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 = get_pcpu(); 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 = get_pcpu(); 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 = get_pcpu(); 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 acquire 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 THREAD_SLEEPING_OK(); 412 sx_xlock(&rm->rm_lock_sx); 413 THREAD_NO_SLEEPING(); 414 } else 415 mtx_lock(&rm->rm_lock_mtx); 416 } 417 418 critical_enter(); 419 pc = get_pcpu(); 420 CPU_CLR(pc->pc_cpuid, &rm->rm_writecpus); 421 rm_tracker_add(pc, tracker); 422 sched_pin(); 423 critical_exit(); 424 425 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 426 sx_xunlock(&rm->rm_lock_sx); 427 else 428 mtx_unlock(&rm->rm_lock_mtx); 429 430 return (1); 431 } 432 433 int 434 _rm_rlock(struct rmlock *rm, struct rm_priotracker *tracker, int trylock) 435 { 436 struct thread *td = curthread; 437 struct pcpu *pc; 438 439 if (SCHEDULER_STOPPED()) 440 return (1); 441 442 tracker->rmp_flags = 0; 443 tracker->rmp_thread = td; 444 tracker->rmp_rmlock = rm; 445 446 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 447 THREAD_NO_SLEEPING(); 448 449 td->td_critnest++; /* critical_enter(); */ 450 451 __compiler_membar(); 452 453 pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */ 454 455 rm_tracker_add(pc, tracker); 456 457 sched_pin(); 458 459 __compiler_membar(); 460 461 td->td_critnest--; 462 463 /* 464 * Fast path to combine two common conditions into a single 465 * conditional jump. 466 */ 467 if (0 == (td->td_owepreempt | 468 CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus))) 469 return (1); 470 471 /* We do not have a read token and need to acquire one. */ 472 return _rm_rlock_hard(rm, tracker, trylock); 473 } 474 475 static void 476 _rm_unlock_hard(struct thread *td,struct rm_priotracker *tracker) 477 { 478 479 if (td->td_owepreempt) { 480 td->td_critnest++; 481 critical_exit(); 482 } 483 484 if (!tracker->rmp_flags) 485 return; 486 487 mtx_lock_spin(&rm_spinlock); 488 LIST_REMOVE(tracker, rmp_qentry); 489 490 if (tracker->rmp_flags & RMPF_SIGNAL) { 491 struct rmlock *rm; 492 struct turnstile *ts; 493 494 rm = tracker->rmp_rmlock; 495 496 turnstile_chain_lock(&rm->lock_object); 497 mtx_unlock_spin(&rm_spinlock); 498 499 ts = turnstile_lookup(&rm->lock_object); 500 501 turnstile_signal(ts, TS_EXCLUSIVE_QUEUE); 502 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 503 turnstile_chain_unlock(&rm->lock_object); 504 } else 505 mtx_unlock_spin(&rm_spinlock); 506 } 507 508 void 509 _rm_runlock(struct rmlock *rm, struct rm_priotracker *tracker) 510 { 511 struct pcpu *pc; 512 struct thread *td = tracker->rmp_thread; 513 514 if (SCHEDULER_STOPPED()) 515 return; 516 517 td->td_critnest++; /* critical_enter(); */ 518 pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */ 519 rm_tracker_remove(pc, tracker); 520 td->td_critnest--; 521 sched_unpin(); 522 523 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 524 THREAD_SLEEPING_OK(); 525 526 if (0 == (td->td_owepreempt | tracker->rmp_flags)) 527 return; 528 529 _rm_unlock_hard(td, tracker); 530 } 531 532 void 533 _rm_wlock(struct rmlock *rm) 534 { 535 struct rm_priotracker *prio; 536 struct turnstile *ts; 537 cpuset_t readcpus; 538 539 if (SCHEDULER_STOPPED()) 540 return; 541 542 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 543 sx_xlock(&rm->rm_lock_sx); 544 else 545 mtx_lock(&rm->rm_lock_mtx); 546 547 if (CPU_CMP(&rm->rm_writecpus, &all_cpus)) { 548 /* Get all read tokens back */ 549 readcpus = all_cpus; 550 CPU_NAND(&readcpus, &rm->rm_writecpus); 551 rm->rm_writecpus = all_cpus; 552 553 /* 554 * Assumes rm->rm_writecpus update is visible on other CPUs 555 * before rm_cleanIPI is called. 556 */ 557 #ifdef SMP 558 smp_rendezvous_cpus(readcpus, 559 smp_no_rendezvous_barrier, 560 rm_cleanIPI, 561 smp_no_rendezvous_barrier, 562 rm); 563 564 #else 565 rm_cleanIPI(rm); 566 #endif 567 568 mtx_lock_spin(&rm_spinlock); 569 while ((prio = LIST_FIRST(&rm->rm_activeReaders)) != NULL) { 570 ts = turnstile_trywait(&rm->lock_object); 571 prio->rmp_flags = RMPF_ONQUEUE | RMPF_SIGNAL; 572 mtx_unlock_spin(&rm_spinlock); 573 turnstile_wait(ts, prio->rmp_thread, 574 TS_EXCLUSIVE_QUEUE); 575 mtx_lock_spin(&rm_spinlock); 576 } 577 mtx_unlock_spin(&rm_spinlock); 578 } 579 } 580 581 void 582 _rm_wunlock(struct rmlock *rm) 583 { 584 585 if (rm->lock_object.lo_flags & LO_SLEEPABLE) 586 sx_xunlock(&rm->rm_lock_sx); 587 else 588 mtx_unlock(&rm->rm_lock_mtx); 589 } 590 591 #if LOCK_DEBUG > 0 592 593 void 594 _rm_wlock_debug(struct rmlock *rm, const char *file, int line) 595 { 596 597 if (SCHEDULER_STOPPED()) 598 return; 599 600 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 601 ("rm_wlock() by idle thread %p on rmlock %s @ %s:%d", 602 curthread, rm->lock_object.lo_name, file, line)); 603 KASSERT(!rm_destroyed(rm), 604 ("rm_wlock() of destroyed rmlock @ %s:%d", file, line)); 605 _rm_assert(rm, RA_UNLOCKED, file, line); 606 607 WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER | LOP_EXCLUSIVE, 608 file, line, NULL); 609 610 _rm_wlock(rm); 611 612 LOCK_LOG_LOCK("RMWLOCK", &rm->lock_object, 0, 0, file, line); 613 WITNESS_LOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line); 614 TD_LOCKS_INC(curthread); 615 } 616 617 void 618 _rm_wunlock_debug(struct rmlock *rm, const char *file, int line) 619 { 620 621 if (SCHEDULER_STOPPED()) 622 return; 623 624 KASSERT(!rm_destroyed(rm), 625 ("rm_wunlock() of destroyed rmlock @ %s:%d", file, line)); 626 _rm_assert(rm, RA_WLOCKED, file, line); 627 WITNESS_UNLOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line); 628 LOCK_LOG_LOCK("RMWUNLOCK", &rm->lock_object, 0, 0, file, line); 629 _rm_wunlock(rm); 630 TD_LOCKS_DEC(curthread); 631 } 632 633 int 634 _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 635 int trylock, const char *file, int line) 636 { 637 638 if (SCHEDULER_STOPPED()) 639 return (1); 640 641 #ifdef INVARIANTS 642 if (!(rm->lock_object.lo_flags & LO_RECURSABLE) && !trylock) { 643 critical_enter(); 644 KASSERT(rm_trackers_present(get_pcpu(), rm, 645 curthread) == 0, 646 ("rm_rlock: recursed on non-recursive rmlock %s @ %s:%d\n", 647 rm->lock_object.lo_name, file, line)); 648 critical_exit(); 649 } 650 #endif 651 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 652 ("rm_rlock() by idle thread %p on rmlock %s @ %s:%d", 653 curthread, rm->lock_object.lo_name, file, line)); 654 KASSERT(!rm_destroyed(rm), 655 ("rm_rlock() of destroyed rmlock @ %s:%d", file, line)); 656 if (!trylock) { 657 KASSERT(!rm_wowned(rm), 658 ("rm_rlock: wlock already held for %s @ %s:%d", 659 rm->lock_object.lo_name, file, line)); 660 WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER, file, line, 661 NULL); 662 } 663 664 if (_rm_rlock(rm, tracker, trylock)) { 665 if (trylock) 666 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 1, file, 667 line); 668 else 669 LOCK_LOG_LOCK("RMRLOCK", &rm->lock_object, 0, 0, file, 670 line); 671 WITNESS_LOCK(&rm->lock_object, 0, file, line); 672 TD_LOCKS_INC(curthread); 673 return (1); 674 } else if (trylock) 675 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 0, file, line); 676 677 return (0); 678 } 679 680 void 681 _rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 682 const char *file, int line) 683 { 684 685 if (SCHEDULER_STOPPED()) 686 return; 687 688 KASSERT(!rm_destroyed(rm), 689 ("rm_runlock() of destroyed rmlock @ %s:%d", file, line)); 690 _rm_assert(rm, RA_RLOCKED, file, line); 691 WITNESS_UNLOCK(&rm->lock_object, 0, file, line); 692 LOCK_LOG_LOCK("RMRUNLOCK", &rm->lock_object, 0, 0, file, line); 693 _rm_runlock(rm, tracker); 694 TD_LOCKS_DEC(curthread); 695 } 696 697 #else 698 699 /* 700 * Just strip out file and line arguments if no lock debugging is enabled in 701 * the kernel - we are called from a kernel module. 702 */ 703 void 704 _rm_wlock_debug(struct rmlock *rm, const char *file, int line) 705 { 706 707 _rm_wlock(rm); 708 } 709 710 void 711 _rm_wunlock_debug(struct rmlock *rm, const char *file, int line) 712 { 713 714 _rm_wunlock(rm); 715 } 716 717 int 718 _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 719 int trylock, const char *file, int line) 720 { 721 722 return _rm_rlock(rm, tracker, trylock); 723 } 724 725 void 726 _rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker, 727 const char *file, int line) 728 { 729 730 _rm_runlock(rm, tracker); 731 } 732 733 #endif 734 735 #ifdef INVARIANT_SUPPORT 736 #ifndef INVARIANTS 737 #undef _rm_assert 738 #endif 739 740 /* 741 * Note that this does not need to use witness_assert() for read lock 742 * assertions since an exact count of read locks held by this thread 743 * is computable. 744 */ 745 void 746 _rm_assert(const struct rmlock *rm, int what, const char *file, int line) 747 { 748 int count; 749 750 if (panicstr != NULL) 751 return; 752 switch (what) { 753 case RA_LOCKED: 754 case RA_LOCKED | RA_RECURSED: 755 case RA_LOCKED | RA_NOTRECURSED: 756 case RA_RLOCKED: 757 case RA_RLOCKED | RA_RECURSED: 758 case RA_RLOCKED | RA_NOTRECURSED: 759 /* 760 * Handle the write-locked case. Unlike other 761 * primitives, writers can never recurse. 762 */ 763 if (rm_wowned(rm)) { 764 if (what & RA_RLOCKED) 765 panic("Lock %s exclusively locked @ %s:%d\n", 766 rm->lock_object.lo_name, file, line); 767 if (what & RA_RECURSED) 768 panic("Lock %s not recursed @ %s:%d\n", 769 rm->lock_object.lo_name, file, line); 770 break; 771 } 772 773 critical_enter(); 774 count = rm_trackers_present(get_pcpu(), rm, curthread); 775 critical_exit(); 776 777 if (count == 0) 778 panic("Lock %s not %slocked @ %s:%d\n", 779 rm->lock_object.lo_name, (what & RA_RLOCKED) ? 780 "read " : "", file, line); 781 if (count > 1) { 782 if (what & RA_NOTRECURSED) 783 panic("Lock %s recursed @ %s:%d\n", 784 rm->lock_object.lo_name, file, line); 785 } else if (what & RA_RECURSED) 786 panic("Lock %s not recursed @ %s:%d\n", 787 rm->lock_object.lo_name, file, line); 788 break; 789 case RA_WLOCKED: 790 if (!rm_wowned(rm)) 791 panic("Lock %s not exclusively locked @ %s:%d\n", 792 rm->lock_object.lo_name, file, line); 793 break; 794 case RA_UNLOCKED: 795 if (rm_wowned(rm)) 796 panic("Lock %s exclusively locked @ %s:%d\n", 797 rm->lock_object.lo_name, file, line); 798 799 critical_enter(); 800 count = rm_trackers_present(get_pcpu(), rm, curthread); 801 critical_exit(); 802 803 if (count != 0) 804 panic("Lock %s read locked @ %s:%d\n", 805 rm->lock_object.lo_name, file, line); 806 break; 807 default: 808 panic("Unknown rm lock assertion: %d @ %s:%d", what, file, 809 line); 810 } 811 } 812 #endif /* INVARIANT_SUPPORT */ 813 814 #ifdef DDB 815 static void 816 print_tracker(struct rm_priotracker *tr) 817 { 818 struct thread *td; 819 820 td = tr->rmp_thread; 821 db_printf(" thread %p (tid %d, pid %d, \"%s\") {", td, td->td_tid, 822 td->td_proc->p_pid, td->td_name); 823 if (tr->rmp_flags & RMPF_ONQUEUE) { 824 db_printf("ONQUEUE"); 825 if (tr->rmp_flags & RMPF_SIGNAL) 826 db_printf(",SIGNAL"); 827 } else 828 db_printf("0"); 829 db_printf("}\n"); 830 } 831 832 static void 833 db_show_rm(const struct lock_object *lock) 834 { 835 struct rm_priotracker *tr; 836 struct rm_queue *queue; 837 const struct rmlock *rm; 838 struct lock_class *lc; 839 struct pcpu *pc; 840 841 rm = (const struct rmlock *)lock; 842 db_printf(" writecpus: "); 843 ddb_display_cpuset(__DEQUALIFY(const cpuset_t *, &rm->rm_writecpus)); 844 db_printf("\n"); 845 db_printf(" per-CPU readers:\n"); 846 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) 847 for (queue = pc->pc_rm_queue.rmq_next; 848 queue != &pc->pc_rm_queue; queue = queue->rmq_next) { 849 tr = (struct rm_priotracker *)queue; 850 if (tr->rmp_rmlock == rm) 851 print_tracker(tr); 852 } 853 db_printf(" active readers:\n"); 854 LIST_FOREACH(tr, &rm->rm_activeReaders, rmp_qentry) 855 print_tracker(tr); 856 lc = LOCK_CLASS(&rm->rm_wlock_object); 857 db_printf("Backing write-lock (%s):\n", lc->lc_name); 858 lc->lc_ddb_show(&rm->rm_wlock_object); 859 } 860 #endif 861