libthread_xu: Implement stub sem_open/sem_close/sem_unlink.
[dragonfly.git] / lib / libthread_xu / thread / thr_sem.c
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1/*
2 * Copyright (C) 2005 David Xu <davidxu@freebsd.org>.
3 * Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
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
16 * distribution.
17 *
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.
29 *
c4dd4100 30 * $DragonFly: src/lib/libthread_xu/thread/thr_sem.c,v 1.6 2007/06/26 23:30:05 josepht Exp $
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31 */
32
fc71f871 33#include "namespace.h"
9e2ee207 34#include <machine/tls.h>
c4dd4100 35#include <sys/semaphore.h>
328161bd 36#include <sys/mman.h>
9e2ee207 37
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38#include <errno.h>
39#include <fcntl.h>
40#include <pthread.h>
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41#include <stdlib.h>
42#include <time.h>
fc71f871 43#include "un-namespace.h"
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44#include "thr_private.h"
45
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46/*
47 * Semaphore definitions.
48 */
49struct sem {
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50 u_int32_t magic;
51 volatile umtx_t count;
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52 int semid;
53 int unused; /* pad */
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54};
55
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56#define SEM_MAGIC ((u_int32_t) 0x09fa4012)
57
58#define SEMID_LWP 0
59#define SEMID_FORK 1
60
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61static inline int
62sem_check_validity(sem_t *sem)
63{
64
328161bd 65 if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC)) {
71b3fa15 66 return (0);
328161bd 67 } else {
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68 errno = EINVAL;
69 return (-1);
70 }
71}
72
73static sem_t
328161bd 74sem_alloc(unsigned int value, int pshared)
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75{
76 sem_t sem;
328161bd 77 int semid;
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78
79 if (value > SEM_VALUE_MAX) {
80 errno = EINVAL;
81 return (NULL);
82 }
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83 if (pshared) {
84 static __thread sem_t sem_base;
85 static __thread int sem_count;
86
87 if (sem_base == NULL) {
88 sem_base = mmap(NULL, getpagesize(),
89 PROT_READ | PROT_WRITE,
90 MAP_ANON | MAP_SHARED,
91 -1, 0);
92 sem_count = getpagesize() / sizeof(*sem);
93 }
94 sem = sem_base++;
95 if (--sem_count == 0)
96 sem_base = NULL;
97 semid = SEMID_FORK;
98 } else {
99 sem = malloc(sizeof(struct sem));
100 semid = SEMID_LWP;
101 }
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102 if (sem == NULL) {
103 errno = ENOSPC;
104 return (NULL);
105 }
106 sem->magic = SEM_MAGIC;
107 sem->count = (u_int32_t)value;
108 sem->semid = semid;
109 return (sem);
110}
111
112int
113_sem_init(sem_t *sem, int pshared, unsigned int value)
114{
328161bd 115 (*sem) = sem_alloc(value, pshared);
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116 if ((*sem) == NULL)
117 return (-1);
118 return (0);
119}
120
121int
122_sem_destroy(sem_t *sem)
123{
124 if (sem_check_validity(sem) != 0)
125 return (-1);
126
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127 (*sem)->magic = 0;
128
129 switch ((*sem)->semid) {
130 case SEMID_LWP:
131 free(*sem);
132 break;
133 case SEMID_FORK:
134 /* memory is left intact */
135 break;
136 }
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137 return (0);
138}
139
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140int
141_sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
142{
143 if (sem_check_validity(sem) != 0)
144 return (-1);
145
146 *sval = (*sem)->count;
147 return (0);
148}
149
150int
151_sem_trywait(sem_t *sem)
152{
153 int val;
154
155 if (sem_check_validity(sem) != 0)
156 return (-1);
157
158 while ((val = (*sem)->count) > 0) {
159 if (atomic_cmpset_int(&(*sem)->count, val, val - 1))
160 return (0);
161 }
162 errno = EAGAIN;
163 return (-1);
164}
165
166int
167_sem_wait(sem_t *sem)
168{
169 struct pthread *curthread;
170 int val, oldcancel, retval;
171
172 if (sem_check_validity(sem) != 0)
173 return (-1);
174
9e2ee207 175 curthread = tls_get_curthread();
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176 _pthread_testcancel();
177 do {
178 while ((val = (*sem)->count) > 0) {
179 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
180 return (0);
181 }
182 oldcancel = _thr_cancel_enter(curthread);
9219c44c 183 retval = _thr_umtx_wait(&(*sem)->count, 0, NULL, 0);
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184 _thr_cancel_leave(curthread, oldcancel);
185 } while (retval == 0);
186 errno = retval;
187 return (-1);
188}
189
fc71f871 190#if 0
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191int
192_sem_timedwait(sem_t * __restrict sem, struct timespec * __restrict abstime)
193{
194 struct timespec ts, ts2;
195 struct pthread *curthread;
196 int val, oldcancel, retval;
197
198 if (sem_check_validity(sem) != 0)
199 return (-1);
200
9e2ee207 201 curthread = tls_get_curthread();
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202
203 /*
204 * The timeout argument is only supposed to
205 * be checked if the thread would have blocked.
206 */
207 _pthread_testcancel();
208 do {
209 while ((val = (*sem)->count) > 0) {
210 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
211 return (0);
212 }
213 if (abstime == NULL) {
214 errno = EINVAL;
215 return (-1);
216 }
217 clock_gettime(CLOCK_REALTIME, &ts);
218 TIMESPEC_SUB(&ts2, abstime, &ts);
219 oldcancel = _thr_cancel_enter(curthread);
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220 retval = _thr_umtx_wait(&(*sem)->count, 0, &ts2,
221 CLOCK_REALTIME);
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222 _thr_cancel_leave(curthread, oldcancel);
223 } while (retval == 0);
224 errno = retval;
225 return (-1);
226}
fc71f871 227#endif
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228
229int
230_sem_post(sem_t *sem)
231{
232 int val;
233
234 if (sem_check_validity(sem) != 0)
235 return (-1);
236
237 /*
238 * sem_post() is required to be safe to call from within
239 * signal handlers, these code should work as that.
240 */
241 do {
242 val = (*sem)->count;
243 } while (!atomic_cmpset_acq_int(&(*sem)->count, val, val + 1));
244 _thr_umtx_wake(&(*sem)->count, val + 1);
245 return (0);
246}
5a1048c8 247
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248sem_t *
249_sem_open(const char *name, int oflag, ...)
250{
251 errno = ENOSYS;
252 return (SEM_FAILED);
253}
254
255int
256_sem_close(sem_t *sem)
257{
258 errno = ENOSYS;
259 return (-1);
260}
261
262int
263_sem_unlink(const char *name)
264{
265 errno = ENOSYS;
266 return (-1);
267}
268
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269__strong_reference(_sem_destroy, sem_destroy);
270__strong_reference(_sem_getvalue, sem_getvalue);
271__strong_reference(_sem_init, sem_init);
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272__strong_reference(_sem_trywait, sem_trywait);
273__strong_reference(_sem_wait, sem_wait);
fc71f871 274#if 0
5a1048c8 275__strong_reference(_sem_timedwait, sem_timedwait);
fc71f871 276#endif
5a1048c8 277__strong_reference(_sem_post, sem_post);
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278__strong_reference(_sem_open, sem_open);
279__strong_reference(_sem_close, sem_close);
280__strong_reference(_sem_unlink, sem_unlink);
5a1048c8 281