Conditions: NOTE: this cannot be called from interrupt context.
+ */
+kern_return_t
+wakeup_all_with_inheritor(event_t event, wait_result_t result)
+{
+ return wakeup_with_inheritor_and_turnstile_type(event,
+ TURNSTILE_SLEEP_INHERITOR,
+ result,
+ FALSE,
+ 0,
+ NULL);
+}
+
+/*
+ * change_sleep_inheritor is independent from the locking primitive.
+ */
+
+/*
+ * Name: change_sleep_inheritor
+ *
+ * Description: Redirect the push of the waiting threads of event to the new inheritor specified.
+ *
+ * Args:
+ * Arg1: event to redirect the push.
+ * Arg2: new inheritor for event.
+ *
+ * Returns: KERN_NOT_WAITING if no threads were waiting, KERN_SUCCESS otherwise.
+ *
+ * Conditions: In case of success, the new inheritor cannot run in user space until another inheritor is specified for the event or a
+ * wakeup for the event is called.
+ * NOTE: this cannot be called from interrupt context.
+ */
+kern_return_t
+change_sleep_inheritor(event_t event, thread_t inheritor)
+{
+ return change_sleep_inheritor_and_turnstile_type(event,
+ inheritor,
+ TURNSTILE_SLEEP_INHERITOR);
+}
+
+void
+kdp_sleep_with_inheritor_find_owner(struct waitq * waitq, __unused event64_t event, thread_waitinfo_t * waitinfo)
+{
+ assert(waitinfo->wait_type == kThreadWaitSleepWithInheritor);
+ assert(waitq_is_turnstile_queue(waitq));
+ waitinfo->owner = 0;
+ waitinfo->context = 0;
+
+ if (waitq_held(waitq)) {
+ return;
+ }
+
+ struct turnstile *turnstile = waitq_to_turnstile(waitq);
+ assert(turnstile->ts_inheritor_flags & TURNSTILE_INHERITOR_THREAD);
+ waitinfo->owner = thread_tid(turnstile->ts_inheritor);
+}
+
+typedef void (*void_func_void)(void);
+
+static kern_return_t
+gate_try_close(gate_t *gate)
+{
+ uintptr_t state;
+ thread_t holder;
+ kern_return_t ret;
+ __assert_only bool waiters;
+ thread_t thread = current_thread();
+
+ if (os_atomic_cmpxchg(&gate->gate_data, 0, GATE_THREAD_TO_STATE(thread), acquire)) {
+ return KERN_SUCCESS;
+ }
+
+ gate_ilock(gate);
+ state = ordered_load_gate(gate);
+ holder = GATE_STATE_TO_THREAD(state);
+
+ if (holder == NULL) {
+ waiters = gate_has_waiters(state);
+ assert(waiters == FALSE);
+
+ state = GATE_THREAD_TO_STATE(current_thread());
+ state |= GATE_ILOCK;
+ ordered_store_gate(gate, state);
+ ret = KERN_SUCCESS;
+ } else {
+ if (holder == current_thread()) {
+ panic("Trying to close a gate already owned by current thread %p", current_thread());
+ }
+ ret = KERN_FAILURE;
+ }
+
+ gate_iunlock(gate);
+ return ret;
+}
+
+static void
+gate_close(gate_t* gate)
+{
+ uintptr_t state;
+ thread_t holder;
+ __assert_only bool waiters;
+ thread_t thread = current_thread();
+
+ if (os_atomic_cmpxchg(&gate->gate_data, 0, GATE_THREAD_TO_STATE(thread), acquire)) {
+ return;
+ }
+
+ gate_ilock(gate);
+ state = ordered_load_gate(gate);
+ holder = GATE_STATE_TO_THREAD(state);
+
+ if (holder != NULL) {
+ panic("Closing a gate already owned by %p from current thread %p", holder, current_thread());
+ }
+
+ waiters = gate_has_waiters(state);
+ assert(waiters == FALSE);
+
+ state = GATE_THREAD_TO_STATE(thread);
+ state |= GATE_ILOCK;
+ ordered_store_gate(gate, state);
+
+ gate_iunlock(gate);
+}
+
+static void
+gate_open_turnstile(gate_t *gate)
+{
+ struct turnstile *ts = NULL;
+
+ ts = turnstile_prepare((uintptr_t)gate, &gate->turnstile, TURNSTILE_NULL, TURNSTILE_KERNEL_MUTEX);
+ waitq_wakeup64_all(&ts->ts_waitq, CAST_EVENT64_T(GATE_EVENT(gate)), THREAD_AWAKENED, WAITQ_ALL_PRIORITIES);
+ turnstile_update_inheritor(ts, TURNSTILE_INHERITOR_NULL, TURNSTILE_IMMEDIATE_UPDATE);
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_HELD);
+ turnstile_complete((uintptr_t)gate, &gate->turnstile, NULL, TURNSTILE_KERNEL_MUTEX);
+ /*
+ * We can do the cleanup while holding the interlock.
+ * It is ok because:
+ * 1. current_thread is the previous inheritor and it is running
+ * 2. new inheritor is NULL.
+ * => No chain of turnstiles needs to be updated.
+ */
+ turnstile_cleanup();
+}
+
+static void
+gate_open(gate_t *gate)
+{
+ uintptr_t state;
+ thread_t holder;
+ bool waiters;
+ thread_t thread = current_thread();
+
+ if (os_atomic_cmpxchg(&gate->gate_data, GATE_THREAD_TO_STATE(thread), 0, release)) {
+ return;
+ }
+
+ gate_ilock(gate);
+ state = ordered_load_gate(gate);
+ holder = GATE_STATE_TO_THREAD(state);
+ waiters = gate_has_waiters(state);
+
+ if (holder != thread) {
+ panic("Opening gate owned by %p from current thread %p", holder, thread);
+ }
+
+ if (waiters) {
+ gate_open_turnstile(gate);
+ }
+
+ state = GATE_ILOCK;
+ ordered_store_gate(gate, state);
+
+ gate_iunlock(gate);
+}
+
+static kern_return_t
+gate_handoff_turnstile(gate_t *gate,
+ int flags,
+ thread_t *thread_woken_up,
+ bool *waiters)
+{
+ struct turnstile *ts = NULL;
+ kern_return_t ret = KERN_FAILURE;
+ thread_t hp_thread;
+
+ ts = turnstile_prepare((uintptr_t)gate, &gate->turnstile, TURNSTILE_NULL, TURNSTILE_KERNEL_MUTEX);
+ /*
+ * Wake up the higest priority thread waiting on the gate
+ */
+ hp_thread = waitq_wakeup64_identify(&ts->ts_waitq, CAST_EVENT64_T(GATE_EVENT(gate)), THREAD_AWAKENED, WAITQ_PROMOTE_ON_WAKE);
+
+ if (hp_thread != NULL) {
+ /*
+ * In this case waitq_wakeup64_identify has called turnstile_update_inheritor for us
+ */
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_HELD);
+ *thread_woken_up = hp_thread;
+ *waiters = turnstile_has_waiters(ts);
+ /*
+ * Note: hp_thread is the new holder and the new inheritor.
+ * In case there are no more waiters, it doesn't need to be the inheritor
+ * and it shouldn't be it by the time it finishes the wait, so that its next open or
+ * handoff can go through the fast path.
+ * We could set the inheritor to NULL here, or the new holder itself can set it
+ * on its way back from the sleep. In the latter case there are more chanses that
+ * new waiters will come by, avoiding to do the opearation at all.
+ */
+ ret = KERN_SUCCESS;
+ } else {
+ /*
+ * waiters can have been woken up by an interrupt and still not
+ * have updated gate->waiters, so we couldn't find them on the waitq.
+ * Update the inheritor to NULL here, so that the current thread can return to userspace
+ * indipendently from when the interrupted waiters will finish the wait.
+ */
+ if (flags == GATE_HANDOFF_OPEN_IF_NO_WAITERS) {
+ turnstile_update_inheritor(ts, TURNSTILE_INHERITOR_NULL, TURNSTILE_IMMEDIATE_UPDATE);
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_HELD);
+ }
+ // there are no waiters.
+ ret = KERN_NOT_WAITING;
+ }
+
+ turnstile_complete((uintptr_t)gate, &gate->turnstile, NULL, TURNSTILE_KERNEL_MUTEX);
+
+ /*
+ * We can do the cleanup while holding the interlock.
+ * It is ok because:
+ * 1. current_thread is the previous inheritor and it is running
+ * 2. new inheritor is NULL or it is a just wokenup thread that will race acquiring the lock
+ * of the gate before trying to sleep.
+ * => No chain of turnstiles needs to be updated.
+ */
+ turnstile_cleanup();
+
+ return ret;
+}
+
+static kern_return_t
+gate_handoff(gate_t *gate,
+ int flags)
+{
+ kern_return_t ret;
+ thread_t new_holder = NULL;
+ uintptr_t state;
+ thread_t holder;
+ bool waiters;
+ thread_t thread = current_thread();
+
+ assert(flags == GATE_HANDOFF_OPEN_IF_NO_WAITERS || flags == GATE_HANDOFF_DEFAULT);
+
+ if (flags == GATE_HANDOFF_OPEN_IF_NO_WAITERS) {
+ if (os_atomic_cmpxchg(&gate->gate_data, GATE_THREAD_TO_STATE(thread), 0, release)) {
+ //gate opened but there were no waiters, so return KERN_NOT_WAITING.
+ return KERN_NOT_WAITING;
+ }
+ }
+
+ gate_ilock(gate);
+ state = ordered_load_gate(gate);
+ holder = GATE_STATE_TO_THREAD(state);
+ waiters = gate_has_waiters(state);
+
+ if (holder != current_thread()) {
+ panic("Handing off gate owned by %p from current thread %p", holder, current_thread());
+ }
+
+ if (waiters) {
+ ret = gate_handoff_turnstile(gate, flags, &new_holder, &waiters);
+ if (ret == KERN_SUCCESS) {
+ state = GATE_THREAD_TO_STATE(new_holder);
+ if (waiters) {
+ state |= GATE_WAITERS;
+ }
+ } else {
+ if (flags == GATE_HANDOFF_OPEN_IF_NO_WAITERS) {
+ state = 0;
+ }
+ }
+ } else {
+ if (flags == GATE_HANDOFF_OPEN_IF_NO_WAITERS) {
+ state = 0;
+ }
+ ret = KERN_NOT_WAITING;
+ }
+ state |= GATE_ILOCK;
+ ordered_store_gate(gate, state);
+
+ gate_iunlock(gate);
+
+ if (new_holder) {
+ thread_deallocate(new_holder);
+ }
+ return ret;
+}
+
+static void_func_void
+gate_steal_turnstile(gate_t *gate,
+ thread_t new_inheritor)
+{
+ struct turnstile *ts = NULL;
+
+ ts = turnstile_prepare((uintptr_t)gate, &gate->turnstile, TURNSTILE_NULL, TURNSTILE_KERNEL_MUTEX);
+
+ turnstile_update_inheritor(ts, new_inheritor, (TURNSTILE_IMMEDIATE_UPDATE | TURNSTILE_INHERITOR_THREAD));
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_HELD);
+ turnstile_complete((uintptr_t)gate, &gate->turnstile, NULL, TURNSTILE_KERNEL_MUTEX);
+
+ /*
+ * turnstile_cleanup might need to update the chain of the old holder.
+ * This operation should happen without the turnstile interlock held.
+ */
+ return turnstile_cleanup;
+}
+
+static void
+gate_steal(gate_t *gate)
+{
+ uintptr_t state;
+ thread_t holder;
+ thread_t thread = current_thread();
+ bool waiters;
+
+ void_func_void func_after_interlock_unlock;
+
+ gate_ilock(gate);
+ state = ordered_load_gate(gate);
+ holder = GATE_STATE_TO_THREAD(state);
+ waiters = gate_has_waiters(state);
+
+ assert(holder != NULL);
+ state = GATE_THREAD_TO_STATE(thread) | GATE_ILOCK;
+ if (waiters) {
+ state |= GATE_WAITERS;
+ ordered_store_gate(gate, state);
+ func_after_interlock_unlock = gate_steal_turnstile(gate, thread);
+ gate_iunlock(gate);
+
+ func_after_interlock_unlock();
+ } else {
+ ordered_store_gate(gate, state);
+ gate_iunlock(gate);
+ }
+}
+
+static void_func_void
+gate_wait_turnstile(gate_t *gate,
+ wait_interrupt_t interruptible,
+ uint64_t deadline,
+ thread_t holder,
+ wait_result_t* wait,
+ bool* waiters)
+{
+ struct turnstile *ts;
+ uintptr_t state;
+
+ ts = turnstile_prepare((uintptr_t)gate, &gate->turnstile, TURNSTILE_NULL, TURNSTILE_KERNEL_MUTEX);
+
+ turnstile_update_inheritor(ts, holder, (TURNSTILE_DELAYED_UPDATE | TURNSTILE_INHERITOR_THREAD));
+ waitq_assert_wait64(&ts->ts_waitq, CAST_EVENT64_T(GATE_EVENT(gate)), interruptible, deadline);
+
+ gate_iunlock(gate);
+
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
+
+ *wait = thread_block(THREAD_CONTINUE_NULL);
+
+ gate_ilock(gate);
+
+ *waiters = turnstile_has_waiters(ts);
+
+ if (!*waiters) {
+ /*
+ * We want to enable the fast path as soon as we see that there are no more waiters.
+ * On the fast path the holder will not do any turnstile operations.
+ * Set the inheritor as NULL here.
+ *
+ * NOTE: if it was an open operation that woke this thread up, the inheritor has
+ * already been set to NULL.
+ */
+ state = ordered_load_gate(gate);
+ holder = GATE_STATE_TO_THREAD(state);
+ if (holder &&
+ ((*wait != THREAD_AWAKENED) || // thread interrupted or timedout
+ holder == current_thread())) { // thread was woken up and it is the new holder
+ turnstile_update_inheritor(ts, TURNSTILE_INHERITOR_NULL, TURNSTILE_IMMEDIATE_UPDATE);
+ turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
+ }
+ }
+
+ turnstile_complete((uintptr_t)gate, &gate->turnstile, NULL, TURNSTILE_KERNEL_MUTEX);
+
+ /*
+ * turnstile_cleanup might need to update the chain of the old holder.
+ * This operation should happen without the turnstile primitive interlock held.
+ */
+ return turnstile_cleanup;
+}
+
+static gate_wait_result_t
+gate_wait(gate_t* gate,
+ wait_interrupt_t interruptible,
+ uint64_t deadline,
+ void (^primitive_unlock)(void),
+ void (^primitive_lock)(void))
+{
+ gate_wait_result_t ret;
+ void_func_void func_after_interlock_unlock;
+ wait_result_t wait_result;
+ uintptr_t state;
+ thread_t holder;
+ bool waiters;
+
+
+ gate_ilock(gate);
+ state = ordered_load_gate(gate);
+ holder = GATE_STATE_TO_THREAD(state);
+
+ if (holder == NULL) {
+ panic("Trying to wait on open gate thread %p gate %p", current_thread(), gate);
+ }
+
+ state |= GATE_WAITERS;
+ ordered_store_gate(gate, state);
+
+ /*
+ * Release the primitive lock before any
+ * turnstile operation. Turnstile
+ * does not support a blocking primitive as
+ * interlock.
+ *
+ * In this way, concurrent threads will be
+ * able to acquire the primitive lock
+ * but still will wait for me through the
+ * gate interlock.
+ */
+ primitive_unlock();
+
+ func_after_interlock_unlock = gate_wait_turnstile( gate,
+ interruptible,
+ deadline,
+ holder,
+ &wait_result,
+ &waiters);
+
+ state = ordered_load_gate(gate);
+ holder = GATE_STATE_TO_THREAD(state);
+
+ switch (wait_result) {
+ case THREAD_INTERRUPTED:
+ case THREAD_TIMED_OUT:
+ assert(holder != current_thread());
+
+ if (waiters) {
+ state |= GATE_WAITERS;
+ } else {
+ state &= ~GATE_WAITERS;
+ }
+ ordered_store_gate(gate, state);
+
+ if (wait_result == THREAD_INTERRUPTED) {
+ ret = GATE_INTERRUPTED;
+ } else {
+ ret = GATE_TIMED_OUT;
+ }
+ break;
+ default:
+ /*
+ * Note it is possible that even if the gate was handed off to
+ * me, someone called gate_steal() before I woke up.
+ *
+ * As well as it is possible that the gate was opened, but someone
+ * closed it while I was waking up.
+ *
+ * In both cases we return GATE_OPENED, as the gate was opened to me
+ * at one point, it is the caller responsibility to check again if
+ * the gate is open.
+ */
+ if (holder == current_thread()) {
+ ret = GATE_HANDOFF;
+ } else {
+ ret = GATE_OPENED;
+ }
+ break;
+ }
+
+ gate_iunlock(gate);
+
+ /*
+ * turnstile func that needs to be executed without
+ * holding the primitive interlock
+ */
+ func_after_interlock_unlock();
+
+ primitive_lock();
+
+ return ret;
+}
+static void
+gate_assert(gate_t *gate, int flags)
+{
+ uintptr_t state;
+ thread_t holder;
+
+ gate_ilock(gate);
+ state = ordered_load_gate(gate);
+ holder = GATE_STATE_TO_THREAD(state);
+
+ switch (flags) {
+ case GATE_ASSERT_CLOSED:
+ assert(holder != NULL);
+ break;
+ case GATE_ASSERT_OPEN:
+ assert(holder == NULL);
+ break;
+ case GATE_ASSERT_HELD:
+ assert(holder == current_thread());
+ break;
+ default:
+ panic("invalid %s flag %d", __func__, flags);
+ }
+
+ gate_iunlock(gate);
+}
+
+static void
+gate_init(gate_t *gate)
+{
+ gate->gate_data = 0;
+ gate->turnstile = NULL;
+}
+
+static void
+gate_destroy(__assert_only gate_t *gate)
+{
+ assert(gate->gate_data == 0);
+ assert(gate->turnstile == NULL);
+}
+
+/*
+ * Name: lck_rw_gate_init
+ *
+ * Description: initializes a variable declared with decl_lck_rw_gate_data.
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_rw_gate_data.
+ */
+void
+lck_rw_gate_init(lck_rw_t *lock, gate_t *gate)
+{
+ (void) lock;
+ gate_init(gate);
+}
+
+/*
+ * Name: lck_rw_gate_destroy
+ *
+ * Description: destroys a variable previously initialized.
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_rw_gate_data.
+ */
+void
+lck_rw_gate_destroy(lck_rw_t *lock, gate_t *gate)
+{
+ (void) lock;
+ gate_destroy(gate);
+}
+
+/*
+ * Name: lck_rw_gate_try_close
+ *
+ * Description: Tries to close the gate.
+ * In case of success the current thread will be set as
+ * the holder of the gate.
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_rw_gate_data.
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ *
+ * Returns:
+ * KERN_SUCCESS in case the gate was successfully closed. The current thread is the new holder
+ * of the gate.
+ * A matching lck_rw_gate_open() or lck_rw_gate_handoff() needs to be called later on
+ * to wake up possible waiters on the gate before returning to userspace.
+ * If the intent is to conditionally probe the gate before waiting, the lock must not be dropped
+ * between the calls to lck_rw_gate_try_close() and lck_rw_gate_wait().
+ *
+ * KERN_FAILURE in case the gate was already closed. Will panic if the current thread was already the holder of the gate.
+ * lck_rw_gate_wait() should be called instead if the intent is to unconditionally wait on this gate.
+ * The calls to lck_rw_gate_try_close() and lck_rw_gate_wait() should
+ * be done without dropping the lock that is protecting the gate in between.
+ */
+int
+lck_rw_gate_try_close(__assert_only lck_rw_t *lock, gate_t *gate)
+{
+ LCK_RW_ASSERT(lock, LCK_RW_ASSERT_HELD);
+
+ return gate_try_close(gate);
+}
+
+/*
+ * Name: lck_rw_gate_close
+ *
+ * Description: Closes the gate. The current thread will be set as
+ * the holder of the gate. Will panic if the gate is already closed.
+ * A matching lck_rw_gate_open() or lck_rw_gate_handoff() needs to be called later on
+ * to wake up possible waiters on the gate before returning to userspace.
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_rw_gate_data.
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ * The gate must be open.
+ *
+ */
+void
+lck_rw_gate_close(__assert_only lck_rw_t *lock, gate_t *gate)
+{
+ LCK_RW_ASSERT(lock, LCK_RW_ASSERT_HELD);
+
+ return gate_close(gate);
+}
+
+/*
+ * Name: lck_rw_gate_open
+ *
+ * Description: Opens the gate and wakes up possible waiters.
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_rw_gate_data.
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ * The current thread must be the holder of the gate.
+ *
+ */
+void
+lck_rw_gate_open(__assert_only lck_rw_t *lock, gate_t *gate)
+{
+ LCK_RW_ASSERT(lock, LCK_RW_ASSERT_HELD);
+
+ gate_open(gate);
+}
+
+/*
+ * Name: lck_rw_gate_handoff
+ *
+ * Description: Tries to transfer the ownership of the gate. The waiter with highest sched
+ * priority will be selected as the new holder of the gate, and woken up,
+ * with the gate remaining in the closed state throughout.
+ * If no waiters are present, the gate will be kept closed and KERN_NOT_WAITING
+ * will be returned.
+ * GATE_HANDOFF_OPEN_IF_NO_WAITERS flag can be used to specify if the gate should be opened in
+ * case no waiters were found.
+ *
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_rw_gate_data.
+ * Arg3: flags - GATE_HANDOFF_DEFAULT or GATE_HANDOFF_OPEN_IF_NO_WAITERS
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ * The current thread must be the holder of the gate.
+ *
+ * Returns:
+ * KERN_SUCCESS in case one of the waiters became the new holder.
+ * KERN_NOT_WAITING in case there were no waiters.
+ *
+ */
+kern_return_t
+lck_rw_gate_handoff(__assert_only lck_rw_t *lock, gate_t *gate, int flags)
+{
+ LCK_RW_ASSERT(lock, LCK_RW_ASSERT_HELD);
+
+ return gate_handoff(gate, flags);
+}
+
+/*
+ * Name: lck_rw_gate_steal
+ *
+ * Description: Set the current ownership of the gate. It sets the current thread as the
+ * new holder of the gate.
+ * A matching lck_rw_gate_open() or lck_rw_gate_handoff() needs to be called later on
+ * to wake up possible waiters on the gate before returning to userspace.
+ * NOTE: the previous holder should not call lck_rw_gate_open() or lck_rw_gate_handoff()
+ * anymore.
+ *
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_rw_gate_data.
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ * The gate must be closed and the current thread must not already be the holder.
+ *
+ */
+void
+lck_rw_gate_steal(__assert_only lck_rw_t *lock, gate_t *gate)
+{
+ LCK_RW_ASSERT(lock, LCK_RW_ASSERT_HELD);
+
+ gate_steal(gate);
+}
+
+/*
+ * Name: lck_rw_gate_wait
+ *
+ * Description: Waits for the current thread to become the holder of the gate or for the
+ * gate to become open. An interruptible mode and deadline can be specified
+ * to return earlier from the wait.
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_rw_gate_data.
+ * Arg3: sleep action. LCK_SLEEP_DEFAULT, LCK_SLEEP_SHARED, LCK_SLEEP_EXCLUSIVE.
+ * Arg3: interruptible flag for wait.
+ * Arg4: deadline
+ *
+ * Conditions: Lock must be held. Returns with the lock held according to the sleep action specified.
+ * Lock will be dropped while waiting.
+ * The gate must be closed.
+ *
+ * Returns: Reason why the thread was woken up.
+ * GATE_HANDOFF - the current thread was handed off the ownership of the gate.
+ * A matching lck_rw_gate_open() or lck_rw_gate_handoff() needs to be called later on
+ * to wake up possible waiters on the gate before returning to userspace.
+ * GATE_OPENED - the gate was opened by the holder.
+ * GATE_TIMED_OUT - the thread was woken up by a timeout.
+ * GATE_INTERRUPTED - the thread was interrupted while sleeping.
+ *
+ */
+gate_wait_result_t
+lck_rw_gate_wait(lck_rw_t *lock, gate_t *gate, lck_sleep_action_t lck_sleep_action, wait_interrupt_t interruptible, uint64_t deadline)
+{
+ __block lck_rw_type_t lck_rw_type = LCK_RW_TYPE_EXCLUSIVE;
+
+ LCK_RW_ASSERT(lock, LCK_RW_ASSERT_HELD);
+
+ if (lck_sleep_action & LCK_SLEEP_UNLOCK) {
+ return gate_wait(gate,
+ interruptible,
+ deadline,
+ ^{lck_rw_type = lck_rw_done(lock);},
+ ^{;});
+ } else if (!(lck_sleep_action & (LCK_SLEEP_SHARED | LCK_SLEEP_EXCLUSIVE))) {
+ return gate_wait(gate,
+ interruptible,
+ deadline,
+ ^{lck_rw_type = lck_rw_done(lock);},
+ ^{lck_rw_lock(lock, lck_rw_type);});
+ } else if (lck_sleep_action & LCK_SLEEP_EXCLUSIVE) {
+ return gate_wait(gate,
+ interruptible,
+ deadline,
+ ^{lck_rw_type = lck_rw_done(lock);},
+ ^{lck_rw_lock_exclusive(lock);});
+ } else {
+ return gate_wait(gate,
+ interruptible,
+ deadline,
+ ^{lck_rw_type = lck_rw_done(lock);},
+ ^{lck_rw_lock_shared(lock);});
+ }
+}
+
+/*
+ * Name: lck_rw_gate_assert
+ *
+ * Description: asserts that the gate is in the specified state.
+ *
+ * Args:
+ * Arg1: lck_rw_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_rw_gate_data.
+ * Arg3: flags to specified assert type.
+ * GATE_ASSERT_CLOSED - the gate is currently closed
+ * GATE_ASSERT_OPEN - the gate is currently opened
+ * GATE_ASSERT_HELD - the gate is currently closed and the current thread is the holder
+ */
+void
+lck_rw_gate_assert(__assert_only lck_rw_t *lock, gate_t *gate, int flags)
+{
+ LCK_RW_ASSERT(lock, LCK_RW_ASSERT_HELD);
+
+ gate_assert(gate, flags);
+ return;
+}
+
+/*
+ * Name: lck_mtx_gate_init
+ *
+ * Description: initializes a variable declared with decl_lck_mtx_gate_data.
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_mtx_gate_data.
+ */
+void
+lck_mtx_gate_init(lck_mtx_t *lock, gate_t *gate)
+{
+ (void) lock;
+ gate_init(gate);
+}
+
+/*
+ * Name: lck_mtx_gate_destroy
+ *
+ * Description: destroys a variable previously initialized
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_mtx_gate_data.
+ */
+void
+lck_mtx_gate_destroy(lck_mtx_t *lock, gate_t *gate)
+{
+ (void) lock;
+ gate_destroy(gate);
+}
+
+/*
+ * Name: lck_mtx_gate_try_close
+ *
+ * Description: Tries to close the gate.
+ * In case of success the current thread will be set as
+ * the holder of the gate.
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_mtx_gate_data.
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ *
+ * Returns:
+ * KERN_SUCCESS in case the gate was successfully closed. The current thread is the new holder
+ * of the gate.
+ * A matching lck_mtx_gate_open() or lck_mtx_gate_handoff() needs to be called later on
+ * to wake up possible waiters on the gate before returning to userspace.
+ * If the intent is to conditionally probe the gate before waiting, the lock must not be dropped
+ * between the calls to lck_mtx_gate_try_close() and lck_mtx_gate_wait().
+ *
+ * KERN_FAILURE in case the gate was already closed. Will panic if the current thread was already the holder of the gate.
+ * lck_mtx_gate_wait() should be called instead if the intent is to unconditionally wait on this gate.
+ * The calls to lck_mtx_gate_try_close() and lck_mtx_gate_wait() should
+ * be done without dropping the lock that is protecting the gate in between.
+ */
+int
+lck_mtx_gate_try_close(__assert_only lck_mtx_t *lock, gate_t *gate)
+{
+ LCK_MTX_ASSERT(lock, LCK_MTX_ASSERT_OWNED);
+
+ return gate_try_close(gate);
+}
+
+/*
+ * Name: lck_mtx_gate_close
+ *
+ * Description: Closes the gate. The current thread will be set as
+ * the holder of the gate. Will panic if the gate is already closed.
+ * A matching lck_mtx_gate_open() or lck_mtx_gate_handoff() needs to be called later on
+ * to wake up possible waiters on the gate before returning to userspace.
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_mtx_gate_data.
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ * The gate must be open.
+ *
+ */
void
-hw_atomic_or_noret(volatile uint32_t *dest, uint32_t mask)
+lck_mtx_gate_close(__assert_only lck_mtx_t *lock, gate_t *gate)
{
- ALIGN_TEST(dest, uint32_t);
- __c11_atomic_fetch_or(ATOMIC_CAST(uint32_t, dest), mask, memory_order_relaxed);
+ LCK_MTX_ASSERT(lock, LCK_MTX_ASSERT_OWNED);
+
+ return gate_close(gate);
+}
+
+/*
+ * Name: lck_mtx_gate_open
+ *
+ * Description: Opens of the gate and wakes up possible waiters.
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_mtx_gate_data.
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ * The current thread must be the holder of the gate.
+ *
+ */
+void
+lck_mtx_gate_open(__assert_only lck_mtx_t *lock, gate_t *gate)
+{
+ LCK_MTX_ASSERT(lock, LCK_MTX_ASSERT_OWNED);
+
+ gate_open(gate);
}
-uint32_t
-hw_atomic_and(volatile uint32_t *dest, uint32_t mask)
+/*
+ * Name: lck_mtx_gate_handoff
+ *
+ * Description: Set the current ownership of the gate. The waiter with highest sched
+ * priority will be selected as the new holder of the gate, and woken up,
+ * with the gate remaining in the closed state throughout.
+ * If no waiters are present, the gate will be kept closed and KERN_NOT_WAITING
+ * will be returned.
+ * OPEN_ON_FAILURE flag can be used to specify if the gate should be opened in
+ * case no waiters were found.
+ *
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_mtx_gate_data.
+ * Arg3: flags - GATE_NO_FALGS or OPEN_ON_FAILURE
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ * The current thread must be the holder of the gate.
+ *
+ * Returns:
+ * KERN_SUCCESS in case one of the waiters became the new holder.
+ * KERN_NOT_WAITING in case there were no waiters.
+ *
+ */
+kern_return_t
+lck_mtx_gate_handoff(__assert_only lck_mtx_t *lock, gate_t *gate, int flags)
{
- ALIGN_TEST(dest, uint32_t);
- return __c11_atomic_fetch_and(ATOMIC_CAST(uint32_t, dest), mask, memory_order_relaxed) & mask;
+ LCK_MTX_ASSERT(lock, LCK_MTX_ASSERT_OWNED);
+
+ return gate_handoff(gate, flags);
}
+/*
+ * Name: lck_mtx_gate_steal
+ *
+ * Description: Steals the ownership of the gate. It sets the current thread as the
+ * new holder of the gate.
+ * A matching lck_mtx_gate_open() or lck_mtx_gate_handoff() needs to be called later on
+ * to wake up possible waiters on the gate before returning to userspace.
+ * NOTE: the previous holder should not call lck_mtx_gate_open() or lck_mtx_gate_handoff()
+ * anymore.
+ *
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_mtx_gate_data.
+ *
+ * Conditions: Lock must be held. Returns with the lock held.
+ * The gate must be closed and the current thread must not already be the holder.
+ *
+ */
void
-hw_atomic_and_noret(volatile uint32_t *dest, uint32_t mask)
+lck_mtx_gate_steal(__assert_only lck_mtx_t *lock, gate_t *gate)
+{
+ LCK_MTX_ASSERT(lock, LCK_MTX_ASSERT_OWNED);
+
+ gate_steal(gate);
+}
+
+/*
+ * Name: lck_mtx_gate_wait
+ *
+ * Description: Waits for the current thread to become the holder of the gate or for the
+ * gate to become open. An interruptible mode and deadline can be specified
+ * to return earlier from the wait.
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_mtx_gate_data.
+ * Arg3: sleep action. LCK_SLEEP_DEFAULT, LCK_SLEEP_UNLOCK, LCK_SLEEP_SPIN, LCK_SLEEP_SPIN_ALWAYS.
+ * Arg3: interruptible flag for wait.
+ * Arg4: deadline
+ *
+ * Conditions: Lock must be held. Returns with the lock held according to the sleep action specified.
+ * Lock will be dropped while waiting.
+ * The gate must be closed.
+ *
+ * Returns: Reason why the thread was woken up.
+ * GATE_HANDOFF - the current thread was handed off the ownership of the gate.
+ * A matching lck_mtx_gate_open() or lck_mtx_gate_handoff() needs to be called later on
+ * to wake up possible waiters on the gate before returning to userspace.
+ * GATE_OPENED - the gate was opened by the holder.
+ * GATE_TIMED_OUT - the thread was woken up by a timeout.
+ * GATE_INTERRUPTED - the thread was interrupted while sleeping.
+ *
+ */
+gate_wait_result_t
+lck_mtx_gate_wait(lck_mtx_t *lock, gate_t *gate, lck_sleep_action_t lck_sleep_action, wait_interrupt_t interruptible, uint64_t deadline)
{
- ALIGN_TEST(dest, uint32_t);
- __c11_atomic_fetch_and(ATOMIC_CAST(uint32_t, dest), mask, memory_order_relaxed);
+ LCK_MTX_ASSERT(lock, LCK_MTX_ASSERT_OWNED);
+
+ if (lck_sleep_action & LCK_SLEEP_UNLOCK) {
+ return gate_wait(gate,
+ interruptible,
+ deadline,
+ ^{lck_mtx_unlock(lock);},
+ ^{;});
+ } else if (lck_sleep_action & LCK_SLEEP_SPIN) {
+ return gate_wait(gate,
+ interruptible,
+ deadline,
+ ^{lck_mtx_unlock(lock);},
+ ^{lck_mtx_lock_spin(lock);});
+ } else if (lck_sleep_action & LCK_SLEEP_SPIN_ALWAYS) {
+ return gate_wait(gate,
+ interruptible,
+ deadline,
+ ^{lck_mtx_unlock(lock);},
+ ^{lck_mtx_lock_spin_always(lock);});
+ } else {
+ return gate_wait(gate,
+ interruptible,
+ deadline,
+ ^{lck_mtx_unlock(lock);},
+ ^{lck_mtx_lock(lock);});
+ }
}
-uint32_t
-hw_compare_and_store(uint32_t oldval, uint32_t newval, volatile uint32_t *dest)
+/*
+ * Name: lck_mtx_gate_assert
+ *
+ * Description: asserts that the gate is in the specified state.
+ *
+ * Args:
+ * Arg1: lck_mtx_t lock used to protect the gate.
+ * Arg2: pointer to the gate data declared with decl_lck_mtx_gate_data.
+ * Arg3: flags to specified assert type.
+ * GATE_ASSERT_CLOSED - the gate is currently closed
+ * GATE_ASSERT_OPEN - the gate is currently opened
+ * GATE_ASSERT_HELD - the gate is currently closed and the current thread is the holder
+ */
+void
+lck_mtx_gate_assert(__assert_only lck_mtx_t *lock, gate_t *gate, int flags)
{
- ALIGN_TEST(dest, uint32_t);
- return __c11_atomic_compare_exchange_strong(ATOMIC_CAST(uint32_t, dest), &oldval, newval,
- memory_order_acq_rel_smp, memory_order_relaxed);
+ LCK_MTX_ASSERT(lock, LCK_MTX_ASSERT_OWNED);
+
+ gate_assert(gate, flags);
}
projects / apple / xnu.git / blobdiff