155 lines
3.5 KiB
C
155 lines
3.5 KiB
C
/*-
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* Copyright (c) 2003 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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#include <errno.h>
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#include <stdlib.h>
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#include <pthread.h>
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#include <atomic_ops.h>
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#include "thr_private.h"
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#define SPIN_COUNT 10000
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int
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pthread_spin_init(pthread_spinlock_t *lock, int pshared)
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{
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struct pthread_spinlock *lck;
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int ret;
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if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
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ret = EINVAL;
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else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL)
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ret = ENOMEM;
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else {
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lck->s_lock = 0;
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lck->s_owner= NULL;
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*lock = lck;
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ret = 0;
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}
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return (ret);
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}
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int
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pthread_spin_destroy(pthread_spinlock_t *lock)
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{
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int ret;
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if (lock == NULL || *lock == NULL)
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ret = EINVAL;
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else if ((*lock)->s_owner != NULL)
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ret = EBUSY;
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else {
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free(*lock);
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*lock = NULL;
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ret = 0;
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}
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return (ret);
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}
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int
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pthread_spin_trylock(pthread_spinlock_t *lock)
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{
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struct pthread_spinlock *lck;
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struct pthread *self = _pthread_self();
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int oldval, ret;
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if (lock == NULL || (lck = *lock) == NULL)
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ret = EINVAL;
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else if (lck->s_owner == self)
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ret = EDEADLK;
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else if (lck->s_lock != 0)
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ret = EBUSY;
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else {
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atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
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if (oldval)
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ret = EBUSY;
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else {
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lck->s_owner = _pthread_self();
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ret = 0;
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}
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}
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return (ret);
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}
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int
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pthread_spin_lock(pthread_spinlock_t *lock)
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{
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struct pthread_spinlock *lck;
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struct pthread *self = _pthread_self();
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int count, oldval, ret;
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if (lock == NULL || (lck = *lock) == NULL)
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ret = EINVAL;
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else if (lck->s_owner == self)
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ret = EDEADLK;
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else {
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do {
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count = SPIN_COUNT;
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while (lck->s_lock) {
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#ifdef __i386__
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/* tell cpu we are spinning */
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__asm __volatile("pause");
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#endif
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if (--count <= 0) {
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count = SPIN_COUNT;
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_pthread_yield();
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}
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}
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atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
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} while (oldval);
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lck->s_owner = self;
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ret = 0;
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}
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return (ret);
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}
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int
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pthread_spin_unlock(pthread_spinlock_t *lock)
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{
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struct pthread_spinlock *lck;
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int ret;
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if (lock == NULL || (lck = *lock) == NULL)
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ret = EINVAL;
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else {
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if (lck->s_owner != _pthread_self())
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ret = EPERM;
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else {
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lck->s_owner = NULL;
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atomic_swap_int((int *)&lck->s_lock, 0, &ret);
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ret = 0;
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}
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}
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return (ret);
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}
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