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 unchanged lines hidden (view full) --- 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 216641 2010-12-22 05:01:52Z 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> --- 5 unchanged lines hidden (view full) --- 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); 49static int cond_broadcast_common(pthread_cond_t *cond); |
50 51/* 52 * Double underscore versions are cancellation points. Single underscore 53 * versions are not and are provided for libc internal usage (which 54 * shouldn't introduce cancellation points). 55 */ 56__weak_reference(__pthread_cond_wait, pthread_cond_wait); 57__weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait); 58 59__weak_reference(_pthread_cond_init, pthread_cond_init); 60__weak_reference(_pthread_cond_destroy, pthread_cond_destroy); 61__weak_reference(_pthread_cond_signal, pthread_cond_signal); 62__weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast); 63 |
64#define CV_PSHARED(cvp) (((cvp)->__flags & USYNC_PROCESS_SHARED) != 0) 65 |
66static int 67cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) 68{ |
69 struct pthread_cond *cvp; 70 int error = 0; |
71 |
72 if ((cvp = (pthread_cond_t) |
73 calloc(1, sizeof(struct pthread_cond))) == NULL) { |
74 error = ENOMEM; |
75 } else { 76 /* 77 * Initialise the condition variable structure: 78 */ 79 if (cond_attr == NULL || *cond_attr == NULL) { |
80 cvp->__clock_id = CLOCK_REALTIME; |
81 } else { |
82 if ((*cond_attr)->c_pshared) 83 cvp->__flags |= USYNC_PROCESS_SHARED; 84 cvp->__clock_id = (*cond_attr)->c_clockid; |
85 } |
86 *cond = cvp; |
87 } |
88 return (error); |
89} 90 91static int 92init_static(struct pthread *thread, pthread_cond_t *cond) 93{ 94 int ret; 95 96 THR_LOCK_ACQUIRE(thread, &_cond_static_lock); --- 4 unchanged lines hidden (view full) --- 101 ret = 0; 102 103 THR_LOCK_RELEASE(thread, &_cond_static_lock); 104 105 return (ret); 106} 107 108#define CHECK_AND_INIT_COND \ |
109 if (__predict_false((cvp = (*cond)) <= THR_COND_DESTROYED)) { \ 110 if (cvp == THR_COND_INITIALIZER) { \ |
111 int ret; \ 112 ret = init_static(_get_curthread(), cond); \ 113 if (ret) \ 114 return (ret); \ |
115 } else if (cvp == THR_COND_DESTROYED) { \ |
116 return (EINVAL); \ 117 } \ |
118 cvp = *cond; \ |
119 } 120 121int 122_pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) 123{ 124 125 *cond = NULL; 126 return (cond_init(cond, cond_attr)); 127} 128 129int 130_pthread_cond_destroy(pthread_cond_t *cond) 131{ |
132 struct pthread_cond *cvp; 133 int error = 0; |
134 |
135 if ((cvp = *cond) == THR_COND_INITIALIZER) 136 error = 0; 137 else if (cvp == THR_COND_DESTROYED) 138 error = EINVAL; |
139 else { |
140 cvp = *cond; |
141 *cond = THR_COND_DESTROYED; |
142 143 /* 144 * Free the memory allocated for the condition 145 * variable structure: 146 */ |
147 free(cvp); |
148 } |
149 return (error); |
150} 151 |
152/* 153 * Cancellation behaivor: 154 * Thread may be canceled at start, if thread is canceled, it means it 155 * did not get a wakeup from pthread_cond_signal(), otherwise, it is 156 * not canceled. 157 * Thread cancellation never cause wakeup from pthread_cond_signal() 158 * to be lost. 159 */ 160static int |
161cond_wait_kernel(struct pthread_cond *cvp, struct pthread_mutex *mp, |
162 const struct timespec *abstime, int cancel) 163{ 164 struct pthread *curthread = _get_curthread(); |
165 int recurse; 166 int error, error2 = 0; |
167 |
168 error = _mutex_cv_detach(mp, &recurse); 169 if (error != 0) 170 return (error); 171 172 if (cancel) { 173 _thr_cancel_enter2(curthread, 0); 174 error = _thr_ucond_wait((struct ucond *)&cvp->__has_kern_waiters, 175 (struct umutex *)&mp->m_lock, abstime, 176 CVWAIT_ABSTIME|CVWAIT_CLOCKID); 177 _thr_cancel_leave(curthread, 0); 178 } else { 179 error = _thr_ucond_wait((struct ucond *)&cvp->__has_kern_waiters, 180 (struct umutex *)&mp->m_lock, abstime, 181 CVWAIT_ABSTIME|CVWAIT_CLOCKID); 182 } 183 |
184 /* |
185 * Note that PP mutex and ROBUST mutex may return 186 * interesting error codes. |
187 */ |
188 if (error == 0) { 189 error2 = _mutex_cv_lock(mp, recurse); 190 } else if (error == EINTR || error == ETIMEDOUT) { 191 error2 = _mutex_cv_lock(mp, recurse); 192 if (error2 == 0 && cancel) 193 _thr_testcancel(curthread); 194 if (error == EINTR) 195 error = 0; 196 } else { 197 /* We know that it didn't unlock the mutex. */ 198 error2 = _mutex_cv_attach(mp, recurse); 199 if (error2 == 0 && cancel) 200 _thr_testcancel(curthread); |
201 } |
202 return (error2 != 0 ? error2 : error); 203} |
204 |
205/* 206 * Thread waits in userland queue whenever possible, when thread 207 * is signaled or broadcasted, it is removed from the queue, and 208 * is saved in curthread's defer_waiters[] buffer, but won't be 209 * woken up until mutex is unlocked. 210 */ |
211 |
212static int 213cond_wait_user(struct pthread_cond *cvp, struct pthread_mutex *mp, 214 const struct timespec *abstime, int cancel) 215{ 216 struct pthread *curthread = _get_curthread(); 217 struct sleepqueue *sq; 218 int recurse; 219 int error; |
220 |
221 if (curthread->wchan != NULL) 222 PANIC("thread was already on queue."); 223 224 if (cancel) 225 _thr_testcancel(curthread); 226 227 _sleepq_lock(cvp); 228 /* 229 * set __has_user_waiters before unlocking mutex, this allows 230 * us to check it without locking in pthread_cond_signal(). 231 */ 232 cvp->__has_user_waiters = 1; 233 curthread->will_sleep = 1; 234 (void)_mutex_cv_unlock(mp, &recurse); 235 curthread->mutex_obj = mp; 236 _sleepq_add(cvp, curthread); 237 for(;;) { 238 _thr_clear_wake(curthread); 239 _sleepq_unlock(cvp); 240 241 if (cancel) { 242 _thr_cancel_enter2(curthread, 0); 243 error = _thr_sleep(curthread, cvp->__clock_id, abstime); 244 _thr_cancel_leave(curthread, 0); 245 } else { 246 error = _thr_sleep(curthread, cvp->__clock_id, abstime); 247 } 248 249 if (curthread->wchan == NULL) { 250 error = 0; 251 goto out; 252 } 253 254 _sleepq_lock(cvp); 255 if (curthread->wchan == NULL) { 256 error = 0; 257 break; 258 } else if (cancel && SHOULD_CANCEL(curthread)) { 259 sq = _sleepq_lookup(cvp); 260 cvp->__has_user_waiters = 261 _sleepq_remove(sq, curthread); 262 _sleepq_unlock(cvp); 263 curthread->mutex_obj = NULL; 264 _mutex_cv_lock(mp, recurse); 265 if (!THR_IN_CRITICAL(curthread)) 266 _pthread_exit(PTHREAD_CANCELED); 267 else /* this should not happen */ 268 return (0); 269 } else if (error == ETIMEDOUT) { 270 sq = _sleepq_lookup(cvp); 271 cvp->__has_user_waiters = 272 _sleepq_remove(sq, curthread); 273 break; 274 } |
275 } |
276 _sleepq_unlock(cvp); 277out: 278 curthread->mutex_obj = NULL; 279 _mutex_cv_lock(mp, recurse); 280 return (error); |
281} 282 |
283static int 284cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 285 const struct timespec *abstime, int cancel) 286{ 287 struct pthread *curthread = _get_curthread(); 288 struct pthread_cond *cvp; 289 struct pthread_mutex *mp; 290 int error; 291 292 CHECK_AND_INIT_COND 293 294 mp = *mutex; 295 296 if ((error = _mutex_owned(curthread, mp)) != 0) 297 return (error); 298 299 if (curthread->attr.sched_policy != SCHED_OTHER || 300 (mp->m_lock.m_flags & (UMUTEX_PRIO_PROTECT|UMUTEX_PRIO_INHERIT| 301 USYNC_PROCESS_SHARED)) != 0 || 302 (cvp->__flags & USYNC_PROCESS_SHARED) != 0) 303 return cond_wait_kernel(cvp, mp, abstime, cancel); 304 else 305 return cond_wait_user(cvp, mp, abstime, cancel); 306} 307 |
308int 309_pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) 310{ 311 312 return (cond_wait_common(cond, mutex, NULL, 0)); 313} 314 315int 316__pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) 317{ 318 319 return (cond_wait_common(cond, mutex, NULL, 1)); 320} 321 322int |
323_pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, |
324 const struct timespec * abstime) 325{ 326 327 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 328 abstime->tv_nsec >= 1000000000) 329 return (EINVAL); 330 331 return (cond_wait_common(cond, mutex, abstime, 0)); --- 7 unchanged lines hidden (view full) --- 339 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 340 abstime->tv_nsec >= 1000000000) 341 return (EINVAL); 342 343 return (cond_wait_common(cond, mutex, abstime, 1)); 344} 345 346static int |
347cond_signal_common(pthread_cond_t *cond) |
348{ 349 struct pthread *curthread = _get_curthread(); |
350 struct pthread *td; 351 struct pthread_cond *cvp; 352 struct pthread_mutex *mp; 353 struct sleepqueue *sq; 354 int *waddr; 355 int pshared; |
356 357 /* 358 * If the condition variable is statically initialized, perform dynamic 359 * initialization. 360 */ 361 CHECK_AND_INIT_COND 362 |
363 pshared = CV_PSHARED(cvp); 364 365 _thr_ucond_signal((struct ucond *)&cvp->__has_kern_waiters); 366 367 if (pshared || cvp->__has_user_waiters == 0) 368 return (0); 369 370 curthread = _get_curthread(); 371 waddr = NULL; 372 _sleepq_lock(cvp); 373 sq = _sleepq_lookup(cvp); 374 if (sq == NULL) { 375 _sleepq_unlock(cvp); 376 return (0); 377 } 378 379 td = _sleepq_first(sq); 380 mp = td->mutex_obj; 381 cvp->__has_user_waiters = _sleepq_remove(sq, td); 382 if (mp->m_owner == curthread) { 383 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 384 _thr_wake_all(curthread->defer_waiters, 385 curthread->nwaiter_defer); 386 curthread->nwaiter_defer = 0; 387 } 388 curthread->defer_waiters[curthread->nwaiter_defer++] = 389 &td->wake_addr->value; 390 mp->m_flags |= PMUTEX_FLAG_DEFERED; 391 } else { 392 waddr = &td->wake_addr->value; 393 } 394 _sleepq_unlock(cvp); 395 if (waddr != NULL) 396 _thr_set_wake(waddr); 397 return (0); |
398} 399 |
400struct broadcast_arg { 401 struct pthread *curthread; 402 unsigned int *waddrs[MAX_DEFER_WAITERS]; 403 int count; 404}; 405 406static void 407drop_cb(struct pthread *td, void *arg) 408{ 409 struct broadcast_arg *ba = arg; 410 struct pthread_mutex *mp; 411 struct pthread *curthread = ba->curthread; 412 413 mp = td->mutex_obj; 414 if (mp->m_owner == curthread) { 415 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 416 _thr_wake_all(curthread->defer_waiters, 417 curthread->nwaiter_defer); 418 curthread->nwaiter_defer = 0; 419 } 420 curthread->defer_waiters[curthread->nwaiter_defer++] = 421 &td->wake_addr->value; 422 mp->m_flags |= PMUTEX_FLAG_DEFERED; 423 } else { 424 if (ba->count >= MAX_DEFER_WAITERS) { 425 _thr_wake_all(ba->waddrs, ba->count); 426 ba->count = 0; 427 } 428 ba->waddrs[ba->count++] = &td->wake_addr->value; 429 } 430} 431 432static int 433cond_broadcast_common(pthread_cond_t *cond) 434{ 435 int pshared; 436 struct pthread_cond *cvp; 437 struct sleepqueue *sq; 438 struct broadcast_arg ba; 439 440 /* 441 * If the condition variable is statically initialized, perform dynamic 442 * initialization. 443 */ 444 CHECK_AND_INIT_COND 445 446 pshared = CV_PSHARED(cvp); 447 448 _thr_ucond_broadcast((struct ucond *)&cvp->__has_kern_waiters); 449 450 if (pshared || cvp->__has_user_waiters == 0) 451 return (0); 452 453 ba.curthread = _get_curthread(); 454 ba.count = 0; 455 456 _sleepq_lock(cvp); 457 sq = _sleepq_lookup(cvp); 458 if (sq == NULL) { 459 _sleepq_unlock(cvp); 460 return (0); 461 } 462 _sleepq_drop(sq, drop_cb, &ba); 463 cvp->__has_user_waiters = 0; 464 _sleepq_unlock(cvp); 465 if (ba.count > 0) 466 _thr_wake_all(ba.waddrs, ba.count); 467 return (0); 468} 469 |
470int 471_pthread_cond_signal(pthread_cond_t * cond) 472{ 473 |
474 return (cond_signal_common(cond)); |
475} 476 477int 478_pthread_cond_broadcast(pthread_cond_t * cond) 479{ 480 |
481 return (cond_broadcast_common(cond)); |
482} |