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 1.2 2005/03/15 11:24:23 davidxu Exp $
34 #include <sys/queue.h>
38 #include <semaphore.h>
42 #include "thr_private.h"
44 __weak_reference(_sem_close, sem_close);
45 __weak_reference(_sem_destroy, sem_destroy);
46 __weak_reference(_sem_getvalue, sem_getvalue);
47 __weak_reference(_sem_init, sem_init);
48 __weak_reference(_sem_open, sem_open);
49 __weak_reference(_sem_trywait, sem_trywait);
50 __weak_reference(_sem_wait, sem_wait);
51 __weak_reference(_sem_timedwait, sem_timedwait);
52 __weak_reference(_sem_post, sem_post);
53 __weak_reference(_sem_unlink, sem_unlink);
56 * Semaphore definitions.
59 #define SEM_MAGIC ((u_int32_t) 0x09fa4012)
61 volatile umtx_t count;
62 int semid; /* kernel based semaphore id. */
66 sem_check_validity(sem_t *sem)
69 if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC))
78 sem_alloc(unsigned int value, int semid)
82 if (value > SEM_VALUE_MAX) {
87 sem = (sem_t)malloc(sizeof(struct sem));
92 sem->magic = SEM_MAGIC;
93 sem->count = (u_int32_t)value;
99 _sem_init(sem_t *sem, int pshared, unsigned int value)
103 * We really can support pshared, but sem_t was
104 * defined as a pointer, if it is a structure,
105 * it will work between processes.
111 (*sem) = sem_alloc(value, -1);
118 _sem_destroy(sem_t *sem)
120 if (sem_check_validity(sem) != 0)
128 _sem_open(const char *name, int oflag, ...)
135 _sem_close(sem_t *sem)
142 _sem_unlink(const char *name)
149 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
151 if (sem_check_validity(sem) != 0)
154 *sval = (*sem)->count;
159 _sem_trywait(sem_t *sem)
163 if (sem_check_validity(sem) != 0)
166 while ((val = (*sem)->count) > 0) {
167 if (atomic_cmpset_int(&(*sem)->count, val, val - 1))
175 _sem_wait(sem_t *sem)
177 struct pthread *curthread;
178 int val, oldcancel, retval;
180 if (sem_check_validity(sem) != 0)
183 curthread = _get_curthread();
184 _pthread_testcancel();
186 while ((val = (*sem)->count) > 0) {
187 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
190 oldcancel = _thr_cancel_enter(curthread);
191 retval = _thr_umtx_wait(&(*sem)->count, 0, NULL, 0);
192 _thr_cancel_leave(curthread, oldcancel);
193 } while (retval == 0);
199 _sem_timedwait(sem_t * __restrict sem, struct timespec * __restrict abstime)
201 struct timespec ts, ts2;
202 struct pthread *curthread;
203 int val, oldcancel, retval;
205 if (sem_check_validity(sem) != 0)
208 curthread = _get_curthread();
211 * The timeout argument is only supposed to
212 * be checked if the thread would have blocked.
214 _pthread_testcancel();
216 while ((val = (*sem)->count) > 0) {
217 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
220 if (abstime == NULL) {
224 clock_gettime(CLOCK_REALTIME, &ts);
225 TIMESPEC_SUB(&ts2, abstime, &ts);
226 oldcancel = _thr_cancel_enter(curthread);
227 retval = _thr_umtx_wait(&(*sem)->count, 0, &ts2,
229 _thr_cancel_leave(curthread, oldcancel);
230 } while (retval == 0);
236 _sem_post(sem_t *sem)
240 if (sem_check_validity(sem) != 0)
244 * sem_post() is required to be safe to call from within
245 * signal handlers, these code should work as that.
249 } while (!atomic_cmpset_acq_int(&(*sem)->count, val, val + 1));
250 _thr_umtx_wake(&(*sem)->count, val + 1);