2 * Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice(s), this list of conditions and the following disclaimer as
10 * the first lines of this file unmodified other than the possible
11 * addition of one or more copyright notices.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice(s), this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
21 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
24 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
25 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
26 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 #include <semaphore.h>
36 #include "thr_private.h"
38 #define _SEM_CHECK_VALIDITY(sem) \
39 if ((*(sem))->magic != SEM_MAGIC) { \
45 __weak_reference(_sem_init, sem_init);
46 __weak_reference(_sem_destroy, sem_destroy);
47 __weak_reference(_sem_open, sem_open);
48 __weak_reference(_sem_close, sem_close);
49 __weak_reference(_sem_unlink, sem_unlink);
50 __weak_reference(_sem_wait, sem_wait);
51 __weak_reference(_sem_trywait, sem_trywait);
52 __weak_reference(_sem_post, sem_post);
53 __weak_reference(_sem_getvalue, sem_getvalue);
57 _sem_init(sem_t *sem, int pshared, unsigned int value)
62 * Range check the arguments.
66 * The user wants a semaphore that can be shared among
67 * processes, which this implementation can't do. Sounds like a
68 * permissions problem to me (yeah right).
75 if (value > SEM_VALUE_MAX) {
81 *sem = (sem_t)malloc(sizeof(struct sem));
89 * Initialize the semaphore.
91 if (pthread_mutex_init(&(*sem)->lock, NULL) != 0) {
98 if (pthread_cond_init(&(*sem)->gtzero, NULL) != 0) {
99 pthread_mutex_destroy(&(*sem)->lock);
106 (*sem)->count = (u_int32_t)value;
107 (*sem)->nwaiters = 0;
108 (*sem)->magic = SEM_MAGIC;
116 _sem_destroy(sem_t *sem)
120 _SEM_CHECK_VALIDITY(sem);
122 /* Make sure there are no waiters. */
123 pthread_mutex_lock(&(*sem)->lock);
124 if ((*sem)->nwaiters > 0) {
125 pthread_mutex_unlock(&(*sem)->lock);
130 pthread_mutex_unlock(&(*sem)->lock);
132 pthread_mutex_destroy(&(*sem)->lock);
133 pthread_cond_destroy(&(*sem)->gtzero);
144 _sem_open(const char *name, int oflag, ...)
151 _sem_close(sem_t *sem)
158 _sem_unlink(const char *name)
165 _sem_wait(sem_t *sem)
169 _thread_enter_cancellation_point();
171 _SEM_CHECK_VALIDITY(sem);
173 pthread_mutex_lock(&(*sem)->lock);
175 while ((*sem)->count == 0) {
177 pthread_cond_wait(&(*sem)->gtzero, &(*sem)->lock);
182 pthread_mutex_unlock(&(*sem)->lock);
186 _thread_leave_cancellation_point();
191 _sem_trywait(sem_t *sem)
195 _SEM_CHECK_VALIDITY(sem);
197 pthread_mutex_lock(&(*sem)->lock);
199 if ((*sem)->count > 0) {
207 pthread_mutex_unlock(&(*sem)->lock);
214 _sem_post(sem_t *sem)
218 _SEM_CHECK_VALIDITY(sem);
221 * sem_post() is required to be safe to call from within signal
222 * handlers. Thus, we must defer signals.
224 pthread_mutex_lock(&(*sem)->lock);
226 /* GIANT_LOCK(curthread); */
229 if ((*sem)->nwaiters > 0)
230 pthread_cond_signal(&(*sem)->gtzero);
232 /* GIANT_UNLOCK(curthread); */
234 pthread_mutex_unlock(&(*sem)->lock);
242 _sem_getvalue(sem_t *sem, int *sval)
246 _SEM_CHECK_VALIDITY(sem);
248 pthread_mutex_lock(&(*sem)->lock);
249 *sval = (int)(*sem)->count;
250 pthread_mutex_unlock(&(*sem)->lock);