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