thr_cond.c revision 164905
1/* 2 * Copyright (c) 2005 David Xu <davidxu@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD: head/lib/libthr/thread/thr_cond.c 164905 2006-12-05 07:23:58Z davidxu $ 27 */ 28 29#include "namespace.h" 30#include <stdlib.h> 31#include <errno.h> 32#include <string.h> 33#include <pthread.h> 34#include <limits.h> 35#include "un-namespace.h" 36 37#include "thr_private.h" 38 39/* 40 * Prototypes 41 */ 42int __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex); 43int __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 44 const struct timespec * abstime); 45static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr); 46static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 47 const struct timespec *abstime, int cancel); 48static int cond_signal_common(pthread_cond_t *cond, int broadcast); 49 50/* 51 * Double underscore versions are cancellation points. Single underscore 52 * versions are not and are provided for libc internal usage (which 53 * shouldn't introduce cancellation points). 54 */ 55__weak_reference(__pthread_cond_wait, pthread_cond_wait); 56__weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait); 57 58__weak_reference(_pthread_cond_init, pthread_cond_init); 59__weak_reference(_pthread_cond_destroy, pthread_cond_destroy); 60__weak_reference(_pthread_cond_signal, pthread_cond_signal); 61__weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast); 62 63static int 64cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) 65{ 66 pthread_cond_t pcond; 67 int rval = 0; 68 69 if ((pcond = (pthread_cond_t) 70 calloc(1, sizeof(struct pthread_cond))) == NULL) { 71 rval = ENOMEM; 72 } else { 73 /* 74 * Initialise the condition variable structure: 75 */ 76 if (cond_attr == NULL || *cond_attr == NULL) { 77 pcond->c_pshared = 0; 78 pcond->c_clockid = CLOCK_REALTIME; 79 } else { 80 pcond->c_pshared = (*cond_attr)->c_pshared; 81 pcond->c_clockid = (*cond_attr)->c_clockid; 82 } 83 _thr_umutex_init(&pcond->c_lock); 84 *cond = pcond; 85 } 86 /* Return the completion status: */ 87 return (rval); 88} 89 90static int 91init_static(struct pthread *thread, pthread_cond_t *cond) 92{ 93 int ret; 94 95 THR_LOCK_ACQUIRE(thread, &_cond_static_lock); 96 97 if (*cond == NULL) 98 ret = cond_init(cond, NULL); 99 else 100 ret = 0; 101 102 THR_LOCK_RELEASE(thread, &_cond_static_lock); 103 104 return (ret); 105} 106 107int 108_pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) 109{ 110 111 *cond = NULL; 112 return (cond_init(cond, cond_attr)); 113} 114 115int 116_pthread_cond_destroy(pthread_cond_t *cond) 117{ 118 struct pthread *curthread = _get_curthread(); 119 struct pthread_cond *cv; 120 int rval = 0; 121 122 if (*cond == NULL) 123 rval = EINVAL; 124 else { 125 cv = *cond; 126 THR_UMUTEX_LOCK(curthread, &cv->c_lock); 127#if 0 128 /* Lock the condition variable structure: */ 129 if (cv->c_kerncv.c_has_waiters) { 130 THR_UMUTEX_UNLOCK(curthread, &cv->c_lock); 131 return (EBUSY); 132 } 133#endif 134 /* 135 * NULL the caller's pointer now that the condition 136 * variable has been destroyed: 137 */ 138 *cond = NULL; 139 THR_UMUTEX_UNLOCK(curthread, &cv->c_lock); 140 141 /* 142 * Free the memory allocated for the condition 143 * variable structure: 144 */ 145 free(cv); 146 147 } 148 /* Return the completion status: */ 149 return (rval); 150} 151 152struct cond_cancel_info 153{ 154 pthread_mutex_t *mutex; 155 pthread_cond_t *cond; 156 int count; 157}; 158 159static void 160cond_cancel_handler(void *arg) 161{ 162 struct pthread *curthread = _get_curthread(); 163 struct cond_cancel_info *info = (struct cond_cancel_info *)arg; 164 pthread_cond_t cv; 165 166 cv = *(info->cond); 167 if ((cv->c_lock.m_owner & ~UMUTEX_CONTESTED) == TID(curthread)) 168 THR_UMUTEX_UNLOCK(curthread, &cv->c_lock); 169 _mutex_cv_lock(info->mutex, info->count); 170} 171 172static int 173cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 174 const struct timespec *abstime, int cancel) 175{ 176 struct pthread *curthread = _get_curthread(); 177 struct timespec ts, ts2, *tsp; 178 struct cond_cancel_info info; 179 pthread_cond_t cv; 180 int ret = 0; 181 182 /* 183 * If the condition variable is statically initialized, 184 * perform the dynamic initialization: 185 */ 186 if (__predict_false(*cond == NULL && 187 (ret = init_static(curthread, cond)) != 0)) 188 return (ret); 189 190 cv = *cond; 191 THR_UMUTEX_LOCK(curthread, &cv->c_lock); 192 ret = _mutex_cv_unlock(mutex, &info.count); 193 if (ret) { 194 THR_UMUTEX_UNLOCK(curthread, &cv->c_lock); 195 return (ret); 196 } 197 198 info.mutex = mutex; 199 info.cond = cond; 200 201 if (abstime != NULL) { 202 clock_gettime(cv->c_clockid, &ts); 203 TIMESPEC_SUB(&ts2, abstime, &ts); 204 tsp = &ts2; 205 } else 206 tsp = NULL; 207 208 if (cancel) { 209 THR_CLEANUP_PUSH(curthread, cond_cancel_handler, &info); 210 _thr_cancel_enter_defer(curthread); 211 ret = _thr_ucond_wait(&cv->c_kerncv, &cv->c_lock, tsp, 1); 212 _thr_cancel_leave_defer(curthread, ret); 213 THR_CLEANUP_POP(curthread, 0); 214 } else { 215 ret = _thr_ucond_wait(&cv->c_kerncv, &cv->c_lock, tsp, 0); 216 } 217 if (ret == EINTR) 218 ret = 0; 219 _mutex_cv_lock(mutex, info.count); 220 return (ret); 221} 222 223int 224_pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) 225{ 226 227 return (cond_wait_common(cond, mutex, NULL, 0)); 228} 229 230int 231__pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) 232{ 233 234 return (cond_wait_common(cond, mutex, NULL, 1)); 235} 236 237int 238_pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex, 239 const struct timespec * abstime) 240{ 241 242 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 243 abstime->tv_nsec >= 1000000000) 244 return (EINVAL); 245 246 return (cond_wait_common(cond, mutex, abstime, 0)); 247} 248 249int 250__pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 251 const struct timespec *abstime) 252{ 253 254 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 255 abstime->tv_nsec >= 1000000000) 256 return (EINVAL); 257 258 return (cond_wait_common(cond, mutex, abstime, 1)); 259} 260 261static int 262cond_signal_common(pthread_cond_t *cond, int broadcast) 263{ 264 struct pthread *curthread = _get_curthread(); 265 pthread_cond_t cv; 266 int ret = 0; 267 268 /* 269 * If the condition variable is statically initialized, perform dynamic 270 * initialization. 271 */ 272 if (__predict_false(*cond == NULL && 273 (ret = init_static(curthread, cond)) != 0)) 274 return (ret); 275 276 cv = *cond; 277 THR_UMUTEX_LOCK(curthread, &cv->c_lock); 278 if (cv->c_kerncv.c_has_waiters) { 279 if (!broadcast) 280 ret = _thr_ucond_signal(&cv->c_kerncv); 281 else 282 ret = _thr_ucond_broadcast(&cv->c_kerncv); 283 } 284 THR_UMUTEX_UNLOCK(curthread, &cv->c_lock); 285 return (ret); 286} 287 288int 289_pthread_cond_signal(pthread_cond_t * cond) 290{ 291 292 return (cond_signal_common(cond, 0)); 293} 294 295int 296_pthread_cond_broadcast(pthread_cond_t * cond) 297{ 298 299 return (cond_signal_common(cond, 1)); 300} 301