1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2007 Stephan Uphoff <ups@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the author nor the names of any co-contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * Machine independent bits of reader/writer lock implementation. 34 */ 35 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include "opt_ddb.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 44 #include <sys/kernel.h> 45 #include <sys/kdb.h> 46 #include <sys/ktr.h> 47 #include <sys/lock.h> 48 #include <sys/mutex.h> 49 #include <sys/proc.h> 50 #include <sys/rmlock.h> 51 #include <sys/sched.h> 52 #include <sys/smp.h> 53 #include <sys/turnstile.h> 54 #include <sys/lock_profile.h> 55 #include <machine/cpu.h> 56 57 #ifdef DDB 58 #include <ddb/ddb.h> 59 #endif 60 61 /* 62 * A cookie to mark destroyed rmlocks. This is stored in the head of 63 * rm_activeReaders. 64 */ 65 #define RM_DESTROYED ((void *)0xdead) 66 67 #define rm_destroyed(rm) \ 68 (LIST_FIRST(&(rm)->rm_activeReaders) == RM_DESTROYED) 69 70 #define RMPF_ONQUEUE 1 71 #define RMPF_SIGNAL 2 72 73 #ifndef INVARIANTS 74 #define _rm_assert(c, what, file, line) 75 #endif 76 77 static void assert_rm(const struct lock_object *lock, int what); 78 #ifdef DDB 79 static void db_show_rm(const struct lock_object *lock); 80 #endif 81 static void lock_rm(struct lock_object *lock, uintptr_t how); 82 #ifdef KDTRACE_HOOKS 83 static int owner_rm(const struct lock_object *lock, struct thread **owner); 84 #endif 85 static uintptr_t unlock_rm(struct lock_object *lock); 86 87 struct lock_class lock_class_rm = { 88 .lc_name = "rm", 89 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 90 .lc_assert = assert_rm, 91 #ifdef DDB 92 .lc_ddb_show = db_show_rm, 93 #endif 94 .lc_lock = lock_rm, 95 .lc_unlock = unlock_rm, 96 #ifdef KDTRACE_HOOKS 97 .lc_owner = owner_rm, 98 #endif 99 }; 100 101 struct lock_class lock_class_rm_sleepable = { 102 .lc_name = "sleepable rm", 103 .lc_flags = LC_SLEEPLOCK | LC_SLEEPABLE | LC_RECURSABLE, 104 .lc_assert = assert_rm, 105 #ifdef DDB 106 .lc_ddb_show = db_show_rm, 107 #endif 108 .lc_lock = lock_rm, 109 .lc_unlock = unlock_rm, 110 #ifdef KDTRACE_HOOKS 111 .lc_owner = owner_rm, 112 #endif 113 }; 114 115 static void 116 assert_rm(const struct lock_object *lock, int what) 117 { 118 119 rm_assert((const struct rmlock *)lock, what); 120 } 121 122 static void 123 lock_rm(struct lock_object *lock, uintptr_t how) 124 { 125 struct rmlock *rm; 126 struct rm_priotracker *tracker; 127 128 rm = (struct rmlock *)lock; 129 if (how == 0) 130 rm_wlock(rm); 131 else { 132 tracker = (struct rm_priotracker *)how; 133 rm_rlock(rm, tracker); 134 } 135 } 136 137 static uintptr_t 138 unlock_rm(struct lock_object *lock) 139 { 140 struct thread *td; 141 struct pcpu *pc; 142 struct rmlock *rm; 143 struct rm_queue *queue; 144 struct rm_priotracker *tracker; 145 uintptr_t how; 146 147 rm = (struct rmlock *)lock; 148 tracker = NULL; 149 how = 0; 150 rm_assert(rm, RA_LOCKED | RA_NOTRECURSED); 151 if (rm_wowned(rm)) 152 rm_wunlock(rm); 153 else { 154 /* 155 * Find the right rm_priotracker structure for curthread. 156 * The guarantee about its uniqueness is given by the fact 157 * we already asserted the lock wasn't recursively acquired. 158 */ 159 critical_enter(); 160 td = curthread; 161 pc = get_pcpu(); 162 for (queue = pc->pc_rm_queue.rmq_next; 163 queue != &pc->pc_rm_queue; queue = queue->rmq_next) { 164 tracker = (struct rm_priotracker *)queue; 165 if ((tracker->rmp_rmlock == rm) && 166 (tracker->rmp_thread == td)) { 167 how = (uintptr_t)tracker; 168 break; 169 } 170 } 171 KASSERT(tracker != NULL, 172 ("rm_priotracker is non-NULL when lock held in read mode")); 173 critical_exit(); 174 rm_runlock(rm, tracker); 175 } 176 return (how); 177 } 178 179 #ifdef KDTRACE_HOOKS 180 static int 181 owner_rm(const struct lock_object *lock, struct thread **owner) 182 { 183 const struct rmlock *rm; 184 struct lock_class *lc; 185 186 rm = (const struct rmlock *)lock; 187 lc = LOCK_CLASS(&rm->rm_wlock_object); 188 return (lc->lc_owner(&rm->rm_wlock_object, owner)); 189 } 190 #endif 191 192 static struct mtx rm_spinlock; 193 194 MTX_SYSINIT(rm_spinlock, &rm_spinlock, "rm_spinlock", MTX_SPIN); 195 196 /* 197 * Add or remove tracker from per-cpu list. 198 * 199 * The per-cpu list can be traversed at any time in forward direction from an 200 * interrupt on the *local* cpu. 201 */ 202 static void inline 203 rm_tracker_add(struct pcpu *pc, struct rm_priotracker *tracker) 204 { 205 struct rm_queue *next; 206 207 /* Initialize all tracker pointers */ 208 tracker->rmp_cpuQueue.rmq_prev = &pc->pc_rm_queue; 209 next = pc->pc_rm_queue.rmq_next; 210 tracker->rmp_cpuQueue.rmq_next = next; 211 212 /* rmq_prev is not used during froward traversal. */ 213 next->rmq_prev = &tracker->rmp_cpuQueue; 214 215 /* Update pointer to first element. */ 216 pc->pc_rm_queue.rmq_next = &tracker->rmp_cpuQueue; 217 } 218 219 /* 220 * Return a count of the number of trackers the thread 'td' already 221 * has on this CPU for the lock 'rm'. 222 */ 223 static int 224 rm_trackers_present(const struct pcpu *pc, const struct rmlock *rm, 225 const struct thread *td) 226 { 227 struct rm_queue *queue; 228 struct rm_priotracker *tracker; 229 int count; 230 231 count = 0; 232 for (queue = pc->pc_rm_queue.rmq_next; queue != &pc->pc_rm_queue; 233 queue = queue->rmq_next) { 234 tracker = (struct rm_priotracker *)queue; 235 if ((tracker->rmp_rmlock == rm) && (tracker->rmp_thread == td)) 236 count++; 237 } 238 return (count); 239 } 240 241 static void inline 242 rm_tracker_remove(struct pcpu *pc, struct rm_priotracker *tracker) 243 { 244 struct rm_queue *next, *prev; 245 246 next = tracker->rmp_cpuQueue.rmq_next; 247 prev = tracker->rmp_cpuQueue.rmq_prev; 248 249 /* Not used during forward traversal. */ 250 next->rmq_prev = prev; 251 252 /* Remove from list. */ 253 prev->rmq_next = next; 254 } 255 256 static void 257 rm_cleanIPI(void *arg) 258 { 259 struct pcpu *pc; 260 struct rmlock *rm = arg; 261 struct rm_priotracker *tracker; 262 struct rm_queue *queue; 263 pc = get_pcpu(); 264 265 for (queue = pc->pc_rm_queue.rmq_next; queue != &pc->pc_rm_queue; 266 queue = queue->rmq_next) { 267 tracker = (struct rm_priotracker *)queue; 268 if (tracker->rmp_rmlock == rm && tracker->rmp_flags == 0) { 269 tracker->rmp_flags = RMPF_ONQUEUE; 270 mtx_lock_spin(&rm_spinlock); 271 LIST_INSERT_HEAD(&rm->rm_activeReaders, tracker, 272 rmp_qentry); 273 mtx_unlock_spin(&rm_spinlock); 274 } 275 } 276 } 277 278 void 279 rm_init_flags(struct rmlock *rm, const char *name, int opts) 280 { 281 struct lock_class *lc; 282 int liflags, xflags; 283 284 liflags = 0; 285 if (!(opts & RM_NOWITNESS)) 286 liflags |= LO_WITNESS; 287 if (opts & RM_RECURSE) 288 liflags |= LO_RECURSABLE; 289 if (opts & RM_NEW) 290 liflags |= LO_NEW; 291 rm->rm_writecpus = all_cpus; 292 LIST_INIT(&rm->rm_activeReaders); 293 if (opts & RM_SLEEPABLE) { 294 liflags |= LO_SLEEPABLE; 295 lc = &lock_class_rm_sleepable; 296 xflags = (opts & RM_NEW ? SX_NEW : 0); 297 sx_init_flags(&rm->rm_lock_sx, "rmlock_sx", 298 xflags | SX_NOWITNESS); 299 } else { 300 lc = &lock_class_rm; 301 xflags = (opts & RM_NEW ? MTX_NEW : 0); 302 mtx_init(&rm->rm_lock_mtx, name, "rmlock_mtx", 303 xflags | MTX_NOWITNESS); 304 } 305 lock_init(&rm->lock_object, lc, name, NULL, liflags); 306 } 307 308 void 309 rm_init(struct rmlock *rm, const char *name) 310 { 311 312 rm_init_flags(rm, name, 0); 313 } 314 315 void 316 rm_destroy(struct rmlock *rm) 317 { 318 319 rm_assert(rm, RA_UNLOCKED); 320 LIST_FIRST(&rm->rm_activeReaders) = RM_DESTROYED; 321 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 322 sx_destroy(&rm->rm_lock_sx); 323 else 324 mtx_destroy(&rm->rm_lock_mtx); 325 lock_destroy(&rm->lock_object); 326 } 327 328 int 329 rm_wowned(const struct rmlock *rm) 330 { 331 332 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 333 return (sx_xlocked(&rm->rm_lock_sx)); 334 else 335 return (mtx_owned(&rm->rm_lock_mtx)); 336 } 337 338 void 339 rm_sysinit(void *arg) 340 { 341 struct rm_args *args; 342 343 args = arg; 344 rm_init_flags(args->ra_rm, args->ra_desc, args->ra_flags); 345 } 346 347 static __noinline 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 = get_pcpu(); 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 acquire 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 THREAD_SLEEPING_OK(); 407 sx_xlock(&rm->rm_lock_sx); 408 THREAD_NO_SLEEPING(); 409 } else 410 mtx_lock(&rm->rm_lock_mtx); 411 } 412 413 critical_enter(); 414 pc = get_pcpu(); 415 CPU_CLR(pc->pc_cpuid, &rm->rm_writecpus); 416 rm_tracker_add(pc, tracker); 417 sched_pin(); 418 critical_exit(); 419 420 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 421 sx_xunlock(&rm->rm_lock_sx); 422 else 423 mtx_unlock(&rm->rm_lock_mtx); 424 425 return (1); 426 } 427 428 int 429 _rm_rlock(struct rmlock *rm, struct rm_priotracker *tracker, int trylock) 430 { 431 struct thread *td = curthread; 432 struct pcpu *pc; 433 434 if (SCHEDULER_STOPPED()) 435 return (1); 436 437 tracker->rmp_flags = 0; 438 tracker->rmp_thread = td; 439 tracker->rmp_rmlock = rm; 440 441 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 442 THREAD_NO_SLEEPING(); 443 444 td->td_critnest++; /* critical_enter(); */ 445 446 __compiler_membar(); 447 448 pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */ 449 450 rm_tracker_add(pc, tracker); 451 452 sched_pin(); 453 454 __compiler_membar(); 455 456 td->td_critnest--; 457 458 /* 459 * Fast path to combine two common conditions into a single 460 * conditional jump. 461 */ 462 if (__predict_true(0 == (td->td_owepreempt | 463 CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus)))) 464 return (1); 465 466 /* We do not have a read token and need to acquire one. */ 467 return _rm_rlock_hard(rm, tracker, trylock); 468 } 469 470 static __noinline void 471 _rm_unlock_hard(struct thread *td,struct rm_priotracker *tracker) 472 { 473 474 if (td->td_owepreempt) { 475 td->td_critnest++; 476 critical_exit(); 477 } 478 479 if (!tracker->rmp_flags) 480 return; 481 482 mtx_lock_spin(&rm_spinlock); 483 LIST_REMOVE(tracker, rmp_qentry); 484 485 if (tracker->rmp_flags & RMPF_SIGNAL) { 486 struct rmlock *rm; 487 struct turnstile *ts; 488 489 rm = tracker->rmp_rmlock; 490 491 turnstile_chain_lock(&rm->lock_object); 492 mtx_unlock_spin(&rm_spinlock); 493 494 ts = turnstile_lookup(&rm->lock_object); 495 496 turnstile_signal(ts, TS_EXCLUSIVE_QUEUE); 497 turnstile_unpend(ts); 498 turnstile_chain_unlock(&rm->lock_object); 499 } else 500 mtx_unlock_spin(&rm_spinlock); 501 } 502 503 void 504 _rm_runlock(struct rmlock *rm, struct rm_priotracker *tracker) 505 { 506 struct pcpu *pc; 507 struct thread *td = tracker->rmp_thread; 508 509 if (SCHEDULER_STOPPED()) 510 return; 511 512 td->td_critnest++; /* critical_enter(); */ 513 pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */ 514 rm_tracker_remove(pc, tracker); 515 td->td_critnest--; 516 sched_unpin(); 517 518 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 519 THREAD_SLEEPING_OK(); 520 521 if (__predict_true(0 == (td->td_owepreempt | tracker->rmp_flags))) 522 return; 523 524 _rm_unlock_hard(td, tracker); 525 } 526 527 void 528 _rm_wlock(struct rmlock *rm) 529 { 530 struct rm_priotracker *prio; 531 struct turnstile *ts; 532 cpuset_t readcpus; 533 534 if (SCHEDULER_STOPPED()) 535 return; 536 537 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 538 sx_xlock(&rm->rm_lock_sx); 539 else 540 mtx_lock(&rm->rm_lock_mtx); 541 542 if (CPU_CMP(&rm->rm_writecpus, &all_cpus)) { 543 /* Get all read tokens back */ 544 readcpus = all_cpus; 545 CPU_NAND(&readcpus, &rm->rm_writecpus); 546 rm->rm_writecpus = all_cpus; 547 548 /* 549 * Assumes rm->rm_writecpus update is visible on other CPUs 550 * before rm_cleanIPI is called. 551 */ 552 #ifdef SMP 553 smp_rendezvous_cpus(readcpus, 554 smp_no_rendezvous_barrier, 555 rm_cleanIPI, 556 smp_no_rendezvous_barrier, 557 rm); 558 559 #else 560 rm_cleanIPI(rm); 561 #endif 562 563 mtx_lock_spin(&rm_spinlock); 564 while ((prio = LIST_FIRST(&rm->rm_activeReaders)) != NULL) { 565 ts = turnstile_trywait(&rm->lock_object); 566 prio->rmp_flags = RMPF_ONQUEUE | RMPF_SIGNAL; 567 mtx_unlock_spin(&rm_spinlock); 568 turnstile_wait(ts, prio->rmp_thread, 569 TS_EXCLUSIVE_QUEUE); 570 mtx_lock_spin(&rm_spinlock); 571 } 572 mtx_unlock_spin(&rm_spinlock); 573 } 574 } 575 576 void 577 _rm_wunlock(struct rmlock *rm) 578 { 579 580 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 581 sx_xunlock(&rm->rm_lock_sx); 582 else 583 mtx_unlock(&rm->rm_lock_mtx); 584 } 585 586 #if LOCK_DEBUG > 0 587 588 void 589 _rm_wlock_debug(struct rmlock *rm, const char *file, int line) 590 { 591 592 if (SCHEDULER_STOPPED()) 593 return; 594 595 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 596 ("rm_wlock() by idle thread %p on rmlock %s @ %s:%d", 597 curthread, rm->lock_object.lo_name, file, line)); 598 KASSERT(!rm_destroyed(rm), 599 ("rm_wlock() of destroyed rmlock @ %s:%d", file, line)); 600 _rm_assert(rm, RA_UNLOCKED, file, line); 601 602 WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER | LOP_EXCLUSIVE, 603 file, line, NULL); 604 605 _rm_wlock(rm); 606 607 LOCK_LOG_LOCK("RMWLOCK", &rm->lock_object, 0, 0, file, line); 608 WITNESS_LOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line); 609 TD_LOCKS_INC(curthread); 610 } 611 612 void 613 _rm_wunlock_debug(struct rmlock *rm, const char *file, int line) 614 { 615 616 if (SCHEDULER_STOPPED()) 617 return; 618 619 KASSERT(!rm_destroyed(rm), 620 ("rm_wunlock() of destroyed rmlock @ %s:%d", file, line)); 621 _rm_assert(rm, RA_WLOCKED, file, line); 622 WITNESS_UNLOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line); 623 LOCK_LOG_LOCK("RMWUNLOCK", &rm->lock_object, 0, 0, file, line); 624 _rm_wunlock(rm); 625 TD_LOCKS_DEC(curthread); 626 } 627 628 int 629 _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 630 int trylock, const char *file, int line) 631 { 632 633 if (SCHEDULER_STOPPED()) 634 return (1); 635 636 #ifdef INVARIANTS 637 if (!(rm->lock_object.lo_flags & LO_RECURSABLE) && !trylock) { 638 critical_enter(); 639 KASSERT(rm_trackers_present(get_pcpu(), rm, 640 curthread) == 0, 641 ("rm_rlock: recursed on non-recursive rmlock %s @ %s:%d\n", 642 rm->lock_object.lo_name, file, line)); 643 critical_exit(); 644 } 645 #endif 646 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 647 ("rm_rlock() by idle thread %p on rmlock %s @ %s:%d", 648 curthread, rm->lock_object.lo_name, file, line)); 649 KASSERT(!rm_destroyed(rm), 650 ("rm_rlock() of destroyed rmlock @ %s:%d", file, line)); 651 if (!trylock) { 652 KASSERT(!rm_wowned(rm), 653 ("rm_rlock: wlock already held for %s @ %s:%d", 654 rm->lock_object.lo_name, file, line)); 655 WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER, file, line, 656 NULL); 657 } 658 659 if (_rm_rlock(rm, tracker, trylock)) { 660 if (trylock) 661 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 1, file, 662 line); 663 else 664 LOCK_LOG_LOCK("RMRLOCK", &rm->lock_object, 0, 0, file, 665 line); 666 WITNESS_LOCK(&rm->lock_object, 0, file, line); 667 TD_LOCKS_INC(curthread); 668 return (1); 669 } else if (trylock) 670 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 0, file, line); 671 672 return (0); 673 } 674 675 void 676 _rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 677 const char *file, int line) 678 { 679 680 if (SCHEDULER_STOPPED()) 681 return; 682 683 KASSERT(!rm_destroyed(rm), 684 ("rm_runlock() of destroyed rmlock @ %s:%d", file, line)); 685 _rm_assert(rm, RA_RLOCKED, file, line); 686 WITNESS_UNLOCK(&rm->lock_object, 0, file, line); 687 LOCK_LOG_LOCK("RMRUNLOCK", &rm->lock_object, 0, 0, file, line); 688 _rm_runlock(rm, tracker); 689 TD_LOCKS_DEC(curthread); 690 } 691 692 #else 693 694 /* 695 * Just strip out file and line arguments if no lock debugging is enabled in 696 * the kernel - we are called from a kernel module. 697 */ 698 void 699 _rm_wlock_debug(struct rmlock *rm, const char *file, int line) 700 { 701 702 _rm_wlock(rm); 703 } 704 705 void 706 _rm_wunlock_debug(struct rmlock *rm, const char *file, int line) 707 { 708 709 _rm_wunlock(rm); 710 } 711 712 int 713 _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 714 int trylock, const char *file, int line) 715 { 716 717 return _rm_rlock(rm, tracker, trylock); 718 } 719 720 void 721 _rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 722 const char *file, int line) 723 { 724 725 _rm_runlock(rm, tracker); 726 } 727 728 #endif 729 730 #ifdef INVARIANT_SUPPORT 731 #ifndef INVARIANTS 732 #undef _rm_assert 733 #endif 734 735 /* 736 * Note that this does not need to use witness_assert() for read lock 737 * assertions since an exact count of read locks held by this thread 738 * is computable. 739 */ 740 void 741 _rm_assert(const struct rmlock *rm, int what, const char *file, int line) 742 { 743 int count; 744 745 if (SCHEDULER_STOPPED()) 746 return; 747 switch (what) { 748 case RA_LOCKED: 749 case RA_LOCKED | RA_RECURSED: 750 case RA_LOCKED | RA_NOTRECURSED: 751 case RA_RLOCKED: 752 case RA_RLOCKED | RA_RECURSED: 753 case RA_RLOCKED | RA_NOTRECURSED: 754 /* 755 * Handle the write-locked case. Unlike other 756 * primitives, writers can never recurse. 757 */ 758 if (rm_wowned(rm)) { 759 if (what & RA_RLOCKED) 760 panic("Lock %s exclusively locked @ %s:%d\n", 761 rm->lock_object.lo_name, file, line); 762 if (what & RA_RECURSED) 763 panic("Lock %s not recursed @ %s:%d\n", 764 rm->lock_object.lo_name, file, line); 765 break; 766 } 767 768 critical_enter(); 769 count = rm_trackers_present(get_pcpu(), rm, curthread); 770 critical_exit(); 771 772 if (count == 0) 773 panic("Lock %s not %slocked @ %s:%d\n", 774 rm->lock_object.lo_name, (what & RA_RLOCKED) ? 775 "read " : "", file, line); 776 if (count > 1) { 777 if (what & RA_NOTRECURSED) 778 panic("Lock %s recursed @ %s:%d\n", 779 rm->lock_object.lo_name, file, line); 780 } else if (what & RA_RECURSED) 781 panic("Lock %s not recursed @ %s:%d\n", 782 rm->lock_object.lo_name, file, line); 783 break; 784 case RA_WLOCKED: 785 if (!rm_wowned(rm)) 786 panic("Lock %s not exclusively locked @ %s:%d\n", 787 rm->lock_object.lo_name, file, line); 788 break; 789 case RA_UNLOCKED: 790 if (rm_wowned(rm)) 791 panic("Lock %s exclusively locked @ %s:%d\n", 792 rm->lock_object.lo_name, file, line); 793 794 critical_enter(); 795 count = rm_trackers_present(get_pcpu(), rm, curthread); 796 critical_exit(); 797 798 if (count != 0) 799 panic("Lock %s read locked @ %s:%d\n", 800 rm->lock_object.lo_name, file, line); 801 break; 802 default: 803 panic("Unknown rm lock assertion: %d @ %s:%d", what, file, 804 line); 805 } 806 } 807 #endif /* INVARIANT_SUPPORT */ 808 809 #ifdef DDB 810 static void 811 print_tracker(struct rm_priotracker *tr) 812 { 813 struct thread *td; 814 815 td = tr->rmp_thread; 816 db_printf(" thread %p (tid %d, pid %d, \"%s\") {", td, td->td_tid, 817 td->td_proc->p_pid, td->td_name); 818 if (tr->rmp_flags & RMPF_ONQUEUE) { 819 db_printf("ONQUEUE"); 820 if (tr->rmp_flags & RMPF_SIGNAL) 821 db_printf(",SIGNAL"); 822 } else 823 db_printf("0"); 824 db_printf("}\n"); 825 } 826 827 static void 828 db_show_rm(const struct lock_object *lock) 829 { 830 struct rm_priotracker *tr; 831 struct rm_queue *queue; 832 const struct rmlock *rm; 833 struct lock_class *lc; 834 struct pcpu *pc; 835 836 rm = (const struct rmlock *)lock; 837 db_printf(" writecpus: "); 838 ddb_display_cpuset(__DEQUALIFY(const cpuset_t *, &rm->rm_writecpus)); 839 db_printf("\n"); 840 db_printf(" per-CPU readers:\n"); 841 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) 842 for (queue = pc->pc_rm_queue.rmq_next; 843 queue != &pc->pc_rm_queue; queue = queue->rmq_next) { 844 tr = (struct rm_priotracker *)queue; 845 if (tr->rmp_rmlock == rm) 846 print_tracker(tr); 847 } 848 db_printf(" active readers:\n"); 849 LIST_FOREACH(tr, &rm->rm_activeReaders, rmp_qentry) 850 print_tracker(tr); 851 lc = LOCK_CLASS(&rm->rm_wlock_object); 852 db_printf("Backing write-lock (%s):\n", lc->lc_name); 853 lc->lc_ddb_show(&rm->rm_wlock_object); 854 } 855 #endif 856