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 <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include "namespace.h" 37 #include <stdlib.h> 38 #include <errno.h> 39 #include <string.h> 40 #include <pthread.h> 41 #include <limits.h> 42 #include "un-namespace.h" 43 44 #include "thr_private.h" 45 46 _Static_assert(sizeof(struct pthread_cond) <= THR_PAGE_SIZE_MIN, 47 "pthread_cond too large"); 48 49 /* 50 * Prototypes 51 */ 52 int __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 53 const struct timespec * abstime); 54 static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr); 55 static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 56 const struct timespec *abstime, int cancel); 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_init, pthread_cond_init); 70 __weak_reference(_thr_cond_init, _pthread_cond_init); 71 __weak_reference(_thr_cond_destroy, pthread_cond_destroy); 72 __weak_reference(_thr_cond_destroy, _pthread_cond_destroy); 73 __weak_reference(_thr_cond_signal, pthread_cond_signal); 74 __weak_reference(_thr_cond_signal, _pthread_cond_signal); 75 __weak_reference(_thr_cond_broadcast, pthread_cond_broadcast); 76 __weak_reference(_thr_cond_broadcast, _pthread_cond_broadcast); 77 78 #define CV_PSHARED(cvp) (((cvp)->kcond.c_flags & USYNC_PROCESS_SHARED) != 0) 79 80 static void 81 cond_init_body(struct pthread_cond *cvp, const struct pthread_cond_attr *cattr) 82 { 83 84 if (cattr == NULL) { 85 cvp->kcond.c_clockid = CLOCK_REALTIME; 86 } else { 87 if (cattr->c_pshared) 88 cvp->kcond.c_flags |= USYNC_PROCESS_SHARED; 89 cvp->kcond.c_clockid = cattr->c_clockid; 90 } 91 } 92 93 static int 94 cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) 95 { 96 struct pthread_cond *cvp; 97 const struct pthread_cond_attr *cattr; 98 int pshared; 99 100 cattr = cond_attr != NULL ? *cond_attr : NULL; 101 if (cattr == NULL || cattr->c_pshared == PTHREAD_PROCESS_PRIVATE) { 102 pshared = 0; 103 cvp = calloc(1, sizeof(struct pthread_cond)); 104 if (cvp == NULL) 105 return (ENOMEM); 106 } else { 107 pshared = 1; 108 cvp = __thr_pshared_offpage(cond, 1); 109 if (cvp == NULL) 110 return (EFAULT); 111 } 112 113 /* 114 * Initialise the condition variable structure: 115 */ 116 cond_init_body(cvp, cattr); 117 *cond = pshared ? THR_PSHARED_PTR : cvp; 118 return (0); 119 } 120 121 static int 122 init_static(struct pthread *thread, pthread_cond_t *cond) 123 { 124 int ret; 125 126 THR_LOCK_ACQUIRE(thread, &_cond_static_lock); 127 128 if (*cond == NULL) 129 ret = cond_init(cond, NULL); 130 else 131 ret = 0; 132 133 THR_LOCK_RELEASE(thread, &_cond_static_lock); 134 135 return (ret); 136 } 137 138 #define CHECK_AND_INIT_COND \ 139 if (*cond == THR_PSHARED_PTR) { \ 140 cvp = __thr_pshared_offpage(cond, 0); \ 141 if (cvp == NULL) \ 142 return (EINVAL); \ 143 } else if (__predict_false((cvp = (*cond)) <= THR_COND_DESTROYED)) { \ 144 if (cvp == THR_COND_INITIALIZER) { \ 145 int ret; \ 146 ret = init_static(_get_curthread(), cond); \ 147 if (ret) \ 148 return (ret); \ 149 } else if (cvp == THR_COND_DESTROYED) { \ 150 return (EINVAL); \ 151 } \ 152 cvp = *cond; \ 153 } 154 155 int 156 _thr_cond_init(pthread_cond_t * __restrict cond, 157 const pthread_condattr_t * __restrict cond_attr) 158 { 159 160 *cond = NULL; 161 return (cond_init(cond, cond_attr)); 162 } 163 164 int 165 _thr_cond_destroy(pthread_cond_t *cond) 166 { 167 struct pthread_cond *cvp; 168 int error; 169 170 error = 0; 171 if (*cond == THR_PSHARED_PTR) { 172 cvp = __thr_pshared_offpage(cond, 0); 173 if (cvp != NULL) { 174 if (cvp->kcond.c_has_waiters) 175 error = EBUSY; 176 else 177 __thr_pshared_destroy(cond); 178 } 179 if (error == 0) 180 *cond = THR_COND_DESTROYED; 181 } else if ((cvp = *cond) == THR_COND_INITIALIZER) { 182 /* nothing */ 183 } else if (cvp == THR_COND_DESTROYED) { 184 error = EINVAL; 185 } else { 186 cvp = *cond; 187 if (cvp->__has_user_waiters || cvp->kcond.c_has_waiters) 188 error = EBUSY; 189 else { 190 *cond = THR_COND_DESTROYED; 191 free(cvp); 192 } 193 } 194 return (error); 195 } 196 197 /* 198 * Cancellation behavior: 199 * Thread may be canceled at start, if thread is canceled, it means it 200 * did not get a wakeup from pthread_cond_signal(), otherwise, it is 201 * not canceled. 202 * Thread cancellation never cause wakeup from pthread_cond_signal() 203 * to be lost. 204 */ 205 static int 206 cond_wait_kernel(struct pthread_cond *cvp, struct pthread_mutex *mp, 207 const struct timespec *abstime, int cancel) 208 { 209 struct pthread *curthread; 210 int error, error2, recurse, robust; 211 212 curthread = _get_curthread(); 213 robust = _mutex_enter_robust(curthread, mp); 214 215 error = _mutex_cv_detach(mp, &recurse); 216 if (error != 0) { 217 if (robust) 218 _mutex_leave_robust(curthread, mp); 219 return (error); 220 } 221 222 if (cancel) 223 _thr_cancel_enter2(curthread, 0); 224 error = _thr_ucond_wait(&cvp->kcond, &mp->m_lock, abstime, 225 CVWAIT_ABSTIME | CVWAIT_CLOCKID); 226 if (cancel) 227 _thr_cancel_leave(curthread, 0); 228 229 /* 230 * Note that PP mutex and ROBUST mutex may return 231 * interesting error codes. 232 */ 233 if (error == 0) { 234 error2 = _mutex_cv_lock(mp, recurse, true); 235 } else if (error == EINTR || error == ETIMEDOUT) { 236 error2 = _mutex_cv_lock(mp, recurse, true); 237 /* 238 * Do not do cancellation on EOWNERDEAD there. The 239 * cancellation cleanup handler will use the protected 240 * state and unlock the mutex without making the state 241 * consistent and the state will be unrecoverable. 242 */ 243 if (error2 == 0 && cancel) { 244 if (robust) { 245 _mutex_leave_robust(curthread, mp); 246 robust = false; 247 } 248 _thr_testcancel(curthread); 249 } 250 251 if (error == EINTR) 252 error = 0; 253 } else { 254 /* We know that it didn't unlock the mutex. */ 255 _mutex_cv_attach(mp, recurse); 256 if (cancel) { 257 if (robust) { 258 _mutex_leave_robust(curthread, mp); 259 robust = false; 260 } 261 _thr_testcancel(curthread); 262 } 263 error2 = 0; 264 } 265 if (robust) 266 _mutex_leave_robust(curthread, mp); 267 return (error2 != 0 ? error2 : error); 268 } 269 270 /* 271 * Thread waits in userland queue whenever possible, when thread 272 * is signaled or broadcasted, it is removed from the queue, and 273 * is saved in curthread's defer_waiters[] buffer, but won't be 274 * woken up until mutex is unlocked. 275 */ 276 277 static int 278 cond_wait_user(struct pthread_cond *cvp, struct pthread_mutex *mp, 279 const struct timespec *abstime, int cancel) 280 { 281 struct pthread *curthread; 282 struct sleepqueue *sq; 283 int deferred, error, error2, recurse; 284 285 curthread = _get_curthread(); 286 if (curthread->wchan != NULL) 287 PANIC("thread %p was already on queue.", curthread); 288 289 if (cancel) 290 _thr_testcancel(curthread); 291 292 _sleepq_lock(cvp); 293 /* 294 * set __has_user_waiters before unlocking mutex, this allows 295 * us to check it without locking in pthread_cond_signal(). 296 */ 297 cvp->__has_user_waiters = 1; 298 deferred = 0; 299 (void)_mutex_cv_unlock(mp, &recurse, &deferred); 300 curthread->mutex_obj = mp; 301 _sleepq_add(cvp, curthread); 302 for(;;) { 303 _thr_clear_wake(curthread); 304 _sleepq_unlock(cvp); 305 if (deferred) { 306 deferred = 0; 307 if ((mp->m_lock.m_owner & UMUTEX_CONTESTED) == 0) 308 (void)_umtx_op_err(&mp->m_lock, 309 UMTX_OP_MUTEX_WAKE2, mp->m_lock.m_flags, 310 0, 0); 311 } 312 if (curthread->nwaiter_defer > 0) { 313 _thr_wake_all(curthread->defer_waiters, 314 curthread->nwaiter_defer); 315 curthread->nwaiter_defer = 0; 316 } 317 318 if (cancel) 319 _thr_cancel_enter2(curthread, 0); 320 error = _thr_sleep(curthread, cvp->kcond.c_clockid, abstime); 321 if (cancel) 322 _thr_cancel_leave(curthread, 0); 323 324 _sleepq_lock(cvp); 325 if (curthread->wchan == NULL) { 326 error = 0; 327 break; 328 } else if (cancel && SHOULD_CANCEL(curthread)) { 329 sq = _sleepq_lookup(cvp); 330 cvp->__has_user_waiters = _sleepq_remove(sq, curthread); 331 _sleepq_unlock(cvp); 332 curthread->mutex_obj = NULL; 333 error2 = _mutex_cv_lock(mp, recurse, false); 334 if (!THR_IN_CRITICAL(curthread)) 335 _pthread_exit(PTHREAD_CANCELED); 336 else /* this should not happen */ 337 return (error2); 338 } else if (error == ETIMEDOUT) { 339 sq = _sleepq_lookup(cvp); 340 cvp->__has_user_waiters = 341 _sleepq_remove(sq, curthread); 342 break; 343 } 344 } 345 _sleepq_unlock(cvp); 346 curthread->mutex_obj = NULL; 347 error2 = _mutex_cv_lock(mp, recurse, false); 348 if (error == 0) 349 error = error2; 350 return (error); 351 } 352 353 static int 354 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, 355 const struct timespec *abstime, int cancel) 356 { 357 struct pthread *curthread = _get_curthread(); 358 struct pthread_cond *cvp; 359 struct pthread_mutex *mp; 360 int error; 361 362 CHECK_AND_INIT_COND 363 364 if (*mutex == THR_PSHARED_PTR) { 365 mp = __thr_pshared_offpage(mutex, 0); 366 if (mp == NULL) 367 return (EINVAL); 368 } else { 369 mp = *mutex; 370 } 371 372 if ((error = _mutex_owned(curthread, mp)) != 0) 373 return (error); 374 375 if (curthread->attr.sched_policy != SCHED_OTHER || 376 (mp->m_lock.m_flags & (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT | 377 USYNC_PROCESS_SHARED)) != 0 || CV_PSHARED(cvp)) 378 return (cond_wait_kernel(cvp, mp, abstime, cancel)); 379 else 380 return (cond_wait_user(cvp, mp, abstime, cancel)); 381 } 382 383 int 384 _thr_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) 385 { 386 387 return (cond_wait_common(cond, mutex, NULL, 0)); 388 } 389 390 int 391 __thr_cond_wait(pthread_cond_t * __restrict cond, 392 pthread_mutex_t * __restrict mutex) 393 { 394 395 return (cond_wait_common(cond, mutex, NULL, 1)); 396 } 397 398 int 399 _thr_cond_timedwait(pthread_cond_t * __restrict cond, 400 pthread_mutex_t * __restrict mutex, 401 const struct timespec * __restrict abstime) 402 { 403 404 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 405 abstime->tv_nsec >= 1000000000) 406 return (EINVAL); 407 408 return (cond_wait_common(cond, mutex, abstime, 0)); 409 } 410 411 int 412 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, 413 const struct timespec *abstime) 414 { 415 416 if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || 417 abstime->tv_nsec >= 1000000000) 418 return (EINVAL); 419 420 return (cond_wait_common(cond, mutex, abstime, 1)); 421 } 422 423 static int 424 cond_signal_common(pthread_cond_t *cond) 425 { 426 struct pthread *curthread = _get_curthread(); 427 struct pthread *td; 428 struct pthread_cond *cvp; 429 struct pthread_mutex *mp; 430 struct sleepqueue *sq; 431 int *waddr; 432 int pshared; 433 434 /* 435 * If the condition variable is statically initialized, perform dynamic 436 * initialization. 437 */ 438 CHECK_AND_INIT_COND 439 440 pshared = CV_PSHARED(cvp); 441 442 _thr_ucond_signal(&cvp->kcond); 443 444 if (pshared || cvp->__has_user_waiters == 0) 445 return (0); 446 447 curthread = _get_curthread(); 448 waddr = NULL; 449 _sleepq_lock(cvp); 450 sq = _sleepq_lookup(cvp); 451 if (sq == NULL) { 452 _sleepq_unlock(cvp); 453 return (0); 454 } 455 456 td = _sleepq_first(sq); 457 mp = td->mutex_obj; 458 cvp->__has_user_waiters = _sleepq_remove(sq, td); 459 if (PMUTEX_OWNER_ID(mp) == TID(curthread)) { 460 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 461 _thr_wake_all(curthread->defer_waiters, 462 curthread->nwaiter_defer); 463 curthread->nwaiter_defer = 0; 464 } 465 curthread->defer_waiters[curthread->nwaiter_defer++] = 466 &td->wake_addr->value; 467 mp->m_flags |= PMUTEX_FLAG_DEFERRED; 468 } else { 469 waddr = &td->wake_addr->value; 470 } 471 _sleepq_unlock(cvp); 472 if (waddr != NULL) 473 _thr_set_wake(waddr); 474 return (0); 475 } 476 477 struct broadcast_arg { 478 struct pthread *curthread; 479 unsigned int *waddrs[MAX_DEFER_WAITERS]; 480 int count; 481 }; 482 483 static void 484 drop_cb(struct pthread *td, void *arg) 485 { 486 struct broadcast_arg *ba = arg; 487 struct pthread_mutex *mp; 488 struct pthread *curthread = ba->curthread; 489 490 mp = td->mutex_obj; 491 if (PMUTEX_OWNER_ID(mp) == TID(curthread)) { 492 if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { 493 _thr_wake_all(curthread->defer_waiters, 494 curthread->nwaiter_defer); 495 curthread->nwaiter_defer = 0; 496 } 497 curthread->defer_waiters[curthread->nwaiter_defer++] = 498 &td->wake_addr->value; 499 mp->m_flags |= PMUTEX_FLAG_DEFERRED; 500 } else { 501 if (ba->count >= MAX_DEFER_WAITERS) { 502 _thr_wake_all(ba->waddrs, ba->count); 503 ba->count = 0; 504 } 505 ba->waddrs[ba->count++] = &td->wake_addr->value; 506 } 507 } 508 509 static int 510 cond_broadcast_common(pthread_cond_t *cond) 511 { 512 int pshared; 513 struct pthread_cond *cvp; 514 struct sleepqueue *sq; 515 struct broadcast_arg ba; 516 517 /* 518 * If the condition variable is statically initialized, perform dynamic 519 * initialization. 520 */ 521 CHECK_AND_INIT_COND 522 523 pshared = CV_PSHARED(cvp); 524 525 _thr_ucond_broadcast(&cvp->kcond); 526 527 if (pshared || cvp->__has_user_waiters == 0) 528 return (0); 529 530 ba.curthread = _get_curthread(); 531 ba.count = 0; 532 533 _sleepq_lock(cvp); 534 sq = _sleepq_lookup(cvp); 535 if (sq == NULL) { 536 _sleepq_unlock(cvp); 537 return (0); 538 } 539 _sleepq_drop(sq, drop_cb, &ba); 540 cvp->__has_user_waiters = 0; 541 _sleepq_unlock(cvp); 542 if (ba.count > 0) 543 _thr_wake_all(ba.waddrs, ba.count); 544 return (0); 545 } 546 547 int 548 _thr_cond_signal(pthread_cond_t * cond) 549 { 550 551 return (cond_signal_common(cond)); 552 } 553 554 int 555 _thr_cond_broadcast(pthread_cond_t * cond) 556 { 557 558 return (cond_broadcast_common(cond)); 559 } 560