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 _thr_umtx_init((umtx_t *)&sem->lock); 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 int 176 _sem_wait(sem_t *sem) 177 { 178 struct pthread *curthread; 179 int val, oldcancel, retval; 180 181 if (sem_check_validity(sem) != 0) 182 return (-1); 183 184 curthread = _get_curthread(); 185 if ((*sem)->syssem != 0) { 186 oldcancel = _thr_cancel_enter(curthread); 187 retval = ksem_wait((*sem)->semid); 188 _thr_cancel_leave(curthread, oldcancel); 189 return (retval); 190 } 191 192 _pthread_testcancel(); 193 do { 194 while ((val = (*sem)->count) > 0) { 195 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1)) 196 return (0); 197 } 198 oldcancel = _thr_cancel_enter(curthread); 199 retval = _thr_umtx_wait((umtx_t *)&(*sem)->count, 0, NULL); 200 _thr_cancel_leave(curthread, oldcancel); 201 } while (retval == 0); 202 errno = retval; 203 return (-1); 204 } 205 206 int 207 _sem_timedwait(sem_t * __restrict sem, 208 const struct timespec * __restrict abstime) 209 { 210 struct timespec ts, ts2; 211 struct pthread *curthread; 212 int val, oldcancel, retval; 213 214 if (sem_check_validity(sem) != 0) 215 return (-1); 216 217 curthread = _get_curthread(); 218 if ((*sem)->syssem != 0) { 219 oldcancel = _thr_cancel_enter(curthread); 220 retval = ksem_timedwait((*sem)->semid, abstime); 221 _thr_cancel_leave(curthread, oldcancel); 222 return (retval); 223 } 224 225 /* 226 * The timeout argument is only supposed to 227 * be checked if the thread would have blocked. 228 */ 229 _pthread_testcancel(); 230 do { 231 while ((val = (*sem)->count) > 0) { 232 if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1)) 233 return (0); 234 } 235 if (abstime == NULL) { 236 errno = EINVAL; 237 return (-1); 238 } 239 clock_gettime(CLOCK_REALTIME, &ts); 240 TIMESPEC_SUB(&ts2, abstime, &ts); 241 oldcancel = _thr_cancel_enter(curthread); 242 retval = _thr_umtx_wait((umtx_t *)&(*sem)->count, 0, &ts2); 243 _thr_cancel_leave(curthread, oldcancel); 244 } while (retval == 0); 245 errno = retval; 246 return (-1); 247 } 248 249 int 250 _sem_post(sem_t *sem) 251 { 252 int val, retval; 253 254 if (sem_check_validity(sem) != 0) 255 return (-1); 256 257 if ((*sem)->syssem != 0) 258 return (ksem_post((*sem)->semid)); 259 260 /* 261 * sem_post() is required to be safe to call from within 262 * signal handlers, these code should work as that. 263 */ 264 do { 265 val = (*sem)->count; 266 } while (!atomic_cmpset_acq_int(&(*sem)->count, val, val + 1)); 267 retval = _thr_umtx_wake((umtx_t *)&(*sem)->count, val + 1); 268 if (retval > 0) 269 retval = 0; 270 return (retval); 271 } 272