kern_rmlock.c revision 328386
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: stable/11/sys/kern/kern_rmlock.c 328386 2018-01-25 02:45:21Z pkelsey $"); 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 75static void assert_rm(const struct lock_object *lock, int what); 76#ifdef DDB 77static void db_show_rm(const struct lock_object *lock); 78#endif 79static void lock_rm(struct lock_object *lock, uintptr_t how); 80#ifdef KDTRACE_HOOKS 81static int owner_rm(const struct lock_object *lock, struct thread **owner); 82#endif 83static uintptr_t unlock_rm(struct lock_object *lock); 84 85struct 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 99struct 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 113static void 114assert_rm(const struct lock_object *lock, int what) 115{ 116 117 rm_assert((const struct rmlock *)lock, what); 118} 119 120static void 121lock_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 135static uintptr_t 136unlock_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 178static int 179owner_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 190static struct mtx rm_spinlock; 191 192MTX_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 */ 200static void inline 201rm_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 */ 221static int 222rm_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 239static void inline 240rm_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 254static void 255rm_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 276void 277rm_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 306void 307rm_init(struct rmlock *rm, const char *name) 308{ 309 310 rm_init_flags(rm, name, 0); 311} 312 313void 314rm_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 326int 327rm_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 336void 337rm_sysinit(void *arg) 338{ 339 struct rm_args *args; 340 341 args = arg; 342 rm_init_flags(args->ra_rm, args->ra_desc, args->ra_flags); 343} 344 345static int 346_rm_rlock_hard(struct rmlock *rm, struct rm_priotracker *tracker, int trylock) 347{ 348 struct pcpu *pc; 349 350 critical_enter(); 351 pc = pcpu_find(curcpu); 352 353 /* Check if we just need to do a proper critical_exit. */ 354 if (!CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus)) { 355 critical_exit(); 356 return (1); 357 } 358 359 /* Remove our tracker from the per-cpu list. */ 360 rm_tracker_remove(pc, tracker); 361 362 /* Check to see if the IPI granted us the lock after all. */ 363 if (tracker->rmp_flags) { 364 /* Just add back tracker - we hold the lock. */ 365 rm_tracker_add(pc, tracker); 366 critical_exit(); 367 return (1); 368 } 369 370 /* 371 * We allow readers to acquire a lock even if a writer is blocked if 372 * the lock is recursive and the reader already holds the lock. 373 */ 374 if ((rm->lock_object.lo_flags & LO_RECURSABLE) != 0) { 375 /* 376 * Just grant the lock if this thread already has a tracker 377 * for this lock on the per-cpu queue. 378 */ 379 if (rm_trackers_present(pc, rm, curthread) != 0) { 380 mtx_lock_spin(&rm_spinlock); 381 LIST_INSERT_HEAD(&rm->rm_activeReaders, tracker, 382 rmp_qentry); 383 tracker->rmp_flags = RMPF_ONQUEUE; 384 mtx_unlock_spin(&rm_spinlock); 385 rm_tracker_add(pc, tracker); 386 critical_exit(); 387 return (1); 388 } 389 } 390 391 sched_unpin(); 392 critical_exit(); 393 394 if (trylock) { 395 if (rm->lock_object.lo_flags & LO_SLEEPABLE) { 396 if (!sx_try_xlock(&rm->rm_lock_sx)) 397 return (0); 398 } else { 399 if (!mtx_trylock(&rm->rm_lock_mtx)) 400 return (0); 401 } 402 } else { 403 if (rm->lock_object.lo_flags & LO_SLEEPABLE) { 404 THREAD_SLEEPING_OK(); 405 sx_xlock(&rm->rm_lock_sx); 406 THREAD_NO_SLEEPING(); 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 426int 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 468static 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 501void 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 525void 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_rendezvous_barrier, 553 rm_cleanIPI, 554 smp_no_rendezvous_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 574void 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#if LOCK_DEBUG > 0 585 586void 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 WITNESS_LOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line); 607 TD_LOCKS_INC(curthread); 608} 609 610void 611_rm_wunlock_debug(struct rmlock *rm, const char *file, int line) 612{ 613 614 if (SCHEDULER_STOPPED()) 615 return; 616 617 KASSERT(!rm_destroyed(rm), 618 ("rm_wunlock() of destroyed rmlock @ %s:%d", file, line)); 619 _rm_assert(rm, RA_WLOCKED, file, line); 620 WITNESS_UNLOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line); 621 LOCK_LOG_LOCK("RMWUNLOCK", &rm->lock_object, 0, 0, file, line); 622 _rm_wunlock(rm); 623 TD_LOCKS_DEC(curthread); 624} 625 626int 627_rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 628 int trylock, const char *file, int line) 629{ 630 631 if (SCHEDULER_STOPPED()) 632 return (1); 633 634#ifdef INVARIANTS 635 if (!(rm->lock_object.lo_flags & LO_RECURSABLE) && !trylock) { 636 critical_enter(); 637 KASSERT(rm_trackers_present(pcpu_find(curcpu), rm, 638 curthread) == 0, 639 ("rm_rlock: recursed on non-recursive rmlock %s @ %s:%d\n", 640 rm->lock_object.lo_name, file, line)); 641 critical_exit(); 642 } 643#endif 644 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 645 ("rm_rlock() by idle thread %p on rmlock %s @ %s:%d", 646 curthread, rm->lock_object.lo_name, file, line)); 647 KASSERT(!rm_destroyed(rm), 648 ("rm_rlock() of destroyed rmlock @ %s:%d", file, line)); 649 if (!trylock) { 650 KASSERT(!rm_wowned(rm), 651 ("rm_rlock: wlock already held for %s @ %s:%d", 652 rm->lock_object.lo_name, file, line)); 653 WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER, file, line, 654 NULL); 655 } 656 657 if (_rm_rlock(rm, tracker, trylock)) { 658 if (trylock) 659 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 1, file, 660 line); 661 else 662 LOCK_LOG_LOCK("RMRLOCK", &rm->lock_object, 0, 0, file, 663 line); 664 WITNESS_LOCK(&rm->lock_object, 0, file, line); 665 TD_LOCKS_INC(curthread); 666 return (1); 667 } else if (trylock) 668 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 0, file, line); 669 670 return (0); 671} 672 673void 674_rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 675 const char *file, int line) 676{ 677 678 if (SCHEDULER_STOPPED()) 679 return; 680 681 KASSERT(!rm_destroyed(rm), 682 ("rm_runlock() of destroyed rmlock @ %s:%d", file, line)); 683 _rm_assert(rm, RA_RLOCKED, file, line); 684 WITNESS_UNLOCK(&rm->lock_object, 0, file, line); 685 LOCK_LOG_LOCK("RMRUNLOCK", &rm->lock_object, 0, 0, file, line); 686 _rm_runlock(rm, tracker); 687 TD_LOCKS_DEC(curthread); 688} 689 690#else 691 692/* 693 * Just strip out file and line arguments if no lock debugging is enabled in 694 * the kernel - we are called from a kernel module. 695 */ 696void 697_rm_wlock_debug(struct rmlock *rm, const char *file, int line) 698{ 699 700 _rm_wlock(rm); 701} 702 703void 704_rm_wunlock_debug(struct rmlock *rm, const char *file, int line) 705{ 706 707 _rm_wunlock(rm); 708} 709 710int 711_rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 712 int trylock, const char *file, int line) 713{ 714 715 return _rm_rlock(rm, tracker, trylock); 716} 717 718void 719_rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 720 const char *file, int line) 721{ 722 723 _rm_runlock(rm, tracker); 724} 725 726#endif 727 728#ifdef INVARIANT_SUPPORT 729#ifndef INVARIANTS 730#undef _rm_assert 731#endif 732 733/* 734 * Note that this does not need to use witness_assert() for read lock 735 * assertions since an exact count of read locks held by this thread 736 * is computable. 737 */ 738void 739_rm_assert(const struct rmlock *rm, int what, const char *file, int line) 740{ 741 int count; 742 743 if (panicstr != NULL) 744 return; 745 switch (what) { 746 case RA_LOCKED: 747 case RA_LOCKED | RA_RECURSED: 748 case RA_LOCKED | RA_NOTRECURSED: 749 case RA_RLOCKED: 750 case RA_RLOCKED | RA_RECURSED: 751 case RA_RLOCKED | RA_NOTRECURSED: 752 /* 753 * Handle the write-locked case. Unlike other 754 * primitives, writers can never recurse. 755 */ 756 if (rm_wowned(rm)) { 757 if (what & RA_RLOCKED) 758 panic("Lock %s exclusively locked @ %s:%d\n", 759 rm->lock_object.lo_name, file, line); 760 if (what & RA_RECURSED) 761 panic("Lock %s not recursed @ %s:%d\n", 762 rm->lock_object.lo_name, file, line); 763 break; 764 } 765 766 critical_enter(); 767 count = rm_trackers_present(pcpu_find(curcpu), rm, curthread); 768 critical_exit(); 769 770 if (count == 0) 771 panic("Lock %s not %slocked @ %s:%d\n", 772 rm->lock_object.lo_name, (what & RA_RLOCKED) ? 773 "read " : "", file, line); 774 if (count > 1) { 775 if (what & RA_NOTRECURSED) 776 panic("Lock %s recursed @ %s:%d\n", 777 rm->lock_object.lo_name, file, line); 778 } else if (what & RA_RECURSED) 779 panic("Lock %s not recursed @ %s:%d\n", 780 rm->lock_object.lo_name, file, line); 781 break; 782 case RA_WLOCKED: 783 if (!rm_wowned(rm)) 784 panic("Lock %s not exclusively locked @ %s:%d\n", 785 rm->lock_object.lo_name, file, line); 786 break; 787 case RA_UNLOCKED: 788 if (rm_wowned(rm)) 789 panic("Lock %s exclusively locked @ %s:%d\n", 790 rm->lock_object.lo_name, file, line); 791 792 critical_enter(); 793 count = rm_trackers_present(pcpu_find(curcpu), rm, curthread); 794 critical_exit(); 795 796 if (count != 0) 797 panic("Lock %s read locked @ %s:%d\n", 798 rm->lock_object.lo_name, file, line); 799 break; 800 default: 801 panic("Unknown rm lock assertion: %d @ %s:%d", what, file, 802 line); 803 } 804} 805#endif /* INVARIANT_SUPPORT */ 806 807#ifdef DDB 808static void 809print_tracker(struct rm_priotracker *tr) 810{ 811 struct thread *td; 812 813 td = tr->rmp_thread; 814 db_printf(" thread %p (tid %d, pid %d, \"%s\") {", td, td->td_tid, 815 td->td_proc->p_pid, td->td_name); 816 if (tr->rmp_flags & RMPF_ONQUEUE) { 817 db_printf("ONQUEUE"); 818 if (tr->rmp_flags & RMPF_SIGNAL) 819 db_printf(",SIGNAL"); 820 } else 821 db_printf("0"); 822 db_printf("}\n"); 823} 824 825static void 826db_show_rm(const struct lock_object *lock) 827{ 828 struct rm_priotracker *tr; 829 struct rm_queue *queue; 830 const struct rmlock *rm; 831 struct lock_class *lc; 832 struct pcpu *pc; 833 834 rm = (const struct rmlock *)lock; 835 db_printf(" writecpus: "); 836 ddb_display_cpuset(__DEQUALIFY(const cpuset_t *, &rm->rm_writecpus)); 837 db_printf("\n"); 838 db_printf(" per-CPU readers:\n"); 839 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) 840 for (queue = pc->pc_rm_queue.rmq_next; 841 queue != &pc->pc_rm_queue; queue = queue->rmq_next) { 842 tr = (struct rm_priotracker *)queue; 843 if (tr->rmp_rmlock == rm) 844 print_tracker(tr); 845 } 846 db_printf(" active readers:\n"); 847 LIST_FOREACH(tr, &rm->rm_activeReaders, rmp_qentry) 848 print_tracker(tr); 849 lc = LOCK_CLASS(&rm->rm_wlock_object); 850 db_printf("Backing write-lock (%s):\n", lc->lc_name); 851 lc->lc_ddb_show(&rm->rm_wlock_object); 852} 853#endif 854