72ce06de36
Further decreases unexpected context switches by defering mutex wakeup until internal sleep queue lock is released.
235 lines
7.2 KiB
C
235 lines
7.2 KiB
C
/*-
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* Copyright (c) 2005 David Xu <davidxu@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _THR_FBSD_UMTX_H_
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#define _THR_FBSD_UMTX_H_
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#include <strings.h>
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#include <sys/umtx.h>
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#define DEFAULT_UMUTEX {0,0,{0,0},{0,0,0,0}}
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#define DEFAULT_URWLOCK {0,0,0,0,{0,0,0,0}}
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int _umtx_op_err(void *, int op, u_long, void *, void *) __hidden;
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int __thr_umutex_lock(struct umutex *mtx, uint32_t id) __hidden;
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int __thr_umutex_lock_spin(struct umutex *mtx, uint32_t id) __hidden;
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int __thr_umutex_timedlock(struct umutex *mtx, uint32_t id,
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const struct timespec *timeout) __hidden;
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int __thr_umutex_unlock(struct umutex *mtx, uint32_t id) __hidden;
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int __thr_umutex_trylock(struct umutex *mtx) __hidden;
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int __thr_umutex_set_ceiling(struct umutex *mtx, uint32_t ceiling,
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uint32_t *oldceiling) __hidden;
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void _thr_umutex_init(struct umutex *mtx) __hidden;
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void _thr_urwlock_init(struct urwlock *rwl) __hidden;
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int _thr_umtx_wait(volatile long *mtx, long exp,
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const struct timespec *timeout) __hidden;
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int _thr_umtx_wait_uint(volatile u_int *mtx, u_int exp,
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const struct timespec *timeout, int shared) __hidden;
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int _thr_umtx_timedwait_uint(volatile u_int *mtx, u_int exp, int clockid,
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const struct timespec *timeout, int shared) __hidden;
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int _thr_umtx_wake(volatile void *mtx, int count, int shared) __hidden;
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int _thr_ucond_wait(struct ucond *cv, struct umutex *m,
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const struct timespec *timeout, int check_unpaking) __hidden;
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void _thr_ucond_init(struct ucond *cv) __hidden;
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int _thr_ucond_signal(struct ucond *cv) __hidden;
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int _thr_ucond_broadcast(struct ucond *cv) __hidden;
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int __thr_rwlock_rdlock(struct urwlock *rwlock, int flags,
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const struct timespec *tsp) __hidden;
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int __thr_rwlock_wrlock(struct urwlock *rwlock,
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const struct timespec *tsp) __hidden;
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int __thr_rwlock_unlock(struct urwlock *rwlock) __hidden;
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/* Internal used only */
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void _thr_rwl_rdlock(struct urwlock *rwlock) __hidden;
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void _thr_rwl_wrlock(struct urwlock *rwlock) __hidden;
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void _thr_rwl_unlock(struct urwlock *rwlock) __hidden;
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static inline int
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_thr_umutex_trylock(struct umutex *mtx, uint32_t id)
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{
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if (atomic_cmpset_acq_32(&mtx->m_owner, UMUTEX_UNOWNED, id))
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return (0);
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if ((mtx->m_flags & UMUTEX_PRIO_PROTECT) == 0)
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return (EBUSY);
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return (__thr_umutex_trylock(mtx));
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}
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static inline int
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_thr_umutex_trylock2(struct umutex *mtx, uint32_t id)
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{
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if (atomic_cmpset_acq_32(&mtx->m_owner, UMUTEX_UNOWNED, id) != 0)
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return (0);
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if ((uint32_t)mtx->m_owner == UMUTEX_CONTESTED &&
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__predict_true((mtx->m_flags & (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT)) == 0))
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if (atomic_cmpset_acq_32(&mtx->m_owner, UMUTEX_CONTESTED, id | UMUTEX_CONTESTED))
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return (0);
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return (EBUSY);
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}
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static inline int
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_thr_umutex_lock(struct umutex *mtx, uint32_t id)
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{
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if (_thr_umutex_trylock2(mtx, id) == 0)
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return (0);
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return (__thr_umutex_lock(mtx, id));
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}
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static inline int
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_thr_umutex_lock_spin(struct umutex *mtx, uint32_t id)
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{
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if (_thr_umutex_trylock2(mtx, id) == 0)
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return (0);
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return (__thr_umutex_lock_spin(mtx, id));
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}
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static inline int
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_thr_umutex_timedlock(struct umutex *mtx, uint32_t id,
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const struct timespec *timeout)
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{
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if (_thr_umutex_trylock2(mtx, id) == 0)
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return (0);
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return (__thr_umutex_timedlock(mtx, id, timeout));
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}
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static inline int
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_thr_umutex_unlock2(struct umutex *mtx, uint32_t id, int *defer)
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{
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uint32_t flags = mtx->m_flags;
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if ((flags & (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT)) == 0) {
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uint32_t owner;
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do {
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owner = mtx->m_owner;
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if (__predict_false((owner & ~UMUTEX_CONTESTED) != id))
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return (EPERM);
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} while (__predict_false(!atomic_cmpset_rel_32(&mtx->m_owner,
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owner, UMUTEX_UNOWNED)));
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if ((owner & UMUTEX_CONTESTED)) {
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if (defer == NULL)
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(void)_umtx_op_err(mtx, UMTX_OP_MUTEX_WAKE2, flags, 0, 0);
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else
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*defer = 1;
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}
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return (0);
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}
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if (atomic_cmpset_rel_32(&mtx->m_owner, id, UMUTEX_UNOWNED))
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return (0);
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return (__thr_umutex_unlock(mtx, id));
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}
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static inline int
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_thr_umutex_unlock(struct umutex *mtx, uint32_t id)
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{
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return _thr_umutex_unlock2(mtx, id, NULL);
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}
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static inline int
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_thr_rwlock_tryrdlock(struct urwlock *rwlock, int flags)
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{
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int32_t state;
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int32_t wrflags;
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if (flags & URWLOCK_PREFER_READER || rwlock->rw_flags & URWLOCK_PREFER_READER)
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wrflags = URWLOCK_WRITE_OWNER;
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else
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wrflags = URWLOCK_WRITE_OWNER | URWLOCK_WRITE_WAITERS;
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state = rwlock->rw_state;
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while (!(state & wrflags)) {
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if (__predict_false(URWLOCK_READER_COUNT(state) == URWLOCK_MAX_READERS))
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return (EAGAIN);
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if (atomic_cmpset_acq_32(&rwlock->rw_state, state, state + 1))
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return (0);
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state = rwlock->rw_state;
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}
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return (EBUSY);
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}
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static inline int
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_thr_rwlock_trywrlock(struct urwlock *rwlock)
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{
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int32_t state;
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state = rwlock->rw_state;
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while (!(state & URWLOCK_WRITE_OWNER) && URWLOCK_READER_COUNT(state) == 0) {
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if (atomic_cmpset_acq_32(&rwlock->rw_state, state, state | URWLOCK_WRITE_OWNER))
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return (0);
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state = rwlock->rw_state;
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}
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return (EBUSY);
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}
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static inline int
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_thr_rwlock_rdlock(struct urwlock *rwlock, int flags, struct timespec *tsp)
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{
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if (_thr_rwlock_tryrdlock(rwlock, flags) == 0)
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return (0);
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return (__thr_rwlock_rdlock(rwlock, flags, tsp));
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}
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static inline int
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_thr_rwlock_wrlock(struct urwlock *rwlock, struct timespec *tsp)
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{
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if (_thr_rwlock_trywrlock(rwlock) == 0)
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return (0);
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return (__thr_rwlock_wrlock(rwlock, tsp));
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}
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static inline int
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_thr_rwlock_unlock(struct urwlock *rwlock)
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{
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int32_t state;
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state = rwlock->rw_state;
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if (state & URWLOCK_WRITE_OWNER) {
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if (atomic_cmpset_rel_32(&rwlock->rw_state, URWLOCK_WRITE_OWNER, 0))
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return (0);
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} else {
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for (;;) {
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if (__predict_false(URWLOCK_READER_COUNT(state) == 0))
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return (EPERM);
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if (!((state & (URWLOCK_WRITE_WAITERS |
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URWLOCK_READ_WAITERS)) &&
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URWLOCK_READER_COUNT(state) == 1)) {
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if (atomic_cmpset_rel_32(&rwlock->rw_state,
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state, state-1))
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return (0);
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state = rwlock->rw_state;
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} else {
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break;
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}
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}
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}
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return (__thr_rwlock_unlock(rwlock));
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}
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#endif
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