1 /*- 2 * Copyright (c) 2007 Stephan Uphoff <ups@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 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the author nor the names of any co-contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 /* 31 * Machine independent bits of reader/writer lock implementation. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include "opt_ddb.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 42 #include <sys/kernel.h> 43 #include <sys/kdb.h> 44 #include <sys/ktr.h> 45 #include <sys/lock.h> 46 #include <sys/mutex.h> 47 #include <sys/proc.h> 48 #include <sys/rmlock.h> 49 #include <sys/sched.h> 50 #include <sys/smp.h> 51 #include <sys/turnstile.h> 52 #include <sys/lock_profile.h> 53 #include <machine/cpu.h> 54 55 #ifdef DDB 56 #include <ddb/ddb.h> 57 #endif 58 59 /* 60 * A cookie to mark destroyed rmlocks. This is stored in the head of 61 * rm_activeReaders. 62 */ 63 #define RM_DESTROYED ((void *)0xdead) 64 65 #define rm_destroyed(rm) \ 66 (LIST_FIRST(&(rm)->rm_activeReaders) == RM_DESTROYED) 67 68 #define RMPF_ONQUEUE 1 69 #define RMPF_SIGNAL 2 70 71 #ifndef INVARIANTS 72 #define _rm_assert(c, what, file, line) 73 #endif 74 75 static void assert_rm(const struct lock_object *lock, int what); 76 #ifdef DDB 77 static void db_show_rm(const struct lock_object *lock); 78 #endif 79 static void lock_rm(struct lock_object *lock, uintptr_t how); 80 #ifdef KDTRACE_HOOKS 81 static int owner_rm(const struct lock_object *lock, struct thread **owner); 82 #endif 83 static uintptr_t unlock_rm(struct lock_object *lock); 84 85 struct lock_class lock_class_rm = { 86 .lc_name = "rm", 87 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 88 .lc_assert = assert_rm, 89 #ifdef DDB 90 .lc_ddb_show = db_show_rm, 91 #endif 92 .lc_lock = lock_rm, 93 .lc_unlock = unlock_rm, 94 #ifdef KDTRACE_HOOKS 95 .lc_owner = owner_rm, 96 #endif 97 }; 98 99 struct lock_class lock_class_rm_sleepable = { 100 .lc_name = "sleepable rm", 101 .lc_flags = LC_SLEEPLOCK | LC_SLEEPABLE | LC_RECURSABLE, 102 .lc_assert = assert_rm, 103 #ifdef DDB 104 .lc_ddb_show = db_show_rm, 105 #endif 106 .lc_lock = lock_rm, 107 .lc_unlock = unlock_rm, 108 #ifdef KDTRACE_HOOKS 109 .lc_owner = owner_rm, 110 #endif 111 }; 112 113 static void 114 assert_rm(const struct lock_object *lock, int what) 115 { 116 117 rm_assert((const struct rmlock *)lock, what); 118 } 119 120 static void 121 lock_rm(struct lock_object *lock, uintptr_t how) 122 { 123 struct rmlock *rm; 124 struct rm_priotracker *tracker; 125 126 rm = (struct rmlock *)lock; 127 if (how == 0) 128 rm_wlock(rm); 129 else { 130 tracker = (struct rm_priotracker *)how; 131 rm_rlock(rm, tracker); 132 } 133 } 134 135 static uintptr_t 136 unlock_rm(struct lock_object *lock) 137 { 138 struct thread *td; 139 struct pcpu *pc; 140 struct rmlock *rm; 141 struct rm_queue *queue; 142 struct rm_priotracker *tracker; 143 uintptr_t how; 144 145 rm = (struct rmlock *)lock; 146 tracker = NULL; 147 how = 0; 148 rm_assert(rm, RA_LOCKED | RA_NOTRECURSED); 149 if (rm_wowned(rm)) 150 rm_wunlock(rm); 151 else { 152 /* 153 * Find the right rm_priotracker structure for curthread. 154 * The guarantee about its uniqueness is given by the fact 155 * we already asserted the lock wasn't recursively acquired. 156 */ 157 critical_enter(); 158 td = curthread; 159 pc = pcpu_find(curcpu); 160 for (queue = pc->pc_rm_queue.rmq_next; 161 queue != &pc->pc_rm_queue; queue = queue->rmq_next) { 162 tracker = (struct rm_priotracker *)queue; 163 if ((tracker->rmp_rmlock == rm) && 164 (tracker->rmp_thread == td)) { 165 how = (uintptr_t)tracker; 166 break; 167 } 168 } 169 KASSERT(tracker != NULL, 170 ("rm_priotracker is non-NULL when lock held in read mode")); 171 critical_exit(); 172 rm_runlock(rm, tracker); 173 } 174 return (how); 175 } 176 177 #ifdef KDTRACE_HOOKS 178 static int 179 owner_rm(const struct lock_object *lock, struct thread **owner) 180 { 181 const struct rmlock *rm; 182 struct lock_class *lc; 183 184 rm = (const struct rmlock *)lock; 185 lc = LOCK_CLASS(&rm->rm_wlock_object); 186 return (lc->lc_owner(&rm->rm_wlock_object, owner)); 187 } 188 #endif 189 190 static struct mtx rm_spinlock; 191 192 MTX_SYSINIT(rm_spinlock, &rm_spinlock, "rm_spinlock", MTX_SPIN); 193 194 /* 195 * Add or remove tracker from per-cpu list. 196 * 197 * The per-cpu list can be traversed at any time in forward direction from an 198 * interrupt on the *local* cpu. 199 */ 200 static void inline 201 rm_tracker_add(struct pcpu *pc, struct rm_priotracker *tracker) 202 { 203 struct rm_queue *next; 204 205 /* Initialize all tracker pointers */ 206 tracker->rmp_cpuQueue.rmq_prev = &pc->pc_rm_queue; 207 next = pc->pc_rm_queue.rmq_next; 208 tracker->rmp_cpuQueue.rmq_next = next; 209 210 /* rmq_prev is not used during froward traversal. */ 211 next->rmq_prev = &tracker->rmp_cpuQueue; 212 213 /* Update pointer to first element. */ 214 pc->pc_rm_queue.rmq_next = &tracker->rmp_cpuQueue; 215 } 216 217 /* 218 * Return a count of the number of trackers the thread 'td' already 219 * has on this CPU for the lock 'rm'. 220 */ 221 static int 222 rm_trackers_present(const struct pcpu *pc, const struct rmlock *rm, 223 const struct thread *td) 224 { 225 struct rm_queue *queue; 226 struct rm_priotracker *tracker; 227 int count; 228 229 count = 0; 230 for (queue = pc->pc_rm_queue.rmq_next; queue != &pc->pc_rm_queue; 231 queue = queue->rmq_next) { 232 tracker = (struct rm_priotracker *)queue; 233 if ((tracker->rmp_rmlock == rm) && (tracker->rmp_thread == td)) 234 count++; 235 } 236 return (count); 237 } 238 239 static void inline 240 rm_tracker_remove(struct pcpu *pc, struct rm_priotracker *tracker) 241 { 242 struct rm_queue *next, *prev; 243 244 next = tracker->rmp_cpuQueue.rmq_next; 245 prev = tracker->rmp_cpuQueue.rmq_prev; 246 247 /* Not used during forward traversal. */ 248 next->rmq_prev = prev; 249 250 /* Remove from list. */ 251 prev->rmq_next = next; 252 } 253 254 static void 255 rm_cleanIPI(void *arg) 256 { 257 struct pcpu *pc; 258 struct rmlock *rm = arg; 259 struct rm_priotracker *tracker; 260 struct rm_queue *queue; 261 pc = pcpu_find(curcpu); 262 263 for (queue = pc->pc_rm_queue.rmq_next; queue != &pc->pc_rm_queue; 264 queue = queue->rmq_next) { 265 tracker = (struct rm_priotracker *)queue; 266 if (tracker->rmp_rmlock == rm && tracker->rmp_flags == 0) { 267 tracker->rmp_flags = RMPF_ONQUEUE; 268 mtx_lock_spin(&rm_spinlock); 269 LIST_INSERT_HEAD(&rm->rm_activeReaders, tracker, 270 rmp_qentry); 271 mtx_unlock_spin(&rm_spinlock); 272 } 273 } 274 } 275 276 void 277 rm_init_flags(struct rmlock *rm, const char *name, int opts) 278 { 279 struct lock_class *lc; 280 int liflags, xflags; 281 282 liflags = 0; 283 if (!(opts & RM_NOWITNESS)) 284 liflags |= LO_WITNESS; 285 if (opts & RM_RECURSE) 286 liflags |= LO_RECURSABLE; 287 if (opts & RM_NEW) 288 liflags |= LO_NEW; 289 rm->rm_writecpus = all_cpus; 290 LIST_INIT(&rm->rm_activeReaders); 291 if (opts & RM_SLEEPABLE) { 292 liflags |= LO_SLEEPABLE; 293 lc = &lock_class_rm_sleepable; 294 xflags = (opts & RM_NEW ? SX_NEW : 0); 295 sx_init_flags(&rm->rm_lock_sx, "rmlock_sx", 296 xflags | SX_NOWITNESS); 297 } else { 298 lc = &lock_class_rm; 299 xflags = (opts & RM_NEW ? MTX_NEW : 0); 300 mtx_init(&rm->rm_lock_mtx, name, "rmlock_mtx", 301 xflags | MTX_NOWITNESS); 302 } 303 lock_init(&rm->lock_object, lc, name, NULL, liflags); 304 } 305 306 void 307 rm_init(struct rmlock *rm, const char *name) 308 { 309 310 rm_init_flags(rm, name, 0); 311 } 312 313 void 314 rm_destroy(struct rmlock *rm) 315 { 316 317 rm_assert(rm, RA_UNLOCKED); 318 LIST_FIRST(&rm->rm_activeReaders) = RM_DESTROYED; 319 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 320 sx_destroy(&rm->rm_lock_sx); 321 else 322 mtx_destroy(&rm->rm_lock_mtx); 323 lock_destroy(&rm->lock_object); 324 } 325 326 int 327 rm_wowned(const struct rmlock *rm) 328 { 329 330 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 331 return (sx_xlocked(&rm->rm_lock_sx)); 332 else 333 return (mtx_owned(&rm->rm_lock_mtx)); 334 } 335 336 void 337 rm_sysinit(void *arg) 338 { 339 struct rm_args *args = arg; 340 341 rm_init(args->ra_rm, args->ra_desc); 342 } 343 344 void 345 rm_sysinit_flags(void *arg) 346 { 347 struct rm_args_flags *args = arg; 348 349 rm_init_flags(args->ra_rm, args->ra_desc, args->ra_opts); 350 } 351 352 static int 353 _rm_rlock_hard(struct rmlock *rm, struct rm_priotracker *tracker, int trylock) 354 { 355 struct pcpu *pc; 356 357 critical_enter(); 358 pc = pcpu_find(curcpu); 359 360 /* Check if we just need to do a proper critical_exit. */ 361 if (!CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus)) { 362 critical_exit(); 363 return (1); 364 } 365 366 /* Remove our tracker from the per-cpu list. */ 367 rm_tracker_remove(pc, tracker); 368 369 /* Check to see if the IPI granted us the lock after all. */ 370 if (tracker->rmp_flags) { 371 /* Just add back tracker - we hold the lock. */ 372 rm_tracker_add(pc, tracker); 373 critical_exit(); 374 return (1); 375 } 376 377 /* 378 * We allow readers to aquire a lock even if a writer is blocked if 379 * the lock is recursive and the reader already holds the lock. 380 */ 381 if ((rm->lock_object.lo_flags & LO_RECURSABLE) != 0) { 382 /* 383 * Just grant the lock if this thread already has a tracker 384 * for this lock on the per-cpu queue. 385 */ 386 if (rm_trackers_present(pc, rm, curthread) != 0) { 387 mtx_lock_spin(&rm_spinlock); 388 LIST_INSERT_HEAD(&rm->rm_activeReaders, tracker, 389 rmp_qentry); 390 tracker->rmp_flags = RMPF_ONQUEUE; 391 mtx_unlock_spin(&rm_spinlock); 392 rm_tracker_add(pc, tracker); 393 critical_exit(); 394 return (1); 395 } 396 } 397 398 sched_unpin(); 399 critical_exit(); 400 401 if (trylock) { 402 if (rm->lock_object.lo_flags & LO_SLEEPABLE) { 403 if (!sx_try_xlock(&rm->rm_lock_sx)) 404 return (0); 405 } else { 406 if (!mtx_trylock(&rm->rm_lock_mtx)) 407 return (0); 408 } 409 } else { 410 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 411 sx_xlock(&rm->rm_lock_sx); 412 else 413 mtx_lock(&rm->rm_lock_mtx); 414 } 415 416 critical_enter(); 417 pc = pcpu_find(curcpu); 418 CPU_CLR(pc->pc_cpuid, &rm->rm_writecpus); 419 rm_tracker_add(pc, tracker); 420 sched_pin(); 421 critical_exit(); 422 423 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 424 sx_xunlock(&rm->rm_lock_sx); 425 else 426 mtx_unlock(&rm->rm_lock_mtx); 427 428 return (1); 429 } 430 431 int 432 _rm_rlock(struct rmlock *rm, struct rm_priotracker *tracker, int trylock) 433 { 434 struct thread *td = curthread; 435 struct pcpu *pc; 436 437 if (SCHEDULER_STOPPED()) 438 return (1); 439 440 tracker->rmp_flags = 0; 441 tracker->rmp_thread = td; 442 tracker->rmp_rmlock = rm; 443 444 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 445 THREAD_NO_SLEEPING(); 446 447 td->td_critnest++; /* critical_enter(); */ 448 449 __compiler_membar(); 450 451 pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */ 452 453 rm_tracker_add(pc, tracker); 454 455 sched_pin(); 456 457 __compiler_membar(); 458 459 td->td_critnest--; 460 461 /* 462 * Fast path to combine two common conditions into a single 463 * conditional jump. 464 */ 465 if (0 == (td->td_owepreempt | 466 CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus))) 467 return (1); 468 469 /* We do not have a read token and need to acquire one. */ 470 return _rm_rlock_hard(rm, tracker, trylock); 471 } 472 473 static void 474 _rm_unlock_hard(struct thread *td,struct rm_priotracker *tracker) 475 { 476 477 if (td->td_owepreempt) { 478 td->td_critnest++; 479 critical_exit(); 480 } 481 482 if (!tracker->rmp_flags) 483 return; 484 485 mtx_lock_spin(&rm_spinlock); 486 LIST_REMOVE(tracker, rmp_qentry); 487 488 if (tracker->rmp_flags & RMPF_SIGNAL) { 489 struct rmlock *rm; 490 struct turnstile *ts; 491 492 rm = tracker->rmp_rmlock; 493 494 turnstile_chain_lock(&rm->lock_object); 495 mtx_unlock_spin(&rm_spinlock); 496 497 ts = turnstile_lookup(&rm->lock_object); 498 499 turnstile_signal(ts, TS_EXCLUSIVE_QUEUE); 500 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 501 turnstile_chain_unlock(&rm->lock_object); 502 } else 503 mtx_unlock_spin(&rm_spinlock); 504 } 505 506 void 507 _rm_runlock(struct rmlock *rm, struct rm_priotracker *tracker) 508 { 509 struct pcpu *pc; 510 struct thread *td = tracker->rmp_thread; 511 512 if (SCHEDULER_STOPPED()) 513 return; 514 515 td->td_critnest++; /* critical_enter(); */ 516 pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */ 517 rm_tracker_remove(pc, tracker); 518 td->td_critnest--; 519 sched_unpin(); 520 521 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 522 THREAD_SLEEPING_OK(); 523 524 if (0 == (td->td_owepreempt | tracker->rmp_flags)) 525 return; 526 527 _rm_unlock_hard(td, tracker); 528 } 529 530 void 531 _rm_wlock(struct rmlock *rm) 532 { 533 struct rm_priotracker *prio; 534 struct turnstile *ts; 535 cpuset_t readcpus; 536 537 if (SCHEDULER_STOPPED()) 538 return; 539 540 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 541 sx_xlock(&rm->rm_lock_sx); 542 else 543 mtx_lock(&rm->rm_lock_mtx); 544 545 if (CPU_CMP(&rm->rm_writecpus, &all_cpus)) { 546 /* Get all read tokens back */ 547 readcpus = all_cpus; 548 CPU_NAND(&readcpus, &rm->rm_writecpus); 549 rm->rm_writecpus = all_cpus; 550 551 /* 552 * Assumes rm->rm_writecpus update is visible on other CPUs 553 * before rm_cleanIPI is called. 554 */ 555 #ifdef SMP 556 smp_rendezvous_cpus(readcpus, 557 smp_no_rendevous_barrier, 558 rm_cleanIPI, 559 smp_no_rendevous_barrier, 560 rm); 561 562 #else 563 rm_cleanIPI(rm); 564 #endif 565 566 mtx_lock_spin(&rm_spinlock); 567 while ((prio = LIST_FIRST(&rm->rm_activeReaders)) != NULL) { 568 ts = turnstile_trywait(&rm->lock_object); 569 prio->rmp_flags = RMPF_ONQUEUE | RMPF_SIGNAL; 570 mtx_unlock_spin(&rm_spinlock); 571 turnstile_wait(ts, prio->rmp_thread, 572 TS_EXCLUSIVE_QUEUE); 573 mtx_lock_spin(&rm_spinlock); 574 } 575 mtx_unlock_spin(&rm_spinlock); 576 } 577 } 578 579 void 580 _rm_wunlock(struct rmlock *rm) 581 { 582 583 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 584 sx_xunlock(&rm->rm_lock_sx); 585 else 586 mtx_unlock(&rm->rm_lock_mtx); 587 } 588 589 #if LOCK_DEBUG > 0 590 591 void 592 _rm_wlock_debug(struct rmlock *rm, const char *file, int line) 593 { 594 595 if (SCHEDULER_STOPPED()) 596 return; 597 598 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 599 ("rm_wlock() by idle thread %p on rmlock %s @ %s:%d", 600 curthread, rm->lock_object.lo_name, file, line)); 601 KASSERT(!rm_destroyed(rm), 602 ("rm_wlock() of destroyed rmlock @ %s:%d", file, line)); 603 _rm_assert(rm, RA_UNLOCKED, file, line); 604 605 WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER | LOP_EXCLUSIVE, 606 file, line, NULL); 607 608 _rm_wlock(rm); 609 610 LOCK_LOG_LOCK("RMWLOCK", &rm->lock_object, 0, 0, file, line); 611 612 WITNESS_LOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line); 613 614 curthread->td_locks++; 615 616 } 617 618 void 619 _rm_wunlock_debug(struct rmlock *rm, const char *file, int line) 620 { 621 622 if (SCHEDULER_STOPPED()) 623 return; 624 625 KASSERT(!rm_destroyed(rm), 626 ("rm_wunlock() of destroyed rmlock @ %s:%d", file, line)); 627 _rm_assert(rm, RA_WLOCKED, file, line); 628 WITNESS_UNLOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line); 629 LOCK_LOG_LOCK("RMWUNLOCK", &rm->lock_object, 0, 0, file, line); 630 _rm_wunlock(rm); 631 curthread->td_locks--; 632 } 633 634 int 635 _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 636 int trylock, const char *file, int line) 637 { 638 639 if (SCHEDULER_STOPPED()) 640 return (1); 641 642 #ifdef INVARIANTS 643 if (!(rm->lock_object.lo_flags & LO_RECURSABLE) && !trylock) { 644 critical_enter(); 645 KASSERT(rm_trackers_present(pcpu_find(curcpu), rm, 646 curthread) == 0, 647 ("rm_rlock: recursed on non-recursive rmlock %s @ %s:%d\n", 648 rm->lock_object.lo_name, file, line)); 649 critical_exit(); 650 } 651 #endif 652 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 653 ("rm_rlock() by idle thread %p on rmlock %s @ %s:%d", 654 curthread, rm->lock_object.lo_name, file, line)); 655 KASSERT(!rm_destroyed(rm), 656 ("rm_rlock() of destroyed rmlock @ %s:%d", file, line)); 657 if (!trylock) { 658 KASSERT(!rm_wowned(rm), 659 ("rm_rlock: wlock already held for %s @ %s:%d", 660 rm->lock_object.lo_name, file, line)); 661 WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER, file, line, 662 NULL); 663 } 664 665 if (_rm_rlock(rm, tracker, trylock)) { 666 if (trylock) 667 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 1, file, 668 line); 669 else 670 LOCK_LOG_LOCK("RMRLOCK", &rm->lock_object, 0, 0, file, 671 line); 672 WITNESS_LOCK(&rm->lock_object, 0, file, line); 673 674 curthread->td_locks++; 675 676 return (1); 677 } else if (trylock) 678 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 0, file, line); 679 680 return (0); 681 } 682 683 void 684 _rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 685 const char *file, int line) 686 { 687 688 if (SCHEDULER_STOPPED()) 689 return; 690 691 KASSERT(!rm_destroyed(rm), 692 ("rm_runlock() of destroyed rmlock @ %s:%d", file, line)); 693 _rm_assert(rm, RA_RLOCKED, file, line); 694 WITNESS_UNLOCK(&rm->lock_object, 0, file, line); 695 LOCK_LOG_LOCK("RMRUNLOCK", &rm->lock_object, 0, 0, file, line); 696 _rm_runlock(rm, tracker); 697 curthread->td_locks--; 698 } 699 700 #else 701 702 /* 703 * Just strip out file and line arguments if no lock debugging is enabled in 704 * the kernel - we are called from a kernel module. 705 */ 706 void 707 _rm_wlock_debug(struct rmlock *rm, const char *file, int line) 708 { 709 710 _rm_wlock(rm); 711 } 712 713 void 714 _rm_wunlock_debug(struct rmlock *rm, const char *file, int line) 715 { 716 717 _rm_wunlock(rm); 718 } 719 720 int 721 _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 722 int trylock, const char *file, int line) 723 { 724 725 return _rm_rlock(rm, tracker, trylock); 726 } 727 728 void 729 _rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 730 const char *file, int line) 731 { 732 733 _rm_runlock(rm, tracker); 734 } 735 736 #endif 737 738 #ifdef INVARIANT_SUPPORT 739 #ifndef INVARIANTS 740 #undef _rm_assert 741 #endif 742 743 /* 744 * Note that this does not need to use witness_assert() for read lock 745 * assertions since an exact count of read locks held by this thread 746 * is computable. 747 */ 748 void 749 _rm_assert(const struct rmlock *rm, int what, const char *file, int line) 750 { 751 int count; 752 753 if (panicstr != NULL) 754 return; 755 switch (what) { 756 case RA_LOCKED: 757 case RA_LOCKED | RA_RECURSED: 758 case RA_LOCKED | RA_NOTRECURSED: 759 case RA_RLOCKED: 760 case RA_RLOCKED | RA_RECURSED: 761 case RA_RLOCKED | RA_NOTRECURSED: 762 /* 763 * Handle the write-locked case. Unlike other 764 * primitives, writers can never recurse. 765 */ 766 if (rm_wowned(rm)) { 767 if (what & RA_RLOCKED) 768 panic("Lock %s exclusively locked @ %s:%d\n", 769 rm->lock_object.lo_name, file, line); 770 if (what & RA_RECURSED) 771 panic("Lock %s not recursed @ %s:%d\n", 772 rm->lock_object.lo_name, file, line); 773 break; 774 } 775 776 critical_enter(); 777 count = rm_trackers_present(pcpu_find(curcpu), rm, curthread); 778 critical_exit(); 779 780 if (count == 0) 781 panic("Lock %s not %slocked @ %s:%d\n", 782 rm->lock_object.lo_name, (what & RA_RLOCKED) ? 783 "read " : "", file, line); 784 if (count > 1) { 785 if (what & RA_NOTRECURSED) 786 panic("Lock %s recursed @ %s:%d\n", 787 rm->lock_object.lo_name, file, line); 788 } else if (what & RA_RECURSED) 789 panic("Lock %s not recursed @ %s:%d\n", 790 rm->lock_object.lo_name, file, line); 791 break; 792 case RA_WLOCKED: 793 if (!rm_wowned(rm)) 794 panic("Lock %s not exclusively locked @ %s:%d\n", 795 rm->lock_object.lo_name, file, line); 796 break; 797 case RA_UNLOCKED: 798 if (rm_wowned(rm)) 799 panic("Lock %s exclusively locked @ %s:%d\n", 800 rm->lock_object.lo_name, file, line); 801 802 critical_enter(); 803 count = rm_trackers_present(pcpu_find(curcpu), rm, curthread); 804 critical_exit(); 805 806 if (count != 0) 807 panic("Lock %s read locked @ %s:%d\n", 808 rm->lock_object.lo_name, file, line); 809 break; 810 default: 811 panic("Unknown rm lock assertion: %d @ %s:%d", what, file, 812 line); 813 } 814 } 815 #endif /* INVARIANT_SUPPORT */ 816 817 #ifdef DDB 818 static void 819 print_tracker(struct rm_priotracker *tr) 820 { 821 struct thread *td; 822 823 td = tr->rmp_thread; 824 db_printf(" thread %p (tid %d, pid %d, \"%s\") {", td, td->td_tid, 825 td->td_proc->p_pid, td->td_name); 826 if (tr->rmp_flags & RMPF_ONQUEUE) { 827 db_printf("ONQUEUE"); 828 if (tr->rmp_flags & RMPF_SIGNAL) 829 db_printf(",SIGNAL"); 830 } else 831 db_printf("0"); 832 db_printf("}\n"); 833 } 834 835 static void 836 db_show_rm(const struct lock_object *lock) 837 { 838 struct rm_priotracker *tr; 839 struct rm_queue *queue; 840 const struct rmlock *rm; 841 struct lock_class *lc; 842 struct pcpu *pc; 843 844 rm = (const struct rmlock *)lock; 845 db_printf(" writecpus: "); 846 ddb_display_cpuset(__DEQUALIFY(const cpuset_t *, &rm->rm_writecpus)); 847 db_printf("\n"); 848 db_printf(" per-CPU readers:\n"); 849 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) 850 for (queue = pc->pc_rm_queue.rmq_next; 851 queue != &pc->pc_rm_queue; queue = queue->rmq_next) { 852 tr = (struct rm_priotracker *)queue; 853 if (tr->rmp_rmlock == rm) 854 print_tracker(tr); 855 } 856 db_printf(" active readers:\n"); 857 LIST_FOREACH(tr, &rm->rm_activeReaders, rmp_qentry) 858 print_tracker(tr); 859 lc = LOCK_CLASS(&rm->rm_wlock_object); 860 db_printf("Backing write-lock (%s):\n", lc->lc_name); 861 lc->lc_ddb_show(&rm->rm_wlock_object); 862 } 863 #endif 864