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
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28 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 #include "namespace.h"
34 #include <sys/types.h>
35 #include <sys/queue.h>
39 #include <semaphore.h>
42 #include <_semaphore.h>
43 #include "un-namespace.h"
45 #include "thr_private.h"
48 __weak_reference(_sem_init, sem_init);
49 __weak_reference(_sem_destroy, sem_destroy);
50 __weak_reference(_sem_getvalue, sem_getvalue);
51 __weak_reference(_sem_trywait, sem_trywait);
52 __weak_reference(_sem_wait, sem_wait);
53 __weak_reference(_sem_timedwait, sem_timedwait);
54 __weak_reference(_sem_post, sem_post);
58 sem_check_validity(sem_t *sem)
61 if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC))
70 sem_alloc(unsigned int value, semid_t semid, int system_sem)
74 if (value > SEM_VALUE_MAX) {
79 sem = (sem_t)malloc(sizeof(struct sem));
84 bzero(sem, sizeof(*sem));
86 * Fortunatly count and nwaiters are adjacency, so we can
87 * use umtx_wait to wait on it, umtx_wait needs an address
88 * can be accessed as a long interger.
90 sem->count = (u_int32_t)value;
92 sem->magic = SEM_MAGIC;
94 sem->syssem = system_sem;
99 _sem_init(sem_t *sem, int pshared, unsigned int value)
103 semid = (semid_t)SEM_USER;
104 if ((pshared != 0) && (ksem_init(&semid, value) != 0))
107 (*sem) = sem_alloc(value, semid, pshared);
108 if ((*sem) == NULL) {
117 _sem_destroy(sem_t *sem)
121 if (sem_check_validity(sem) != 0)
125 * If this is a system semaphore let the kernel track it otherwise
126 * make sure there are no waiters.
128 if ((*sem)->syssem != 0)
129 retval = ksem_destroy((*sem)->semid);
140 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
144 if (sem_check_validity(sem) != 0)
147 if ((*sem)->syssem != 0)
148 retval = ksem_getvalue((*sem)->semid, sval);
150 *sval = (int)(*sem)->count;
157 _sem_trywait(sem_t *sem)
161 if (sem_check_validity(sem) != 0)
164 if ((*sem)->syssem != 0)
165 return (ksem_trywait((*sem)->semid));
167 while ((val = (*sem)->count) > 0) {
168 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
176 sem_cancel_handler(void *arg)
180 atomic_add_int(&(*sem)->nwaiters, -1);
181 if ((*sem)->nwaiters && (*sem)->count)
182 _thr_umtx_wake(&(*sem)->count, 1, 0);
186 _sem_wait(sem_t *sem)
188 struct pthread *curthread;
191 if (sem_check_validity(sem) != 0)
194 curthread = _get_curthread();
195 if ((*sem)->syssem != 0) {
196 _thr_cancel_enter(curthread);
197 retval = ksem_wait((*sem)->semid);
198 _thr_cancel_leave(curthread);
202 _pthread_testcancel();
204 while ((val = (*sem)->count) > 0) {
205 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
208 atomic_add_int(&(*sem)->nwaiters, 1);
209 THR_CLEANUP_PUSH(curthread, sem_cancel_handler, sem);
210 _thr_cancel_enter(curthread);
211 retval = _thr_umtx_wait_uint(&(*sem)->count, 0, NULL, 0);
212 _thr_cancel_leave(curthread);
213 THR_CLEANUP_POP(curthread, 0);
214 atomic_add_int(&(*sem)->nwaiters, -1);
215 } while (retval == 0);
221 _sem_timedwait(sem_t * __restrict sem,
222 const struct timespec * __restrict abstime)
224 struct timespec ts, ts2;
225 struct pthread *curthread;
228 if (sem_check_validity(sem) != 0)
231 curthread = _get_curthread();
232 if ((*sem)->syssem != 0) {
233 _thr_cancel_enter(curthread);
234 retval = ksem_timedwait((*sem)->semid, abstime);
235 _thr_cancel_leave(curthread);
240 * The timeout argument is only supposed to
241 * be checked if the thread would have blocked.
243 _pthread_testcancel();
245 while ((val = (*sem)->count) > 0) {
246 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
249 if (abstime == NULL) {
253 clock_gettime(CLOCK_REALTIME, &ts);
254 TIMESPEC_SUB(&ts2, abstime, &ts);
255 atomic_add_int(&(*sem)->nwaiters, 1);
256 THR_CLEANUP_PUSH(curthread, sem_cancel_handler, sem);
257 _thr_cancel_enter(curthread);
258 retval = _thr_umtx_wait_uint((uint32_t*)&(*sem)->count, 0, &ts2, 0);
259 _thr_cancel_leave(curthread);
260 THR_CLEANUP_POP(curthread, 0);
261 atomic_add_int(&(*sem)->nwaiters, -1);
262 } while (retval == 0);
268 * sem_post() is required to be safe to call from within
269 * signal handlers, these code should work as that.
273 _sem_post(sem_t *sem)
277 if (sem_check_validity(sem) != 0)
280 if ((*sem)->syssem != 0)
281 return (ksem_post((*sem)->semid));
283 atomic_add_rel_int(&(*sem)->count, 1);
285 if ((*sem)->nwaiters) {
286 retval = _thr_umtx_wake(&(*sem)->count, 1, 0);