diff options
Diffstat (limited to 'lib/libpthread/thread/thr_pspinlock.c')
| -rw-r--r-- | lib/libpthread/thread/thr_pspinlock.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/lib/libpthread/thread/thr_pspinlock.c b/lib/libpthread/thread/thr_pspinlock.c new file mode 100644 index 0000000..b58d712 --- /dev/null +++ b/lib/libpthread/thread/thr_pspinlock.c @@ -0,0 +1,160 @@ +/*- + * Copyright (c) 2003 David Xu <davidxu@freebsd.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include <errno.h> +#include <stdlib.h> +#include <pthread.h> +#include <atomic_ops.h> +#include "thr_private.h" + +#define SPIN_COUNT 10000 + +__weak_reference(_pthread_spin_init, pthread_spin_init); +__weak_reference(_pthread_spin_destroy, pthread_spin_destroy); +__weak_reference(_pthread_spin_trylock, pthread_spin_trylock); +__weak_reference(_pthread_spin_lock, pthread_spin_lock); +__weak_reference(_pthread_spin_unlock, pthread_spin_unlock); + +int +_pthread_spin_init(pthread_spinlock_t *lock, int pshared) +{ + struct pthread_spinlock *lck; + int ret; + + if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE) + ret = EINVAL; + else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL) + ret = ENOMEM; + else { + lck->s_lock = 0; + lck->s_owner= NULL; + *lock = lck; + ret = 0; + } + + return (ret); +} + +int +_pthread_spin_destroy(pthread_spinlock_t *lock) +{ + int ret; + + if (lock == NULL || *lock == NULL) + ret = EINVAL; + else if ((*lock)->s_owner != NULL) + ret = EBUSY; + else { + free(*lock); + *lock = NULL; + ret = 0; + } + + return (ret); +} + +int +_pthread_spin_trylock(pthread_spinlock_t *lock) +{ + struct pthread_spinlock *lck; + struct pthread *self = _pthread_self(); + int oldval, ret; + + if (lock == NULL || (lck = *lock) == NULL) + ret = EINVAL; + else if (lck->s_owner == self) + ret = EDEADLK; + else if (lck->s_lock != 0) + ret = EBUSY; + else { + atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval); + if (oldval) + ret = EBUSY; + else { + lck->s_owner = _pthread_self(); + ret = 0; + } + } + return (ret); +} + +int +_pthread_spin_lock(pthread_spinlock_t *lock) +{ + struct pthread_spinlock *lck; + struct pthread *self = _pthread_self(); + int count, oldval, ret; + + if (lock == NULL || (lck = *lock) == NULL) + ret = EINVAL; + else if (lck->s_owner == self) + ret = EDEADLK; + else { + do { + count = SPIN_COUNT; + while (lck->s_lock) { +#ifdef __i386__ + /* tell cpu we are spinning */ + __asm __volatile("pause"); +#endif + if (--count <= 0) { + count = SPIN_COUNT; + _pthread_yield(); + } + } + atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval); + } while (oldval); + + lck->s_owner = self; + ret = 0; + } + + return (ret); +} + +int +_pthread_spin_unlock(pthread_spinlock_t *lock) +{ + struct pthread_spinlock *lck; + int ret; + + if (lock == NULL || (lck = *lock) == NULL) + ret = EINVAL; + else { + if (lck->s_owner != _pthread_self()) + ret = EPERM; + else { + lck->s_owner = NULL; + atomic_swap_int((int *)&lck->s_lock, 0, &ret); + ret = 0; + } + } + + return (ret); +} + |
