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 * $DragonFly: src/lib/libthread_xu/thread/thr_sem.c,v 1.6 2007/06/26 23:30:05 josepht Exp $
33 #include "namespace.h"
34 #include <machine/tls.h>
35 #include <sys/semaphore.h>
42 #include "un-namespace.h"
43 #include "thr_private.h"
46 * Semaphore definitions.
49 #define SEM_MAGIC ((u_int32_t) 0x09fa4012)
51 volatile umtx_t count;
52 int semid; /* kernel based semaphore id. */
56 sem_check_validity(sem_t *sem)
59 if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC))
68 sem_alloc(unsigned int value, int semid)
72 if (value > SEM_VALUE_MAX) {
77 sem = (sem_t)malloc(sizeof(struct sem));
82 sem->magic = SEM_MAGIC;
83 sem->count = (u_int32_t)value;
89 _sem_init(sem_t *sem, int pshared, unsigned int value)
93 * We really can support pshared, but sem_t was
94 * defined as a pointer, if it is a structure,
95 * it will work between processes.
101 (*sem) = sem_alloc(value, -1);
108 _sem_destroy(sem_t *sem)
110 if (sem_check_validity(sem) != 0)
118 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
120 if (sem_check_validity(sem) != 0)
123 *sval = (*sem)->count;
128 _sem_trywait(sem_t *sem)
132 if (sem_check_validity(sem) != 0)
135 while ((val = (*sem)->count) > 0) {
136 if (atomic_cmpset_int(&(*sem)->count, val, val - 1))
144 _sem_wait(sem_t *sem)
146 struct pthread *curthread;
147 int val, oldcancel, retval;
149 if (sem_check_validity(sem) != 0)
152 curthread = tls_get_curthread();
153 _pthread_testcancel();
155 while ((val = (*sem)->count) > 0) {
156 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
159 oldcancel = _thr_cancel_enter(curthread);
160 retval = _thr_umtx_wait(&(*sem)->count, 0, NULL, 0);
161 _thr_cancel_leave(curthread, oldcancel);
162 } while (retval == 0);
169 _sem_timedwait(sem_t * __restrict sem, struct timespec * __restrict abstime)
171 struct timespec ts, ts2;
172 struct pthread *curthread;
173 int val, oldcancel, retval;
175 if (sem_check_validity(sem) != 0)
178 curthread = tls_get_curthread();
181 * The timeout argument is only supposed to
182 * be checked if the thread would have blocked.
184 _pthread_testcancel();
186 while ((val = (*sem)->count) > 0) {
187 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
190 if (abstime == NULL) {
194 clock_gettime(CLOCK_REALTIME, &ts);
195 TIMESPEC_SUB(&ts2, abstime, &ts);
196 oldcancel = _thr_cancel_enter(curthread);
197 retval = _thr_umtx_wait(&(*sem)->count, 0, &ts2,
199 _thr_cancel_leave(curthread, oldcancel);
200 } while (retval == 0);
207 _sem_post(sem_t *sem)
211 if (sem_check_validity(sem) != 0)
215 * sem_post() is required to be safe to call from within
216 * signal handlers, these code should work as that.
220 } while (!atomic_cmpset_acq_int(&(*sem)->count, val, val + 1));
221 _thr_umtx_wake(&(*sem)->count, val + 1);
225 __strong_reference(_sem_destroy, sem_destroy);
226 __strong_reference(_sem_getvalue, sem_getvalue);
227 __strong_reference(_sem_init, sem_init);
228 __strong_reference(_sem_trywait, sem_trywait);
229 __strong_reference(_sem_wait, sem_wait);
231 __strong_reference(_sem_timedwait, sem_timedwait);
233 __strong_reference(_sem_post, sem_post);