1 /*- 2 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. Berkeley Software Design Inc's name may not be used to endorse or 13 * promote products derived from this software without specific prior 14 * written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 29 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 30 * $FreeBSD$ 31 */ 32 33 /* 34 * Machine independent bits of mutex implementation and implementation of 35 * `witness' structure & related debugging routines. 36 */ 37 38 /* 39 * Main Entry: witness 40 * Pronunciation: 'wit-n&s 41 * Function: noun 42 * Etymology: Middle English witnesse, from Old English witnes knowledge, 43 * testimony, witness, from 2wit 44 * Date: before 12th century 45 * 1 : attestation of a fact or event : TESTIMONY 46 * 2 : one that gives evidence; specifically : one who testifies in 47 * a cause or before a judicial tribunal 48 * 3 : one asked to be present at a transaction so as to be able to 49 * testify to its having taken place 50 * 4 : one who has personal knowledge of something 51 * 5 a : something serving as evidence or proof : SIGN 52 * b : public affirmation by word or example of usually 53 * religious faith or conviction <the heroic witness to divine 54 * life -- Pilot> 55 * 6 capitalized : a member of the Jehovah's Witnesses 56 */ 57 58 #include "opt_ddb.h" 59 60 #include <sys/param.h> 61 #include <sys/bus.h> 62 #include <sys/kernel.h> 63 #include <sys/lock.h> 64 #include <sys/malloc.h> 65 #include <sys/mutex.h> 66 #include <sys/proc.h> 67 #include <sys/resourcevar.h> 68 #include <sys/sysctl.h> 69 #include <sys/systm.h> 70 #include <sys/vmmeter.h> 71 #include <sys/ktr.h> 72 73 #include <machine/atomic.h> 74 #include <machine/bus.h> 75 #include <machine/clock.h> 76 #include <machine/cpu.h> 77 78 #include <ddb/ddb.h> 79 80 #include <vm/vm.h> 81 #include <vm/vm_extern.h> 82 83 /* 84 * Internal utility macros. 85 */ 86 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 87 88 #define mtx_owner(m) (mtx_unowned((m)) ? NULL \ 89 : (struct thread *)((m)->mtx_lock & MTX_FLAGMASK)) 90 91 #define SET_PRIO(td, pri) (td)->td_ksegrp->kg_pri.pri_level = (pri) 92 93 /* 94 * Lock classes for sleep and spin mutexes. 95 */ 96 struct lock_class lock_class_mtx_sleep = { 97 "sleep mutex", 98 LC_SLEEPLOCK | LC_RECURSABLE 99 }; 100 struct lock_class lock_class_mtx_spin = { 101 "spin mutex", 102 LC_SPINLOCK | LC_RECURSABLE 103 }; 104 105 /* 106 * Prototypes for non-exported routines. 107 */ 108 static void propagate_priority(struct thread *); 109 110 static void 111 propagate_priority(struct thread *td) 112 { 113 struct ksegrp *kg = td->td_ksegrp; 114 int pri = kg->kg_pri.pri_level; 115 struct mtx *m = td->td_blocked; 116 117 mtx_assert(&sched_lock, MA_OWNED); 118 for (;;) { 119 struct thread *td1; 120 121 td = mtx_owner(m); 122 123 if (td == NULL) { 124 /* 125 * This really isn't quite right. Really 126 * ought to bump priority of thread that 127 * next acquires the mutex. 128 */ 129 MPASS(m->mtx_lock == MTX_CONTESTED); 130 return; 131 } 132 133 MPASS(td->td_proc->p_magic == P_MAGIC); 134 KASSERT(td->td_proc->p_stat != SSLEEP, ("sleeping thread owns a mutex")); 135 if (kg->kg_pri.pri_level <= pri) /* lower is higher priority */ 136 return; 137 138 /* 139 * Bump this thread's priority. 140 */ 141 SET_PRIO(td, pri); 142 143 /* 144 * If lock holder is actually running, just bump priority. 145 */ 146 /* XXXKSE this test is not sufficient */ 147 if (td->td_kse && (td->td_kse->ke_oncpu != NOCPU)) { 148 MPASS(td->td_proc->p_stat == SRUN 149 || td->td_proc->p_stat == SZOMB 150 || td->td_proc->p_stat == SSTOP); 151 return; 152 } 153 154 #ifndef SMP 155 /* 156 * For UP, we check to see if td is curthread (this shouldn't 157 * ever happen however as it would mean we are in a deadlock.) 158 */ 159 KASSERT(td != curthread, ("Deadlock detected")); 160 #endif 161 162 /* 163 * If on run queue move to new run queue, and quit. 164 * XXXKSE this gets a lot more complicated under threads 165 * but try anyhow. 166 */ 167 if (td->td_proc->p_stat == SRUN) { 168 MPASS(td->td_blocked == NULL); 169 remrunqueue(td); 170 setrunqueue(td); 171 return; 172 } 173 174 /* 175 * If we aren't blocked on a mutex, we should be. 176 */ 177 KASSERT(td->td_proc->p_stat == SMTX, ( 178 "process %d(%s):%d holds %s but isn't blocked on a mutex\n", 179 td->td_proc->p_pid, td->td_proc->p_comm, td->td_proc->p_stat, 180 m->mtx_object.lo_name)); 181 182 /* 183 * Pick up the mutex that td is blocked on. 184 */ 185 m = td->td_blocked; 186 MPASS(m != NULL); 187 188 /* 189 * Check if the thread needs to be moved up on 190 * the blocked chain 191 */ 192 if (td == TAILQ_FIRST(&m->mtx_blocked)) { 193 continue; 194 } 195 196 td1 = TAILQ_PREV(td, threadqueue, td_blkq); 197 if (td1->td_ksegrp->kg_pri.pri_level <= pri) { 198 continue; 199 } 200 201 /* 202 * Remove thread from blocked chain and determine where 203 * it should be moved up to. Since we know that td1 has 204 * a lower priority than td, we know that at least one 205 * thread in the chain has a lower priority and that 206 * td1 will thus not be NULL after the loop. 207 */ 208 TAILQ_REMOVE(&m->mtx_blocked, td, td_blkq); 209 TAILQ_FOREACH(td1, &m->mtx_blocked, td_blkq) { 210 MPASS(td1->td_proc->p_magic == P_MAGIC); 211 if (td1->td_ksegrp->kg_pri.pri_level > pri) 212 break; 213 } 214 215 MPASS(td1 != NULL); 216 TAILQ_INSERT_BEFORE(td1, td, td_blkq); 217 CTR4(KTR_LOCK, 218 "propagate_priority: p %p moved before %p on [%p] %s", 219 td, td1, m, m->mtx_object.lo_name); 220 } 221 } 222 223 /* 224 * Function versions of the inlined __mtx_* macros. These are used by 225 * modules and can also be called from assembly language if needed. 226 */ 227 void 228 _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 229 { 230 231 __mtx_lock_flags(m, opts, file, line); 232 } 233 234 void 235 _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 236 { 237 238 __mtx_unlock_flags(m, opts, file, line); 239 } 240 241 void 242 _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 243 { 244 245 __mtx_lock_spin_flags(m, opts, file, line); 246 } 247 248 void 249 _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 250 { 251 252 __mtx_unlock_spin_flags(m, opts, file, line); 253 } 254 255 /* 256 * The important part of mtx_trylock{,_flags}() 257 * Tries to acquire lock `m.' We do NOT handle recursion here; we assume that 258 * if we're called, it's because we know we don't already own this lock. 259 */ 260 int 261 _mtx_trylock(struct mtx *m, int opts, const char *file, int line) 262 { 263 int rval; 264 265 MPASS(curthread != NULL); 266 267 /* 268 * _mtx_trylock does not accept MTX_NOSWITCH option. 269 */ 270 KASSERT((opts & MTX_NOSWITCH) == 0, 271 ("mtx_trylock() called with invalid option flag(s) %d", opts)); 272 273 rval = _obtain_lock(m, curthread); 274 275 LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line); 276 if (rval) { 277 /* 278 * We do not handle recursion in _mtx_trylock; see the 279 * note at the top of the routine. 280 */ 281 KASSERT(!mtx_recursed(m), 282 ("mtx_trylock() called on a recursed mutex")); 283 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 284 file, line); 285 } 286 287 return (rval); 288 } 289 290 /* 291 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 292 * 293 * We call this if the lock is either contested (i.e. we need to go to 294 * sleep waiting for it), or if we need to recurse on it. 295 */ 296 void 297 _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line) 298 { 299 struct thread *td = curthread; 300 struct ksegrp *kg = td->td_ksegrp; 301 302 if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)td) { 303 m->mtx_recurse++; 304 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 305 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 306 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 307 return; 308 } 309 310 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 311 CTR4(KTR_LOCK, 312 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 313 m->mtx_object.lo_name, (void *)m->mtx_lock, file, line); 314 315 while (!_obtain_lock(m, td)) { 316 uintptr_t v; 317 struct thread *td1; 318 319 mtx_lock_spin(&sched_lock); 320 /* 321 * Check if the lock has been released while spinning for 322 * the sched_lock. 323 */ 324 if ((v = m->mtx_lock) == MTX_UNOWNED) { 325 mtx_unlock_spin(&sched_lock); 326 continue; 327 } 328 329 /* 330 * The mutex was marked contested on release. This means that 331 * there are threads blocked on it. 332 */ 333 if (v == MTX_CONTESTED) { 334 td1 = TAILQ_FIRST(&m->mtx_blocked); 335 MPASS(td1 != NULL); 336 m->mtx_lock = (uintptr_t)td | MTX_CONTESTED; 337 338 if (td1->td_ksegrp->kg_pri.pri_level < kg->kg_pri.pri_level) 339 SET_PRIO(td, td1->td_ksegrp->kg_pri.pri_level); 340 mtx_unlock_spin(&sched_lock); 341 return; 342 } 343 344 /* 345 * If the mutex isn't already contested and a failure occurs 346 * setting the contested bit, the mutex was either released 347 * or the state of the MTX_RECURSED bit changed. 348 */ 349 if ((v & MTX_CONTESTED) == 0 && 350 !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, 351 (void *)(v | MTX_CONTESTED))) { 352 mtx_unlock_spin(&sched_lock); 353 continue; 354 } 355 356 /* 357 * We deffinately must sleep for this lock. 358 */ 359 mtx_assert(m, MA_NOTOWNED); 360 361 #ifdef notyet 362 /* 363 * If we're borrowing an interrupted thread's VM context, we 364 * must clean up before going to sleep. 365 */ 366 if (td->td_ithd != NULL) { 367 struct ithd *it = td->td_ithd; 368 369 if (it->it_interrupted) { 370 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 371 CTR2(KTR_LOCK, 372 "_mtx_lock_sleep: %p interrupted %p", 373 it, it->it_interrupted); 374 intr_thd_fixup(it); 375 } 376 } 377 #endif 378 379 /* 380 * Put us on the list of threads blocked on this mutex. 381 */ 382 if (TAILQ_EMPTY(&m->mtx_blocked)) { 383 td1 = (struct thread *)(m->mtx_lock & MTX_FLAGMASK); 384 LIST_INSERT_HEAD(&td1->td_contested, m, mtx_contested); 385 TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_blkq); 386 } else { 387 TAILQ_FOREACH(td1, &m->mtx_blocked, td_blkq) 388 if (td1->td_ksegrp->kg_pri.pri_level > kg->kg_pri.pri_level) 389 break; 390 if (td1) 391 TAILQ_INSERT_BEFORE(td1, td, td_blkq); 392 else 393 TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_blkq); 394 } 395 396 /* 397 * Save who we're blocked on. 398 */ 399 td->td_blocked = m; 400 td->td_mtxname = m->mtx_object.lo_name; 401 td->td_proc->p_stat = SMTX; 402 propagate_priority(td); 403 404 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 405 CTR3(KTR_LOCK, 406 "_mtx_lock_sleep: p %p blocked on [%p] %s", td, m, 407 m->mtx_object.lo_name); 408 409 td->td_proc->p_stats->p_ru.ru_nvcsw++; 410 mi_switch(); 411 412 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 413 CTR3(KTR_LOCK, 414 "_mtx_lock_sleep: p %p free from blocked on [%p] %s", 415 td, m, m->mtx_object.lo_name); 416 417 mtx_unlock_spin(&sched_lock); 418 } 419 420 return; 421 } 422 423 /* 424 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 425 * 426 * This is only called if we need to actually spin for the lock. Recursion 427 * is handled inline. 428 */ 429 void 430 _mtx_lock_spin(struct mtx *m, int opts, critical_t mtx_crit, const char *file, 431 int line) 432 { 433 int i = 0; 434 435 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 436 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 437 438 for (;;) { 439 if (_obtain_lock(m, curthread)) 440 break; 441 442 /* Give interrupts a chance while we spin. */ 443 critical_exit(mtx_crit); 444 while (m->mtx_lock != MTX_UNOWNED) { 445 if (i++ < 1000000) 446 continue; 447 if (i++ < 6000000) 448 DELAY(1); 449 #ifdef DDB 450 else if (!db_active) 451 #else 452 else 453 #endif 454 panic("spin lock %s held by %p for > 5 seconds", 455 m->mtx_object.lo_name, (void *)m->mtx_lock); 456 } 457 mtx_crit = critical_enter(); 458 } 459 460 m->mtx_savecrit = mtx_crit; 461 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 462 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 463 464 return; 465 } 466 467 /* 468 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 469 * 470 * We are only called here if the lock is recursed or contested (i.e. we 471 * need to wake up a blocked thread). 472 */ 473 void 474 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 475 { 476 struct thread *td, *td1; 477 struct mtx *m1; 478 int pri; 479 struct ksegrp *kg; 480 481 td = curthread; 482 kg = td->td_ksegrp; 483 484 if (mtx_recursed(m)) { 485 if (--(m->mtx_recurse) == 0) 486 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 487 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 488 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 489 return; 490 } 491 492 mtx_lock_spin(&sched_lock); 493 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 494 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 495 496 td1 = TAILQ_FIRST(&m->mtx_blocked); 497 MPASS(td->td_proc->p_magic == P_MAGIC); 498 MPASS(td1->td_proc->p_magic == P_MAGIC); 499 500 TAILQ_REMOVE(&m->mtx_blocked, td1, td_blkq); 501 502 if (TAILQ_EMPTY(&m->mtx_blocked)) { 503 LIST_REMOVE(m, mtx_contested); 504 _release_lock_quick(m); 505 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 506 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); 507 } else 508 atomic_store_rel_ptr(&m->mtx_lock, (void *)MTX_CONTESTED); 509 510 pri = PRI_MAX; 511 LIST_FOREACH(m1, &td->td_contested, mtx_contested) { 512 int cp = TAILQ_FIRST(&m1->mtx_blocked)->td_ksegrp->kg_pri.pri_level; 513 if (cp < pri) 514 pri = cp; 515 } 516 517 if (pri > kg->kg_pri.pri_native) 518 pri = kg->kg_pri.pri_native; 519 SET_PRIO(td, pri); 520 521 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 522 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p contested setrunqueue %p", 523 m, td1); 524 525 td1->td_blocked = NULL; 526 td1->td_proc->p_stat = SRUN; 527 setrunqueue(td1); 528 529 if ((opts & MTX_NOSWITCH) == 0 && td1->td_ksegrp->kg_pri.pri_level < pri) { 530 #ifdef notyet 531 if (td->td_ithd != NULL) { 532 struct ithd *it = td->td_ithd; 533 534 if (it->it_interrupted) { 535 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 536 CTR2(KTR_LOCK, 537 "_mtx_unlock_sleep: %p interrupted %p", 538 it, it->it_interrupted); 539 intr_thd_fixup(it); 540 } 541 } 542 #endif 543 setrunqueue(td); 544 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 545 CTR2(KTR_LOCK, 546 "_mtx_unlock_sleep: %p switching out lock=%p", m, 547 (void *)m->mtx_lock); 548 549 td->td_proc->p_stats->p_ru.ru_nivcsw++; 550 mi_switch(); 551 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 552 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p", 553 m, (void *)m->mtx_lock); 554 } 555 556 mtx_unlock_spin(&sched_lock); 557 558 return; 559 } 560 561 /* 562 * All the unlocking of MTX_SPIN locks is done inline. 563 * See the _rel_spin_lock() macro for the details. 564 */ 565 566 /* 567 * The backing function for the INVARIANTS-enabled mtx_assert() 568 */ 569 #ifdef INVARIANT_SUPPORT 570 void 571 _mtx_assert(struct mtx *m, int what, const char *file, int line) 572 { 573 574 if (panicstr != NULL) 575 return; 576 switch (what) { 577 case MA_OWNED: 578 case MA_OWNED | MA_RECURSED: 579 case MA_OWNED | MA_NOTRECURSED: 580 if (!mtx_owned(m)) 581 panic("mutex %s not owned at %s:%d", 582 m->mtx_object.lo_name, file, line); 583 if (mtx_recursed(m)) { 584 if ((what & MA_NOTRECURSED) != 0) 585 panic("mutex %s recursed at %s:%d", 586 m->mtx_object.lo_name, file, line); 587 } else if ((what & MA_RECURSED) != 0) { 588 panic("mutex %s unrecursed at %s:%d", 589 m->mtx_object.lo_name, file, line); 590 } 591 break; 592 case MA_NOTOWNED: 593 if (mtx_owned(m)) 594 panic("mutex %s owned at %s:%d", 595 m->mtx_object.lo_name, file, line); 596 break; 597 default: 598 panic("unknown mtx_assert at %s:%d", file, line); 599 } 600 } 601 #endif 602 603 /* 604 * The MUTEX_DEBUG-enabled mtx_validate() 605 * 606 * Most of these checks have been moved off into the LO_INITIALIZED flag 607 * maintained by the witness code. 608 */ 609 #ifdef MUTEX_DEBUG 610 611 void mtx_validate __P((struct mtx *)); 612 613 void 614 mtx_validate(struct mtx *m) 615 { 616 617 /* 618 * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly 619 * we can re-enable the kernacc() checks. 620 */ 621 #ifndef __alpha__ 622 /* 623 * Can't call kernacc() from early init386(), especially when 624 * initializing Giant mutex, because some stuff in kernacc() 625 * requires Giant itself. 626 */ 627 if (!cold) 628 if (!kernacc((caddr_t)m, sizeof(m), 629 VM_PROT_READ | VM_PROT_WRITE)) 630 panic("Can't read and write to mutex %p", m); 631 #endif 632 } 633 #endif 634 635 /* 636 * Mutex initialization routine; initialize lock `m' of type contained in 637 * `opts' with options contained in `opts' and description `description.' 638 */ 639 void 640 mtx_init(struct mtx *m, const char *description, int opts) 641 { 642 struct lock_object *lock; 643 644 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 645 MTX_SLEEPABLE | MTX_NOWITNESS)) == 0); 646 647 #ifdef MUTEX_DEBUG 648 /* Diagnostic and error correction */ 649 mtx_validate(m); 650 #endif 651 652 bzero(m, sizeof(*m)); 653 lock = &m->mtx_object; 654 if (opts & MTX_SPIN) 655 lock->lo_class = &lock_class_mtx_spin; 656 else 657 lock->lo_class = &lock_class_mtx_sleep; 658 lock->lo_name = description; 659 if (opts & MTX_QUIET) 660 lock->lo_flags = LO_QUIET; 661 if (opts & MTX_RECURSE) 662 lock->lo_flags |= LO_RECURSABLE; 663 if (opts & MTX_SLEEPABLE) 664 lock->lo_flags |= LO_SLEEPABLE; 665 if ((opts & MTX_NOWITNESS) == 0) 666 lock->lo_flags |= LO_WITNESS; 667 668 m->mtx_lock = MTX_UNOWNED; 669 TAILQ_INIT(&m->mtx_blocked); 670 671 LOCK_LOG_INIT(lock, opts); 672 673 WITNESS_INIT(lock); 674 } 675 676 /* 677 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 678 * passed in as a flag here because if the corresponding mtx_init() was 679 * called with MTX_QUIET set, then it will already be set in the mutex's 680 * flags. 681 */ 682 void 683 mtx_destroy(struct mtx *m) 684 { 685 686 LOCK_LOG_DESTROY(&m->mtx_object, 0); 687 688 if (!mtx_owned(m)) 689 MPASS(mtx_unowned(m)); 690 else { 691 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 692 693 /* Tell witness this isn't locked to make it happy. */ 694 WITNESS_UNLOCK(&m->mtx_object, LOP_EXCLUSIVE | LOP_NOSWITCH, 695 __FILE__, __LINE__); 696 } 697 698 WITNESS_DESTROY(&m->mtx_object); 699 } 700