1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2005 David Xu <davidxu@freebsd.org> 5 * Copyright (c) 2015 The FreeBSD Foundation 6 * All rights reserved. 7 * 8 * Portions of this software were developed by Konstantin Belousov 9 * under sponsorship from the FreeBSD Foundation. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice unmodified, this list of conditions, and the following 16 * disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 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 _Static_assert(sizeof(struct pthread_cond) <= THR_PAGE_SIZE_MIN, 44 "pthread_cond too large"); 45 46 /* 47 * Prototypes 48 */ 49 int __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 50 const struct timespec * abstime); 51 static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr); 52 static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 53 const struct timespec *abstime, int cancel); 54 static int cond_signal_common(pthread_cond_t *cond); 55 static int cond_broadcast_common(pthread_cond_t *cond); 56 57 /* 58 * Double underscore versions are cancellation points. Single underscore 59 * versions are not and are provided for libc internal usage (which 60 * shouldn't introduce cancellation points). 61 */ 62 __weak_reference(__thr_cond_wait, pthread_cond_wait); 63 __weak_reference(__thr_cond_wait, __pthread_cond_wait); 64 __weak_reference(_thr_cond_wait, _pthread_cond_wait); 65 __weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait); 66 __weak_reference(_thr_cond_init, pthread_cond_init); 67 __weak_reference(_thr_cond_init, _pthread_cond_init); 68 __weak_reference(_thr_cond_destroy, pthread_cond_destroy); 69 __weak_reference(_thr_cond_destroy, _pthread_cond_destroy); 70 __weak_reference(_thr_cond_signal, pthread_cond_signal); 71 __weak_reference(_thr_cond_signal, _pthread_cond_signal); 72 __weak_reference(_thr_cond_broadcast, pthread_cond_broadcast); 73 __weak_reference(_thr_cond_broadcast, _pthread_cond_broadcast); 74 75 #define CV_PSHARED(cvp) (((cvp)->kcond.c_flags & USYNC_PROCESS_SHARED) != 0) 76 77 static void 78 cond_init_body(struct pthread_cond *cvp, const struct pthread_cond_attr *cattr) 79 { 80 81 if (cattr == NULL) { 82 cvp->kcond.c_clockid = CLOCK_REALTIME; 83 } else { 84 if (cattr->c_pshared) 85 cvp->kcond.c_flags |= USYNC_PROCESS_SHARED; 86 cvp->kcond.c_clockid = cattr->c_clockid; 87 } 88 } 89 90 static int 91 cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) 92 { 93 struct pthread_cond *cvp; 94 const struct pthread_cond_attr *cattr; 95 int pshared; 96 97 cattr = cond_attr != NULL ? *cond_attr : NULL; 98 if (cattr == NULL || cattr->c_pshared == PTHREAD_PROCESS_PRIVATE) { 99 pshared = 0; 100 cvp = calloc(1, sizeof(struct pthread_cond)); 101 if (cvp == NULL) 102 return (ENOMEM); 103 } else { 104 pshared = 1; 105 cvp = __thr_pshared_offpage(cond, 1); 106 if (cvp == NULL) 107 return (EFAULT); 108 } 109 110 /* 111 * Initialise the condition variable structure: 112 */ 113 cond_init_body(cvp, cattr); 114 *cond = pshared ? THR_PSHARED_PTR : cvp; 115 return (0); 116 } 117 118 static int 119 init_static(struct pthread *thread, pthread_cond_t *cond) 120 { 121 int ret; 122 123 THR_LOCK_ACQUIRE(thread, &_cond_static_lock); 124 125 if (*cond == NULL) 126 ret = cond_init(cond, NULL); 127 else 128 ret = 0; 129 130 THR_LOCK_RELEASE(thread, &_cond_static_lock); 131 132 return (ret); 133 } 134 135 #define CHECK_AND_INIT_COND \ 136 if (*cond == THR_PSHARED_PTR) { \ 137 cvp = __thr_pshared_offpage(cond, 0); \ 138 if (cvp == NULL) \ 139 return (EINVAL); \ 140 } else if (__predict_false((cvp = (*cond)) <= THR_COND_DESTROYED)) { \ 141 if (cvp == THR_COND_INITIALIZER) { \ 142 int ret; \ 143 ret = init_static(_get_curthread(), cond); \ 144 if (ret) \ 145 return (ret); \ 146 } else if (cvp == THR_COND_DESTROYED) { \ 147 return (EINVAL); \ 148 } \ 149 cvp = *cond; \ 150 } 151 152 int 153 _thr_cond_init(pthread_cond_t * __restrict cond, 154 const pthread_condattr_t * __restrict cond_attr) 155 { 156 157 *cond = NULL; 158 return (cond_init(cond, cond_attr)); 159 } 160 161 int 162 _thr_cond_destroy(pthread_cond_t *cond) 163 { 164 struct pthread_cond *cvp; 165 int error; 166 167 error = 0; 168 if (*cond == THR_PSHARED_PTR) { 169 cvp = __thr_pshared_offpage(cond, 0); 170 if (cvp != NULL) { 171 if (cvp->kcond.c_has_waiters) 172 error = EBUSY; 173 else 174 __thr_pshared_destroy(cond); 175 } 176 if (error == 0) 177 *cond = THR_COND_DESTROYED; 178 } else if ((cvp = *cond) == THR_COND_INITIALIZER) { 179 /* nothing */ 180 } else if (cvp == THR_COND_DESTROYED) { 181 error = EINVAL; 182 } else { 183 cvp = *cond; 184 if (cvp->__has_user_waiters || cvp->kcond.c_has_waiters) 185 error = EBUSY; 186 else { 187 *cond = THR_COND_DESTROYED; 188 free(cvp); 189 } 190 } 191 return (error); 192 } 193 194 /* 195 * Cancellation behavior: 196 * Thread may be canceled at start, if thread is canceled, it means it 197 * did not get a wakeup from pthread_cond_signal(), otherwise, it is 198 * not canceled. 199 * Thread cancellation never cause wakeup from pthread_cond_signal() 200 * to be lost. 201 */ 202 static int 203 cond_wait_kernel(struct pthread_cond *cvp, struct pthread_mutex *mp, 204 const struct timespec *abstime, int cancel) 205 { 206 struct pthread *curthread; 207 int error, error2, recurse, robust; 208 209 curthread = _get_curthread(); 210 robust = _mutex_enter_robust(curthread, mp); 211 212 error = _mutex_cv_detach(mp, &recurse); 213 if (error != 0) { 214 if (robust) 215 _mutex_leave_robust(curthread, mp); 216 return (error); 217 } 218 219 if (cancel) 220 _thr_cancel_enter2(curthread, 0); 221 error = _thr_ucond_wait(&cvp->kcond, &mp->m_lock, abstime, 222 CVWAIT_ABSTIME | CVWAIT_CLOCKID); 223 if (cancel) 224 _thr_cancel_leave(curthread, 0); 225 226 /* 227 * Note that PP mutex and ROBUST mutex may return 228 * interesting error codes. 229 */ 230 if (error == 0) { 231 error2 = _mutex_cv_lock(mp, recurse, true); 232 } else if (error == EINTR || error == ETIMEDOUT) { 233 error2 = _mutex_cv_lock(mp, recurse, true); 234 /* 235 * Do not do cancellation on EOWNERDEAD there. The 236 * cancellation cleanup handler will use the protected 237 * state and unlock the mutex without making the state 238 * consistent and the state will be unrecoverable. 239 */ 240 if (error2 == 0 && cancel) { 241 if (robust) { 242 _mutex_leave_robust(curthread, mp); 243 robust = false; 244 } 245 _thr_testcancel(curthread); 246 } 247 248 if (error == EINTR) 249 error = 0; 250 } else { 251 /* We know that it didn't unlock the mutex. */ 252 _mutex_cv_attach(mp, recurse); 253 if (cancel) { 254 if (robust) { 255 _mutex_leave_robust(curthread, mp); 256 robust = false; 257 } 258 _thr_testcancel(curthread); 259 } 260 error2 = 0; 261 } 262 if (robust) 263 _mutex_leave_robust(curthread, mp); 264 return (error2 != 0 ? error2 : error); 265 } 266 267 /* 268 * Thread waits in userland queue whenever possible, when thread 269 * is signaled or broadcasted, it is removed from the queue, and 270 * is saved in curthread's defer_waiters[] buffer, but won't be 271 * woken up until mutex is unlocked. 272 */ 273 274 static int 275 cond_wait_user(struct pthread_cond *cvp, struct pthread_mutex *mp, 276 const struct timespec *abstime, int cancel) 277 { 278 struct pthread *curthread; 279 struct sleepqueue *sq; 280 int deferred, error, error2, recurse; 281 282 curthread = _get_curthread(); 283 if (curthread->wchan != NULL) 284 PANIC("thread %p was already on queue.", curthread); 285 286 if (cancel) 287 _thr_testcancel(curthread); 288 289 _sleepq_lock(cvp); 290 /* 291 * set __has_user_waiters before unlocking mutex, this allows 292 * us to check it without locking in pthread_cond_signal(). 293 */ 294 cvp->__has_user_waiters = 1; 295 deferred = 0; 296 (void)_mutex_cv_unlock(mp, &recurse, &deferred); 297 curthread->mutex_obj = mp; 298 _sleepq_add(cvp, curthread); 299 for(;;) { 300 _thr_clear_wake(curthread); 301 _sleepq_unlock(cvp); 302 if (deferred) { 303 deferred = 0; 304 if ((mp->m_lock.m_owner & UMUTEX_CONTESTED) == 0) 305 (void)_umtx_op_err(&mp->m_lock, 306 UMTX_OP_MUTEX_WAKE2, mp->m_lock.m_flags, 307 0, 0); 308 } 309 if (curthread->nwaiter_defer > 0) { 310 _thr_wake_all(curthread->defer_waiters, 311 curthread->nwaiter_defer); 312 curthread->nwaiter_defer = 0; 313 } 314 315 if (cancel) 316 _thr_cancel_enter2(curthread, 0); 317 error = _thr_sleep(curthread, cvp->kcond.c_clockid, abstime); 318 if (cancel) 319 _thr_cancel_leave(curthread, 0); 320 321 _sleepq_lock(cvp); 322 if (curthread->wchan == NULL) { 323 error = 0; 324 break; 325 } else if (cancel && SHOULD_CANCEL(curthread)) { 326 sq = _sleepq_lookup(cvp); 327 cvp->__has_user_waiters = _sleepq_remove(sq, curthread); 328 _sleepq_unlock(cvp); 329 curthread->mutex_obj = NULL; 330 error2 = _mutex_cv_lock(mp, recurse, false); 331 if (!THR_IN_CRITICAL(curthread)) 332 _pthread_exit(PTHREAD_CANCELED); 333 else /* this should not happen */ 334 return (error2); 335 } else if (error == ETIMEDOUT) { 336 sq = _sleepq_lookup(cvp); 337 cvp->__has_user_waiters = 338 _sleepq_remove(sq, curthread); 339 break; 340 } 341 } 342 _sleepq_unlock(cvp); 343 curthread->mutex_obj = NULL; 344 error2 = _mutex_cv_lock(mp, recurse, false); 345 if (error == 0) 346 error = error2; 347 return (error); 348 } 349 350 static int 351 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 352 const struct timespec *abstime, int cancel) 353 { 354 struct pthread *curthread = _get_curthread(); 355 struct pthread_cond *cvp; 356 struct pthread_mutex *mp; 357 int error; 358 359 CHECK_AND_INIT_COND 360 361 if (*mutex == THR_PSHARED_PTR) { 362 mp = __thr_pshared_offpage(mutex, 0); 363 if (mp == NULL) 364 return (EINVAL); 365 } else { 366 mp = *mutex; 367 } 368 369 if ((error = _mutex_owned(curthread, mp)) != 0) 370 return (error); 371 372 if (curthread->attr.sched_policy != SCHED_OTHER || 373 (mp->m_lock.m_flags & (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT | 374 USYNC_PROCESS_SHARED)) != 0 || CV_PSHARED(cvp)) 375 return (cond_wait_kernel(cvp, mp, abstime, cancel)); 376 else 377 return (cond_wait_user(cvp, mp, abstime, cancel)); 378 } 379 380 int 381 _thr_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) 382 { 383 384 return (cond_wait_common(cond, mutex, NULL, 0)); 385 } 386 387 int 388 __thr_cond_wait(pthread_cond_t * __restrict cond, 389 pthread_mutex_t * __restrict mutex) 390 { 391 392 return (cond_wait_common(cond, mutex, NULL, 1)); 393 } 394 395 int 396 _thr_cond_timedwait(pthread_cond_t * __restrict cond, 397 pthread_mutex_t * __restrict mutex, 398 const struct timespec * __restrict abstime) 399 { 400 401 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 402 abstime->tv_nsec >= 1000000000) 403 return (EINVAL); 404 405 return (cond_wait_common(cond, mutex, abstime, 0)); 406 } 407 408 int 409 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 410 const struct timespec *abstime) 411 { 412 413 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 414 abstime->tv_nsec >= 1000000000) 415 return (EINVAL); 416 417 return (cond_wait_common(cond, mutex, abstime, 1)); 418 } 419 420 static int 421 cond_signal_common(pthread_cond_t *cond) 422 { 423 struct pthread *curthread = _get_curthread(); 424 struct pthread *td; 425 struct pthread_cond *cvp; 426 struct pthread_mutex *mp; 427 struct sleepqueue *sq; 428 int *waddr; 429 int pshared; 430 431 /* 432 * If the condition variable is statically initialized, perform dynamic 433 * initialization. 434 */ 435 CHECK_AND_INIT_COND 436 437 pshared = CV_PSHARED(cvp); 438 439 _thr_ucond_signal(&cvp->kcond); 440 441 if (pshared || cvp->__has_user_waiters == 0) 442 return (0); 443 444 curthread = _get_curthread(); 445 waddr = NULL; 446 _sleepq_lock(cvp); 447 sq = _sleepq_lookup(cvp); 448 if (sq == NULL) { 449 _sleepq_unlock(cvp); 450 return (0); 451 } 452 453 td = _sleepq_first(sq); 454 mp = td->mutex_obj; 455 cvp->__has_user_waiters = _sleepq_remove(sq, td); 456 if (PMUTEX_OWNER_ID(mp) == TID(curthread)) { 457 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 458 _thr_wake_all(curthread->defer_waiters, 459 curthread->nwaiter_defer); 460 curthread->nwaiter_defer = 0; 461 } 462 curthread->defer_waiters[curthread->nwaiter_defer++] = 463 &td->wake_addr->value; 464 mp->m_flags |= PMUTEX_FLAG_DEFERRED; 465 } else { 466 waddr = &td->wake_addr->value; 467 } 468 _sleepq_unlock(cvp); 469 if (waddr != NULL) 470 _thr_set_wake(waddr); 471 return (0); 472 } 473 474 struct broadcast_arg { 475 struct pthread *curthread; 476 unsigned int *waddrs[MAX_DEFER_WAITERS]; 477 int count; 478 }; 479 480 static void 481 drop_cb(struct pthread *td, void *arg) 482 { 483 struct broadcast_arg *ba = arg; 484 struct pthread_mutex *mp; 485 struct pthread *curthread = ba->curthread; 486 487 mp = td->mutex_obj; 488 if (PMUTEX_OWNER_ID(mp) == TID(curthread)) { 489 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 490 _thr_wake_all(curthread->defer_waiters, 491 curthread->nwaiter_defer); 492 curthread->nwaiter_defer = 0; 493 } 494 curthread->defer_waiters[curthread->nwaiter_defer++] = 495 &td->wake_addr->value; 496 mp->m_flags |= PMUTEX_FLAG_DEFERRED; 497 } else { 498 if (ba->count >= MAX_DEFER_WAITERS) { 499 _thr_wake_all(ba->waddrs, ba->count); 500 ba->count = 0; 501 } 502 ba->waddrs[ba->count++] = &td->wake_addr->value; 503 } 504 } 505 506 static int 507 cond_broadcast_common(pthread_cond_t *cond) 508 { 509 int pshared; 510 struct pthread_cond *cvp; 511 struct sleepqueue *sq; 512 struct broadcast_arg ba; 513 514 /* 515 * If the condition variable is statically initialized, perform dynamic 516 * initialization. 517 */ 518 CHECK_AND_INIT_COND 519 520 pshared = CV_PSHARED(cvp); 521 522 _thr_ucond_broadcast(&cvp->kcond); 523 524 if (pshared || cvp->__has_user_waiters == 0) 525 return (0); 526 527 ba.curthread = _get_curthread(); 528 ba.count = 0; 529 530 _sleepq_lock(cvp); 531 sq = _sleepq_lookup(cvp); 532 if (sq == NULL) { 533 _sleepq_unlock(cvp); 534 return (0); 535 } 536 _sleepq_drop(sq, drop_cb, &ba); 537 cvp->__has_user_waiters = 0; 538 _sleepq_unlock(cvp); 539 if (ba.count > 0) 540 _thr_wake_all(ba.waddrs, ba.count); 541 return (0); 542 } 543 544 int 545 _thr_cond_signal(pthread_cond_t * cond) 546 { 547 548 return (cond_signal_common(cond)); 549 } 550 551 int 552 _thr_cond_broadcast(pthread_cond_t * cond) 553 { 554 555 return (cond_broadcast_common(cond)); 556 } 557