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>
43 #include "un-namespace.h"
44 #include "thr_private.h"
47 * Semaphore definitions.
51 volatile umtx_t count;
56 #define SEM_MAGIC ((u_int32_t) 0x09fa4012)
62 sem_check_validity(sem_t *sem)
65 if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC)) {
74 sem_alloc(unsigned int value, int pshared)
79 if (value > SEM_VALUE_MAX) {
84 static __thread sem_t sem_base;
85 static __thread int sem_count;
87 if (sem_base == NULL) {
88 sem_base = mmap(NULL, getpagesize(),
89 PROT_READ | PROT_WRITE,
90 MAP_ANON | MAP_SHARED,
92 sem_count = getpagesize() / sizeof(*sem);
99 sem = malloc(sizeof(struct sem));
106 sem->magic = SEM_MAGIC;
107 sem->count = (u_int32_t)value;
113 _sem_init(sem_t *sem, int pshared, unsigned int value)
115 (*sem) = sem_alloc(value, pshared);
122 _sem_destroy(sem_t *sem)
124 if (sem_check_validity(sem) != 0)
129 switch ((*sem)->semid) {
134 /* memory is left intact */
141 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
143 if (sem_check_validity(sem) != 0)
146 *sval = (*sem)->count;
151 _sem_trywait(sem_t *sem)
155 if (sem_check_validity(sem) != 0)
158 while ((val = (*sem)->count) > 0) {
159 if (atomic_cmpset_int(&(*sem)->count, val, val - 1))
167 _sem_wait(sem_t *sem)
169 struct pthread *curthread;
170 int val, oldcancel, retval;
172 if (sem_check_validity(sem) != 0)
175 curthread = tls_get_curthread();
176 _pthread_testcancel();
178 while ((val = (*sem)->count) > 0) {
179 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
182 oldcancel = _thr_cancel_enter(curthread);
183 retval = _thr_umtx_wait(&(*sem)->count, 0, NULL, 0);
184 _thr_cancel_leave(curthread, oldcancel);
185 } while (retval == 0);
192 _sem_timedwait(sem_t * __restrict sem, struct timespec * __restrict abstime)
194 struct timespec ts, ts2;
195 struct pthread *curthread;
196 int val, oldcancel, retval;
198 if (sem_check_validity(sem) != 0)
201 curthread = tls_get_curthread();
204 * The timeout argument is only supposed to
205 * be checked if the thread would have blocked.
207 _pthread_testcancel();
209 while ((val = (*sem)->count) > 0) {
210 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
213 if (abstime == NULL) {
217 clock_gettime(CLOCK_REALTIME, &ts);
218 TIMESPEC_SUB(&ts2, abstime, &ts);
219 oldcancel = _thr_cancel_enter(curthread);
220 retval = _thr_umtx_wait(&(*sem)->count, 0, &ts2,
222 _thr_cancel_leave(curthread, oldcancel);
223 } while (retval == 0);
230 _sem_post(sem_t *sem)
234 if (sem_check_validity(sem) != 0)
238 * sem_post() is required to be safe to call from within
239 * signal handlers, these code should work as that.
243 } while (!atomic_cmpset_acq_int(&(*sem)->count, val, val + 1));
244 _thr_umtx_wake(&(*sem)->count, val + 1);
248 __strong_reference(_sem_destroy, sem_destroy);
249 __strong_reference(_sem_getvalue, sem_getvalue);
250 __strong_reference(_sem_init, sem_init);
251 __strong_reference(_sem_trywait, sem_trywait);
252 __strong_reference(_sem_wait, sem_wait);
254 __strong_reference(_sem_timedwait, sem_timedwait);
256 __strong_reference(_sem_post, sem_post);