* Copyright (c) 2000-2003, 2007, 2008 Apple Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
- *
+ *
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
- *
+ *
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
- *
+ *
* @APPLE_LICENSE_HEADER_END@
*/
/*
#include "resolver.h"
#include "internal.h"
#include "kern/kern_trace.h"
-#include <sys/syscall.h>
-#include "os/atomic.h"
+#ifndef BUILDING_VARIANT /* [ */
#ifdef PLOCKSTAT
#include "plockstat.h"
+/* This function is never called and exists to provide never-fired dtrace
+ * probes so that user d scripts don't get errors.
+ */
+PTHREAD_NOEXPORT PTHREAD_USED
+void
+_plockstat_never_fired(void)
+{
+ PLOCKSTAT_MUTEX_SPIN(NULL);
+ PLOCKSTAT_MUTEX_SPUN(NULL, 0, 0);
+}
#else /* !PLOCKSTAT */
#define PLOCKSTAT_MUTEX_SPIN(x)
#define PLOCKSTAT_MUTEX_SPUN(x, y, z)
#define PLOCKSTAT_MUTEX_RELEASE(x, y)
#endif /* PLOCKSTAT */
-extern int __unix_conforming;
+#define BLOCK_FAIL_PLOCKSTAT 0
+#define BLOCK_SUCCESS_PLOCKSTAT 1
+
+#define PTHREAD_MUTEX_INIT_UNUSED 1
-#ifndef BUILDING_VARIANT
+PTHREAD_NOEXPORT PTHREAD_WEAK
+int _pthread_mutex_lock_init_slow(_pthread_mutex *mutex, bool trylock);
PTHREAD_NOEXPORT PTHREAD_WEAK // prevent inlining of return value into callers
-int
-_pthread_mutex_unlock_slow(pthread_mutex_t *omutex);
+int _pthread_mutex_fairshare_lock_slow(_pthread_mutex *mutex, bool trylock);
PTHREAD_NOEXPORT PTHREAD_WEAK // prevent inlining of return value into callers
-int
-_pthread_mutex_lock_slow(pthread_mutex_t *omutex, bool trylock);
+int _pthread_mutex_firstfit_lock_slow(_pthread_mutex *mutex, bool trylock);
-PTHREAD_NOEXPORT PTHREAD_WEAK // prevent inlining of return value into _pthread_mutex_lock
-int
-_pthread_mutex_lock_wait(pthread_mutex_t *omutex, uint64_t newval64, uint64_t oldtid);
+PTHREAD_NOEXPORT PTHREAD_WEAK // prevent inlining of return value into callers
+int _pthread_mutex_fairshare_unlock_slow(_pthread_mutex *mutex);
-#endif /* BUILDING_VARIANT */
+PTHREAD_NOEXPORT PTHREAD_WEAK // prevent inlining of return value into callers
+int _pthread_mutex_firstfit_unlock_slow(_pthread_mutex *mutex);
-#define DEBUG_TRACE_POINTS 0
+PTHREAD_NOEXPORT PTHREAD_WEAK // prevent inlining of return value into callers
+int _pthread_mutex_corruption_abort(_pthread_mutex *mutex);
+
+extern int __pthread_mutex_default_opt_policy PTHREAD_NOEXPORT;
+
+
+int __pthread_mutex_default_opt_policy PTHREAD_NOEXPORT =
+ _PTHREAD_MTX_OPT_POLICY_DEFAULT;
+
+static inline bool
+_pthread_mutex_policy_validate(int policy)
+{
+ return (policy >= 0 && policy < _PTHREAD_MUTEX_POLICY_LAST);
+}
+
+static inline int
+_pthread_mutex_policy_to_opt(int policy)
+{
+ switch (policy) {
+ case PTHREAD_MUTEX_POLICY_FAIRSHARE_NP:
+ return _PTHREAD_MTX_OPT_POLICY_FAIRSHARE;
+ case PTHREAD_MUTEX_POLICY_FIRSTFIT_NP:
+ return _PTHREAD_MTX_OPT_POLICY_FIRSTFIT;
+ default:
+ __builtin_unreachable();
+ }
+}
+
+PTHREAD_NOEXPORT
+void
+_pthread_mutex_global_init(const char *envp[],
+ struct _pthread_registration_data *registration_data)
+{
+
+ int opt = _PTHREAD_MTX_OPT_POLICY_DEFAULT;
+ if (registration_data->mutex_default_policy) {
+ int policy = registration_data->mutex_default_policy;
+ if (_pthread_mutex_policy_validate(policy)) {
+ opt = _pthread_mutex_policy_to_opt(policy);
+ }
+ }
+
+ const char *envvar = _simple_getenv(envp, "PTHREAD_MUTEX_DEFAULT_POLICY");
+ if (envvar) {
+ int policy = envvar[0] - '0';
+ if (_pthread_mutex_policy_validate(policy)) {
+ opt = _pthread_mutex_policy_to_opt(policy);
+ }
+ }
+
+ if (opt != __pthread_mutex_default_opt_policy) {
+ __pthread_mutex_default_opt_policy = opt;
+ }
+}
-#if DEBUG_TRACE_POINTS
-extern int __syscall(int number, ...);
-#define DEBUG_TRACE(x, a, b, c, d) __syscall(SYS_kdebug_trace, TRACE_##x, a, b, c, d)
-#else
-#define DEBUG_TRACE(x, a, b, c, d) do { } while(0)
-#endif
-#include <machine/cpu_capabilities.h>
-static inline int _pthread_mutex_init(_pthread_mutex *mutex, const pthread_mutexattr_t *attr, uint32_t static_type);
+PTHREAD_ALWAYS_INLINE
+static inline int _pthread_mutex_init(_pthread_mutex *mutex,
+ const pthread_mutexattr_t *attr, uint32_t static_type);
+
+typedef union mutex_seq {
+ uint32_t seq[2];
+ struct { uint32_t lgenval; uint32_t ugenval; };
+ struct { uint32_t mgen; uint32_t ugen; };
+ uint64_t seq_LU;
+ uint64_t _Atomic atomic_seq_LU;
+} mutex_seq;
+
+_Static_assert(sizeof(mutex_seq) == 2 * sizeof(uint32_t),
+ "Incorrect mutex_seq size");
#if !__LITTLE_ENDIAN__
#error MUTEX_GETSEQ_ADDR assumes little endian layout of 2 32-bit sequence words
PTHREAD_ALWAYS_INLINE
static inline void
-MUTEX_GETSEQ_ADDR(_pthread_mutex *mutex,
- volatile uint64_t **seqaddr)
+MUTEX_GETSEQ_ADDR(_pthread_mutex *mutex, mutex_seq **seqaddr)
{
- // addr of m_seq[1] for misaligned, m_seq[0] for aligned mutex struct
- *seqaddr = (volatile uint64_t *)(((uintptr_t)&mutex->m_seq[1]) & ~0x7ul);
+ // 64-bit aligned address inside m_seq array (&m_seq[0] for aligned mutex)
+ // We don't require more than byte alignment on OS X. rdar://22278325
+ *seqaddr = (void *)(((uintptr_t)mutex->m_seq + 0x7ul) & ~0x7ul);
}
PTHREAD_ALWAYS_INLINE
static inline void
-MUTEX_GETTID_ADDR(_pthread_mutex *mutex,
- volatile uint64_t **tidaddr)
+MUTEX_GETTID_ADDR(_pthread_mutex *mutex, uint64_t **tidaddr)
{
- // addr of m_tid[1] for misaligned, m_tid[0] for aligned mutex struct
- *tidaddr = (volatile uint64_t *)(((uintptr_t)&mutex->m_tid[1]) & ~0x7ul);
+ // 64-bit aligned address inside m_tid array (&m_tid[0] for aligned mutex)
+ // We don't require more than byte alignment on OS X. rdar://22278325
+ *tidaddr = (void*)(((uintptr_t)mutex->m_tid + 0x7ul) & ~0x7ul);
}
-#ifndef BUILDING_VARIANT /* [ */
-#ifndef OS_UP_VARIANT_ONLY
+PTHREAD_ALWAYS_INLINE
+static inline void
+mutex_seq_load(mutex_seq *seqaddr, mutex_seq *oldseqval)
+{
+ oldseqval->seq_LU = seqaddr->seq_LU;
+}
-#define BLOCK_FAIL_PLOCKSTAT 0
-#define BLOCK_SUCCESS_PLOCKSTAT 1
+#define mutex_seq_atomic_load(seqaddr, oldseqval, m) \
+ mutex_seq_atomic_load_##m(seqaddr, oldseqval)
-#ifdef PLOCKSTAT
-/* This function is never called and exists to provide never-fired dtrace
- * probes so that user d scripts don't get errors.
- */
-PTHREAD_NOEXPORT PTHREAD_USED
-void
-_plockstat_never_fired(void)
+PTHREAD_ALWAYS_INLINE PTHREAD_USED
+static inline bool
+mutex_seq_atomic_cmpxchgv_relaxed(mutex_seq *seqaddr, mutex_seq *oldseqval,
+ mutex_seq *newseqval)
{
- PLOCKSTAT_MUTEX_SPIN(NULL);
- PLOCKSTAT_MUTEX_SPUN(NULL, 0, 0);
+ return os_atomic_cmpxchgv(&seqaddr->atomic_seq_LU, oldseqval->seq_LU,
+ newseqval->seq_LU, &oldseqval->seq_LU, relaxed);
+}
+
+PTHREAD_ALWAYS_INLINE PTHREAD_USED
+static inline bool
+mutex_seq_atomic_cmpxchgv_acquire(mutex_seq *seqaddr, mutex_seq *oldseqval,
+ mutex_seq *newseqval)
+{
+ return os_atomic_cmpxchgv(&seqaddr->atomic_seq_LU, oldseqval->seq_LU,
+ newseqval->seq_LU, &oldseqval->seq_LU, acquire);
+}
+
+PTHREAD_ALWAYS_INLINE PTHREAD_USED
+static inline bool
+mutex_seq_atomic_cmpxchgv_release(mutex_seq *seqaddr, mutex_seq *oldseqval,
+ mutex_seq *newseqval)
+{
+ return os_atomic_cmpxchgv(&seqaddr->atomic_seq_LU, oldseqval->seq_LU,
+ newseqval->seq_LU, &oldseqval->seq_LU, release);
}
-#endif // PLOCKSTAT
+
+#define mutex_seq_atomic_cmpxchgv(seqaddr, oldseqval, newseqval, m)\
+ mutex_seq_atomic_cmpxchgv_##m(seqaddr, oldseqval, newseqval)
/*
* Initialize a mutex variable, possibly with additional attributes.
* Public interface - so don't trust the lock - initialize it first.
*/
+PTHREAD_NOEXPORT_VARIANT
int
pthread_mutex_init(pthread_mutex_t *omutex, const pthread_mutexattr_t *attr)
{
return EBUSY;
#endif
_pthread_mutex *mutex = (_pthread_mutex *)omutex;
- LOCK_INIT(mutex->lock);
+ _PTHREAD_LOCK_INIT(mutex->lock);
return (_pthread_mutex_init(mutex, attr, 0x7));
}
+PTHREAD_NOEXPORT_VARIANT
int
pthread_mutex_getprioceiling(const pthread_mutex_t *omutex, int *prioceiling)
{
int res = EINVAL;
_pthread_mutex *mutex = (_pthread_mutex *)omutex;
if (_pthread_mutex_check_signature(mutex)) {
- LOCK(mutex->lock);
+ _PTHREAD_LOCK(mutex->lock);
*prioceiling = mutex->prioceiling;
res = 0;
- UNLOCK(mutex->lock);
+ _PTHREAD_UNLOCK(mutex->lock);
}
return res;
}
+PTHREAD_NOEXPORT_VARIANT
int
-pthread_mutex_setprioceiling(pthread_mutex_t *omutex, int prioceiling, int *old_prioceiling)
+pthread_mutex_setprioceiling(pthread_mutex_t *omutex, int prioceiling,
+ int *old_prioceiling)
{
int res = EINVAL;
_pthread_mutex *mutex = (_pthread_mutex *)omutex;
if (_pthread_mutex_check_signature(mutex)) {
- LOCK(mutex->lock);
- if (prioceiling >= -999 || prioceiling <= 999) {
+ _PTHREAD_LOCK(mutex->lock);
+ if (prioceiling >= -999 && prioceiling <= 999) {
*old_prioceiling = mutex->prioceiling;
- mutex->prioceiling = prioceiling;
+ mutex->prioceiling = (int16_t)prioceiling;
res = 0;
}
- UNLOCK(mutex->lock);
+ _PTHREAD_UNLOCK(mutex->lock);
}
return res;
}
+
int
-pthread_mutexattr_getprioceiling(const pthread_mutexattr_t *attr, int *prioceiling)
+pthread_mutexattr_getprioceiling(const pthread_mutexattr_t *attr,
+ int *prioceiling)
{
int res = EINVAL;
if (attr->sig == _PTHREAD_MUTEX_ATTR_SIG) {
return res;
}
+int
+pthread_mutexattr_getpolicy_np(const pthread_mutexattr_t *attr, int *policy)
+{
+ int res = EINVAL;
+ if (attr->sig == _PTHREAD_MUTEX_ATTR_SIG) {
+ switch (attr->opt) {
+ case _PTHREAD_MTX_OPT_POLICY_FAIRSHARE:
+ *policy = PTHREAD_MUTEX_POLICY_FAIRSHARE_NP;
+ res = 0;
+ break;
+ case _PTHREAD_MTX_OPT_POLICY_FIRSTFIT:
+ *policy = PTHREAD_MUTEX_POLICY_FIRSTFIT_NP;
+ res = 0;
+ break;
+ }
+ }
+ return res;
+}
+
int
pthread_mutexattr_gettype(const pthread_mutexattr_t *attr, int *type)
{
{
attr->prioceiling = _PTHREAD_DEFAULT_PRIOCEILING;
attr->protocol = _PTHREAD_DEFAULT_PROTOCOL;
- attr->policy = _PTHREAD_MUTEX_POLICY_FAIRSHARE;
+ attr->opt = __pthread_mutex_default_opt_policy;
attr->type = PTHREAD_MUTEX_DEFAULT;
attr->sig = _PTHREAD_MUTEX_ATTR_SIG;
attr->pshared = _PTHREAD_DEFAULT_PSHARED;
{
int res = EINVAL;
if (attr->sig == _PTHREAD_MUTEX_ATTR_SIG) {
- if (prioceiling >= -999 || prioceiling <= 999) {
+ if (prioceiling >= -999 && prioceiling <= 999) {
attr->prioceiling = prioceiling;
res = 0;
}
{
int res = EINVAL;
if (attr->sig == _PTHREAD_MUTEX_ATTR_SIG) {
+ // <rdar://problem/35844519> the first-fit implementation was broken
+ // pre-Liberty so this mapping exists to ensure that the old first-fit
+ // define (2) is no longer valid when used on older systems.
switch (policy) {
- case _PTHREAD_MUTEX_POLICY_FAIRSHARE:
- case _PTHREAD_MUTEX_POLICY_FIRSTFIT:
- attr->policy = policy;
- res = 0;
- break;
+ case PTHREAD_MUTEX_POLICY_FAIRSHARE_NP:
+ attr->opt = _PTHREAD_MTX_OPT_POLICY_FAIRSHARE;
+ res = 0;
+ break;
+ case PTHREAD_MUTEX_POLICY_FIRSTFIT_NP:
+ attr->opt = _PTHREAD_MTX_OPT_POLICY_FIRSTFIT;
+ res = 0;
+ break;
}
}
return res;
return res;
}
-// XXX remove
-void
-cthread_yield(void)
-{
- sched_yield();
-}
-
-void
-pthread_yield_np(void)
-{
- sched_yield();
-}
-
-
-/*
- * Temp: till pshared is fixed correctly
- */
int
pthread_mutexattr_setpshared(pthread_mutexattr_t *attr, int pshared)
{
if (attr->sig == _PTHREAD_MUTEX_ATTR_SIG) {
#if __DARWIN_UNIX03
- if (( pshared == PTHREAD_PROCESS_PRIVATE) || (pshared == PTHREAD_PROCESS_SHARED))
+ if (( pshared == PTHREAD_PROCESS_PRIVATE) ||
+ (pshared == PTHREAD_PROCESS_SHARED))
#else /* __DARWIN_UNIX03 */
if ( pshared == PTHREAD_PROCESS_PRIVATE)
#endif /* __DARWIN_UNIX03 */
{
- attr->pshared = pshared;
+ attr->pshared = pshared;
res = 0;
}
}
return res;
}
-PTHREAD_NOEXPORT PTHREAD_WEAK // prevent inlining of return value into callers
+PTHREAD_NOEXPORT PTHREAD_NOINLINE PTHREAD_NORETURN
int
-_pthread_mutex_corruption_abort(_pthread_mutex *mutex);
+_pthread_mutex_corruption_abort(_pthread_mutex *mutex)
+{
+ PTHREAD_ABORT("pthread_mutex corruption: mutex owner changed in the "
+ "middle of lock/unlock");
+}
+
PTHREAD_NOINLINE
-int
-_pthread_mutex_corruption_abort(_pthread_mutex *mutex)
+static int
+_pthread_mutex_check_init_slow(_pthread_mutex *mutex)
+{
+ int res = EINVAL;
+
+ if (_pthread_mutex_check_signature_init(mutex)) {
+ _PTHREAD_LOCK(mutex->lock);
+ if (_pthread_mutex_check_signature_init(mutex)) {
+ // initialize a statically initialized mutex to provide
+ // compatibility for misbehaving applications.
+ // (unlock should not be the first operation on a mutex)
+ res = _pthread_mutex_init(mutex, NULL, (mutex->sig & 0xf));
+ } else if (_pthread_mutex_check_signature(mutex)) {
+ res = 0;
+ }
+ _PTHREAD_UNLOCK(mutex->lock);
+ } else if (_pthread_mutex_check_signature(mutex)) {
+ res = 0;
+ }
+ if (res != 0) {
+ PLOCKSTAT_MUTEX_ERROR((pthread_mutex_t *)mutex, res);
+ }
+ return res;
+}
+
+PTHREAD_ALWAYS_INLINE
+static inline int
+_pthread_mutex_check_init(_pthread_mutex *mutex)
+{
+ int res = 0;
+ if (!_pthread_mutex_check_signature(mutex)) {
+ return _pthread_mutex_check_init_slow(mutex);
+ }
+ return res;
+}
+
+PTHREAD_ALWAYS_INLINE
+static inline bool
+_pthread_mutex_is_fairshare(_pthread_mutex *mutex)
+{
+ return (mutex->mtxopts.options.policy == _PTHREAD_MTX_OPT_POLICY_FAIRSHARE);
+}
+
+PTHREAD_ALWAYS_INLINE
+static inline bool
+_pthread_mutex_is_firstfit(_pthread_mutex *mutex)
+{
+ return (mutex->mtxopts.options.policy == _PTHREAD_MTX_OPT_POLICY_FIRSTFIT);
+}
+
+PTHREAD_ALWAYS_INLINE
+static inline bool
+_pthread_mutex_is_recursive(_pthread_mutex *mutex)
+{
+ return (mutex->mtxopts.options.type == PTHREAD_MUTEX_RECURSIVE);
+}
+
+PTHREAD_ALWAYS_INLINE
+static int
+_pthread_mutex_lock_handle_options(_pthread_mutex *mutex, bool trylock,
+ uint64_t *tidaddr)
+{
+ if (mutex->mtxopts.options.type == PTHREAD_MUTEX_NORMAL) {
+ // NORMAL does not do EDEADLK checking
+ return 0;
+ }
+
+ uint64_t selfid = _pthread_selfid_direct();
+ if (os_atomic_load(tidaddr, relaxed) == selfid) {
+ if (_pthread_mutex_is_recursive(mutex)) {
+ if (mutex->mtxopts.options.lock_count < USHRT_MAX) {
+ mutex->mtxopts.options.lock_count += 1;
+ return mutex->mtxopts.options.lock_count;
+ } else {
+ return -EAGAIN;
+ }
+ } else if (trylock) { /* PTHREAD_MUTEX_ERRORCHECK */
+ // <rdar://problem/16261552> as per OpenGroup, trylock cannot
+ // return EDEADLK on a deadlock, it should return EBUSY.
+ return -EBUSY;
+ } else { /* PTHREAD_MUTEX_ERRORCHECK */
+ return -EDEADLK;
+ }
+ }
+
+ // Not recursive, or recursive but first lock.
+ return 0;
+}
+
+PTHREAD_ALWAYS_INLINE
+static int
+_pthread_mutex_unlock_handle_options(_pthread_mutex *mutex, uint64_t *tidaddr)
{
- PTHREAD_ABORT("pthread_mutex corruption: mutex %p owner changed in the middle of lock/unlock");
- return EINVAL; // NOTREACHED
+ if (mutex->mtxopts.options.type == PTHREAD_MUTEX_NORMAL) {
+ // NORMAL does not do EDEADLK checking
+ return 0;
+ }
+
+ uint64_t selfid = _pthread_selfid_direct();
+ if (os_atomic_load(tidaddr, relaxed) != selfid) {
+ return -EPERM;
+ } else if (_pthread_mutex_is_recursive(mutex) &&
+ --mutex->mtxopts.options.lock_count) {
+ return 1;
+ }
+ return 0;
}
/*
* the unlock path will then transition to D=[L5 U4 TID0] and then finally
* E=[L5 U5 TID0].
*
- * If a contender comes in after B, the mutex will instead transition to E=[L6+KE U4 TID0]
- * and then F=[L6+KE U4 TID940]. If a contender comes in after C, it will transition to
- * F=[L6+KE U4 TID940] directly. In both cases, the contender will enter the kernel with either
- * mutexwait(U4, TID0) or mutexwait(U4, TID940). The first owner will unlock the mutex
- * by first updating the owner to G=[L6+KE U4 TID-1] and then doing the actual unlock to
- * H=[L6+KE U5 TID=-1] before entering the kernel with mutexdrop(U5, -1) to signal the next waiter
- * (potentially as a prepost). When the waiter comes out of the kernel, it will update the owner to
- * I=[L6+KE U5 TID941]. An unlock at this point is simply J=[L6 U5 TID0] and then K=[L6 U6 TID0].
+ * If a contender comes in after B, the mutex will instead transition to
+ * E=[L6+KE U4 TID0] and then F=[L6+KE U4 TID940]. If a contender comes in after
+ * C, it will transition to F=[L6+KE U4 TID940] directly. In both cases, the
+ * contender will enter the kernel with either mutexwait(U4, TID0) or
+ * mutexwait(U4, TID940). The first owner will unlock the mutex by first
+ * updating the owner to G=[L6+KE U4 TID-1] and then doing the actual unlock to
+ * H=[L6+KE U5 TID=-1] before entering the kernel with mutexdrop(U5, -1) to
+ * signal the next waiter (potentially as a prepost). When the waiter comes out
+ * of the kernel, it will update the owner to I=[L6+KE U5 TID941]. An unlock at
+ * this point is simply J=[L6 U5 TID0] and then K=[L6 U6 TID0].
*
- * At various points along these timelines, since the sequence words and TID are written independently,
- * a thread may get preempted and another thread might see inconsistent data. In the worst case, another
- * thread may see the TID in the SWITCHING (-1) state or unlocked (0) state for longer because the
- * owning thread was preempted.
+ * At various points along these timelines, since the sequence words and TID are
+ * written independently, a thread may get preempted and another thread might
+ * see inconsistent data. In the worst case, another thread may see the TID in
+ * the SWITCHING (-1) state or unlocked (0) state for longer because the owning
+ * thread was preempted.
*/
/*
- * Drop the mutex unlock references from cond_wait. or mutex_unlock.
+ * Drop the mutex unlock references from cond_wait or mutex_unlock.
*/
PTHREAD_ALWAYS_INLINE
static inline int
-_pthread_mutex_unlock_updatebits(_pthread_mutex *mutex, uint32_t *flagsp, uint32_t **pmtxp, uint32_t *mgenp, uint32_t *ugenp)
+_pthread_mutex_fairshare_unlock_updatebits(_pthread_mutex *mutex,
+ uint32_t *flagsp, uint32_t **pmtxp, uint32_t *mgenp, uint32_t *ugenp)
{
- bool firstfit = (mutex->mtxopts.options.policy == _PTHREAD_MUTEX_POLICY_FIRSTFIT);
- uint32_t lgenval, ugenval, flags;
- uint64_t oldtid, newtid;
- volatile uint64_t *tidaddr;
- MUTEX_GETTID_ADDR(mutex, &tidaddr);
-
- flags = mutex->mtxopts.value;
+ uint32_t flags = mutex->mtxopts.value;
flags &= ~_PTHREAD_MTX_OPT_NOTIFY; // no notification by default
- if (mutex->mtxopts.options.type != PTHREAD_MUTEX_NORMAL) {
- uint64_t selfid = _pthread_selfid_direct();
-
- if (*tidaddr != selfid) {
- //PTHREAD_ABORT("dropping recur or error mutex not owned by the thread");
- PLOCKSTAT_MUTEX_ERROR((pthread_mutex_t *)mutex, EPERM);
- return EPERM;
- } else if (mutex->mtxopts.options.type == PTHREAD_MUTEX_RECURSIVE &&
- --mutex->mtxopts.options.lock_count) {
- PLOCKSTAT_MUTEX_RELEASE((pthread_mutex_t *)mutex, 1);
- if (flagsp != NULL) {
- *flagsp = flags;
- }
- return 0;
+ mutex_seq *seqaddr;
+ MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
+
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
+
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+ uint64_t oldtid, newtid;
+
+ int res = _pthread_mutex_unlock_handle_options(mutex, tidaddr);
+ if (res > 0) {
+ // Valid recursive unlock
+ if (flagsp) {
+ *flagsp = flags;
}
+ PLOCKSTAT_MUTEX_RELEASE((pthread_mutex_t *)mutex, 1);
+ return 0;
+ } else if (res < 0) {
+ PLOCKSTAT_MUTEX_ERROR((pthread_mutex_t *)mutex, -res);
+ return -res;
}
- uint64_t oldval64, newval64;
- volatile uint64_t *seqaddr;
- MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
-
- bool clearprepost, clearnotify, spurious;
+ bool clearnotify, spurious;
do {
- oldval64 = *seqaddr;
- oldtid = *tidaddr;
- lgenval = (uint32_t)oldval64;
- ugenval = (uint32_t)(oldval64 >> 32);
+ newseq = oldseq;
+ oldtid = os_atomic_load(tidaddr, relaxed);
- clearprepost = false;
clearnotify = false;
spurious = false;
- int numwaiters = diff_genseq(lgenval, ugenval); // pending waiters
-
+ // pending waiters
+ int numwaiters = diff_genseq(oldseq.lgenval, oldseq.ugenval);
if (numwaiters == 0) {
- // spurious unlock; do not touch tid
+ // spurious unlock (unlock of unlocked lock)
spurious = true;
} else {
- ugenval += PTHRW_INC;
+ newseq.ugenval += PTHRW_INC;
- if ((lgenval & PTHRW_COUNT_MASK) == (ugenval & PTHRW_COUNT_MASK)) {
- // our unlock sequence matches to lock sequence, so if the CAS is successful, the mutex is unlocked
+ if ((oldseq.lgenval & PTHRW_COUNT_MASK) ==
+ (newseq.ugenval & PTHRW_COUNT_MASK)) {
+ // our unlock sequence matches to lock sequence, so if the
+ // CAS is successful, the mutex is unlocked
/* do not reset Ibit, just K&E */
- lgenval &= ~(PTH_RWL_KBIT | PTH_RWL_EBIT);
+ newseq.lgenval &= ~(PTH_RWL_KBIT | PTH_RWL_EBIT);
clearnotify = true;
newtid = 0; // clear owner
} else {
- if (firstfit) {
- lgenval &= ~PTH_RWL_EBIT; // reset E bit so another can acquire meanwhile
- newtid = 0;
- } else {
- newtid = PTHREAD_MTX_TID_SWITCHING;
- }
+ newtid = PTHREAD_MTX_TID_SWITCHING;
// need to signal others waiting for mutex
flags |= _PTHREAD_MTX_OPT_NOTIFY;
}
-
+
if (newtid != oldtid) {
- // We're giving up the mutex one way or the other, so go ahead and update the owner to SWITCHING
- // or 0 so that once the CAS below succeeds, there is no stale ownership information.
- // If the CAS of the seqaddr fails, we may loop, but it's still valid for the owner
- // to be SWITCHING/0
+ // We're giving up the mutex one way or the other, so go ahead
+ // and update the owner to 0 so that once the CAS below
+ // succeeds, there is no stale ownership information. If the
+ // CAS of the seqaddr fails, we may loop, but it's still valid
+ // for the owner to be SWITCHING/0
if (!os_atomic_cmpxchg(tidaddr, oldtid, newtid, relaxed)) {
// we own this mutex, nobody should be updating it except us
return _pthread_mutex_corruption_abort(mutex);
if (clearnotify || spurious) {
flags &= ~_PTHREAD_MTX_OPT_NOTIFY;
- if (firstfit && ((lgenval & PTH_RWL_PBIT) != 0)) {
- clearprepost = true;
- lgenval &= ~PTH_RWL_PBIT;
- }
}
-
- newval64 = (((uint64_t)ugenval) << 32);
- newval64 |= lgenval;
+ } while (!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq, release));
- } while (!os_atomic_cmpxchg(seqaddr, oldval64, newval64, release));
-
- if (clearprepost) {
- __psynch_cvclrprepost(mutex, lgenval, ugenval, 0, 0, lgenval, (flags | _PTHREAD_MTX_OPT_MUTEX));
- }
+ PTHREAD_TRACE(psynch_mutex_unlock_updatebits, mutex, oldseq.lgenval,
+ newseq.lgenval, oldtid);
if (mgenp != NULL) {
- *mgenp = lgenval;
+ *mgenp = newseq.lgenval;
}
if (ugenp != NULL) {
- *ugenp = ugenval;
+ *ugenp = newseq.ugenval;
}
if (pmtxp != NULL) {
*pmtxp = (uint32_t *)mutex;
return 0;
}
-PTHREAD_NOEXPORT
-int
-__mtx_droplock(_pthread_mutex *mutex, uint32_t *flagsp, uint32_t **pmtxp, uint32_t *mgenp, uint32_t *ugenp)
-{
- return _pthread_mutex_unlock_updatebits(mutex, flagsp, pmtxp, mgenp, ugenp);
-}
-
PTHREAD_ALWAYS_INLINE
static inline int
-_pthread_mutex_lock_updatebits(_pthread_mutex *mutex, uint64_t selfid)
+_pthread_mutex_fairshare_lock_updatebits(_pthread_mutex *mutex, uint64_t selfid)
{
- int res = 0;
- int firstfit = (mutex->mtxopts.options.policy == _PTHREAD_MUTEX_POLICY_FIRSTFIT);
- int isebit = 0;
+ bool firstfit = _pthread_mutex_is_firstfit(mutex);
+ bool gotlock = true;
- uint32_t lgenval, ugenval;
- uint64_t oldval64, newval64;
- volatile uint64_t *seqaddr;
+ mutex_seq *seqaddr;
MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
- uint64_t oldtid;
- volatile uint64_t *tidaddr;
+
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
+
+ uint64_t *tidaddr;
MUTEX_GETTID_ADDR(mutex, &tidaddr);
do {
- do {
- oldval64 = *seqaddr;
- oldtid = *tidaddr;
- lgenval = (uint32_t)oldval64;
- ugenval = (uint32_t)(oldval64 >> 32);
-
- // E bit was set on first pass through the loop but is no longer
- // set. Apparently we spin until it arrives.
- // XXX: verify this is desired behavior.
- } while (isebit && (lgenval & PTH_RWL_EBIT) == 0);
-
- if (isebit) {
- // first fit mutex now has the E bit set. Return 1.
- res = 1;
- break;
- }
+ newseq = oldseq;
if (firstfit) {
- isebit = (lgenval & PTH_RWL_EBIT) != 0;
- } else if ((lgenval & (PTH_RWL_KBIT|PTH_RWL_EBIT)) == (PTH_RWL_KBIT|PTH_RWL_EBIT)) {
- // fairshare mutex and the bits are already set, just update tid
+ // firstfit locks can have the lock stolen out from under a locker
+ // between the unlock from the kernel and this lock path. When this
+ // happens, we still want to set the K bit before leaving the loop
+ // (or notice if the lock unlocks while we try to update).
+ gotlock = !is_rwl_ebit_set(oldseq.lgenval);
+ } else if ((oldseq.lgenval & (PTH_RWL_KBIT | PTH_RWL_EBIT)) ==
+ (PTH_RWL_KBIT | PTH_RWL_EBIT)) {
+ // bit are already set, just update the owner tidaddr
break;
}
- // either first fit or no E bit set
- // update the bits
- lgenval |= PTH_RWL_KBIT | PTH_RWL_EBIT;
-
- newval64 = (((uint64_t)ugenval) << 32);
- newval64 |= lgenval;
-
- // set s and b bit
- // Retry if CAS fails, or if it succeeds with firstfit and E bit already set
- } while (!os_atomic_cmpxchg(seqaddr, oldval64, newval64, acquire) || (firstfit && isebit));
+ newseq.lgenval |= PTH_RWL_KBIT | PTH_RWL_EBIT;
+ } while (!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq,
+ acquire));
- if (res == 0) {
- if (!os_atomic_cmpxchg(tidaddr, oldtid, selfid, relaxed)) {
- // we own this mutex, nobody should be updating it except us
- return _pthread_mutex_corruption_abort(mutex);
- }
+ if (gotlock) {
+ os_atomic_store(tidaddr, selfid, relaxed);
}
- return res;
+ PTHREAD_TRACE(psynch_mutex_lock_updatebits, mutex, oldseq.lgenval,
+ newseq.lgenval, 0);
+
+ // failing to take the lock in firstfit returns 1 to force the caller
+ // to wait in the kernel
+ return gotlock ? 0 : 1;
}
PTHREAD_NOINLINE
static int
-__mtx_markprepost(_pthread_mutex *mutex, uint32_t updateval, int firstfit)
+_pthread_mutex_fairshare_lock_wait(_pthread_mutex *mutex, mutex_seq newseq,
+ uint64_t oldtid)
{
- uint32_t flags;
- uint32_t lgenval, ugenval;
- uint64_t oldval64, newval64;
-
- volatile uint64_t *seqaddr;
- MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
-
- if (firstfit != 0 && (updateval & PTH_RWL_PBIT) != 0) {
- int clearprepost;
- do {
- clearprepost = 0;
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+ uint64_t selfid = _pthread_selfid_direct();
- flags = mutex->mtxopts.value;
+ PLOCKSTAT_MUTEX_BLOCK((pthread_mutex_t *)mutex);
+ do {
+ uint32_t updateval;
+ do {
+ updateval = __psynch_mutexwait(mutex, newseq.lgenval,
+ newseq.ugenval, oldtid, mutex->mtxopts.value);
+ oldtid = os_atomic_load(tidaddr, relaxed);
+ } while (updateval == (uint32_t)-1);
- oldval64 = *seqaddr;
- lgenval = (uint32_t)oldval64;
- ugenval = (uint32_t)(oldval64 >> 32);
+ // returns 0 on succesful update; in firstfit it may fail with 1
+ } while (_pthread_mutex_fairshare_lock_updatebits(mutex, selfid) == 1);
+ PLOCKSTAT_MUTEX_BLOCKED((pthread_mutex_t *)mutex, BLOCK_SUCCESS_PLOCKSTAT);
- /* update the bits */
- if ((lgenval & PTHRW_COUNT_MASK) == (ugenval & PTHRW_COUNT_MASK)) {
- clearprepost = 1;
- lgenval &= ~PTH_RWL_PBIT;
- } else {
- lgenval |= PTH_RWL_PBIT;
- }
- newval64 = (((uint64_t)ugenval) << 32);
- newval64 |= lgenval;
- } while (!os_atomic_cmpxchg(seqaddr, oldval64, newval64, release));
-
- if (clearprepost != 0) {
- __psynch_cvclrprepost(mutex, lgenval, ugenval, 0, 0, lgenval, (flags | _PTHREAD_MTX_OPT_MUTEX));
- }
- }
return 0;
}
-PTHREAD_NOINLINE
-static int
-_pthread_mutex_check_init_slow(pthread_mutex_t *omutex)
+PTHREAD_NOEXPORT PTHREAD_NOINLINE
+int
+_pthread_mutex_fairshare_lock_slow(_pthread_mutex *omutex, bool trylock)
{
- int res = EINVAL;
+ int res, recursive = 0;
_pthread_mutex *mutex = (_pthread_mutex *)omutex;
- if (_pthread_mutex_check_signature_init(mutex)) {
- LOCK(mutex->lock);
- if (_pthread_mutex_check_signature_init(mutex)) {
- // initialize a statically initialized mutex to provide
- // compatibility for misbehaving applications.
- // (unlock should not be the first operation on a mutex)
- res = _pthread_mutex_init(mutex, NULL, (mutex->sig & 0xf));
- } else if (_pthread_mutex_check_signature(mutex)) {
- res = 0;
- }
- UNLOCK(mutex->lock);
- } else if (_pthread_mutex_check_signature(mutex)) {
+ mutex_seq *seqaddr;
+ MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
+
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
+
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+ uint64_t oldtid, selfid = _pthread_selfid_direct();
+
+ res = _pthread_mutex_lock_handle_options(mutex, trylock, tidaddr);
+ if (res > 0) {
+ recursive = 1;
res = 0;
+ goto out;
+ } else if (res < 0) {
+ res = -res;
+ goto out;
}
- if (res != 0) {
- PLOCKSTAT_MUTEX_ERROR(omutex, res);
- }
- return res;
-}
-
-PTHREAD_ALWAYS_INLINE
-static inline int
-_pthread_mutex_check_init(pthread_mutex_t *omutex)
-{
- int res = 0;
- _pthread_mutex *mutex = (_pthread_mutex *)omutex;
-
- if (!_pthread_mutex_check_signature(mutex)) {
- return _pthread_mutex_check_init_slow(omutex);
- }
- return res;
-}
-
-PTHREAD_NOINLINE
-int
-_pthread_mutex_lock_wait(pthread_mutex_t *omutex, uint64_t newval64, uint64_t oldtid)
-{
- _pthread_mutex *mutex = (_pthread_mutex *)omutex;
- uint32_t lgenval = (uint32_t)newval64;
- uint32_t ugenval = (uint32_t)(newval64 >> 32);
-
- volatile uint64_t *tidaddr;
- MUTEX_GETTID_ADDR(mutex, &tidaddr);
- uint64_t selfid = _pthread_selfid_direct();
-
- PLOCKSTAT_MUTEX_BLOCK(omutex);
- do {
- uint32_t updateval;
- do {
- updateval = __psynch_mutexwait(omutex, lgenval, ugenval, oldtid, mutex->mtxopts.value);
- oldtid = *tidaddr;
- } while (updateval == (uint32_t)-1);
-
- // returns 0 on succesful update; in firstfit it may fail with 1
- } while (_pthread_mutex_lock_updatebits(mutex, selfid) == 1);
- PLOCKSTAT_MUTEX_BLOCKED(omutex, BLOCK_SUCCESS_PLOCKSTAT);
-
- return 0;
-}
-
-int
-_pthread_mutex_lock_slow(pthread_mutex_t *omutex, bool trylock)
-{
- int res;
- _pthread_mutex *mutex = (_pthread_mutex *)omutex;
-
- res = _pthread_mutex_check_init(omutex);
- if (res != 0) {
- return res;
- }
-
- uint64_t oldtid;
- volatile uint64_t *tidaddr;
- MUTEX_GETTID_ADDR(mutex, &tidaddr);
- uint64_t selfid = _pthread_selfid_direct();
-
- if (mutex->mtxopts.options.type != PTHREAD_MUTEX_NORMAL) {
- if (*tidaddr == selfid) {
- if (mutex->mtxopts.options.type == PTHREAD_MUTEX_RECURSIVE) {
- if (mutex->mtxopts.options.lock_count < USHRT_MAX) {
- mutex->mtxopts.options.lock_count++;
- PLOCKSTAT_MUTEX_ACQUIRE(omutex, 1, 0);
- res = 0;
- } else {
- res = EAGAIN;
- PLOCKSTAT_MUTEX_ERROR(omutex, res);
- }
- } else if (trylock) { /* PTHREAD_MUTEX_ERRORCHECK */
- // <rdar://problem/16261552> as per OpenGroup, trylock cannot
- // return EDEADLK on a deadlock, it should return EBUSY.
- res = EBUSY;
- PLOCKSTAT_MUTEX_ERROR(omutex, res);
- } else { /* PTHREAD_MUTEX_ERRORCHECK */
- res = EDEADLK;
- PLOCKSTAT_MUTEX_ERROR(omutex, res);
- }
- return res;
- }
- }
-
- uint64_t oldval64, newval64;
- volatile uint64_t *seqaddr;
- MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
-
- uint32_t lgenval, ugenval;
- bool gotlock = false;
+ bool gotlock;
do {
- oldval64 = *seqaddr;
- oldtid = *tidaddr;
- lgenval = (uint32_t)oldval64;
- ugenval = (uint32_t)(oldval64 >> 32);
+ newseq = oldseq;
+ oldtid = os_atomic_load(tidaddr, relaxed);
- gotlock = ((lgenval & PTH_RWL_EBIT) == 0);
+ gotlock = ((oldseq.lgenval & PTH_RWL_EBIT) == 0);
if (trylock && !gotlock) {
// A trylock on a held lock will fail immediately. But since
} else {
// Increment the lock sequence number and force the lock into E+K
// mode, whether "gotlock" is true or not.
- lgenval += PTHRW_INC;
- lgenval |= PTH_RWL_EBIT | PTH_RWL_KBIT;
+ newseq.lgenval += PTHRW_INC;
+ newseq.lgenval |= PTH_RWL_EBIT | PTH_RWL_KBIT;
}
+ } while (!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq, acquire));
- newval64 = (((uint64_t)ugenval) << 32);
- newval64 |= lgenval;
-
- // Set S and B bit
- } while (!os_atomic_cmpxchg(seqaddr, oldval64, newval64, acquire));
+ PTHREAD_TRACE(psynch_mutex_lock_updatebits, omutex, oldseq.lgenval,
+ newseq.lgenval, 0);
if (gotlock) {
os_atomic_store(tidaddr, selfid, relaxed);
res = 0;
- DEBUG_TRACE(psynch_mutex_ulock, omutex, lgenval, ugenval, selfid);
- PLOCKSTAT_MUTEX_ACQUIRE(omutex, 0, 0);
+ PTHREAD_TRACE(psynch_mutex_ulock, omutex, newseq.lgenval,
+ newseq.ugenval, selfid);
} else if (trylock) {
res = EBUSY;
- DEBUG_TRACE(psynch_mutex_utrylock_failed, omutex, lgenval, ugenval, oldtid);
- PLOCKSTAT_MUTEX_ERROR(omutex, res);
+ PTHREAD_TRACE(psynch_mutex_utrylock_failed, omutex, newseq.lgenval,
+ newseq.ugenval, oldtid);
} else {
- res = _pthread_mutex_lock_wait(omutex, newval64, oldtid);
+ PTHREAD_TRACE(psynch_mutex_ulock | DBG_FUNC_START, omutex,
+ newseq.lgenval, newseq.ugenval, oldtid);
+ res = _pthread_mutex_fairshare_lock_wait(mutex, newseq, oldtid);
+ PTHREAD_TRACE(psynch_mutex_ulock | DBG_FUNC_END, omutex,
+ newseq.lgenval, newseq.ugenval, oldtid);
}
- if (res == 0 && mutex->mtxopts.options.type == PTHREAD_MUTEX_RECURSIVE) {
+ if (res == 0 && _pthread_mutex_is_recursive(mutex)) {
mutex->mtxopts.options.lock_count = 1;
}
- PLOCKSTAT_MUTEX_ACQUIRE(omutex, 0, 0);
+out:
+#if PLOCKSTAT
+ if (res == 0) {
+ PLOCKSTAT_MUTEX_ACQUIRE((pthread_mutex_t *)mutex, recursive, 0);
+ } else {
+ PLOCKSTAT_MUTEX_ERROR((pthread_mutex_t *)mutex, res);
+ }
+#endif
return res;
}
-#endif // OS_UP_VARIANT_ONLY
-
-PTHREAD_ALWAYS_INLINE
+PTHREAD_NOINLINE
static inline int
-_pthread_mutex_lock(pthread_mutex_t *omutex, bool trylock)
+_pthread_mutex_fairshare_lock(_pthread_mutex *mutex, bool trylock)
{
-#if PLOCKSTAT || DEBUG_TRACE_POINTS
- if (PLOCKSTAT_MUTEX_ACQUIRE_ENABLED() || PLOCKSTAT_MUTEX_ERROR_ENABLED() ||
- DEBUG_TRACE_POINTS) {
- return _pthread_mutex_lock_slow(omutex, trylock);
+#if ENABLE_USERSPACE_TRACE
+ return _pthread_mutex_fairshare_lock_slow(mutex, trylock);
+#elif PLOCKSTAT
+ if (PLOCKSTAT_MUTEX_ACQUIRE_ENABLED() || PLOCKSTAT_MUTEX_ERROR_ENABLED()) {
+ return _pthread_mutex_fairshare_lock_slow(mutex, trylock);
}
#endif
- _pthread_mutex *mutex = (_pthread_mutex *)omutex;
- if (!_pthread_mutex_check_signature_fast(mutex)) {
- return _pthread_mutex_lock_slow(omutex, trylock);
- }
- uint64_t oldtid;
- volatile uint64_t *tidaddr;
+ uint64_t *tidaddr;
MUTEX_GETTID_ADDR(mutex, &tidaddr);
uint64_t selfid = _pthread_selfid_direct();
- uint64_t oldval64, newval64;
- volatile uint64_t *seqaddr;
+ mutex_seq *seqaddr;
MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
- uint32_t lgenval, ugenval;
- bool gotlock = false;
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
+
+ if (os_unlikely(oldseq.lgenval & PTH_RWL_EBIT)) {
+ return _pthread_mutex_fairshare_lock_slow(mutex, trylock);
+ }
+ bool gotlock;
do {
- oldval64 = *seqaddr;
- oldtid = *tidaddr;
- lgenval = (uint32_t)oldval64;
- ugenval = (uint32_t)(oldval64 >> 32);
+ newseq = oldseq;
- gotlock = ((lgenval & PTH_RWL_EBIT) == 0);
+ gotlock = ((oldseq.lgenval & PTH_RWL_EBIT) == 0);
if (trylock && !gotlock) {
// A trylock on a held lock will fail immediately. But since
// we did not load the sequence words atomically, perform a
// no-op CAS64 to ensure that nobody has unlocked concurrently.
- } else {
+ } else if (os_likely(gotlock)) {
// Increment the lock sequence number and force the lock into E+K
// mode, whether "gotlock" is true or not.
- lgenval += PTHRW_INC;
- lgenval |= PTH_RWL_EBIT | PTH_RWL_KBIT;
+ newseq.lgenval += PTHRW_INC;
+ newseq.lgenval |= PTH_RWL_EBIT | PTH_RWL_KBIT;
+ } else {
+ return _pthread_mutex_fairshare_lock_slow(mutex, trylock);
}
+ } while (os_unlikely(!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq,
+ acquire)));
- newval64 = (((uint64_t)ugenval) << 32);
- newval64 |= lgenval;
-
- // Set S and B bit
- } while (!os_atomic_cmpxchg(seqaddr, oldval64, newval64, acquire));
-
- if (os_fastpath(gotlock)) {
+ if (os_likely(gotlock)) {
os_atomic_store(tidaddr, selfid, relaxed);
return 0;
} else if (trylock) {
return EBUSY;
} else {
- return _pthread_mutex_lock_wait(omutex, newval64, oldtid);
+ __builtin_trap();
}
}
-PTHREAD_NOEXPORT_VARIANT
-int
-pthread_mutex_lock(pthread_mutex_t *mutex)
+PTHREAD_NOINLINE
+static int
+_pthread_mutex_fairshare_unlock_drop(_pthread_mutex *mutex, mutex_seq newseq,
+ uint32_t flags)
{
- return _pthread_mutex_lock(mutex, false);
+ int res;
+ uint32_t updateval;
+
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+
+ PTHREAD_TRACE(psynch_mutex_uunlock | DBG_FUNC_START, mutex, newseq.lgenval,
+ newseq.ugenval, os_atomic_load(tidaddr, relaxed));
+
+ updateval = __psynch_mutexdrop(mutex, newseq.lgenval, newseq.ugenval,
+ os_atomic_load(tidaddr, relaxed), flags);
+
+ PTHREAD_TRACE(psynch_mutex_uunlock | DBG_FUNC_END, mutex, updateval, 0, 0);
+
+ if (updateval == (uint32_t)-1) {
+ res = errno;
+
+ if (res == EINTR) {
+ res = 0;
+ }
+ if (res != 0) {
+ PTHREAD_ABORT("__psynch_mutexdrop failed with error %d", res);
+ }
+ return res;
+ }
+
+ return 0;
}
-PTHREAD_NOEXPORT_VARIANT
+PTHREAD_NOEXPORT PTHREAD_NOINLINE
int
-pthread_mutex_trylock(pthread_mutex_t *mutex)
+_pthread_mutex_fairshare_unlock_slow(_pthread_mutex *mutex)
{
- return _pthread_mutex_lock(mutex, true);
-}
+ int res;
+ mutex_seq newseq;
+ uint32_t flags;
-#ifndef OS_UP_VARIANT_ONLY
-/*
- * Unlock a mutex.
- * TODO: Priority inheritance stuff
- */
+ res = _pthread_mutex_fairshare_unlock_updatebits(mutex, &flags, NULL,
+ &newseq.lgenval, &newseq.ugenval);
+ if (res != 0) return res;
+
+ if ((flags & _PTHREAD_MTX_OPT_NOTIFY) != 0) {
+ return _pthread_mutex_fairshare_unlock_drop(mutex, newseq, flags);
+ } else {
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+ PTHREAD_TRACE(psynch_mutex_uunlock, mutex, newseq.lgenval,
+ newseq.ugenval, os_atomic_load(tidaddr, relaxed));
+ }
+
+ return 0;
+}
PTHREAD_NOINLINE
static int
-_pthread_mutex_unlock_drop(pthread_mutex_t *omutex, uint64_t newval64, uint32_t flags)
+_pthread_mutex_fairshare_unlock(_pthread_mutex *mutex)
{
- int res;
- _pthread_mutex *mutex = (_pthread_mutex *)omutex;
- uint32_t lgenval = (uint32_t)newval64;
- uint32_t ugenval = (uint32_t)(newval64 >> 32);
+#if ENABLE_USERSPACE_TRACE
+ return _pthread_mutex_fairshare_unlock_slow(mutex);
+#elif PLOCKSTAT
+ if (PLOCKSTAT_MUTEX_RELEASE_ENABLED() || PLOCKSTAT_MUTEX_ERROR_ENABLED()) {
+ return _pthread_mutex_fairshare_unlock_slow(mutex);
+ }
+#endif
- uint32_t updateval;
- int firstfit = (mutex->mtxopts.options.policy == _PTHREAD_MUTEX_POLICY_FIRSTFIT);
- volatile uint64_t *tidaddr;
+ uint64_t *tidaddr;
MUTEX_GETTID_ADDR(mutex, &tidaddr);
- updateval = __psynch_mutexdrop(omutex, lgenval, ugenval, *tidaddr, flags);
+ mutex_seq *seqaddr;
+ MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
- if (updateval == (uint32_t)-1) {
- res = errno;
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
+
+ int numwaiters = diff_genseq(oldseq.lgenval, oldseq.ugenval);
+ if (os_unlikely(numwaiters == 0)) {
+ // spurious unlock (unlock of unlocked lock)
+ return 0;
+ }
+
+ // We're giving up the mutex one way or the other, so go ahead and
+ // update the owner to 0 so that once the CAS below succeeds, there
+ // is no stale ownership information. If the CAS of the seqaddr
+ // fails, we may loop, but it's still valid for the owner to be
+ // SWITCHING/0
+ os_atomic_store(tidaddr, 0, relaxed);
+
+ do {
+ newseq = oldseq;
+ newseq.ugenval += PTHRW_INC;
+
+ if (os_likely((oldseq.lgenval & PTHRW_COUNT_MASK) ==
+ (newseq.ugenval & PTHRW_COUNT_MASK))) {
+ // if we succeed in performing the CAS we can be sure of a fast
+ // path (only needing the CAS) unlock, if:
+ // a. our lock and unlock sequence are equal
+ // b. we don't need to clear an unlock prepost from the kernel
+
+ // do not reset Ibit, just K&E
+ newseq.lgenval &= ~(PTH_RWL_KBIT | PTH_RWL_EBIT);
+ } else {
+ return _pthread_mutex_fairshare_unlock_slow(mutex);
+ }
+ } while (os_unlikely(!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq,
+ release)));
+
+ return 0;
+}
+
+#pragma mark firstfit
+
+PTHREAD_ALWAYS_INLINE
+static inline int
+_pthread_mutex_firstfit_unlock_updatebits(_pthread_mutex *mutex,
+ uint32_t *flagsp, uint32_t **mutexp, uint32_t *lvalp, uint32_t *uvalp)
+{
+ uint32_t flags = mutex->mtxopts.value & ~_PTHREAD_MTX_OPT_NOTIFY;
+ bool kernel_wake;
+
+ mutex_seq *seqaddr;
+ MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
+
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
+
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+ uint64_t oldtid;
+
+ int res = _pthread_mutex_unlock_handle_options(mutex, tidaddr);
+ if (res > 0) {
+ // Valid recursive unlock
+ if (flagsp) {
+ *flagsp = flags;
+ }
+ PLOCKSTAT_MUTEX_RELEASE((pthread_mutex_t *)mutex, 1);
+ return 0;
+ } else if (res < 0) {
+ PLOCKSTAT_MUTEX_ERROR((pthread_mutex_t *)mutex, -res);
+ return -res;
+ }
+
+ do {
+ newseq = oldseq;
+ oldtid = os_atomic_load(tidaddr, relaxed);
+ // More than one kernel waiter means we need to do a wake.
+ kernel_wake = diff_genseq(oldseq.lgenval, oldseq.ugenval) > 0;
+ newseq.lgenval &= ~PTH_RWL_EBIT;
+
+ if (kernel_wake) {
+ // Going to the kernel post-unlock removes a single waiter unlock
+ // from the mutex counts.
+ newseq.ugenval += PTHRW_INC;
+ }
+
+ if (oldtid != 0) {
+ if (!os_atomic_cmpxchg(tidaddr, oldtid, 0, relaxed)) {
+ return _pthread_mutex_corruption_abort(mutex);
+ }
+ }
+ } while (!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq, release));
+
+ PTHREAD_TRACE(psynch_ffmutex_unlock_updatebits, mutex, oldseq.lgenval,
+ newseq.lgenval, newseq.ugenval);
+
+ if (kernel_wake) {
+ // We choose to return this out via flags because the condition
+ // variable also uses this to determine whether to do a kernel wake
+ // when beginning a cvwait.
+ flags |= _PTHREAD_MTX_OPT_NOTIFY;
+ }
+ if (lvalp) {
+ *lvalp = newseq.lgenval;
+ }
+ if (uvalp) {
+ *uvalp = newseq.ugenval;
+ }
+ if (mutexp) {
+ *mutexp = (uint32_t *)mutex;
+ }
+ if (flagsp) {
+ *flagsp = flags;
+ }
+ return 0;
+}
+
+PTHREAD_NOEXPORT PTHREAD_NOINLINE
+static int
+_pthread_mutex_firstfit_wake(_pthread_mutex *mutex, mutex_seq newseq,
+ uint32_t flags)
+{
+ PTHREAD_TRACE(psynch_ffmutex_wake, mutex, newseq.lgenval, newseq.ugenval,
+ 0);
+ int res = __psynch_mutexdrop(mutex, newseq.lgenval, newseq.ugenval, 0,
+ flags);
+ if (res == -1) {
+ res = errno;
if (res == EINTR) {
res = 0;
}
if (res != 0) {
- PTHREAD_ABORT("__p_mutexdrop failed with error %d", res);
+ PTHREAD_ABORT("__psynch_mutexdrop failed with error %d", res);
}
return res;
- } else if (firstfit == 1) {
- if ((updateval & PTH_RWL_PBIT) != 0) {
- __mtx_markprepost(mutex, updateval, firstfit);
+ }
+ return 0;
+}
+
+PTHREAD_NOEXPORT PTHREAD_NOINLINE
+int
+_pthread_mutex_firstfit_unlock_slow(_pthread_mutex *mutex)
+{
+ mutex_seq newseq;
+ uint32_t flags;
+ int res;
+
+ res = _pthread_mutex_firstfit_unlock_updatebits(mutex, &flags, NULL,
+ &newseq.lgenval, &newseq.ugenval);
+ if (res != 0) return res;
+
+ if (flags & _PTHREAD_MTX_OPT_NOTIFY) {
+ return _pthread_mutex_firstfit_wake(mutex, newseq, flags);
+ }
+ return 0;
+}
+
+PTHREAD_ALWAYS_INLINE
+static bool
+_pthread_mutex_firstfit_lock_updatebits(_pthread_mutex *mutex, uint64_t selfid,
+ mutex_seq *newseqp)
+{
+ bool gotlock;
+
+ mutex_seq *seqaddr;
+ MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
+
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
+
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+
+ PTHREAD_TRACE(psynch_ffmutex_lock_updatebits | DBG_FUNC_START, mutex,
+ oldseq.lgenval, oldseq.ugenval, 0);
+
+ do {
+ newseq = oldseq;
+ gotlock = is_rwl_ebit_clear(oldseq.lgenval);
+
+ if (gotlock) {
+ // If we see the E-bit cleared, we should just attempt to take it.
+ newseq.lgenval |= PTH_RWL_EBIT;
+ } else {
+ // If we failed to get the lock then we need to put ourselves back
+ // in the queue of waiters. The previous unlocker that woke us out
+ // of the kernel consumed the S-count for our previous wake. So
+ // take another ticket on L and go back in the kernel to sleep.
+ newseq.lgenval += PTHRW_INC;
}
+ } while (!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq, acquire));
+
+ if (gotlock) {
+ os_atomic_store(tidaddr, selfid, relaxed);
+ }
+
+ PTHREAD_TRACE(psynch_ffmutex_lock_updatebits | DBG_FUNC_END, mutex,
+ newseq.lgenval, newseq.ugenval, 0);
+
+ if (newseqp) {
+ *newseqp = newseq;
}
+ return gotlock;
+}
+
+PTHREAD_NOINLINE
+static int
+_pthread_mutex_firstfit_lock_wait(_pthread_mutex *mutex, mutex_seq newseq,
+ uint64_t oldtid)
+{
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+ uint64_t selfid = _pthread_selfid_direct();
+
+ PLOCKSTAT_MUTEX_BLOCK((pthread_mutex_t *)mutex);
+ do {
+ uint32_t uval;
+ do {
+ PTHREAD_TRACE(psynch_ffmutex_wait | DBG_FUNC_START, mutex,
+ newseq.lgenval, newseq.ugenval, mutex->mtxopts.value);
+ uval = __psynch_mutexwait(mutex, newseq.lgenval, newseq.ugenval,
+ oldtid, mutex->mtxopts.value);
+ PTHREAD_TRACE(psynch_ffmutex_wait | DBG_FUNC_END, mutex,
+ uval, 0, 0);
+ oldtid = os_atomic_load(tidaddr, relaxed);
+ } while (uval == (uint32_t)-1);
+ } while (!_pthread_mutex_firstfit_lock_updatebits(mutex, selfid, &newseq));
+ PLOCKSTAT_MUTEX_BLOCKED((pthread_mutex_t *)mutex, BLOCK_SUCCESS_PLOCKSTAT);
return 0;
}
+PTHREAD_NOEXPORT PTHREAD_NOINLINE
int
-_pthread_mutex_unlock_slow(pthread_mutex_t *omutex)
+_pthread_mutex_firstfit_lock_slow(_pthread_mutex *mutex, bool trylock)
{
- int res;
- _pthread_mutex *mutex = (_pthread_mutex *)omutex;
- uint32_t mtxgen, mtxugen, flags;
+ int res, recursive = 0;
- // Initialize static mutexes for compatibility with misbehaving
- // applications (unlock should not be the first operation on a mutex).
- res = _pthread_mutex_check_init(omutex);
- if (res != 0) {
- return res;
+ mutex_seq *seqaddr;
+ MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
+
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
+
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+ uint64_t oldtid, selfid = _pthread_selfid_direct();
+
+ res = _pthread_mutex_lock_handle_options(mutex, trylock, tidaddr);
+ if (res > 0) {
+ recursive = 1;
+ res = 0;
+ goto out;
+ } else if (res < 0) {
+ res = -res;
+ goto out;
}
- res = _pthread_mutex_unlock_updatebits(mutex, &flags, NULL, &mtxgen, &mtxugen);
- if (res != 0) {
- return res;
+ PTHREAD_TRACE(psynch_ffmutex_lock_updatebits | DBG_FUNC_START, mutex,
+ oldseq.lgenval, oldseq.ugenval, 0);
+
+ bool gotlock;
+ do {
+ newseq = oldseq;
+ oldtid = os_atomic_load(tidaddr, relaxed);
+
+ gotlock = is_rwl_ebit_clear(oldseq.lgenval);
+ if (trylock && !gotlock) {
+ // We still want to perform the CAS here, even though it won't
+ // do anything so that it fails if someone unlocked while we were
+ // in the loop
+ } else if (gotlock) {
+ // In first-fit, getting the lock simply adds the E-bit
+ newseq.lgenval |= PTH_RWL_EBIT;
+ } else {
+ // Failed to get the lock, increment the L-val and go to
+ // the kernel to sleep
+ newseq.lgenval += PTHRW_INC;
+ }
+ } while (!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq, acquire));
+
+ PTHREAD_TRACE(psynch_ffmutex_lock_updatebits | DBG_FUNC_END, mutex,
+ newseq.lgenval, newseq.ugenval, 0);
+
+ if (gotlock) {
+ os_atomic_store(tidaddr, selfid, relaxed);
+ res = 0;
+ PTHREAD_TRACE(psynch_mutex_ulock, mutex, newseq.lgenval,
+ newseq.ugenval, selfid);
+ } else if (trylock) {
+ res = EBUSY;
+ PTHREAD_TRACE(psynch_mutex_utrylock_failed, mutex, newseq.lgenval,
+ newseq.ugenval, oldtid);
+ } else {
+ PTHREAD_TRACE(psynch_mutex_ulock | DBG_FUNC_START, mutex,
+ newseq.lgenval, newseq.ugenval, oldtid);
+ res = _pthread_mutex_firstfit_lock_wait(mutex, newseq, oldtid);
+ PTHREAD_TRACE(psynch_mutex_ulock | DBG_FUNC_END, mutex,
+ newseq.lgenval, newseq.ugenval, oldtid);
}
- if ((flags & _PTHREAD_MTX_OPT_NOTIFY) != 0) {
- uint64_t newval64;
- newval64 = (((uint64_t)mtxugen) << 32);
- newval64 |= mtxgen;
- return _pthread_mutex_unlock_drop(omutex, newval64, flags);
+ if (res == 0 && _pthread_mutex_is_recursive(mutex)) {
+ mutex->mtxopts.options.lock_count = 1;
+ }
+
+out:
+#if PLOCKSTAT
+ if (res == 0) {
+ PLOCKSTAT_MUTEX_ACQUIRE((pthread_mutex_t *)mutex, recursive, 0);
} else {
- volatile uint64_t *tidaddr;
- MUTEX_GETTID_ADDR(mutex, &tidaddr);
- DEBUG_TRACE(psynch_mutex_uunlock, omutex, mtxgen, mtxugen, *tidaddr);
+ PLOCKSTAT_MUTEX_ERROR((pthread_mutex_t *)mutex, res);
}
+#endif
+ return res;
+}
- return 0;
+#pragma mark fast path
+
+PTHREAD_NOEXPORT PTHREAD_NOINLINE
+int
+_pthread_mutex_droplock(_pthread_mutex *mutex, uint32_t *flagsp,
+ uint32_t **pmtxp, uint32_t *mgenp, uint32_t *ugenp)
+{
+ if (_pthread_mutex_is_fairshare(mutex)) {
+ return _pthread_mutex_fairshare_unlock_updatebits(mutex, flagsp,
+ pmtxp, mgenp, ugenp);
+ }
+ return _pthread_mutex_firstfit_unlock_updatebits(mutex, flagsp, pmtxp,
+ mgenp, ugenp);
+}
+
+PTHREAD_NOEXPORT PTHREAD_NOINLINE
+int
+_pthread_mutex_lock_init_slow(_pthread_mutex *mutex, bool trylock)
+{
+ int res;
+
+ res = _pthread_mutex_check_init(mutex);
+ if (res != 0) return res;
+
+ if (os_unlikely(_pthread_mutex_is_fairshare(mutex))) {
+ return _pthread_mutex_fairshare_lock_slow(mutex, trylock);
+ }
+ return _pthread_mutex_firstfit_lock_slow(mutex, trylock);
}
-#endif // OS_UP_VARIANT_ONLY
+PTHREAD_NOEXPORT PTHREAD_NOINLINE
+static int
+_pthread_mutex_unlock_init_slow(_pthread_mutex *mutex)
+{
+ int res;
+
+ // Initialize static mutexes for compatibility with misbehaving
+ // applications (unlock should not be the first operation on a mutex).
+ res = _pthread_mutex_check_init(mutex);
+ if (res != 0) return res;
+
+ if (os_unlikely(_pthread_mutex_is_fairshare(mutex))) {
+ return _pthread_mutex_fairshare_unlock_slow(mutex);
+ }
+ return _pthread_mutex_firstfit_unlock_slow(mutex);
+}
PTHREAD_NOEXPORT_VARIANT
int
pthread_mutex_unlock(pthread_mutex_t *omutex)
{
-#if PLOCKSTAT || DEBUG_TRACE_POINTS
- if (PLOCKSTAT_MUTEX_RELEASE_ENABLED() || PLOCKSTAT_MUTEX_ERROR_ENABLED() ||
- DEBUG_TRACE_POINTS) {
- return _pthread_mutex_unlock_slow(omutex);
- }
-#endif
_pthread_mutex *mutex = (_pthread_mutex *)omutex;
- if (!_pthread_mutex_check_signature_fast(mutex)) {
- return _pthread_mutex_unlock_slow(omutex);
+ if (os_unlikely(!_pthread_mutex_check_signature_fast(mutex))) {
+ return _pthread_mutex_unlock_init_slow(mutex);
}
- volatile uint64_t *tidaddr;
+ if (os_unlikely(_pthread_mutex_is_fairshare(mutex))) {
+ return _pthread_mutex_fairshare_unlock(mutex);
+ }
+
+#if ENABLE_USERSPACE_TRACE
+ return _pthread_mutex_firstfit_unlock_slow(mutex);
+#elif PLOCKSTAT
+ if (PLOCKSTAT_MUTEX_RELEASE_ENABLED() || PLOCKSTAT_MUTEX_ERROR_ENABLED()) {
+ return _pthread_mutex_firstfit_unlock_slow(mutex);
+ }
+#endif
+
+ /*
+ * This is the first-fit fast path. The fairshare fast-ish path is in
+ * _pthread_mutex_firstfit_unlock()
+ */
+ uint64_t *tidaddr;
MUTEX_GETTID_ADDR(mutex, &tidaddr);
- uint64_t oldval64, newval64;
- volatile uint64_t *seqaddr;
+ mutex_seq *seqaddr;
MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
- uint32_t lgenval, ugenval;
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
- do {
- oldval64 = *seqaddr;
- lgenval = (uint32_t)oldval64;
- ugenval = (uint32_t)(oldval64 >> 32);
+ // We're giving up the mutex one way or the other, so go ahead and
+ // update the owner to 0 so that once the CAS below succeeds, there
+ // is no stale ownership information. If the CAS of the seqaddr
+ // fails, we may loop, but it's still valid for the owner to be
+ // SWITCHING/0
+ os_atomic_store(tidaddr, 0, relaxed);
- int numwaiters = diff_genseq(lgenval, ugenval); // pending waiters
+ do {
+ newseq = oldseq;
- if (numwaiters == 0) {
- // spurious unlock; do not touch tid
+ if (diff_genseq(oldseq.lgenval, oldseq.ugenval) == 0) {
+ // No outstanding waiters in kernel, we can simply drop the E-bit
+ // and return.
+ newseq.lgenval &= ~PTH_RWL_EBIT;
} else {
- ugenval += PTHRW_INC;
+ return _pthread_mutex_firstfit_unlock_slow(mutex);
+ }
+ } while (os_unlikely(!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq,
+ release)));
+
+ return 0;
+}
- if ((lgenval & PTHRW_COUNT_MASK) == (ugenval & PTHRW_COUNT_MASK)) {
- // our unlock sequence matches to lock sequence, so if the CAS is successful, the mutex is unlocked
+PTHREAD_ALWAYS_INLINE
+static inline int
+_pthread_mutex_firstfit_lock(pthread_mutex_t *omutex, bool trylock)
+{
+ _pthread_mutex *mutex = (_pthread_mutex *)omutex;
+ if (os_unlikely(!_pthread_mutex_check_signature_fast(mutex))) {
+ return _pthread_mutex_lock_init_slow(mutex, trylock);
+ }
- /* do not reset Ibit, just K&E */
- lgenval &= ~(PTH_RWL_KBIT | PTH_RWL_EBIT);
- } else {
- return _pthread_mutex_unlock_slow(omutex);
- }
+ if (os_unlikely(_pthread_mutex_is_fairshare(mutex))) {
+ return _pthread_mutex_fairshare_lock(mutex, trylock);
+ }
- // We're giving up the mutex one way or the other, so go ahead and update the owner
- // to 0 so that once the CAS below succeeds, there is no stale ownership information.
- // If the CAS of the seqaddr fails, we may loop, but it's still valid for the owner
- // to be SWITCHING/0
- os_atomic_store(tidaddr, 0, relaxed);
- }
+#if ENABLE_USERSPACE_TRACE
+ return _pthread_mutex_firstfit_lock_slow(mutex, trylock);
+#elif PLOCKSTAT
+ if (PLOCKSTAT_MUTEX_ACQUIRE_ENABLED() || PLOCKSTAT_MUTEX_ERROR_ENABLED()) {
+ return _pthread_mutex_firstfit_lock_slow(mutex, trylock);
+ }
+#endif
+
+ /*
+ * This is the first-fit fast path. The fairshare fast-ish path is in
+ * _pthread_mutex_firstfit_lock()
+ */
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+ uint64_t selfid = _pthread_selfid_direct();
- newval64 = (((uint64_t)ugenval) << 32);
- newval64 |= lgenval;
+ mutex_seq *seqaddr;
+ MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
- } while (!os_atomic_cmpxchg(seqaddr, oldval64, newval64, release));
+ mutex_seq oldseq, newseq;
+ mutex_seq_load(seqaddr, &oldseq);
- return 0;
+ if (os_unlikely(oldseq.lgenval & PTH_RWL_EBIT)) {
+ return _pthread_mutex_firstfit_lock_slow(mutex, trylock);
+ }
+
+ bool gotlock;
+ do {
+ newseq = oldseq;
+ gotlock = is_rwl_ebit_clear(oldseq.lgenval);
+
+ if (trylock && !gotlock) {
+ // A trylock on a held lock will fail immediately. But since
+ // we did not load the sequence words atomically, perform a
+ // no-op CAS64 to ensure that nobody has unlocked concurrently.
+ } else if (os_likely(gotlock)) {
+ // In first-fit, getting the lock simply adds the E-bit
+ newseq.lgenval |= PTH_RWL_EBIT;
+ } else {
+ return _pthread_mutex_firstfit_lock_slow(mutex, trylock);
+ }
+ } while (os_unlikely(!mutex_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq,
+ acquire)));
+
+ if (os_likely(gotlock)) {
+ os_atomic_store(tidaddr, selfid, relaxed);
+ return 0;
+ } else if (trylock) {
+ return EBUSY;
+ } else {
+ __builtin_trap();
+ }
+}
+
+PTHREAD_NOEXPORT_VARIANT
+int
+pthread_mutex_lock(pthread_mutex_t *mutex)
+{
+ return _pthread_mutex_firstfit_lock(mutex, false);
}
-#ifndef OS_UP_VARIANT_ONLY
+PTHREAD_NOEXPORT_VARIANT
+int
+pthread_mutex_trylock(pthread_mutex_t *mutex)
+{
+ return _pthread_mutex_firstfit_lock(mutex, true);
+}
+PTHREAD_ALWAYS_INLINE
static inline int
-_pthread_mutex_init(_pthread_mutex *mutex, const pthread_mutexattr_t *attr, uint32_t static_type)
+_pthread_mutex_init(_pthread_mutex *mutex, const pthread_mutexattr_t *attr,
+ uint32_t static_type)
{
+ mutex->mtxopts.value = 0;
+ mutex->mtxopts.options.mutex = 1;
if (attr) {
if (attr->sig != _PTHREAD_MUTEX_ATTR_SIG) {
return EINVAL;
}
- mutex->prioceiling = attr->prioceiling;
+ mutex->prioceiling = (int16_t)attr->prioceiling;
mutex->mtxopts.options.protocol = attr->protocol;
- mutex->mtxopts.options.policy = attr->policy;
+ mutex->mtxopts.options.policy = attr->opt;
mutex->mtxopts.options.type = attr->type;
mutex->mtxopts.options.pshared = attr->pshared;
} else {
mutex->prioceiling = _PTHREAD_DEFAULT_PRIOCEILING;
mutex->mtxopts.options.protocol = _PTHREAD_DEFAULT_PROTOCOL;
if (static_type != 3) {
- mutex->mtxopts.options.policy = _PTHREAD_MUTEX_POLICY_FAIRSHARE;
+ mutex->mtxopts.options.policy = __pthread_mutex_default_opt_policy;
} else {
- mutex->mtxopts.options.policy = _PTHREAD_MUTEX_POLICY_FIRSTFIT;
+ mutex->mtxopts.options.policy = _PTHREAD_MTX_OPT_POLICY_FIRSTFIT;
}
mutex->mtxopts.options.pshared = _PTHREAD_DEFAULT_PSHARED;
}
-
- mutex->mtxopts.options.notify = 0;
- mutex->mtxopts.options.unused = 0;
- mutex->mtxopts.options.hold = 0;
- mutex->mtxopts.options.mutex = 1;
- mutex->mtxopts.options.lock_count = 0;
-
- mutex->m_tid[0] = 0;
- mutex->m_tid[1] = 0;
- mutex->m_seq[0] = 0;
- mutex->m_seq[1] = 0;
- mutex->m_seq[2] = 0;
- mutex->prioceiling = 0;
mutex->priority = 0;
- mutex->mtxopts.options.misalign = (((uintptr_t)&mutex->m_seq[0]) & 0x7ul) != 0;
- if (mutex->mtxopts.options.misalign) {
- mutex->m_tid[0] = ~0u;
- } else {
- mutex->m_seq[2] = ~0u;
+ mutex_seq *seqaddr;
+ MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
+
+ uint64_t *tidaddr;
+ MUTEX_GETTID_ADDR(mutex, &tidaddr);
+
+#if PTHREAD_MUTEX_INIT_UNUSED
+ if ((uint32_t*)tidaddr != mutex->m_tid) {
+ mutex->mtxopts.options.misalign = 1;
+ __builtin_memset(mutex->m_tid, 0xff, sizeof(mutex->m_tid));
}
+ __builtin_memset(mutex->m_mis, 0xff, sizeof(mutex->m_mis));
+#endif // PTHREAD_MUTEX_INIT_UNUSED
+ *tidaddr = 0;
+ *seqaddr = (mutex_seq){ };
long sig = _PTHREAD_MUTEX_SIG;
if (mutex->mtxopts.options.type == PTHREAD_MUTEX_NORMAL &&
- mutex->mtxopts.options.policy == _PTHREAD_MUTEX_POLICY_FAIRSHARE) {
+ (_pthread_mutex_is_fairshare(mutex) ||
+ _pthread_mutex_is_firstfit(mutex))) {
// rdar://18148854 _pthread_mutex_lock & pthread_mutex_unlock fastpath
sig = _PTHREAD_MUTEX_SIG_fast;
}
- // unused, purely for detecting copied mutexes and smashes during debugging:
- mutex->reserved2[0] = ~(uintptr_t)mutex; // use ~ to hide from leaks
- mutex->reserved2[1] = (uintptr_t)sig;
+#if PTHREAD_MUTEX_INIT_UNUSED
+ // For detecting copied mutexes and smashes during debugging
+ uint32_t sig32 = (uint32_t)sig;
+#if defined(__LP64__)
+ uintptr_t guard = ~(uintptr_t)mutex; // use ~ to hide from leaks
+ __builtin_memcpy(mutex->_reserved, &guard, sizeof(guard));
+ mutex->_reserved[2] = sig32;
+ mutex->_reserved[3] = sig32;
+ mutex->_pad = sig32;
+#else
+ mutex->_reserved[0] = sig32;
+#endif
+#endif // PTHREAD_MUTEX_INIT_UNUSED
// Ensure all contents are properly set before setting signature.
#if defined(__LP64__)
// the 64bit 'sig' long value in the struct. rdar://problem/21610439
uint32_t *sig32_ptr = (uint32_t*)&mutex->sig;
uint32_t *sig32_val = (uint32_t*)&sig;
- *(sig32_ptr+1) = *(sig32_val+1);
+ *(sig32_ptr + 1) = *(sig32_val + 1);
os_atomic_store(sig32_ptr, *sig32_val, release);
#else
os_atomic_store2o(mutex, sig, sig, release);
return 0;
}
+PTHREAD_NOEXPORT_VARIANT
int
pthread_mutex_destroy(pthread_mutex_t *omutex)
{
int res = EINVAL;
- LOCK(mutex->lock);
+ _PTHREAD_LOCK(mutex->lock);
if (_pthread_mutex_check_signature(mutex)) {
- uint32_t lgenval, ugenval;
- uint64_t oldval64;
- volatile uint64_t *seqaddr;
+ mutex_seq *seqaddr;
MUTEX_GETSEQ_ADDR(mutex, &seqaddr);
- volatile uint64_t *tidaddr;
+
+ mutex_seq seq;
+ mutex_seq_load(seqaddr, &seq);
+
+ uint64_t *tidaddr;
MUTEX_GETTID_ADDR(mutex, &tidaddr);
- oldval64 = *seqaddr;
- lgenval = (uint32_t)oldval64;
- ugenval = (uint32_t)(oldval64 >> 32);
- if ((*tidaddr == (uint64_t)0) &&
- ((lgenval & PTHRW_COUNT_MASK) == (ugenval & PTHRW_COUNT_MASK))) {
+ if ((os_atomic_load(tidaddr, relaxed) == 0) &&
+ (seq.lgenval & PTHRW_COUNT_MASK) ==
+ (seq.ugenval & PTHRW_COUNT_MASK)) {
mutex->sig = _PTHREAD_NO_SIG;
res = 0;
} else {
mutex->sig = _PTHREAD_NO_SIG;
res = 0;
}
- UNLOCK(mutex->lock);
-
- return res;
-}
+ _PTHREAD_UNLOCK(mutex->lock);
-#endif // OS_UP_VARIANT_ONLY
+ return res;
+}
#endif /* !BUILDING_VARIANT ] */
-#ifndef OS_UP_VARIANT_ONLY
/*
* Destroy a mutex attribute structure.
*/
return 0;
}
-#endif // OS_UP_VARIANT_ONLY
projects / apple / libpthread.git / blobdiff