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 * 30 * $FreeBSD$ 31 */ 32 33 #include "namespace.h" 34 #include <sys/types.h> 35 #include <sys/queue.h> 36 #include <errno.h> 37 #include <fcntl.h> 38 #include <pthread.h> 39 #include <semaphore.h> 40 #include <stdlib.h> 41 #include <time.h> 42 #include <_semaphore.h> 43 #include "un-namespace.h" 44 45 #include "thr_private.h" 46 47 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); 55 56 57 static inline int 58 sem_check_validity(sem_t *sem) 59 { 60 61 if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC)) 62 return (0); 63 else { 64 errno = EINVAL; 65 return (-1); 66 } 67 } 68 69 static sem_t 70 sem_alloc(unsigned int value, semid_t semid, int system_sem) 71 { 72 sem_t sem; 73 74 if (value > SEM_VALUE_MAX) { 75 errno = EINVAL; 76 return (NULL); 77 } 78 79 sem = (sem_t)malloc(sizeof(struct sem)); 80 if (sem == NULL) { 81 errno = ENOSPC; 82 return (NULL); 83 } 84 bzero(sem, sizeof(*sem)); 85 /* 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. 89 */ 90 sem->count = (u_int32_t)value; 91 sem->nwaiters = 0; 92 sem->magic = SEM_MAGIC; 93 sem->semid = semid; 94 sem->syssem = system_sem; 95 return (sem); 96 } 97 98 int 99 _sem_init(sem_t *sem, int pshared, unsigned int value) 100 { 101 semid_t semid; 102 103 semid = (semid_t)SEM_USER; 104 if ((pshared != 0) && (ksem_init(&semid, value) != 0)) 105 return (-1); 106 107 (*sem) = sem_alloc(value, semid, pshared); 108 if ((*sem) == NULL) { 109 if (pshared != 0) 110 ksem_destroy(semid); 111 return (-1); 112 } 113 return (0); 114 } 115 116 int 117 _sem_destroy(sem_t *sem) 118 { 119 int retval; 120 121 if (sem_check_validity(sem) != 0) 122 return (-1); 123 124 /* 125 * If this is a system semaphore let the kernel track it otherwise 126 * make sure there are no waiters. 127 */ 128 if ((*sem)->syssem != 0) 129 retval = ksem_destroy((*sem)->semid); 130 else { 131 retval = 0; 132 (*sem)->magic = 0; 133 } 134 if (retval == 0) 135 free(*sem); 136 return (retval); 137 } 138 139 int 140 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval) 141 { 142 int retval; 143 144 if (sem_check_validity(sem) != 0) 145 return (-1); 146 147 if ((*sem)->syssem != 0) 148 retval = ksem_getvalue((*sem)->semid, sval); 149 else { 150 *sval = (int)(*sem)->count; 151 retval = 0; 152 } 153 return (retval); 154 } 155 156 int 157 _sem_trywait(sem_t *sem) 158 { 159 int val; 160 161 if (sem_check_validity(sem) != 0) 162 return (-1); 163 164 if ((*sem)->syssem != 0) 165 return (ksem_trywait((*sem)->semid)); 166 167 while ((val = (*sem)->count) > 0) { 168 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1)) 169 return (0); 170 } 171 errno = EAGAIN; 172 return (-1); 173 } 174 175 static void 176 sem_cancel_handler(void *arg) 177 { 178 sem_t *sem = arg; 179 180 atomic_add_int(&(*sem)->nwaiters, -1); 181 } 182 183 int 184 _sem_wait(sem_t *sem) 185 { 186 struct pthread *curthread; 187 int val, retval; 188 189 if (sem_check_validity(sem) != 0) 190 return (-1); 191 192 curthread = _get_curthread(); 193 if ((*sem)->syssem != 0) { 194 _thr_cancel_enter(curthread); 195 retval = ksem_wait((*sem)->semid); 196 _thr_cancel_leave(curthread); 197 return (retval); 198 } 199 200 _pthread_testcancel(); 201 do { 202 while ((val = (*sem)->count) > 0) { 203 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1)) 204 return (0); 205 } 206 atomic_add_int(&(*sem)->nwaiters, 1); 207 THR_CLEANUP_PUSH(curthread, sem_cancel_handler, sem); 208 _thr_cancel_enter(curthread); 209 retval = _thr_umtx_wait_uint(&(*sem)->count, 0, NULL); 210 _thr_cancel_leave(curthread); 211 THR_CLEANUP_POP(curthread, 0); 212 atomic_add_int(&(*sem)->nwaiters, -1); 213 } while (retval == 0); 214 errno = retval; 215 return (-1); 216 } 217 218 int 219 _sem_timedwait(sem_t * __restrict sem, 220 const struct timespec * __restrict abstime) 221 { 222 struct timespec ts, ts2; 223 struct pthread *curthread; 224 int val, retval; 225 226 if (sem_check_validity(sem) != 0) 227 return (-1); 228 229 curthread = _get_curthread(); 230 if ((*sem)->syssem != 0) { 231 _thr_cancel_enter(curthread); 232 retval = ksem_timedwait((*sem)->semid, abstime); 233 _thr_cancel_leave(curthread); 234 return (retval); 235 } 236 237 /* 238 * The timeout argument is only supposed to 239 * be checked if the thread would have blocked. 240 */ 241 _pthread_testcancel(); 242 do { 243 while ((val = (*sem)->count) > 0) { 244 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1)) 245 return (0); 246 } 247 if (abstime == NULL) { 248 errno = EINVAL; 249 return (-1); 250 } 251 clock_gettime(CLOCK_REALTIME, &ts); 252 TIMESPEC_SUB(&ts2, abstime, &ts); 253 atomic_add_int(&(*sem)->nwaiters, 1); 254 THR_CLEANUP_PUSH(curthread, sem_cancel_handler, sem); 255 _thr_cancel_enter(curthread); 256 retval = _thr_umtx_wait_uint(&(*sem)->count, 0, &ts2); 257 _thr_cancel_leave(curthread); 258 THR_CLEANUP_POP(curthread, 0); 259 atomic_add_int(&(*sem)->nwaiters, -1); 260 } while (retval == 0); 261 errno = retval; 262 return (-1); 263 } 264 265 /* 266 * sem_post() is required to be safe to call from within 267 * signal handlers, these code should work as that. 268 */ 269 270 int 271 _sem_post(sem_t *sem) 272 { 273 int retval = 0; 274 275 if (sem_check_validity(sem) != 0) 276 return (-1); 277 278 if ((*sem)->syssem != 0) 279 return (ksem_post((*sem)->semid)); 280 281 atomic_add_rel_int(&(*sem)->count, 1); 282 283 if ((*sem)->nwaiters) { 284 retval = _thr_umtx_wake(&(*sem)->count, 1); 285 if (retval != 0) 286 retval = -1; 287 } 288 return (retval); 289 } 290