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_clockwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 50 clockid_t clockid, const struct timespec *abstime); 51 int __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 52 const struct timespec * abstime); 53 static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr); 54 static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 55 clockid_t clockid, const struct timespec *abstime, bool cancel, 56 bool clockwait); 57 static int cond_signal_common(pthread_cond_t *cond); 58 static int cond_broadcast_common(pthread_cond_t *cond); 59 60 /* 61 * Double underscore versions are cancellation points. Single underscore 62 * versions are not and are provided for libc internal usage (which 63 * shouldn't introduce cancellation points). 64 */ 65 __weak_reference(__thr_cond_wait, pthread_cond_wait); 66 __weak_reference(__thr_cond_wait, __pthread_cond_wait); 67 __weak_reference(_thr_cond_wait, _pthread_cond_wait); 68 __weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait); 69 __weak_reference(_thr_cond_timedwait, _pthread_cond_timedwait); 70 __weak_reference(__pthread_cond_clockwait, pthread_cond_clockwait); 71 __weak_reference(_thr_cond_init, pthread_cond_init); 72 __weak_reference(_thr_cond_init, _pthread_cond_init); 73 __weak_reference(_thr_cond_destroy, pthread_cond_destroy); 74 __weak_reference(_thr_cond_destroy, _pthread_cond_destroy); 75 __weak_reference(_thr_cond_signal, pthread_cond_signal); 76 __weak_reference(_thr_cond_signal, _pthread_cond_signal); 77 __weak_reference(_thr_cond_broadcast, pthread_cond_broadcast); 78 __weak_reference(_thr_cond_broadcast, _pthread_cond_broadcast); 79 80 #define CV_PSHARED(cvp) (((cvp)->kcond.c_flags & USYNC_PROCESS_SHARED) != 0) 81 82 static void 83 cond_init_body(struct pthread_cond *cvp, const struct pthread_cond_attr *cattr) 84 { 85 86 if (cattr == NULL) { 87 cvp->kcond.c_clockid = CLOCK_REALTIME; 88 } else { 89 if (cattr->c_pshared) 90 cvp->kcond.c_flags |= USYNC_PROCESS_SHARED; 91 cvp->kcond.c_clockid = cattr->c_clockid; 92 } 93 } 94 95 static int 96 cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) 97 { 98 struct pthread_cond *cvp; 99 const struct pthread_cond_attr *cattr; 100 int pshared; 101 102 cattr = cond_attr != NULL ? *cond_attr : NULL; 103 if (cattr == NULL || cattr->c_pshared == PTHREAD_PROCESS_PRIVATE) { 104 pshared = 0; 105 cvp = calloc(1, sizeof(struct pthread_cond)); 106 if (cvp == NULL) 107 return (ENOMEM); 108 } else { 109 pshared = 1; 110 cvp = __thr_pshared_offpage(cond, 1); 111 if (cvp == NULL) 112 return (EFAULT); 113 } 114 115 /* 116 * Initialise the condition variable structure: 117 */ 118 cond_init_body(cvp, cattr); 119 *cond = pshared ? THR_PSHARED_PTR : cvp; 120 return (0); 121 } 122 123 static int 124 init_static(struct pthread *thread, pthread_cond_t *cond) 125 { 126 int ret; 127 128 THR_LOCK_ACQUIRE(thread, &_cond_static_lock); 129 130 if (*cond == NULL) 131 ret = cond_init(cond, NULL); 132 else 133 ret = 0; 134 135 THR_LOCK_RELEASE(thread, &_cond_static_lock); 136 137 return (ret); 138 } 139 140 #define CHECK_AND_INIT_COND \ 141 if (*cond == THR_PSHARED_PTR) { \ 142 cvp = __thr_pshared_offpage(cond, 0); \ 143 if (cvp == NULL) \ 144 return (EINVAL); \ 145 } else if (__predict_false((cvp = (*cond)) <= THR_COND_DESTROYED)) { \ 146 if (cvp == THR_COND_INITIALIZER) { \ 147 int ret; \ 148 ret = init_static(_get_curthread(), cond); \ 149 if (ret) \ 150 return (ret); \ 151 } else if (cvp == THR_COND_DESTROYED) { \ 152 return (EINVAL); \ 153 } \ 154 cvp = *cond; \ 155 } 156 157 int 158 _thr_cond_init(pthread_cond_t * __restrict cond, 159 const pthread_condattr_t * __restrict cond_attr) 160 { 161 162 *cond = NULL; 163 return (cond_init(cond, cond_attr)); 164 } 165 166 int 167 _thr_cond_destroy(pthread_cond_t *cond) 168 { 169 struct pthread_cond *cvp; 170 int error; 171 172 error = 0; 173 if (*cond == THR_PSHARED_PTR) { 174 cvp = __thr_pshared_offpage(cond, 0); 175 if (cvp != NULL) { 176 if (cvp->kcond.c_has_waiters) 177 error = EBUSY; 178 else 179 __thr_pshared_destroy(cond); 180 } 181 if (error == 0) 182 *cond = THR_COND_DESTROYED; 183 } else if ((cvp = *cond) == THR_COND_INITIALIZER) { 184 /* nothing */ 185 } else if (cvp == THR_COND_DESTROYED) { 186 error = EINVAL; 187 } else { 188 cvp = *cond; 189 if (cvp->__has_user_waiters || cvp->kcond.c_has_waiters) 190 error = EBUSY; 191 else { 192 *cond = THR_COND_DESTROYED; 193 free(cvp); 194 } 195 } 196 return (error); 197 } 198 199 /* 200 * Cancellation behavior: 201 * Thread may be canceled at start, if thread is canceled, it means it 202 * did not get a wakeup from pthread_cond_signal(), otherwise, it is 203 * not canceled. 204 * Thread cancellation never cause wakeup from pthread_cond_signal() 205 * to be lost. 206 */ 207 static int 208 cond_wait_kernel(struct pthread_cond *cvp, struct pthread_mutex *mp, 209 clockid_t clockid, const struct timespec *abstime, bool cancel, 210 bool clockwait) 211 { 212 struct pthread *curthread; 213 struct _umtx_time utime; 214 int error, error2, recurse, robust; 215 216 curthread = _get_curthread(); 217 robust = _mutex_enter_robust(curthread, mp); 218 219 error = _mutex_cv_detach(mp, &recurse); 220 if (error != 0) { 221 if (robust) 222 _mutex_leave_robust(curthread, mp); 223 return (error); 224 } 225 226 if (cancel) 227 _thr_cancel_enter2(curthread, 0); 228 if (clockwait) { 229 utime._timeout = *abstime; 230 utime._flags = UMTX_ABSTIME; 231 utime._clockid = clockid; 232 error = _thr_ucond_wait(&cvp->kcond, &mp->m_lock, NULL, 233 &utime, CVWAIT_UMTX_TIME); 234 } else { 235 error = _thr_ucond_wait(&cvp->kcond, &mp->m_lock, abstime, 236 NULL, CVWAIT_ABSTIME | CVWAIT_CLOCKID); 237 } 238 if (cancel) 239 _thr_cancel_leave(curthread, 0); 240 241 /* 242 * Note that PP mutex and ROBUST mutex may return 243 * interesting error codes. 244 */ 245 if (error == 0) { 246 error2 = _mutex_cv_lock(mp, recurse, true); 247 } else if (error == EINTR || error == ETIMEDOUT) { 248 error2 = _mutex_cv_lock(mp, recurse, true); 249 /* 250 * Do not do cancellation on EOWNERDEAD there. The 251 * cancellation cleanup handler will use the protected 252 * state and unlock the mutex without making the state 253 * consistent and the state will be unrecoverable. 254 */ 255 if (error2 == 0 && cancel) { 256 if (robust) { 257 _mutex_leave_robust(curthread, mp); 258 robust = false; 259 } 260 _thr_testcancel(curthread); 261 } 262 263 if (error == EINTR) 264 error = 0; 265 } else { 266 /* We know that it didn't unlock the mutex. */ 267 _mutex_cv_attach(mp, recurse); 268 if (cancel) { 269 if (robust) { 270 _mutex_leave_robust(curthread, mp); 271 robust = false; 272 } 273 _thr_testcancel(curthread); 274 } 275 error2 = 0; 276 } 277 if (robust) 278 _mutex_leave_robust(curthread, mp); 279 return (error2 != 0 ? error2 : error); 280 } 281 282 /* 283 * Thread waits in userland queue whenever possible, when thread 284 * is signaled or broadcasted, it is removed from the queue, and 285 * is saved in curthread's defer_waiters[] buffer, but won't be 286 * woken up until mutex is unlocked. 287 */ 288 289 static int 290 cond_wait_user(struct pthread_cond *cvp, struct pthread_mutex *mp, 291 clockid_t clockid, const struct timespec *abstime, bool cancel) 292 { 293 struct pthread *curthread; 294 struct sleepqueue *sq; 295 int deferred, error, error2, recurse; 296 297 curthread = _get_curthread(); 298 if (curthread->wchan != NULL) 299 PANIC("thread %p was already on queue.", curthread); 300 301 if (cancel) 302 _thr_testcancel(curthread); 303 304 _sleepq_lock(cvp); 305 /* 306 * set __has_user_waiters before unlocking mutex, this allows 307 * us to check it without locking in pthread_cond_signal(). 308 */ 309 cvp->__has_user_waiters = 1; 310 deferred = 0; 311 (void)_mutex_cv_unlock(mp, &recurse, &deferred); 312 curthread->mutex_obj = mp; 313 _sleepq_add(cvp, curthread); 314 for(;;) { 315 _thr_clear_wake(curthread); 316 _sleepq_unlock(cvp); 317 if (deferred) { 318 deferred = 0; 319 if ((mp->m_lock.m_owner & UMUTEX_CONTESTED) == 0) 320 (void)_umtx_op_err(&mp->m_lock, 321 UMTX_OP_MUTEX_WAKE2, mp->m_lock.m_flags, 322 0, 0); 323 } 324 if (curthread->nwaiter_defer > 0) { 325 _thr_wake_all(curthread->defer_waiters, 326 curthread->nwaiter_defer); 327 curthread->nwaiter_defer = 0; 328 } 329 330 if (cancel) 331 _thr_cancel_enter2(curthread, 0); 332 error = _thr_sleep(curthread, clockid, abstime); 333 if (cancel) 334 _thr_cancel_leave(curthread, 0); 335 336 _sleepq_lock(cvp); 337 if (curthread->wchan == NULL) { 338 error = 0; 339 break; 340 } else if (cancel && SHOULD_CANCEL(curthread)) { 341 sq = _sleepq_lookup(cvp); 342 cvp->__has_user_waiters = _sleepq_remove(sq, curthread); 343 _sleepq_unlock(cvp); 344 curthread->mutex_obj = NULL; 345 error2 = _mutex_cv_lock(mp, recurse, false); 346 if (!THR_IN_CRITICAL(curthread)) 347 _pthread_exit(PTHREAD_CANCELED); 348 else /* this should not happen */ 349 return (error2); 350 } else if (error == ETIMEDOUT) { 351 sq = _sleepq_lookup(cvp); 352 cvp->__has_user_waiters = 353 _sleepq_remove(sq, curthread); 354 break; 355 } 356 } 357 _sleepq_unlock(cvp); 358 curthread->mutex_obj = NULL; 359 error2 = _mutex_cv_lock(mp, recurse, false); 360 if (error == 0) 361 error = error2; 362 return (error); 363 } 364 365 static int 366 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 367 clockid_t clockid, const struct timespec *abstime, bool cancel, 368 bool clockwait) 369 { 370 struct pthread *curthread = _get_curthread(); 371 struct pthread_cond *cvp; 372 struct pthread_mutex *mp; 373 int error; 374 375 CHECK_AND_INIT_COND 376 377 if (!clockwait) 378 clockid = cvp->kcond.c_clockid; 379 380 if (*mutex == THR_PSHARED_PTR) { 381 mp = __thr_pshared_offpage(mutex, 0); 382 if (mp == NULL) 383 return (EINVAL); 384 } else { 385 mp = *mutex; 386 } 387 388 if ((error = _mutex_owned(curthread, mp)) != 0) 389 return (error); 390 391 if (curthread->attr.sched_policy != SCHED_OTHER || 392 (mp->m_lock.m_flags & (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT | 393 USYNC_PROCESS_SHARED)) != 0 || CV_PSHARED(cvp)) { 394 return (cond_wait_kernel(cvp, mp, clockid, abstime, cancel, 395 clockwait)); 396 } else { 397 return (cond_wait_user(cvp, mp, clockid, abstime, cancel)); 398 } 399 } 400 401 int 402 _thr_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) 403 { 404 return (cond_wait_common(cond, mutex, 0, NULL, false, false)); 405 } 406 407 int 408 __thr_cond_wait(pthread_cond_t * __restrict cond, 409 pthread_mutex_t * __restrict mutex) 410 { 411 return (cond_wait_common(cond, mutex, 0, NULL, true, false)); 412 } 413 414 int 415 _thr_cond_timedwait(pthread_cond_t * __restrict cond, 416 pthread_mutex_t * __restrict mutex, 417 const struct timespec * __restrict abstime) 418 { 419 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 420 abstime->tv_nsec >= 1000000000) 421 return (EINVAL); 422 423 return (cond_wait_common(cond, mutex, 0, abstime, false, false)); 424 } 425 426 int 427 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 428 const struct timespec *abstime) 429 { 430 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 431 abstime->tv_nsec >= 1000000000) 432 return (EINVAL); 433 434 return (cond_wait_common(cond, mutex, 0, abstime, true, false)); 435 } 436 437 int 438 __pthread_cond_clockwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 439 clockid_t clockid, const struct timespec *abstime) 440 { 441 442 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 443 abstime->tv_nsec >= 1000000000) 444 return (EINVAL); 445 446 return (cond_wait_common(cond, mutex, clockid, abstime, true, true)); 447 } 448 449 static int 450 cond_signal_common(pthread_cond_t *cond) 451 { 452 struct pthread *curthread = _get_curthread(); 453 struct pthread *td; 454 struct pthread_cond *cvp; 455 struct pthread_mutex *mp; 456 struct sleepqueue *sq; 457 int *waddr; 458 int pshared; 459 460 /* 461 * If the condition variable is statically initialized, perform dynamic 462 * initialization. 463 */ 464 CHECK_AND_INIT_COND 465 466 pshared = CV_PSHARED(cvp); 467 468 _thr_ucond_signal(&cvp->kcond); 469 470 if (pshared || cvp->__has_user_waiters == 0) 471 return (0); 472 473 curthread = _get_curthread(); 474 waddr = NULL; 475 _sleepq_lock(cvp); 476 sq = _sleepq_lookup(cvp); 477 if (sq == NULL) { 478 _sleepq_unlock(cvp); 479 return (0); 480 } 481 482 td = _sleepq_first(sq); 483 mp = td->mutex_obj; 484 cvp->__has_user_waiters = _sleepq_remove(sq, td); 485 if (PMUTEX_OWNER_ID(mp) == TID(curthread)) { 486 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 487 _thr_wake_all(curthread->defer_waiters, 488 curthread->nwaiter_defer); 489 curthread->nwaiter_defer = 0; 490 } 491 curthread->defer_waiters[curthread->nwaiter_defer++] = 492 &td->wake_addr->value; 493 mp->m_flags |= PMUTEX_FLAG_DEFERRED; 494 } else { 495 waddr = &td->wake_addr->value; 496 } 497 _sleepq_unlock(cvp); 498 if (waddr != NULL) 499 _thr_set_wake(waddr); 500 return (0); 501 } 502 503 struct broadcast_arg { 504 struct pthread *curthread; 505 unsigned int *waddrs[MAX_DEFER_WAITERS]; 506 int count; 507 }; 508 509 static void 510 drop_cb(struct pthread *td, void *arg) 511 { 512 struct broadcast_arg *ba = arg; 513 struct pthread_mutex *mp; 514 struct pthread *curthread = ba->curthread; 515 516 mp = td->mutex_obj; 517 if (PMUTEX_OWNER_ID(mp) == TID(curthread)) { 518 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 519 _thr_wake_all(curthread->defer_waiters, 520 curthread->nwaiter_defer); 521 curthread->nwaiter_defer = 0; 522 } 523 curthread->defer_waiters[curthread->nwaiter_defer++] = 524 &td->wake_addr->value; 525 mp->m_flags |= PMUTEX_FLAG_DEFERRED; 526 } else { 527 if (ba->count >= MAX_DEFER_WAITERS) { 528 _thr_wake_all(ba->waddrs, ba->count); 529 ba->count = 0; 530 } 531 ba->waddrs[ba->count++] = &td->wake_addr->value; 532 } 533 } 534 535 static int 536 cond_broadcast_common(pthread_cond_t *cond) 537 { 538 int pshared; 539 struct pthread_cond *cvp; 540 struct sleepqueue *sq; 541 struct broadcast_arg ba; 542 543 /* 544 * If the condition variable is statically initialized, perform dynamic 545 * initialization. 546 */ 547 CHECK_AND_INIT_COND 548 549 pshared = CV_PSHARED(cvp); 550 551 _thr_ucond_broadcast(&cvp->kcond); 552 553 if (pshared || cvp->__has_user_waiters == 0) 554 return (0); 555 556 ba.curthread = _get_curthread(); 557 ba.count = 0; 558 559 _sleepq_lock(cvp); 560 sq = _sleepq_lookup(cvp); 561 if (sq == NULL) { 562 _sleepq_unlock(cvp); 563 return (0); 564 } 565 _sleepq_drop(sq, drop_cb, &ba); 566 cvp->__has_user_waiters = 0; 567 _sleepq_unlock(cvp); 568 if (ba.count > 0) 569 _thr_wake_all(ba.waddrs, ba.count); 570 return (0); 571 } 572 573 int 574 _thr_cond_signal(pthread_cond_t * cond) 575 { 576 577 return (cond_signal_common(cond)); 578 } 579 580 int 581 _thr_cond_broadcast(pthread_cond_t * cond) 582 { 583 584 return (cond_broadcast_common(cond)); 585 } 586