freebsd-dev/lib/libpthread/thread/thr_sem.c

268 lines
6.2 KiB
C

/*
* Copyright (C) 2000 Jason Evans <jasone@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(s), this list of conditions and the following disclaimer as
* the first lines of this file unmodified other than the possible
* addition of one or more copyright notices.
* 2. Redistributions in binary form must reproduce the above copyright
* notice(s), 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 COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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 "namespace.h"
#include <sys/types.h>
#include <sys/queue.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <semaphore.h>
#include <stdlib.h>
#include <time.h>
#include <_semaphore.h>
#include "un-namespace.h"
#include "libc_private.h"
#include "thr_private.h"
LT10_COMPAT_PRIVATE(_sem_init);
LT10_COMPAT_DEFAULT(sem_init);
LT10_COMPAT_PRIVATE(_sem_wait);
LT10_COMPAT_DEFAULT(sem_wait);
LT10_COMPAT_PRIVATE(_sem_timedwait);
LT10_COMPAT_DEFAULT(sem_timedwait);
LT10_COMPAT_PRIVATE(_sem_post);
LT10_COMPAT_DEFAULT(sem_post);
__weak_reference(_sem_init, sem_init);
__weak_reference(_sem_wait, sem_wait);
__weak_reference(_sem_timedwait, sem_timedwait);
__weak_reference(_sem_post, sem_post);
static inline int
sem_check_validity(sem_t *sem)
{
if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC))
return (0);
else {
errno = EINVAL;
return (-1);
}
}
static void
decrease_nwaiters(void *arg)
{
sem_t *sem = (sem_t *)arg;
(*sem)->nwaiters--;
/*
* this function is called from cancellation point,
* the mutex should already be hold.
*/
_pthread_mutex_unlock(&(*sem)->lock);
}
static sem_t
sem_alloc(unsigned int value, semid_t semid, int system_sem)
{
sem_t sem;
if (value > SEM_VALUE_MAX) {
errno = EINVAL;
return (NULL);
}
sem = (sem_t)malloc(sizeof(struct sem));
if (sem == NULL) {
errno = ENOSPC;
return (NULL);
}
/*
* Initialize the semaphore.
*/
if (_pthread_mutex_init(&sem->lock, NULL) != 0) {
free(sem);
errno = ENOSPC;
return (NULL);
}
if (_pthread_cond_init(&sem->gtzero, NULL) != 0) {
_pthread_mutex_destroy(&sem->lock);
free(sem);
errno = ENOSPC;
return (NULL);
}
sem->count = (u_int32_t)value;
sem->nwaiters = 0;
sem->magic = SEM_MAGIC;
sem->semid = semid;
sem->syssem = system_sem;
return (sem);
}
int
_sem_init(sem_t *sem, int pshared, unsigned int value)
{
semid_t semid;
semid = (semid_t)SEM_USER;
if ((pshared != 0) && (ksem_init(&semid, value) != 0))
return (-1);
(*sem) = sem_alloc(value, semid, pshared);
if ((*sem) == NULL) {
if (pshared != 0)
ksem_destroy(semid);
return (-1);
}
return (0);
}
int
_sem_wait(sem_t *sem)
{
struct pthread *curthread;
int retval;
if (sem_check_validity(sem) != 0)
return (-1);
curthread = _get_curthread();
if ((*sem)->syssem != 0) {
_thr_cancel_enter(curthread);
retval = ksem_wait((*sem)->semid);
_thr_cancel_leave(curthread, retval != 0);
}
else {
_pthread_testcancel();
_pthread_mutex_lock(&(*sem)->lock);
while ((*sem)->count <= 0) {
(*sem)->nwaiters++;
THR_CLEANUP_PUSH(curthread, decrease_nwaiters, sem);
_pthread_cond_wait(&(*sem)->gtzero, &(*sem)->lock);
THR_CLEANUP_POP(curthread, 0);
(*sem)->nwaiters--;
}
(*sem)->count--;
_pthread_mutex_unlock(&(*sem)->lock);
retval = 0;
}
return (retval);
}
int
_sem_timedwait(sem_t * __restrict sem,
const struct timespec * __restrict abs_timeout)
{
struct pthread *curthread;
int retval;
int timeout_invalid;
if (sem_check_validity(sem) != 0)
return (-1);
if ((*sem)->syssem != 0) {
curthread = _get_curthread();
_thr_cancel_enter(curthread);
retval = ksem_timedwait((*sem)->semid, abs_timeout);
_thr_cancel_leave(curthread, retval != 0);
}
else {
/*
* The timeout argument is only supposed to
* be checked if the thread would have blocked.
* This is checked outside of the lock so a
* segfault on an invalid address doesn't end
* up leaving the mutex locked.
*/
_pthread_testcancel();
timeout_invalid = (abs_timeout->tv_nsec >= 1000000000) ||
(abs_timeout->tv_nsec < 0);
_pthread_mutex_lock(&(*sem)->lock);
if ((*sem)->count <= 0) {
if (timeout_invalid) {
_pthread_mutex_unlock(&(*sem)->lock);
errno = EINVAL;
return (-1);
}
(*sem)->nwaiters++;
_pthread_cleanup_push(decrease_nwaiters, sem);
_pthread_cond_timedwait(&(*sem)->gtzero,
&(*sem)->lock, abs_timeout);
_pthread_cleanup_pop(0);
(*sem)->nwaiters--;
}
if ((*sem)->count == 0) {
errno = ETIMEDOUT;
retval = -1;
}
else {
(*sem)->count--;
retval = 0;
}
_pthread_mutex_unlock(&(*sem)->lock);
}
return (retval);
}
int
_sem_post(sem_t *sem)
{
struct pthread *curthread;
int retval;
if (sem_check_validity(sem) != 0)
return (-1);
if ((*sem)->syssem != 0)
retval = ksem_post((*sem)->semid);
else {
/*
* sem_post() is required to be safe to call from within
* signal handlers. Thus, we must enter a critical region.
*/
curthread = _get_curthread();
_thr_critical_enter(curthread);
_pthread_mutex_lock(&(*sem)->lock);
(*sem)->count++;
if ((*sem)->nwaiters > 0)
_pthread_cond_signal(&(*sem)->gtzero);
_pthread_mutex_unlock(&(*sem)->lock);
_thr_critical_leave(curthread);
retval = 0;
}
return (retval);
}