lib/libthr/thread/thr_cond.c

   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  * $FreeBSD$
  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  */
  42 int     __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex);
  43 int     __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
  44                        const struct timespec * abstime);
  45 static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr);
  46 static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
  47                     const struct timespec *abstime, int cancel);
  48 static 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
  63 static int
  64 cond_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
  90 static int
  91 init_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
 107 int
 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
 115 int
 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                 /*
 128                  * NULL the caller's pointer now that the condition
 129                  * variable has been destroyed:
 130                  */
 131                 *cond = NULL;
 132                 THR_UMUTEX_UNLOCK(curthread, &cv->c_lock);
 133
 134                 /*
 135                  * Free the memory allocated for the condition
 136                  * variable structure:
 137                  */
 138                 free(cv);
 139         }
 140         /* Return the completion status: */
 141         return (rval);
 142 }
 143
 144 struct cond_cancel_info
 145 {
 146         pthread_mutex_t *mutex;
 147         pthread_cond_t  *cond;
 148         int             count;
 149 };
 150
 151 static void
 152 cond_cancel_handler(void *arg)
 153 {
 154         struct pthread *curthread = _get_curthread();
 155         struct cond_cancel_info *info = (struct cond_cancel_info *)arg;
 156         pthread_cond_t  cv;
 157
 158         if (info->cond != NULL) {
 159                 cv = *(info->cond);
 160                 THR_UMUTEX_UNLOCK(curthread, &cv->c_lock);
 161         }
 162         _mutex_cv_lock(info->mutex, info->count);
 163 }
 164
 165 static int
 166 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
 167         const struct timespec *abstime, int cancel)
 168 {
 169         struct pthread  *curthread = _get_curthread();
 170         struct timespec ts, ts2, *tsp;
 171         struct cond_cancel_info info;
 172         pthread_cond_t  cv;
 173         int             ret = 0;
 174
 175         /*
 176          * If the condition variable is statically initialized,
 177          * perform the dynamic initialization:
 178          */
 179         if (__predict_false(*cond == NULL &&
 180             (ret = init_static(curthread, cond)) != 0))
 181                 return (ret);
 182
 183         cv = *cond;
 184         THR_UMUTEX_LOCK(curthread, &cv->c_lock);
 185         ret = _mutex_cv_unlock(mutex, &info.count);
 186         if (ret) {
 187                 THR_UMUTEX_UNLOCK(curthread, &cv->c_lock);
 188                 return (ret);
 189         }
 190
 191         info.mutex = mutex;
 192         info.cond  = cond;
 193
 194         if (abstime != NULL) {
 195                 clock_gettime(cv->c_clockid, &ts);
 196                 TIMESPEC_SUB(&ts2, abstime, &ts);
 197                 tsp = &ts2;
 198         } else
 199                 tsp = NULL;
 200
 201         if (cancel) {
 202                 THR_CLEANUP_PUSH(curthread, cond_cancel_handler, &info);
 203                 _thr_cancel_enter_defer(curthread);
 204                 ret = _thr_ucond_wait(&cv->c_kerncv, &cv->c_lock, tsp, 1);
 205                 info.cond = NULL;
 206                 _thr_cancel_leave_defer(curthread, ret);
 207                 THR_CLEANUP_POP(curthread, 0);
 208         } else {
 209                 ret = _thr_ucond_wait(&cv->c_kerncv, &cv->c_lock, tsp, 0);
 210         }
 211         if (ret == EINTR)
 212                 ret = 0;
 213         _mutex_cv_lock(mutex, info.count);
 214         return (ret);
 215 }
 216
 217 int
 218 _pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 219 {
 220
 221         return (cond_wait_common(cond, mutex, NULL, 0));
 222 }
 223
 224 int
 225 __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 226 {
 227
 228         return (cond_wait_common(cond, mutex, NULL, 1));
 229 }
 230
 231 int
 232 _pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
 233                        const struct timespec * abstime)
 234 {
 235
 236         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 237             abstime->tv_nsec >= 1000000000)
 238                 return (EINVAL);
 239
 240         return (cond_wait_common(cond, mutex, abstime, 0));
 241 }
 242
 243 int
 244 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
 245                        const struct timespec *abstime)
 246 {
 247
 248         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 249             abstime->tv_nsec >= 1000000000)
 250                 return (EINVAL);
 251
 252         return (cond_wait_common(cond, mutex, abstime, 1));
 253 }
 254
 255 static int
 256 cond_signal_common(pthread_cond_t *cond, int broadcast)
 257 {
 258         struct pthread  *curthread = _get_curthread();
 259         pthread_cond_t  cv;
 260         int             ret = 0;
 261
 262         /*
 263          * If the condition variable is statically initialized, perform dynamic
 264          * initialization.
 265          */
 266         if (__predict_false(*cond == NULL &&
 267             (ret = init_static(curthread, cond)) != 0))
 268                 return (ret);
 269
 270         cv = *cond;
 271         THR_UMUTEX_LOCK(curthread, &cv->c_lock);
 272         if (!broadcast)
 273                 ret = _thr_ucond_signal(&cv->c_kerncv);
 274         else
 275                 ret = _thr_ucond_broadcast(&cv->c_kerncv);
 276         THR_UMUTEX_UNLOCK(curthread, &cv->c_lock);
 277         return (ret);
 278 }
 279
 280 int
 281 _pthread_cond_signal(pthread_cond_t * cond)
 282 {
 283
 284         return (cond_signal_common(cond, 0));
 285 }
 286
 287 int
 288 _pthread_cond_broadcast(pthread_cond_t * cond)
 289 {
 290
 291         return (cond_signal_common(cond, 1));
 292 }