1 /* 2 * Copyright (c) 2005 David Xu <davidxu@freebsd.org> 3 * Copyright (c) 2015 The FreeBSD Foundation 4 * All rights reserved. 5 * 6 * Portions of this software were developed by Konstantin Belousov 7 * under sponsorship from the FreeBSD Foundation. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice unmodified, this list of conditions, and the following 14 * disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 * 30 * $FreeBSD$ 31 */ 32 33 #include "namespace.h" 34 #include <stdlib.h> 35 #include <errno.h> 36 #include <string.h> 37 #include <pthread.h> 38 #include <limits.h> 39 #include "un-namespace.h" 40 41 #include "thr_private.h" 42 43 /* 44 * Prototypes 45 */ 46 int __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex); 47 int __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 48 const struct timespec * abstime); 49 static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr); 50 static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 51 const struct timespec *abstime, int cancel); 52 static int cond_signal_common(pthread_cond_t *cond); 53 static int cond_broadcast_common(pthread_cond_t *cond); 54 55 /* 56 * Double underscore versions are cancellation points. Single underscore 57 * versions are not and are provided for libc internal usage (which 58 * shouldn't introduce cancellation points). 59 */ 60 __weak_reference(__pthread_cond_wait, pthread_cond_wait); 61 __weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait); 62 63 __weak_reference(_pthread_cond_init, pthread_cond_init); 64 __weak_reference(_pthread_cond_destroy, pthread_cond_destroy); 65 __weak_reference(_pthread_cond_signal, pthread_cond_signal); 66 __weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast); 67 68 #define CV_PSHARED(cvp) (((cvp)->__flags & USYNC_PROCESS_SHARED) != 0) 69 70 static void 71 cond_init_body(struct pthread_cond *cvp, const struct pthread_cond_attr *cattr) 72 { 73 74 if (cattr == NULL) { 75 cvp->__clock_id = CLOCK_REALTIME; 76 } else { 77 if (cattr->c_pshared) 78 cvp->__flags |= USYNC_PROCESS_SHARED; 79 cvp->__clock_id = cattr->c_clockid; 80 } 81 } 82 83 static int 84 cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) 85 { 86 struct pthread_cond *cvp; 87 const struct pthread_cond_attr *cattr; 88 int pshared; 89 90 cattr = cond_attr != NULL ? *cond_attr : NULL; 91 if (cattr == NULL || cattr->c_pshared == PTHREAD_PROCESS_PRIVATE) { 92 pshared = 0; 93 cvp = calloc(1, sizeof(struct pthread_cond)); 94 if (cvp == NULL) 95 return (ENOMEM); 96 } else { 97 pshared = 1; 98 cvp = __thr_pshared_offpage(cond, 1); 99 if (cvp == NULL) 100 return (EFAULT); 101 } 102 103 /* 104 * Initialise the condition variable structure: 105 */ 106 cond_init_body(cvp, cattr); 107 *cond = pshared ? THR_PSHARED_PTR : cvp; 108 return (0); 109 } 110 111 static int 112 init_static(struct pthread *thread, pthread_cond_t *cond) 113 { 114 int ret; 115 116 THR_LOCK_ACQUIRE(thread, &_cond_static_lock); 117 118 if (*cond == NULL) 119 ret = cond_init(cond, NULL); 120 else 121 ret = 0; 122 123 THR_LOCK_RELEASE(thread, &_cond_static_lock); 124 125 return (ret); 126 } 127 128 #define CHECK_AND_INIT_COND \ 129 if (*cond == THR_PSHARED_PTR) { \ 130 cvp = __thr_pshared_offpage(cond, 0); \ 131 if (cvp == NULL) \ 132 return (EINVAL); \ 133 } else if (__predict_false((cvp = (*cond)) <= THR_COND_DESTROYED)) { \ 134 if (cvp == THR_COND_INITIALIZER) { \ 135 int ret; \ 136 ret = init_static(_get_curthread(), cond); \ 137 if (ret) \ 138 return (ret); \ 139 } else if (cvp == THR_COND_DESTROYED) { \ 140 return (EINVAL); \ 141 } \ 142 cvp = *cond; \ 143 } 144 145 int 146 _pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) 147 { 148 149 *cond = NULL; 150 return (cond_init(cond, cond_attr)); 151 } 152 153 int 154 _pthread_cond_destroy(pthread_cond_t *cond) 155 { 156 struct pthread_cond *cvp; 157 int error; 158 159 error = 0; 160 if (*cond == THR_PSHARED_PTR) { 161 cvp = __thr_pshared_offpage(cond, 0); 162 if (cvp != NULL) 163 __thr_pshared_destroy(cond); 164 *cond = THR_COND_DESTROYED; 165 } else if ((cvp = *cond) == THR_COND_INITIALIZER) { 166 /* nothing */ 167 } else if (cvp == THR_COND_DESTROYED) { 168 error = EINVAL; 169 } else { 170 cvp = *cond; 171 *cond = THR_COND_DESTROYED; 172 free(cvp); 173 } 174 return (error); 175 } 176 177 /* 178 * Cancellation behavior: 179 * Thread may be canceled at start, if thread is canceled, it means it 180 * did not get a wakeup from pthread_cond_signal(), otherwise, it is 181 * not canceled. 182 * Thread cancellation never cause wakeup from pthread_cond_signal() 183 * to be lost. 184 */ 185 static int 186 cond_wait_kernel(struct pthread_cond *cvp, struct pthread_mutex *mp, 187 const struct timespec *abstime, int cancel) 188 { 189 struct pthread *curthread = _get_curthread(); 190 int recurse; 191 int error, error2 = 0; 192 193 error = _mutex_cv_detach(mp, &recurse); 194 if (error != 0) 195 return (error); 196 197 if (cancel) { 198 _thr_cancel_enter2(curthread, 0); 199 error = _thr_ucond_wait((struct ucond *)&cvp->__has_kern_waiters, 200 (struct umutex *)&mp->m_lock, abstime, 201 CVWAIT_ABSTIME|CVWAIT_CLOCKID); 202 _thr_cancel_leave(curthread, 0); 203 } else { 204 error = _thr_ucond_wait((struct ucond *)&cvp->__has_kern_waiters, 205 (struct umutex *)&mp->m_lock, abstime, 206 CVWAIT_ABSTIME|CVWAIT_CLOCKID); 207 } 208 209 /* 210 * Note that PP mutex and ROBUST mutex may return 211 * interesting error codes. 212 */ 213 if (error == 0) { 214 error2 = _mutex_cv_lock(mp, recurse); 215 } else if (error == EINTR || error == ETIMEDOUT) { 216 error2 = _mutex_cv_lock(mp, recurse); 217 if (error2 == 0 && cancel) 218 _thr_testcancel(curthread); 219 if (error == EINTR) 220 error = 0; 221 } else { 222 /* We know that it didn't unlock the mutex. */ 223 error2 = _mutex_cv_attach(mp, recurse); 224 if (error2 == 0 && cancel) 225 _thr_testcancel(curthread); 226 } 227 return (error2 != 0 ? error2 : error); 228 } 229 230 /* 231 * Thread waits in userland queue whenever possible, when thread 232 * is signaled or broadcasted, it is removed from the queue, and 233 * is saved in curthread's defer_waiters[] buffer, but won't be 234 * woken up until mutex is unlocked. 235 */ 236 237 static int 238 cond_wait_user(struct pthread_cond *cvp, struct pthread_mutex *mp, 239 const struct timespec *abstime, int cancel) 240 { 241 struct pthread *curthread = _get_curthread(); 242 struct sleepqueue *sq; 243 int recurse; 244 int error; 245 int defered; 246 247 if (curthread->wchan != NULL) 248 PANIC("thread was already on queue."); 249 250 if (cancel) 251 _thr_testcancel(curthread); 252 253 _sleepq_lock(cvp); 254 /* 255 * set __has_user_waiters before unlocking mutex, this allows 256 * us to check it without locking in pthread_cond_signal(). 257 */ 258 cvp->__has_user_waiters = 1; 259 defered = 0; 260 (void)_mutex_cv_unlock(mp, &recurse, &defered); 261 curthread->mutex_obj = mp; 262 _sleepq_add(cvp, curthread); 263 for(;;) { 264 _thr_clear_wake(curthread); 265 _sleepq_unlock(cvp); 266 if (defered) { 267 defered = 0; 268 if ((mp->m_lock.m_owner & UMUTEX_CONTESTED) == 0) 269 (void)_umtx_op_err(&mp->m_lock, UMTX_OP_MUTEX_WAKE2, 270 mp->m_lock.m_flags, 0, 0); 271 } 272 if (curthread->nwaiter_defer > 0) { 273 _thr_wake_all(curthread->defer_waiters, 274 curthread->nwaiter_defer); 275 curthread->nwaiter_defer = 0; 276 } 277 278 if (cancel) { 279 _thr_cancel_enter2(curthread, 0); 280 error = _thr_sleep(curthread, cvp->__clock_id, abstime); 281 _thr_cancel_leave(curthread, 0); 282 } else { 283 error = _thr_sleep(curthread, cvp->__clock_id, abstime); 284 } 285 286 _sleepq_lock(cvp); 287 if (curthread->wchan == NULL) { 288 error = 0; 289 break; 290 } else if (cancel && SHOULD_CANCEL(curthread)) { 291 sq = _sleepq_lookup(cvp); 292 cvp->__has_user_waiters = 293 _sleepq_remove(sq, curthread); 294 _sleepq_unlock(cvp); 295 curthread->mutex_obj = NULL; 296 _mutex_cv_lock(mp, recurse); 297 if (!THR_IN_CRITICAL(curthread)) 298 _pthread_exit(PTHREAD_CANCELED); 299 else /* this should not happen */ 300 return (0); 301 } else if (error == ETIMEDOUT) { 302 sq = _sleepq_lookup(cvp); 303 cvp->__has_user_waiters = 304 _sleepq_remove(sq, curthread); 305 break; 306 } 307 } 308 _sleepq_unlock(cvp); 309 curthread->mutex_obj = NULL; 310 _mutex_cv_lock(mp, recurse); 311 return (error); 312 } 313 314 static int 315 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 316 const struct timespec *abstime, int cancel) 317 { 318 struct pthread *curthread = _get_curthread(); 319 struct pthread_cond *cvp; 320 struct pthread_mutex *mp; 321 int error; 322 323 CHECK_AND_INIT_COND 324 325 if (*mutex == THR_PSHARED_PTR) { 326 mp = __thr_pshared_offpage(mutex, 0); 327 if (mp == NULL) 328 return (EINVAL); 329 } else { 330 mp = *mutex; 331 } 332 333 if ((error = _mutex_owned(curthread, mp)) != 0) 334 return (error); 335 336 if (curthread->attr.sched_policy != SCHED_OTHER || 337 (mp->m_lock.m_flags & (UMUTEX_PRIO_PROTECT|UMUTEX_PRIO_INHERIT| 338 USYNC_PROCESS_SHARED)) != 0 || 339 (cvp->__flags & USYNC_PROCESS_SHARED) != 0) 340 return cond_wait_kernel(cvp, mp, abstime, cancel); 341 else 342 return cond_wait_user(cvp, mp, abstime, cancel); 343 } 344 345 int 346 _pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) 347 { 348 349 return (cond_wait_common(cond, mutex, NULL, 0)); 350 } 351 352 int 353 __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) 354 { 355 356 return (cond_wait_common(cond, mutex, NULL, 1)); 357 } 358 359 int 360 _pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 361 const struct timespec * abstime) 362 { 363 364 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 365 abstime->tv_nsec >= 1000000000) 366 return (EINVAL); 367 368 return (cond_wait_common(cond, mutex, abstime, 0)); 369 } 370 371 int 372 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 373 const struct timespec *abstime) 374 { 375 376 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 377 abstime->tv_nsec >= 1000000000) 378 return (EINVAL); 379 380 return (cond_wait_common(cond, mutex, abstime, 1)); 381 } 382 383 static int 384 cond_signal_common(pthread_cond_t *cond) 385 { 386 struct pthread *curthread = _get_curthread(); 387 struct pthread *td; 388 struct pthread_cond *cvp; 389 struct pthread_mutex *mp; 390 struct sleepqueue *sq; 391 int *waddr; 392 int pshared; 393 394 /* 395 * If the condition variable is statically initialized, perform dynamic 396 * initialization. 397 */ 398 CHECK_AND_INIT_COND 399 400 pshared = CV_PSHARED(cvp); 401 402 _thr_ucond_signal((struct ucond *)&cvp->__has_kern_waiters); 403 404 if (pshared || cvp->__has_user_waiters == 0) 405 return (0); 406 407 curthread = _get_curthread(); 408 waddr = NULL; 409 _sleepq_lock(cvp); 410 sq = _sleepq_lookup(cvp); 411 if (sq == NULL) { 412 _sleepq_unlock(cvp); 413 return (0); 414 } 415 416 td = _sleepq_first(sq); 417 mp = td->mutex_obj; 418 cvp->__has_user_waiters = _sleepq_remove(sq, td); 419 if (mp->m_owner == TID(curthread)) { 420 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 421 _thr_wake_all(curthread->defer_waiters, 422 curthread->nwaiter_defer); 423 curthread->nwaiter_defer = 0; 424 } 425 curthread->defer_waiters[curthread->nwaiter_defer++] = 426 &td->wake_addr->value; 427 mp->m_flags |= PMUTEX_FLAG_DEFERED; 428 } else { 429 waddr = &td->wake_addr->value; 430 } 431 _sleepq_unlock(cvp); 432 if (waddr != NULL) 433 _thr_set_wake(waddr); 434 return (0); 435 } 436 437 struct broadcast_arg { 438 struct pthread *curthread; 439 unsigned int *waddrs[MAX_DEFER_WAITERS]; 440 int count; 441 }; 442 443 static void 444 drop_cb(struct pthread *td, void *arg) 445 { 446 struct broadcast_arg *ba = arg; 447 struct pthread_mutex *mp; 448 struct pthread *curthread = ba->curthread; 449 450 mp = td->mutex_obj; 451 if (mp->m_owner == TID(curthread)) { 452 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 453 _thr_wake_all(curthread->defer_waiters, 454 curthread->nwaiter_defer); 455 curthread->nwaiter_defer = 0; 456 } 457 curthread->defer_waiters[curthread->nwaiter_defer++] = 458 &td->wake_addr->value; 459 mp->m_flags |= PMUTEX_FLAG_DEFERED; 460 } else { 461 if (ba->count >= MAX_DEFER_WAITERS) { 462 _thr_wake_all(ba->waddrs, ba->count); 463 ba->count = 0; 464 } 465 ba->waddrs[ba->count++] = &td->wake_addr->value; 466 } 467 } 468 469 static int 470 cond_broadcast_common(pthread_cond_t *cond) 471 { 472 int pshared; 473 struct pthread_cond *cvp; 474 struct sleepqueue *sq; 475 struct broadcast_arg ba; 476 477 /* 478 * If the condition variable is statically initialized, perform dynamic 479 * initialization. 480 */ 481 CHECK_AND_INIT_COND 482 483 pshared = CV_PSHARED(cvp); 484 485 _thr_ucond_broadcast((struct ucond *)&cvp->__has_kern_waiters); 486 487 if (pshared || cvp->__has_user_waiters == 0) 488 return (0); 489 490 ba.curthread = _get_curthread(); 491 ba.count = 0; 492 493 _sleepq_lock(cvp); 494 sq = _sleepq_lookup(cvp); 495 if (sq == NULL) { 496 _sleepq_unlock(cvp); 497 return (0); 498 } 499 _sleepq_drop(sq, drop_cb, &ba); 500 cvp->__has_user_waiters = 0; 501 _sleepq_unlock(cvp); 502 if (ba.count > 0) 503 _thr_wake_all(ba.waddrs, ba.count); 504 return (0); 505 } 506 507 int 508 _pthread_cond_signal(pthread_cond_t * cond) 509 { 510 511 return (cond_signal_common(cond)); 512 } 513 514 int 515 _pthread_cond_broadcast(pthread_cond_t * cond) 516 { 517 518 return (cond_broadcast_common(cond)); 519 } 520