lib/libthread_xu/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  * $DragonFly: src/lib/libthread_xu/thread/thr_cond.c,v 1.4 2005/03/29 19:26:20 joerg Exp $
  27  */
  28
  29 #include <machine/tls.h>
  30
  31 #include <stdlib.h>
  32 #include <errno.h>
  33 #include <string.h>
  34 #include <pthread.h>
  35 #include <limits.h>
  36
  37 #include "thr_private.h"
  38
  39 /*
  40  * Prototypes
  41  */
  42 static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr);
  43 static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
  44                     const struct timespec *abstime, int cancel);
  45 static int cond_signal_common(pthread_cond_t *cond, int broadcast);
  46
  47 /*
  48  * Double underscore versions are cancellation points.  Single underscore
  49  * versions are not and are provided for libc internal usage (which
  50  * shouldn't introduce cancellation points).
  51  */
  52 __weak_reference(__pthread_cond_wait, pthread_cond_wait);
  53 __weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait);
  54
  55 __weak_reference(_pthread_cond_init, pthread_cond_init);
  56 __weak_reference(_pthread_cond_destroy, pthread_cond_destroy);
  57 __weak_reference(_pthread_cond_signal, pthread_cond_signal);
  58 __weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
  59
  60 static int
  61 cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
  62 {
  63         pthread_cond_t  pcond;
  64         int             rval = 0;
  65
  66         if ((pcond = (pthread_cond_t)
  67             malloc(sizeof(struct pthread_cond))) == NULL) {
  68                 rval = ENOMEM;
  69         } else {
  70                 /*
  71                  * Initialise the condition variable structure:
  72                  */
  73                 _thr_umtx_init(&pcond->c_lock);
  74                 pcond->c_seqno = 0;
  75                 pcond->c_waiters = 0;
  76                 pcond->c_wakeups = 0;
  77                 if (cond_attr == NULL || *cond_attr == NULL) {
  78                         pcond->c_pshared = 0;
  79                         pcond->c_clockid = CLOCK_REALTIME;
  80                 } else {
  81                         pcond->c_pshared = (*cond_attr)->c_pshared;
  82                         pcond->c_clockid = (*cond_attr)->c_clockid;
  83                 }
  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         *cond = NULL;
 111         return cond_init(cond, cond_attr);
 112 }
 113
 114 int
 115 _pthread_cond_destroy(pthread_cond_t *cond)
 116 {
 117         struct pthread_cond     *cv;
 118         struct pthread          *curthread = tls_get_curthread();
 119         int                     rval = 0;
 120
 121         if (*cond == NULL)
 122                 rval = EINVAL;
 123         else {
 124                 /* Lock the condition variable structure: */
 125                 THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
 126                 if ((*cond)->c_waiters + (*cond)->c_wakeups != 0) {
 127                         THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
 128                         return (EBUSY);
 129                 }
 130
 131                 /*
 132                  * NULL the caller's pointer now that the condition
 133                  * variable has been destroyed:
 134                  */
 135                 cv = *cond;
 136                 *cond = NULL;
 137
 138                 /* Unlock the condition variable structure: */
 139                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 140
 141                 /* Free the cond lock structure: */
 142
 143                 /*
 144                  * Free the memory allocated for the condition
 145                  * variable structure:
 146                  */
 147                 free(cv);
 148
 149         }
 150         /* Return the completion status: */
 151         return (rval);
 152 }
 153
 154 struct cond_cancel_info
 155 {
 156         pthread_mutex_t *mutex;
 157         pthread_cond_t  *cond;
 158         long            seqno;
 159 };
 160
 161 static void
 162 cond_cancel_handler(void *arg)
 163 {
 164         struct pthread *curthread = tls_get_curthread();
 165         struct cond_cancel_info *cci = (struct cond_cancel_info *)arg;
 166         pthread_cond_t cv;
 167
 168         cv = *(cci->cond);
 169         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 170         if (cv->c_seqno != cci->seqno && cv->c_wakeups != 0) {
 171                 if (cv->c_waiters > 0) {
 172                         cv->c_seqno++;
 173                         _thr_umtx_wake(&cv->c_seqno, 1);
 174                 } else
 175                         cv->c_wakeups--;
 176         } else {
 177                 cv->c_waiters--;
 178         }
 179         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 180
 181         _mutex_cv_lock(cci->mutex);
 182 }
 183
 184 static int
 185 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
 186         const struct timespec *abstime, int cancel)
 187 {
 188         struct pthread  *curthread = tls_get_curthread();
 189         struct timespec ts, ts2, *tsp;
 190         struct cond_cancel_info cci;
 191         pthread_cond_t  cv;
 192         long            seq, oldseq;
 193         int             oldcancel;
 194         int             ret = 0;
 195
 196         /*
 197          * If the condition variable is statically initialized,
 198          * perform the dynamic initialization:
 199          */
 200         if (__predict_false(*cond == NULL &&
 201             (ret = init_static(curthread, cond)) != 0))
 202                 return (ret);
 203
 204         cv = *cond;
 205         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 206         ret = _mutex_cv_unlock(mutex);
 207         if (ret) {
 208                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 209                 return (ret);
 210         }
 211         oldseq = seq = cv->c_seqno;
 212         cci.mutex = mutex;
 213         cci.cond  = cond;
 214         cci.seqno = oldseq;
 215
 216         cv->c_waiters++;
 217         do {
 218                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 219
 220                 if (abstime != NULL) {
 221                         clock_gettime(cv->c_clockid, &ts);
 222                         TIMESPEC_SUB(&ts2, abstime, &ts);
 223                         tsp = &ts2;
 224                 } else
 225                         tsp = NULL;
 226
 227                 if (cancel) {
 228                         THR_CLEANUP_PUSH(curthread, cond_cancel_handler, &cci);
 229                         oldcancel = _thr_cancel_enter(curthread);
 230                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp,
 231                                 cv->c_clockid);
 232                         _thr_cancel_leave(curthread, oldcancel);
 233                         THR_CLEANUP_POP(curthread, 0);
 234                 } else {
 235                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp,
 236                                 cv->c_clockid);
 237                 }
 238
 239                 THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 240                 seq = cv->c_seqno;
 241                 if (abstime != NULL && ret == ETIMEDOUT)
 242                         break;
 243
 244                 /*
 245                  * loop if we have never been told to wake up
 246                  * or we lost a race.
 247                  */
 248         } while (seq == oldseq || cv->c_wakeups == 0);
 249
 250         if (seq != oldseq && cv->c_wakeups != 0) {
 251                 cv->c_wakeups--;
 252                 ret = 0;
 253         } else {
 254                 cv->c_waiters--;
 255         }
 256         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 257         _mutex_cv_lock(mutex);
 258         return (ret);
 259 }
 260
 261 int
 262 _pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 263 {
 264
 265         return (cond_wait_common(cond, mutex, NULL, 0));
 266 }
 267
 268 __strong_reference(_pthread_cond_wait, _thr_cond_wait);
 269
 270 int
 271 __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 272 {
 273
 274         return (cond_wait_common(cond, mutex, NULL, 1));
 275 }
 276
 277 int
 278 _pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
 279                        const struct timespec * abstime)
 280 {
 281         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 282             abstime->tv_nsec >= 1000000000)
 283                 return (EINVAL);
 284
 285         return (cond_wait_common(cond, mutex, abstime, 0));
 286 }
 287
 288 __strong_reference(_pthread_cond_timedwait, _thr_cond_timedwait);
 289
 290 int
 291 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
 292                        const struct timespec *abstime)
 293 {
 294         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 295             abstime->tv_nsec >= 1000000000)
 296                 return (EINVAL);
 297
 298         return (cond_wait_common(cond, mutex, abstime, 1));
 299 }
 300
 301 static int
 302 cond_signal_common(pthread_cond_t *cond, int broadcast)
 303 {
 304         struct pthread  *curthread = tls_get_curthread();
 305         pthread_cond_t  cv;
 306         int             ret = 0;
 307
 308         /*
 309          * If the condition variable is statically initialized, perform dynamic
 310          * initialization.
 311          */
 312         if (__predict_false(*cond == NULL &&
 313             (ret = init_static(curthread, cond)) != 0))
 314                 return (ret);
 315
 316         cv = *cond;
 317         /* Lock the condition variable structure. */
 318         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 319         if (cv->c_waiters) {
 320                 if (!broadcast) {
 321                         cv->c_wakeups++;
 322                         cv->c_waiters--;
 323                         cv->c_seqno++;
 324                         _thr_umtx_wake(&cv->c_seqno, 1);
 325                 } else {
 326                         cv->c_wakeups += cv->c_waiters;
 327                         cv->c_waiters = 0;
 328                         cv->c_seqno++;
 329                         _thr_umtx_wake(&cv->c_seqno, INT_MAX);
 330                 }
 331         }
 332         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 333         return (ret);
 334 }
 335
 336 int
 337 _pthread_cond_signal(pthread_cond_t * cond)
 338 {
 339
 340         return (cond_signal_common(cond, 0));
 341 }
 342
 343 __strong_reference(_pthread_cond_signal, _thr_cond_signal);
 344
 345 int
 346 _pthread_cond_broadcast(pthread_cond_t * cond)
 347 {
 348
 349         return (cond_signal_common(cond, 1));
 350 }
 351
 352 __strong_reference(_pthread_cond_broadcast, _thr_cond_broadcast);