* 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
* 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@
*/
/*-
* $FreeBSD: src/lib/libc_r/uthread/uthread_rwlock.c,v 1.6 2001/04/10 04:19:20 deischen Exp $
*/
-/*
- * POSIX Pthread Library
+/*
+ * POSIX Pthread Library
* -- Read Write Lock support
* 4/24/02: A. Ramesh
* Ported from FreeBSD
*/
+#include "resolver.h"
#include "internal.h"
-#include <stdio.h> /* For printf(). */
-
-extern int __unix_conforming;
#ifdef PLOCKSTAT
#include "plockstat.h"
#define BLOCK_FAIL_PLOCKSTAT 0
#define BLOCK_SUCCESS_PLOCKSTAT 1
-/* maximum number of times a read lock may be obtained */
-#define MAX_READ_LOCKS (INT_MAX - 1)
+#define PTHREAD_RWLOCK_INIT_UNUSED 1
+
+// maximum number of times a read lock may be obtained
+#define MAX_READ_LOCKS (INT_MAX - 1)
+
+
+#if defined(__LP64__)
+#define RWLOCK_USE_INT128 1
+#endif
+
+typedef union rwlock_seq {
+ uint32_t seq[4];
+ struct { uint32_t lcntval; uint32_t rw_seq; uint32_t ucntval; };
+ struct { uint32_t lgen; uint32_t rw_wc; uint32_t ugen; };
+#if RWLOCK_USE_INT128
+ unsigned __int128 seq_LSU;
+ unsigned __int128 _Atomic atomic_seq_LSU;
+#endif
+ struct {
+ uint64_t seq_LS;
+ uint32_t seq_U;
+ uint32_t _pad;
+ };
+ struct {
+ uint64_t _Atomic atomic_seq_LS;
+ uint32_t _Atomic atomic_seq_U;
+ uint32_t _Atomic _atomic_pad;
+ };
+} rwlock_seq;
+
+_Static_assert(sizeof(rwlock_seq) == 4 * sizeof(uint32_t),
+ "Incorrect rwlock_seq size");
+
+typedef enum rwlock_seqfields {
+ RWLOCK_SEQ_NONE = 0,
+ RWLOCK_SEQ_LS = 1,
+ RWLOCK_SEQ_U = 2,
+ RWLOCK_SEQ_LSU = RWLOCK_SEQ_LS | RWLOCK_SEQ_U,
+} rwlock_seqfields;
+
+#if PTHREAD_DEBUG_LOG
+#define RWLOCK_DEBUG_SEQ(op, rwlock, oldseq, newseq, updateval, f) \
+ if (_pthread_debuglog >= 0) { \
+ _simple_dprintf(_pthread_debuglog, "rw_" #op " %p tck %7llu thr %llx " \
+ "L %x -> %x S %x -> %x U %x -> %x updt %x\n", rwlock, \
+ mach_absolute_time() - _pthread_debugstart, _pthread_threadid_self_np_direct(), \
+ (f) & RWLOCK_SEQ_LS ? (oldseq).lcntval : 0, \
+ (f) & RWLOCK_SEQ_LS ? (newseq).lcntval : 0, \
+ (f) & RWLOCK_SEQ_LS ? (oldseq).rw_seq : 0, \
+ (f) & RWLOCK_SEQ_LS ? (newseq).rw_seq : 0, \
+ (f) & RWLOCK_SEQ_U ? (oldseq).ucntval : 0, \
+ (f) & RWLOCK_SEQ_U ? (newseq).ucntval : 0, updateval); }
+#else
+#define RWLOCK_DEBUG_SEQ(m, rwlock, oldseq, newseq, updateval, f)
+#endif
+
+#if !__LITTLE_ENDIAN__
+#error RWLOCK_GETSEQ_ADDR assumes little endian layout of sequence words
+#endif
+
+OS_ALWAYS_INLINE
+static inline void
+RWLOCK_GETSEQ_ADDR(pthread_rwlock_t *rwlock, rwlock_seq **seqaddr)
+{
+ // 128-bit aligned address inside rw_seq & rw_mis arrays
+ *seqaddr = (void*)(((uintptr_t)rwlock->rw_seq + 0xful) & ~0xful);
+}
+
+OS_ALWAYS_INLINE
+static inline void
+RWLOCK_GETTID_ADDR(pthread_rwlock_t *rwlock, uint64_t **tidaddr)
+{
+ // 64-bit aligned address inside rw_tid array (&rw_tid[0] for aligned lock)
+ *tidaddr = (void*)(((uintptr_t)rwlock->rw_tid + 0x7ul) & ~0x7ul);
+}
+
+OS_ALWAYS_INLINE
+static inline void
+rwlock_seq_load(rwlock_seq *seqaddr, rwlock_seq *oldseqval,
+ const rwlock_seqfields seqfields)
+{
+ switch (seqfields) {
+ case RWLOCK_SEQ_LSU:
+#if RWLOCK_USE_INT128
+ oldseqval->seq_LSU = seqaddr->seq_LSU;
+#else
+ oldseqval->seq_LS = seqaddr->seq_LS;
+ oldseqval->seq_U = seqaddr->seq_U;
+#endif
+ break;
+ case RWLOCK_SEQ_LS:
+ oldseqval->seq_LS = seqaddr->seq_LS;
+ break;
+#if DEBUG // unused
+ case RWLOCK_SEQ_U:
+ oldseqval->seq_U = seqaddr->seq_U;
+ break;
+#endif // unused
+ default:
+ __builtin_trap();
+ }
+}
+
+OS_ALWAYS_INLINE
+static inline void
+rwlock_seq_atomic_load_relaxed(rwlock_seq *seqaddr, rwlock_seq *oldseqval,
+ const rwlock_seqfields seqfields)
+{
+ switch (seqfields) {
+ case RWLOCK_SEQ_LSU:
+#if RWLOCK_USE_INT128
+#if defined(__arm64__) && defined(__ARM_ARCH_8_2__)
+ // Workaround clang armv81 codegen bug for 128bit os_atomic_load
+ // rdar://problem/31213932
+ oldseqval->seq_LSU = seqaddr->seq_LSU;
+ while (!os_atomic_cmpxchgv(&seqaddr->atomic_seq_LSU,
+ oldseqval->seq_LSU, oldseqval->seq_LSU, &oldseqval->seq_LSU,
+ relaxed));
+#else
+ oldseqval->seq_LSU = os_atomic_load_wide(&seqaddr->atomic_seq_LSU, relaxed);
+#endif
+#else
+ oldseqval->seq_LS = os_atomic_load_wide(&seqaddr->atomic_seq_LS, relaxed);
+ oldseqval->seq_U = os_atomic_load(&seqaddr->atomic_seq_U, relaxed);
+#endif
+ break;
+ case RWLOCK_SEQ_LS:
+ oldseqval->seq_LS = os_atomic_load_wide(&seqaddr->atomic_seq_LS, relaxed);
+ break;
+#if DEBUG // unused
+ case RWLOCK_SEQ_U:
+ oldseqval->seq_U = os_atomic_load(&seqaddr->atomic_seq_U, relaxed);
+ break;
+#endif // unused
+ default:
+ __builtin_trap();
+ }
+}
+
+#define rwlock_seq_atomic_load(seqaddr, oldseqval, seqfields, m) \
+ rwlock_seq_atomic_load_##m(seqaddr, oldseqval, seqfields)
-#include <platform/string.h>
-#include <platform/compat.h>
+OS_ALWAYS_INLINE
+static inline rwlock_seqfields
+rwlock_seq_atomic_cmpxchgv_relaxed(rwlock_seq *seqaddr, rwlock_seq *oldseqval,
+ rwlock_seq *newseqval, const rwlock_seqfields seqfields)
+{
+ bool r;
+ rwlock_seqfields updated_seqfields = RWLOCK_SEQ_NONE;
+ switch (seqfields) {
+#if DEBUG // unused
+ case RWLOCK_SEQ_LSU:
+#if RWLOCK_USE_INT128
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_LSU, oldseqval->seq_LSU,
+ newseqval->seq_LSU, &oldseqval->seq_LSU, relaxed);
+ if (r) updated_seqfields = RWLOCK_SEQ_LSU;
+#else
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_LS, oldseqval->seq_LS,
+ newseqval->seq_LS, &oldseqval->seq_LS, relaxed);
+ if (r) {
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_U, oldseqval->seq_U,
+ newseqval->seq_U, &oldseqval->seq_U, relaxed);
+ if (!r) oldseqval->seq_LS = newseqval->seq_LS;
+ updated_seqfields = r ? RWLOCK_SEQ_LSU : RWLOCK_SEQ_LS;
+ } else {
+ oldseqval->seq_U = os_atomic_load(&seqaddr->atomic_seq_U, relaxed);
+ }
+#endif
+ break;
+ case RWLOCK_SEQ_U:
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_U, oldseqval->seq_U,
+ newseqval->seq_U, &oldseqval->seq_U, relaxed);
+ if (r) updated_seqfields = RWLOCK_SEQ_U;
+ break;
+#endif // unused
+ case RWLOCK_SEQ_LS:
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_LS, oldseqval->seq_LS,
+ newseqval->seq_LS, &oldseqval->seq_LS, relaxed);
+ if (r) updated_seqfields = RWLOCK_SEQ_LS;
+ break;
+ default:
+ __builtin_trap();
+ }
+ return updated_seqfields;
+}
-__private_extern__ int __pthread_rwlock_init(_pthread_rwlock *rwlock, const pthread_rwlockattr_t *attr);
-__private_extern__ void _pthread_rwlock_updateval(_pthread_rwlock *rwlock, uint32_t updateval);
+OS_ALWAYS_INLINE
+static inline rwlock_seqfields
+rwlock_seq_atomic_cmpxchgv_acquire(rwlock_seq *seqaddr, rwlock_seq *oldseqval,
+ rwlock_seq *newseqval, const rwlock_seqfields seqfields)
+{
+ bool r;
+ rwlock_seqfields updated_seqfields = RWLOCK_SEQ_NONE;
+ switch (seqfields) {
+#if DEBUG // unused
+ case RWLOCK_SEQ_LSU:
+#if RWLOCK_USE_INT128
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_LSU, oldseqval->seq_LSU,
+ newseqval->seq_LSU, &oldseqval->seq_LSU, acquire);
+ if (r) updated_seqfields = RWLOCK_SEQ_LSU;
+#else
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_LS, oldseqval->seq_LS,
+ newseqval->seq_LS, &oldseqval->seq_LS, acquire);
+ if (r) {
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_U, oldseqval->seq_U,
+ newseqval->seq_U, &oldseqval->seq_U, relaxed);
+ if (!r) oldseqval->seq_LS = newseqval->seq_LS;
+ updated_seqfields = r ? RWLOCK_SEQ_LSU : RWLOCK_SEQ_LS;
+ } else {
+ oldseqval->seq_U = os_atomic_load(&seqaddr->atomic_seq_U, relaxed);
+ }
+#endif
+ break;
+ case RWLOCK_SEQ_U:
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_U, oldseqval->seq_U,
+ newseqval->seq_U, &oldseqval->seq_U, acquire);
+ if (r) updated_seqfields = RWLOCK_SEQ_U;
+ break;
+#endif // unused
+ case RWLOCK_SEQ_LS:
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_LS, oldseqval->seq_LS,
+ newseqval->seq_LS, &oldseqval->seq_LS, acquire);
+ if (r) updated_seqfields = RWLOCK_SEQ_LS;
+ break;
+ default:
+ __builtin_trap();
+ }
+ return updated_seqfields;
+}
-static void
-RWLOCK_GETSEQ_ADDR(_pthread_rwlock *rwlock,
- volatile uint32_t **lcntaddr,
- volatile uint32_t **ucntaddr,
- volatile uint32_t **seqaddr)
+OS_ALWAYS_INLINE
+static inline rwlock_seqfields
+rwlock_seq_atomic_cmpxchgv_release(rwlock_seq *seqaddr, rwlock_seq *oldseqval,
+ rwlock_seq *newseqval, const rwlock_seqfields seqfields)
{
- if (rwlock->pshared == PTHREAD_PROCESS_SHARED) {
- if (rwlock->misalign) {
- *lcntaddr = &rwlock->rw_seq[1];
- *seqaddr = &rwlock->rw_seq[2];
- *ucntaddr = &rwlock->rw_seq[3];
+ bool r;
+ rwlock_seqfields updated_seqfields = RWLOCK_SEQ_NONE;
+ switch (seqfields) {
+ case RWLOCK_SEQ_LSU:
+#if RWLOCK_USE_INT128
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_LSU, oldseqval->seq_LSU,
+ newseqval->seq_LSU, &oldseqval->seq_LSU, release);
+ if (r) updated_seqfields = RWLOCK_SEQ_LSU;
+#else
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_U, oldseqval->seq_U,
+ newseqval->seq_U, &oldseqval->seq_U, release);
+ if (r) {
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_LS, oldseqval->seq_LS,
+ newseqval->seq_LS, &oldseqval->seq_LS, relaxed);
+ if (!r) oldseqval->seq_U = newseqval->seq_U;
+ updated_seqfields = r ? RWLOCK_SEQ_LSU : RWLOCK_SEQ_U;
} else {
- *lcntaddr = &rwlock->rw_seq[0];
- *seqaddr = &rwlock->rw_seq[1];
- *ucntaddr = &rwlock->rw_seq[2];
+ oldseqval->seq_LS = os_atomic_load_wide(&seqaddr->atomic_seq_LS,
+ relaxed);
}
- } else {
- *lcntaddr = rwlock->rw_lcntaddr;
- *seqaddr = rwlock->rw_seqaddr;
- *ucntaddr = rwlock->rw_ucntaddr;
+#endif
+ break;
+ case RWLOCK_SEQ_LS:
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_LS, oldseqval->seq_LS,
+ newseqval->seq_LS, &oldseqval->seq_LS, release);
+ if (r) updated_seqfields = RWLOCK_SEQ_LS;
+ break;
+#if DEBUG // unused
+ case RWLOCK_SEQ_U:
+ r = os_atomic_cmpxchgv(&seqaddr->atomic_seq_U, oldseqval->seq_U,
+ newseqval->seq_U, &oldseqval->seq_U, release);
+ if (r) updated_seqfields = RWLOCK_SEQ_U;
+ break;
+#endif // unused
+ default:
+ __builtin_trap();
}
+ return updated_seqfields;
}
+#define rwlock_seq_atomic_cmpxchgv(seqaddr, oldseqval, newseqval, seqfields, m)\
+ rwlock_seq_atomic_cmpxchgv_##m(seqaddr, oldseqval, newseqval, seqfields)
+
#ifndef BUILDING_VARIANT /* [ */
-static uint32_t modbits(uint32_t lgenval, uint32_t updateval, uint32_t savebits);
int
pthread_rwlockattr_init(pthread_rwlockattr_t *attr)
return 0;
}
-int
+int
pthread_rwlockattr_destroy(pthread_rwlockattr_t *attr)
{
attr->sig = _PTHREAD_NO_SIG;
{
int res = EINVAL;
if (attr->sig == _PTHREAD_RWLOCK_ATTR_SIG) {
-#if __DARWIN_UNIX03
- if (( pshared == PTHREAD_PROCESS_PRIVATE) || (pshared == PTHREAD_PROCESS_SHARED))
-#else /* __DARWIN_UNIX03 */
- if ( pshared == PTHREAD_PROCESS_PRIVATE)
-#endif /* __DARWIN_UNIX03 */
+ if (( pshared == PTHREAD_PROCESS_PRIVATE) ||
+ (pshared == PTHREAD_PROCESS_SHARED))
{
attr->pshared = pshared ;
res = 0;
return res;
}
-__private_extern__ int
-__pthread_rwlock_init(_pthread_rwlock *rwlock, const pthread_rwlockattr_t *attr)
+#endif /* !BUILDING_VARIANT ] */
+
+OS_ALWAYS_INLINE
+static inline int
+_pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
{
- // Force RWLOCK_GETSEQ_ADDR to calculate addresses by setting pshared.
- rwlock->pshared = PTHREAD_PROCESS_SHARED;
- rwlock->misalign = (((uintptr_t)&rwlock->rw_seq[0]) & 0x7) != 0;
- RWLOCK_GETSEQ_ADDR(rwlock, &rwlock->rw_lcntaddr, &rwlock->rw_ucntaddr, &rwlock->rw_seqaddr);
- *rwlock->rw_lcntaddr = PTHRW_RWLOCK_INIT;
- *rwlock->rw_seqaddr = PTHRW_RWS_INIT;
- *rwlock->rw_ucntaddr = 0;
+ uint64_t *tidaddr;
+ RWLOCK_GETTID_ADDR(rwlock, &tidaddr);
+
+ rwlock_seq *seqaddr;
+ RWLOCK_GETSEQ_ADDR(rwlock, &seqaddr);
+
+#if PTHREAD_RWLOCK_INIT_UNUSED
+ if ((uint32_t*)tidaddr != rwlock->rw_tid) {
+ rwlock->misalign = 1;
+ __builtin_memset(rwlock->rw_tid, 0xff, sizeof(rwlock->rw_tid));
+ }
+ if ((uint32_t*)seqaddr != rwlock->rw_seq) {
+ __builtin_memset(rwlock->rw_seq, 0xff, sizeof(rwlock->rw_seq));
+ }
+ __builtin_memset(rwlock->rw_mis, 0xff, sizeof(rwlock->rw_mis));
+#endif // PTHREAD_MUTEX_INIT_UNUSED
+ *tidaddr = 0;
+ *seqaddr = (rwlock_seq){
+ .lcntval = PTHRW_RWLOCK_INIT,
+ .rw_seq = PTHRW_RWS_INIT,
+ .ucntval = 0,
+ };
if (attr != NULL && attr->pshared == PTHREAD_PROCESS_SHARED) {
rwlock->pshared = PTHREAD_PROCESS_SHARED;
rwlock->pshared = _PTHREAD_DEFAULT_PSHARED;
rwlock->rw_flags = PTHRW_KERN_PROCESS_PRIVATE;
}
-
- rwlock->rw_owner = NULL;
+
+ long sig = _PTHREAD_RWLOCK_SIG;
+
+#if DEBUG
bzero(rwlock->_reserved, sizeof(rwlock->_reserved));
+#endif
+#if PTHREAD_RWLOCK_INIT_UNUSED
+ // For detecting copied rwlocks and smashes during debugging
+ uint32_t sig32 = (uint32_t)sig;
+ uintptr_t guard = ~(uintptr_t)rwlock; // use ~ to hide from leaks
+ __builtin_memcpy(rwlock->_reserved, &guard, sizeof(guard));
+#define countof(x) (sizeof(x) / sizeof(x[0]))
+ rwlock->_reserved[countof(rwlock->_reserved) - 1] = sig32;
+#if defined(__LP64__)
+ rwlock->_pad = sig32;
+#endif
+#endif // PTHREAD_RWLOCK_INIT_UNUSED
// Ensure all contents are properly set before setting signature.
- OSMemoryBarrier();
- rwlock->sig = _PTHREAD_RWLOCK_SIG;
-
+#if defined(__LP64__)
+ // For binary compatibility reasons we cannot require natural alignment of
+ // the 64bit 'sig' long value in the struct. rdar://problem/21610439
+ uint32_t *sig32_ptr = (uint32_t*)&rwlock->sig;
+ uint32_t *sig32_val = (uint32_t*)&sig;
+ *(sig32_ptr + 1) = *(sig32_val + 1);
+ os_atomic_store(sig32_ptr, *sig32_val, release);
+#else
+ os_atomic_store(&rwlock->sig, sig, release);
+#endif
+
return 0;
}
static uint32_t
-modbits(uint32_t lgenval, uint32_t updateval, uint32_t savebits)
+_pthread_rwlock_modbits(uint32_t lgenval, uint32_t updateval, uint32_t savebits)
{
uint32_t lval = lgenval & PTHRW_BIT_MASK;
uint32_t uval = updateval & PTHRW_BIT_MASK;
uint32_t rval, nlval;
nlval = (lval | uval) & ~(PTH_RWL_MBIT);
-
- /* reconcile bits on the lock with what kernel needs to set */
+
+ // reconcile bits on the lock with what kernel needs to set
if ((uval & PTH_RWL_KBIT) == 0 && (lval & PTH_RWL_WBIT) == 0) {
nlval &= ~PTH_RWL_KBIT;
}
if (savebits != 0) {
- if ((savebits & PTH_RWS_WSVBIT) != 0 && (nlval & PTH_RWL_WBIT) == 0 && (nlval & PTH_RWL_EBIT) == 0) {
+ if ((savebits & PTH_RWS_WSVBIT) != 0 && (nlval & PTH_RWL_WBIT) == 0 &&
+ (nlval & PTH_RWL_EBIT) == 0) {
nlval |= (PTH_RWL_WBIT | PTH_RWL_KBIT);
}
}
return(rval);
}
-__private_extern__ void
-_pthread_rwlock_updateval(_pthread_rwlock *rwlock, uint32_t updateval)
+OS_ALWAYS_INLINE
+static inline void
+_pthread_rwlock_updateval(pthread_rwlock_t *rwlock, uint32_t updateval)
{
bool isoverlap = (updateval & PTH_RWL_MBIT) != 0;
- uint64_t oldval64, newval64;
- volatile uint32_t *lcntaddr, *ucntaddr, *seqaddr;
-
- /* TBD: restore U bit */
- RWLOCK_GETSEQ_ADDR(rwlock, &lcntaddr, &ucntaddr, &seqaddr);
+ // TBD: restore U bit
+ rwlock_seq *seqaddr;
+ RWLOCK_GETSEQ_ADDR(rwlock, &seqaddr);
+ rwlock_seq oldseq, newseq;
+ rwlock_seq_load(seqaddr, &oldseq, RWLOCK_SEQ_LS);
do {
- uint32_t lcntval = *lcntaddr;
- uint32_t rw_seq = *seqaddr;
-
- uint32_t newval, newsval;
- if (isoverlap || is_rws_setunlockinit(rw_seq) != 0) {
+ newseq = oldseq;
+ if (isoverlap || is_rws_unlockinit_set(oldseq.rw_seq)) {
// Set S word to the specified value
- uint32_t savebits = (rw_seq & PTHRW_RWS_SAVEMASK);
- newval = modbits(lcntval, updateval, savebits);
- newsval = rw_seq + (updateval & PTHRW_COUNT_MASK);
+ uint32_t savebits = (oldseq.rw_seq & PTHRW_RWS_SAVEMASK);
+ newseq.lcntval = _pthread_rwlock_modbits(oldseq.lcntval, updateval,
+ savebits);
+ newseq.rw_seq += (updateval & PTHRW_COUNT_MASK);
if (!isoverlap) {
- newsval &= PTHRW_COUNT_MASK;
+ newseq.rw_seq &= PTHRW_COUNT_MASK;
}
- newsval &= ~PTHRW_RWS_SAVEMASK;
- } else {
- newval = lcntval;
- newsval = rw_seq;
+ newseq.rw_seq &= ~PTHRW_RWS_SAVEMASK;
}
-
- oldval64 = (((uint64_t)rw_seq) << 32);
- oldval64 |= lcntval;
- newval64 = (((uint64_t)newsval) << 32);
- newval64 |= newval;
- } while (OSAtomicCompareAndSwap64Barrier(oldval64, newval64, (volatile int64_t *)lcntaddr) != TRUE);
+ } while (!rwlock_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq,
+ RWLOCK_SEQ_LS, relaxed));
+ RWLOCK_DEBUG_SEQ(update, rwlock, oldseq, newseq, updateval, RWLOCK_SEQ_LS);
}
-#endif /* !BUILDING_VARIANT ] */
-
-static int
-_pthread_rwlock_check_busy(_pthread_rwlock *rwlock)
+OS_ALWAYS_INLINE
+static inline int
+_pthread_rwlock_check_busy(pthread_rwlock_t *rwlock)
{
int res = 0;
-
- volatile uint32_t *lcntaddr, *ucntaddr, *seqaddr;
-
- RWLOCK_GETSEQ_ADDR(rwlock, &lcntaddr, &ucntaddr, &seqaddr);
-
- uint32_t rw_lcnt = *lcntaddr;
- uint32_t rw_ucnt = *ucntaddr;
-
- if ((rw_lcnt & PTHRW_COUNT_MASK) != rw_ucnt) {
+
+ rwlock_seq *seqaddr;
+ RWLOCK_GETSEQ_ADDR(rwlock, &seqaddr);
+
+ rwlock_seq seq;
+ rwlock_seq_atomic_load(seqaddr, &seq, RWLOCK_SEQ_LSU, relaxed);
+ if ((seq.lcntval & PTHRW_COUNT_MASK) != seq.ucntval) {
res = EBUSY;
}
-
+
return res;
}
+PTHREAD_NOEXPORT_VARIANT
int
-pthread_rwlock_destroy(pthread_rwlock_t *orwlock)
+pthread_rwlock_destroy(pthread_rwlock_t *rwlock)
{
int res = 0;
- _pthread_rwlock *rwlock = (_pthread_rwlock *)orwlock;
- if (rwlock->sig == _PTHREAD_RWLOCK_SIG) {
-#if __DARWIN_UNIX03
+ _pthread_lock_lock(&rwlock->lock);
+ if (_pthread_rwlock_check_signature(rwlock)) {
res = _pthread_rwlock_check_busy(rwlock);
-#endif /* __DARWIN_UNIX03 */
- } else if (rwlock->sig != _PTHREAD_RWLOCK_SIG_init) {
+ } else if (!_pthread_rwlock_check_signature_init(rwlock)) {
res = EINVAL;
}
if (res == 0) {
rwlock->sig = _PTHREAD_NO_SIG;
}
+ _pthread_lock_unlock(&rwlock->lock);
return res;
}
-
+PTHREAD_NOEXPORT_VARIANT
int
-pthread_rwlock_init(pthread_rwlock_t *orwlock, const pthread_rwlockattr_t *attr)
+pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
{
int res = 0;
- _pthread_rwlock *rwlock = (_pthread_rwlock *)orwlock;
-
-#if __DARWIN_UNIX03
+
if (attr && attr->sig != _PTHREAD_RWLOCK_ATTR_SIG) {
res = EINVAL;
}
- if (res == 0 && rwlock->sig == _PTHREAD_RWLOCK_SIG) {
+ if (res == 0 && _pthread_rwlock_check_signature(rwlock)) {
res = _pthread_rwlock_check_busy(rwlock);
}
-#endif
if (res == 0) {
- LOCK_INIT(rwlock->lock);
- res = __pthread_rwlock_init(rwlock, attr);
+ _pthread_lock_init(&rwlock->lock);
+ res = _pthread_rwlock_init(rwlock, attr);
}
return res;
}
+OS_NOINLINE
static int
-_pthread_rwlock_check_init(pthread_rwlock_t *orwlock)
+_pthread_rwlock_check_init_slow(pthread_rwlock_t *rwlock)
{
- int res = 0;
- _pthread_rwlock *rwlock = (_pthread_rwlock *)orwlock;
- if (rwlock->sig != _PTHREAD_RWLOCK_SIG) {
- res = EINVAL;
- if (rwlock->sig == _PTHREAD_RWLOCK_SIG_init) {
- LOCK(rwlock->lock);
- if (rwlock->sig == _PTHREAD_RWLOCK_SIG_init) {
- res = __pthread_rwlock_init(rwlock, NULL);
- } else if (rwlock->sig == _PTHREAD_RWLOCK_SIG){
- res = 0;
- }
- UNLOCK(rwlock->lock);
- }
- if (res != 0) {
- PLOCKSTAT_RW_ERROR(orwlock, READ_LOCK_PLOCKSTAT, res);
+ int res = EINVAL;
+
+ if (_pthread_rwlock_check_signature_init(rwlock)) {
+ _pthread_lock_lock(&rwlock->lock);
+ if (_pthread_rwlock_check_signature_init(rwlock)) {
+ res = _pthread_rwlock_init(rwlock, NULL);
+ } else if (_pthread_rwlock_check_signature(rwlock)){
+ res = 0;
}
+ _pthread_lock_unlock(&rwlock->lock);
+ } else if (_pthread_rwlock_check_signature(rwlock)){
+ res = 0;
+ }
+ if (res != 0) {
+ PLOCKSTAT_RW_ERROR(rwlock, READ_LOCK_PLOCKSTAT, res);
+ }
+ return res;
+}
+
+OS_ALWAYS_INLINE
+static inline int
+_pthread_rwlock_check_init(pthread_rwlock_t *rwlock)
+{
+ int res = 0;
+
+ if (!_pthread_rwlock_check_signature(rwlock)) {
+ return _pthread_rwlock_check_init_slow(rwlock);
}
return res;
}
+OS_NOINLINE
static int
-_pthread_rwlock_lock(pthread_rwlock_t *orwlock, bool readlock, bool trylock)
+_pthread_rwlock_lock_wait(pthread_rwlock_t *rwlock, bool readlock,
+ rwlock_seq newseq)
{
int res;
- _pthread_rwlock *rwlock = (_pthread_rwlock *)orwlock;
- res = _pthread_rwlock_check_init(orwlock);
- if (res != 0) {
- return res;
- }
+#ifdef PLOCKSTAT
+ int plockstat = readlock ? READ_LOCK_PLOCKSTAT : WRITE_LOCK_PLOCKSTAT;
+#endif
- uint64_t oldval64, newval64;
- volatile uint32_t *lcntaddr, *ucntaddr, *seqaddr;
- RWLOCK_GETSEQ_ADDR(rwlock, &lcntaddr, &ucntaddr, &seqaddr);
+ if (readlock) {
+ RWLOCK_DEBUG_SEQ(rdlock, rwlock, oldseq, newseq, gotlock,
+ RWLOCK_SEQ_LSU);
+ } else {
+ RWLOCK_DEBUG_SEQ(wrlock, rwlock, oldseq, newseq, gotlock,
+ RWLOCK_SEQ_LSU);
+ }
- uint32_t newval, newsval;
- uint32_t lcntval, ucntval, rw_seq;
+ uint32_t updateval;
- bool gotlock;
- bool retry;
- int retry_count = 0;
+ PLOCKSTAT_RW_BLOCK(rwlock, plockstat);
do {
- res = 0;
- retry = false;
-
- lcntval = *lcntaddr;
- ucntval = *ucntaddr;
- rw_seq = *seqaddr;
-
-#if __DARWIN_UNIX03
- if (is_rwl_ebit_set(lcntval)) {
- if (rwlock->rw_owner == pthread_self()) {
- res = EDEADLK;
- break;
- }
+ if (readlock) {
+ updateval = __psynch_rw_rdlock(rwlock, newseq.lcntval,
+ newseq.ucntval, newseq.rw_seq, rwlock->rw_flags);
+ } else {
+ updateval = __psynch_rw_wrlock(rwlock, newseq.lcntval,
+ newseq.ucntval, newseq.rw_seq, rwlock->rw_flags);
}
-#endif /* __DARWIN_UNIX03 */
+ if (updateval == (uint32_t)-1) {
+ res = errno;
+ } else {
+ res = 0;
+ }
+ } while (res == EINTR);
+
+ if (res == 0) {
+ _pthread_rwlock_updateval(rwlock, updateval);
+ PLOCKSTAT_RW_BLOCKED(rwlock, plockstat, BLOCK_SUCCESS_PLOCKSTAT);
+ } else {
+ PLOCKSTAT_RW_BLOCKED(rwlock, plockstat, BLOCK_FAIL_PLOCKSTAT);
+ PTHREAD_INTERNAL_CRASH(res, "kernel rwlock returned unknown error");
+ }
- oldval64 = (((uint64_t)rw_seq) << 32);
- oldval64 |= lcntval;
+ return res;
+}
- /* if l bit is on or u and k bit is clear, acquire lock in userland */
+OS_NOINLINE
+int
+_pthread_rwlock_lock_slow(pthread_rwlock_t *rwlock, bool readlock,
+ bool trylock)
+{
+ int res;
+
+#ifdef PLOCKSTAT
+ int plockstat = readlock ? READ_LOCK_PLOCKSTAT : WRITE_LOCK_PLOCKSTAT;
+#endif
+
+ res = _pthread_rwlock_check_init(rwlock);
+ if (res != 0) return res;
+
+ rwlock_seq *seqaddr;
+ RWLOCK_GETSEQ_ADDR(rwlock, &seqaddr);
+
+ rwlock_seq oldseq, newseq;
+ rwlock_seq_atomic_load(seqaddr, &oldseq, RWLOCK_SEQ_LSU, relaxed);
+
+ uint64_t *tidaddr;
+ RWLOCK_GETTID_ADDR(rwlock, &tidaddr);
+ uint64_t selfid = _pthread_threadid_self_np_direct();
+ if (is_rwl_ebit_set(oldseq.lcntval)) {
+ if (os_atomic_load_wide(tidaddr, relaxed) == selfid) return EDEADLK;
+ }
+
+ int retry_count;
+ bool gotlock;
+ do {
+ retry_count = 0;
+retry:
+ newseq = oldseq;
+
+ // if W and K bit are clear or U bit is on, acquire lock in userland
if (readlock) {
- gotlock = can_rwl_readinuser(lcntval);
+ gotlock = (oldseq.lcntval & (PTH_RWL_WBIT | PTH_RWL_KBIT)) == 0;
} else {
- gotlock = (lcntval & PTH_RWL_RBIT) != 0;
+ gotlock = (oldseq.lcntval & PTH_RWL_UBIT) != 0;
}
- uint32_t bits = 0;
- uint32_t mask = ~0ul;
-
- newval = lcntval + PTHRW_INC;
-
- if (gotlock) {
+ 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 CAS to ensure that nobody has unlocked concurrently.
+ } else if (gotlock) {
if (readlock) {
- if (diff_genseq(lcntval, ucntval) >= PTHRW_MAX_READERS) {
- /* since ucntval may be newer, just redo */
+ if (diff_genseq(oldseq.lcntval, oldseq.ucntval) >=
+ PTHRW_MAX_READERS) {
+ // since ucntval may be newer, just redo
retry_count++;
if (retry_count > 1024) {
+ gotlock = false;
res = EAGAIN;
- break;
+ goto out;
} else {
sched_yield();
- retry = true;
- continue;
+ rwlock_seq_atomic_load(seqaddr, &oldseq,
+ RWLOCK_SEQ_LSU, relaxed);
+ goto retry;
}
}
-
- // Need to update L (remove R bit) and S word
- mask = PTH_RWLOCK_RESET_RBIT;
+ // Need to update L (remove U bit) and S word
+ newseq.lcntval &= ~PTH_RWL_UBIT;
} else {
- mask = PTHRW_COUNT_MASK;
- bits = PTH_RWL_IBIT | PTH_RWL_KBIT | PTH_RWL_EBIT;
+ newseq.lcntval &= PTHRW_COUNT_MASK;
+ newseq.lcntval |= PTH_RWL_IBIT | PTH_RWL_KBIT | PTH_RWL_EBIT;
}
- newsval = rw_seq + PTHRW_INC;
- } else if (trylock) {
- res = EBUSY;
- break;
+ newseq.lcntval += PTHRW_INC;
+ newseq.rw_seq += PTHRW_INC;
} else {
if (readlock) {
- // Need to block in kernel. Remove R bit.
- mask = PTH_RWLOCK_RESET_RBIT;
+ // Need to block in kernel. Remove U bit.
+ newseq.lcntval &= ~PTH_RWL_UBIT;
} else {
- bits = PTH_RWL_KBIT | PTH_RWL_WBIT;
+ newseq.lcntval |= PTH_RWL_KBIT | PTH_RWL_WBIT;
}
- newsval = rw_seq;
- if (is_rws_setseq(rw_seq)) {
- newsval &= PTHRW_SW_Reset_BIT_MASK;
- newsval |= (newval & PTHRW_COUNT_MASK);
+ newseq.lcntval += PTHRW_INC;
+ if (is_rws_sbit_set(oldseq.rw_seq)) {
+ // Clear the S bit and set S to L
+ newseq.rw_seq &= (PTHRW_BIT_MASK & ~PTH_RWS_SBIT);
+ newseq.rw_seq |= (oldseq.lcntval & PTHRW_COUNT_MASK);
}
}
- newval = (newval & mask) | bits;
- newval64 = (((uint64_t)newsval) << 32);
- newval64 |= newval;
+ } while (!rwlock_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq,
+ RWLOCK_SEQ_LS, acquire));
- } while (retry || OSAtomicCompareAndSwap64Barrier(oldval64, newval64, (volatile int64_t *)lcntaddr) != TRUE);
+ if (gotlock) {
+ if (!readlock) os_atomic_store_wide(tidaddr, selfid, relaxed);
+ res = 0;
+ } else if (trylock) {
+ res = EBUSY;
+ } else {
+ res = _pthread_rwlock_lock_wait(rwlock, readlock, newseq);
+ }
+out:
#ifdef PLOCKSTAT
- int plockstat = readlock ? READ_LOCK_PLOCKSTAT : WRITE_LOCK_PLOCKSTAT;
+ if (res == 0) {
+ PLOCKSTAT_RW_ACQUIRE(rwlock, plockstat);
+ } else {
+ PLOCKSTAT_RW_ERROR(rwlock, plockstat, res);
+ }
+#endif
+
+ return res;
+}
+
+OS_ALWAYS_INLINE
+static inline int
+_pthread_rwlock_lock(pthread_rwlock_t *rwlock, bool readlock, bool trylock)
+{
+#if PLOCKSTAT
+ if (PLOCKSTAT_RW_ACQUIRE_ENABLED() || PLOCKSTAT_RW_ERROR_ENABLED()) {
+ return _pthread_rwlock_lock_slow(rwlock, readlock, trylock);
+ }
#endif
- // Unable to acquire in userland, transition to kernel.
- if (res == 0 && !gotlock) {
- uint32_t updateval;
+ if (os_unlikely(!_pthread_rwlock_check_signature(rwlock))) {
+ return _pthread_rwlock_lock_slow(rwlock, readlock, trylock);
+ }
+
+ rwlock_seq *seqaddr;
+ RWLOCK_GETSEQ_ADDR(rwlock, &seqaddr);
+
+ rwlock_seq oldseq, newseq;
+ // no need to perform a single-copy-atomic 128-bit load in the fastpath,
+ // if stores to L and U are seen out of order, we will fallback to the
+ // slowpath below (which has rwlock_seq_atomic_load)
+ rwlock_seq_load(seqaddr, &oldseq, RWLOCK_SEQ_LSU);
+
+ if (os_unlikely(is_rwl_ebit_set(oldseq.lcntval))) {
+ return _pthread_rwlock_lock_slow(rwlock, readlock, trylock);
+ }
+
+ bool gotlock;
+ do {
+ newseq = oldseq;
+
+ // if W and K bit are clear or U bit is on, acquire lock in userland
+ if (readlock) {
+ gotlock = (oldseq.lcntval & (PTH_RWL_WBIT | PTH_RWL_KBIT)) == 0;
+ } else {
+ gotlock = (oldseq.lcntval & PTH_RWL_UBIT) != 0;
+ }
- PLOCKSTAT_RW_BLOCK(orwlock, plockstat);
-
- do {
+ 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 CAS to ensure that nobody has unlocked concurrently.
+ } else if (os_likely(gotlock)) {
if (readlock) {
- updateval = __psynch_rw_rdlock(orwlock, newval, ucntval, newsval, rwlock->rw_flags);
- } else {
- updateval = __psynch_rw_wrlock(orwlock, newval, ucntval, newsval, rwlock->rw_flags);
- }
- if (updateval == (uint32_t)-1) {
- res = errno;
+ if (os_unlikely(diff_genseq(oldseq.lcntval, oldseq.ucntval) >=
+ PTHRW_MAX_READERS)) {
+ return _pthread_rwlock_lock_slow(rwlock, readlock, trylock);
+ }
+ // Need to update L (remove U bit) and S word
+ newseq.lcntval &= ~PTH_RWL_UBIT;
} else {
- res = 0;
+ newseq.lcntval &= PTHRW_COUNT_MASK;
+ newseq.lcntval |= PTH_RWL_IBIT | PTH_RWL_KBIT | PTH_RWL_EBIT;
}
- } while (res == EINTR);
-
- if (res == 0) {
- _pthread_rwlock_updateval(rwlock, updateval);
- PLOCKSTAT_RW_BLOCKED(orwlock, plockstat, BLOCK_SUCCESS_PLOCKSTAT);
+ newseq.lcntval += PTHRW_INC;
+ newseq.rw_seq += PTHRW_INC;
} else {
- PLOCKSTAT_RW_BLOCKED(orwlock, plockstat, BLOCK_FAIL_PLOCKSTAT);
- uint64_t myid;
- (void)pthread_threadid_np(pthread_self(), &myid);
- PTHREAD_ABORT("kernel lock returned unknown error %x with tid %x\n", updateval, (uint32_t)myid);
+ return _pthread_rwlock_lock_slow(rwlock, readlock, trylock);
}
- }
-
- if (res == 0) {
-#if __DARWIN_UNIX03
+ } while (os_unlikely(!rwlock_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq,
+ RWLOCK_SEQ_LS, acquire)));
+
+ if (os_likely(gotlock)) {
if (!readlock) {
- rwlock->rw_owner = pthread_self();
+ uint64_t *tidaddr;
+ RWLOCK_GETTID_ADDR(rwlock, &tidaddr);
+ uint64_t selfid = _pthread_threadid_self_np_direct();
+ os_atomic_store_wide(tidaddr, selfid, relaxed);
}
-#endif /* __DARWIN_UNIX03 */
- PLOCKSTAT_RW_ACQUIRE(orwlock, plockstat);
+ return 0;
+ } else if (trylock) {
+ return EBUSY;
} else {
- PLOCKSTAT_RW_ERROR(orwlock, plockstat, res);
+ __builtin_trap();
}
-
- return res;
}
+PTHREAD_NOEXPORT_VARIANT
int
-pthread_rwlock_rdlock(pthread_rwlock_t *orwlock)
+pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
{
// read lock, no try
- return _pthread_rwlock_lock(orwlock, true, false);
+ return _pthread_rwlock_lock(rwlock, true, false);
}
+PTHREAD_NOEXPORT_VARIANT
int
-pthread_rwlock_tryrdlock(pthread_rwlock_t *orwlock)
+pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock)
{
// read lock, try lock
- return _pthread_rwlock_lock(orwlock, true, true);
+ return _pthread_rwlock_lock(rwlock, true, true);
}
+PTHREAD_NOEXPORT_VARIANT
int
-pthread_rwlock_wrlock(pthread_rwlock_t *orwlock)
+pthread_rwlock_wrlock(pthread_rwlock_t *rwlock)
{
// write lock, no try
- return _pthread_rwlock_lock(orwlock, false, false);
+ return _pthread_rwlock_lock(rwlock, false, false);
}
+PTHREAD_NOEXPORT_VARIANT
int
-pthread_rwlock_trywrlock(pthread_rwlock_t *orwlock)
+pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock)
{
// write lock, try lock
- return _pthread_rwlock_lock(orwlock, false, true);
+ return _pthread_rwlock_lock(rwlock, false, true);
}
+OS_NOINLINE
+static int
+_pthread_rwlock_unlock_drop(pthread_rwlock_t *rwlock, rwlock_seq oldseq,
+ rwlock_seq newseq)
+{
+ int res;
+
+ RWLOCK_DEBUG_SEQ(unlock, rwlock, oldseq, newseq, !droplock, RWLOCK_SEQ_LSU);
+ uint32_t updateval;
+ do {
+ updateval = __psynch_rw_unlock(rwlock, oldseq.lcntval,
+ newseq.ucntval, newseq.rw_seq, rwlock->rw_flags);
+ if (updateval == (uint32_t)-1) {
+ res = errno;
+ } else {
+ res = 0;
+ RWLOCK_DEBUG_SEQ(wakeup, rwlock, oldseq, newseq, updateval,
+ RWLOCK_SEQ_LSU);
+ }
+ } while (res == EINTR);
+
+ if (res != 0) {
+ PTHREAD_INTERNAL_CRASH(res, "kernel rwunlock returned unknown error");
+ }
+
+ return res;
+}
+
+OS_NOINLINE
int
-pthread_rwlock_unlock(pthread_rwlock_t *orwlock)
+_pthread_rwlock_unlock_slow(pthread_rwlock_t *rwlock,
+ rwlock_seqfields updated_seqfields)
{
int res;
- _pthread_rwlock *rwlock = (_pthread_rwlock *)orwlock;
+ rwlock_seqfields seqfields = RWLOCK_SEQ_LSU;
#ifdef PLOCKSTAT
int wrlock = 0;
#endif
- res = _pthread_rwlock_check_init(orwlock);
- if (res != 0) {
- return res;
+ res = _pthread_rwlock_check_init(rwlock);
+ if (res != 0) return res;
+
+ rwlock_seq *seqaddr;
+ RWLOCK_GETSEQ_ADDR(rwlock, &seqaddr);
+
+ rwlock_seq oldseq, newseq;
+ rwlock_seq_load(seqaddr, &oldseq, seqfields);
+
+ if ((oldseq.lcntval & PTH_RWL_UBIT) != 0) {
+ // spurious unlock (unlock of unlocked lock)
+ return 0;
}
- uint64_t oldval64 = 0, newval64 = 0;
- volatile uint32_t *lcntaddr, *ucntaddr, *seqaddr;
- RWLOCK_GETSEQ_ADDR(rwlock, &lcntaddr, &ucntaddr, &seqaddr);
+ if (is_rwl_ebit_set(oldseq.lcntval)) {
+#ifdef PLOCKSTAT
+ wrlock = 1;
+#endif
+ uint64_t *tidaddr;
+ RWLOCK_GETTID_ADDR(rwlock, &tidaddr);
+ os_atomic_store_wide(tidaddr, 0, relaxed);
+ }
bool droplock;
- bool reload;
- bool incr_ucnt = true;
- bool check_spurious = true;
- uint32_t lcntval, ucntval, rw_seq, ulval = 0, newval, newsval;
-
do {
- reload = false;
- droplock = true;
+ // stop loading & updating fields that have successfully been stored
+ seqfields &= ~updated_seqfields;
- lcntval = *lcntaddr;
- ucntval = *ucntaddr;
- rw_seq = *seqaddr;
-
- oldval64 = (((uint64_t)rw_seq) << 32);
- oldval64 |= lcntval;
+ newseq = oldseq;
+ if (seqfields & RWLOCK_SEQ_U) {
+ newseq.ucntval += PTHRW_INC;
+ }
- // check for spurious unlocks
- if (check_spurious) {
- if ((lcntval & PTH_RWL_RBIT) != 0) {
- droplock = false;
+ droplock = false;
+ uint32_t oldlcnt = (oldseq.lcntval & PTHRW_COUNT_MASK);
+ if (newseq.ucntval == oldlcnt) {
+ // last unlock, set L with U and init bits and set S to L with S bit
+ newseq.lcntval = oldlcnt | PTHRW_RWLOCK_INIT;
+ newseq.rw_seq = oldlcnt | PTHRW_RWS_INIT;
+ } else {
+ // no L/S update if lock is not exclusive or no writer pending
+ if ((oldseq.lcntval &
+ (PTH_RWL_EBIT | PTH_RWL_WBIT | PTH_RWL_KBIT)) == 0) {
+ continue;
+ }
- newval64 = oldval64;
+ // kernel transition only needed if U == S
+ if (newseq.ucntval != (oldseq.rw_seq & PTHRW_COUNT_MASK)) {
continue;
}
- check_spurious = false;
+
+ droplock = true;
+ // reset all bits and set K
+ newseq.lcntval = oldlcnt | PTH_RWL_KBIT;
+ // set I bit on S word
+ newseq.rw_seq |= PTH_RWS_IBIT;
+ if ((oldseq.lcntval & PTH_RWL_WBIT) != 0) {
+ newseq.rw_seq |= PTH_RWS_WSVBIT;
+ }
}
+ } while (seqfields != (updated_seqfields = rwlock_seq_atomic_cmpxchgv(
+ seqaddr, &oldseq, &newseq, seqfields, release)));
- if (is_rwl_ebit_set(lcntval)) {
-#ifdef PLOCKSTAT
- wrlock = 1;
+ if (droplock) {
+ res = _pthread_rwlock_unlock_drop(rwlock, oldseq, newseq);
+ }
+
+ PLOCKSTAT_RW_RELEASE(rwlock, wrlock);
+
+ return res;
+}
+
+PTHREAD_NOEXPORT_VARIANT
+int
+pthread_rwlock_unlock(pthread_rwlock_t *rwlock)
+{
+ rwlock_seqfields seqfields = RWLOCK_SEQ_LSU;
+ rwlock_seqfields updated_seqfields = RWLOCK_SEQ_NONE;
+
+#if PLOCKSTAT
+ if (PLOCKSTAT_RW_RELEASE_ENABLED() || PLOCKSTAT_RW_ERROR_ENABLED()) {
+ return _pthread_rwlock_unlock_slow(rwlock, updated_seqfields);
+ }
#endif
-#if __DARWIN_UNIX03
- rwlock->rw_owner = NULL;
-#endif /* __DARWIN_UNIX03 */
- }
- // update U
- if (incr_ucnt) {
- ulval = (ucntval + PTHRW_INC);
- incr_ucnt = (OSAtomicCompareAndSwap32Barrier(ucntval, ulval, (volatile int32_t *)ucntaddr) != TRUE);
- newval64 = oldval64;
- reload = true;
- continue;
- }
+ if (os_unlikely(!_pthread_rwlock_check_signature(rwlock))) {
+ return _pthread_rwlock_unlock_slow(rwlock, updated_seqfields);
+ }
- // last unlock, note U is already updated ?
- if ((lcntval & PTHRW_COUNT_MASK) == (ulval & PTHRW_COUNT_MASK)) {
- /* Set L with R and init bits and set S to L */
- newval = (lcntval & PTHRW_COUNT_MASK)| PTHRW_RWLOCK_INIT;
- newsval = (lcntval & PTHRW_COUNT_MASK)| PTHRW_RWS_INIT;
+ rwlock_seq *seqaddr;
+ RWLOCK_GETSEQ_ADDR(rwlock, &seqaddr);
- droplock = false;
- } else {
- /* if it is not exclusive or no Writer/yield pending, skip */
- if ((lcntval & (PTH_RWL_EBIT | PTH_RWL_WBIT | PTH_RWL_KBIT)) == 0) {
- droplock = false;
- break;
- }
+ rwlock_seq oldseq, newseq;
+ rwlock_seq_load(seqaddr, &oldseq, seqfields);
- /* kernel transition needed? */
- /* U+1 == S? */
- if ((ulval + PTHRW_INC) != (rw_seq & PTHRW_COUNT_MASK)) {
- droplock = false;
- break;
- }
+ if (os_unlikely(oldseq.lcntval & PTH_RWL_UBIT)) {
+ // spurious unlock (unlock of unlocked lock)
+ return 0;
+ }
- /* reset all bits and set k */
- newval = (lcntval & PTHRW_COUNT_MASK) | PTH_RWL_KBIT;
- /* set I bit on S word */
- newsval = rw_seq | PTH_RWS_IBIT;
- if ((lcntval & PTH_RWL_WBIT) != 0) {
- newsval |= PTH_RWS_WSVBIT;
- }
- }
+ if (is_rwl_ebit_set(oldseq.lcntval)) {
+ uint64_t *tidaddr;
+ RWLOCK_GETTID_ADDR(rwlock, &tidaddr);
+ os_atomic_store_wide(tidaddr, 0, relaxed);
+ }
- newval64 = (((uint64_t)newsval) << 32);
- newval64 |= newval;
+ do {
+ if (updated_seqfields) {
+ return _pthread_rwlock_unlock_slow(rwlock, updated_seqfields);
+ }
- } while (OSAtomicCompareAndSwap64Barrier(oldval64, newval64, (volatile int64_t *)lcntaddr) != TRUE || reload);
+ newseq = oldseq;
+ if (seqfields & RWLOCK_SEQ_U) {
+ newseq.ucntval += PTHRW_INC;
+ }
- if (droplock) {
- uint32_t updateval;
- do {
- updateval = __psynch_rw_unlock(orwlock, lcntval, ulval, newsval, rwlock->rw_flags);
- if (updateval == (uint32_t)-1) {
- res = errno;
+ uint32_t oldlcnt = (oldseq.lcntval & PTHRW_COUNT_MASK);
+ if (os_likely(newseq.ucntval == oldlcnt)) {
+ // last unlock, set L with U and init bits and set S to L with S bit
+ newseq.lcntval = oldlcnt | PTHRW_RWLOCK_INIT;
+ newseq.rw_seq = oldlcnt | PTHRW_RWS_INIT;
+ } else {
+ if (os_likely((oldseq.lcntval &
+ (PTH_RWL_EBIT | PTH_RWL_WBIT | PTH_RWL_KBIT)) == 0 ||
+ newseq.ucntval != (oldseq.rw_seq & PTHRW_COUNT_MASK))) {
+ // no L/S update if lock is not exclusive or no writer pending
+ // kernel transition only needed if U == S
} else {
- res = 0;
+ return _pthread_rwlock_unlock_slow(rwlock, updated_seqfields);
}
- } while (res == EINTR);
-
- if (res != 0) {
- uint64_t myid = 0;
- (void)pthread_threadid_np(pthread_self(), &myid);
- PTHREAD_ABORT("rwunlock from kernel with unknown error %x: tid %x\n", res, (uint32_t)myid);
}
- }
+ } while (os_unlikely(seqfields != (updated_seqfields =
+ rwlock_seq_atomic_cmpxchgv(seqaddr, &oldseq, &newseq, seqfields,
+ release))));
- PLOCKSTAT_RW_RELEASE(orwlock, wrlock);
-
- return res;
+ return 0;
}
projects / apple / libpthread.git / blobdiff