2 * Copyright (C) 2005 David Xu <davidxu@freebsd.org>.
3 * Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice(s), this list of conditions and the following disclaimer as
11 * the first lines of this file unmodified other than the possible
12 * addition of one or more copyright notices.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice(s), this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
19 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
25 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
26 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
27 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
28 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 * $FreeBSD: src/lib/libpthread/thread/thr_sem.c,v 1.16 2004/12/18 18:07:37 deischen Exp $
31 * $DragonFly: src/lib/libthread_xu/thread/thr_sem.c,v 1.3 2005/03/29 19:26:20 joerg Exp $
34 #include <sys/queue.h>
36 #include <machine/tls.h>
41 #include <semaphore.h>
45 #include "thr_private.h"
47 __weak_reference(_sem_close, sem_close);
48 __weak_reference(_sem_destroy, sem_destroy);
49 __weak_reference(_sem_getvalue, sem_getvalue);
50 __weak_reference(_sem_init, sem_init);
51 __weak_reference(_sem_open, sem_open);
52 __weak_reference(_sem_trywait, sem_trywait);
53 __weak_reference(_sem_wait, sem_wait);
54 __weak_reference(_sem_timedwait, sem_timedwait);
55 __weak_reference(_sem_post, sem_post);
56 __weak_reference(_sem_unlink, sem_unlink);
59 * Semaphore definitions.
62 #define SEM_MAGIC ((u_int32_t) 0x09fa4012)
64 volatile umtx_t count;
65 int semid; /* kernel based semaphore id. */
69 sem_check_validity(sem_t *sem)
72 if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC))
81 sem_alloc(unsigned int value, int semid)
85 if (value > SEM_VALUE_MAX) {
90 sem = (sem_t)malloc(sizeof(struct sem));
95 sem->magic = SEM_MAGIC;
96 sem->count = (u_int32_t)value;
102 _sem_init(sem_t *sem, int pshared, unsigned int value)
106 * We really can support pshared, but sem_t was
107 * defined as a pointer, if it is a structure,
108 * it will work between processes.
114 (*sem) = sem_alloc(value, -1);
121 _sem_destroy(sem_t *sem)
123 if (sem_check_validity(sem) != 0)
131 _sem_open(const char *name, int oflag, ...)
138 _sem_close(sem_t *sem)
145 _sem_unlink(const char *name)
152 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
154 if (sem_check_validity(sem) != 0)
157 *sval = (*sem)->count;
162 _sem_trywait(sem_t *sem)
166 if (sem_check_validity(sem) != 0)
169 while ((val = (*sem)->count) > 0) {
170 if (atomic_cmpset_int(&(*sem)->count, val, val - 1))
178 _sem_wait(sem_t *sem)
180 struct pthread *curthread;
181 int val, oldcancel, retval;
183 if (sem_check_validity(sem) != 0)
186 curthread = tls_get_curthread();
187 _pthread_testcancel();
189 while ((val = (*sem)->count) > 0) {
190 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
193 oldcancel = _thr_cancel_enter(curthread);
194 retval = _thr_umtx_wait(&(*sem)->count, 0, NULL, 0);
195 _thr_cancel_leave(curthread, oldcancel);
196 } while (retval == 0);
202 _sem_timedwait(sem_t * __restrict sem, struct timespec * __restrict abstime)
204 struct timespec ts, ts2;
205 struct pthread *curthread;
206 int val, oldcancel, retval;
208 if (sem_check_validity(sem) != 0)
211 curthread = tls_get_curthread();
214 * The timeout argument is only supposed to
215 * be checked if the thread would have blocked.
217 _pthread_testcancel();
219 while ((val = (*sem)->count) > 0) {
220 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
223 if (abstime == NULL) {
227 clock_gettime(CLOCK_REALTIME, &ts);
228 TIMESPEC_SUB(&ts2, abstime, &ts);
229 oldcancel = _thr_cancel_enter(curthread);
230 retval = _thr_umtx_wait(&(*sem)->count, 0, &ts2,
232 _thr_cancel_leave(curthread, oldcancel);
233 } while (retval == 0);
239 _sem_post(sem_t *sem)
243 if (sem_check_validity(sem) != 0)
247 * sem_post() is required to be safe to call from within
248 * signal handlers, these code should work as that.
252 } while (!atomic_cmpset_acq_int(&(*sem)->count, val, val + 1));
253 _thr_umtx_wake(&(*sem)->count, val + 1);