kern_mutex.c revision 174005
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 */ 31 32/* 33 * Machine independent bits of mutex implementation. 34 */ 35 36#include <sys/cdefs.h> 37__FBSDID("$FreeBSD: head/sys/kern/kern_mutex.c 174005 2007-11-28 05:50:45Z attilio $"); 38 39#include "opt_adaptive_mutexes.h" 40#include "opt_ddb.h" 41#include "opt_global.h" 42#include "opt_sched.h" 43 44#include <sys/param.h> 45#include <sys/systm.h> 46#include <sys/bus.h> 47#include <sys/conf.h> 48#include <sys/kdb.h> 49#include <sys/kernel.h> 50#include <sys/ktr.h> 51#include <sys/lock.h> 52#include <sys/malloc.h> 53#include <sys/mutex.h> 54#include <sys/proc.h> 55#include <sys/resourcevar.h> 56#include <sys/sched.h> 57#include <sys/sbuf.h> 58#include <sys/sysctl.h> 59#include <sys/turnstile.h> 60#include <sys/vmmeter.h> 61#include <sys/lock_profile.h> 62 63#include <machine/atomic.h> 64#include <machine/bus.h> 65#include <machine/cpu.h> 66 67#include <ddb/ddb.h> 68 69#include <fs/devfs/devfs_int.h> 70 71#include <vm/vm.h> 72#include <vm/vm_extern.h> 73 74#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 75#define ADAPTIVE_MUTEXES 76#endif 77 78/* 79 * Internal utility macros. 80 */ 81#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 82 83#define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 84 85#define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 86 87static void assert_mtx(struct lock_object *lock, int what); 88#ifdef DDB 89static void db_show_mtx(struct lock_object *lock); 90#endif 91static void lock_mtx(struct lock_object *lock, int how); 92static void lock_spin(struct lock_object *lock, int how); 93static int unlock_mtx(struct lock_object *lock); 94static int unlock_spin(struct lock_object *lock); 95 96/* 97 * Lock classes for sleep and spin mutexes. 98 */ 99struct lock_class lock_class_mtx_sleep = { 100 .lc_name = "sleep mutex", 101 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 102 .lc_assert = assert_mtx, 103#ifdef DDB 104 .lc_ddb_show = db_show_mtx, 105#endif 106 .lc_lock = lock_mtx, 107 .lc_unlock = unlock_mtx, 108}; 109struct lock_class lock_class_mtx_spin = { 110 .lc_name = "spin mutex", 111 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 112 .lc_assert = assert_mtx, 113#ifdef DDB 114 .lc_ddb_show = db_show_mtx, 115#endif 116 .lc_lock = lock_spin, 117 .lc_unlock = unlock_spin, 118}; 119 120/* 121 * System-wide mutexes 122 */ 123struct mtx blocked_lock; 124struct mtx Giant; 125 126#ifdef LOCK_PROFILING 127static inline void lock_profile_init(void) 128{ 129 int i; 130 /* Initialize the mutex profiling locks */ 131 for (i = 0; i < LPROF_LOCK_SIZE; i++) { 132 mtx_init(&lprof_locks[i], "mprof lock", 133 NULL, MTX_SPIN|MTX_QUIET|MTX_NOPROFILE); 134 } 135} 136#else 137static inline void lock_profile_init(void) {;} 138#endif 139 140void 141assert_mtx(struct lock_object *lock, int what) 142{ 143 144 mtx_assert((struct mtx *)lock, what); 145} 146 147void 148lock_mtx(struct lock_object *lock, int how) 149{ 150 151 mtx_lock((struct mtx *)lock); 152} 153 154void 155lock_spin(struct lock_object *lock, int how) 156{ 157 158 panic("spin locks can only use msleep_spin"); 159} 160 161int 162unlock_mtx(struct lock_object *lock) 163{ 164 struct mtx *m; 165 166 m = (struct mtx *)lock; 167 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 168 mtx_unlock(m); 169 return (0); 170} 171 172int 173unlock_spin(struct lock_object *lock) 174{ 175 176 panic("spin locks can only use msleep_spin"); 177} 178 179/* 180 * Function versions of the inlined __mtx_* macros. These are used by 181 * modules and can also be called from assembly language if needed. 182 */ 183void 184_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 185{ 186 187 MPASS(curthread != NULL); 188 KASSERT(m->mtx_lock != MTX_DESTROYED, 189 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 190 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 191 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 192 file, line)); 193 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 194 file, line); 195 196 _get_sleep_lock(m, curthread, opts, file, line); 197 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 198 line); 199 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 200 curthread->td_locks++; 201} 202 203void 204_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 205{ 206 MPASS(curthread != NULL); 207 KASSERT(m->mtx_lock != MTX_DESTROYED, 208 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 209 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 210 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 211 file, line)); 212 curthread->td_locks--; 213 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 214 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 215 line); 216 mtx_assert(m, MA_OWNED); 217 218 if (m->mtx_recurse == 0) 219 lock_profile_release_lock(&m->lock_object); 220 _rel_sleep_lock(m, curthread, opts, file, line); 221} 222 223void 224_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 225{ 226 227 MPASS(curthread != NULL); 228 KASSERT(m->mtx_lock != MTX_DESTROYED, 229 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 230 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 231 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 232 m->lock_object.lo_name, file, line)); 233 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 234 file, line); 235 _get_spin_lock(m, curthread, opts, file, line); 236 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 237 line); 238 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 239} 240 241void 242_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 243{ 244 245 MPASS(curthread != NULL); 246 KASSERT(m->mtx_lock != MTX_DESTROYED, 247 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 248 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 249 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 250 m->lock_object.lo_name, file, line)); 251 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 252 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 253 line); 254 mtx_assert(m, MA_OWNED); 255 256 _rel_spin_lock(m); 257} 258 259/* 260 * The important part of mtx_trylock{,_flags}() 261 * Tries to acquire lock `m.' If this function is called on a mutex that 262 * is already owned, it will recursively acquire the lock. 263 */ 264int 265_mtx_trylock(struct mtx *m, int opts, const char *file, int line) 266{ 267 int rval, contested = 0; 268 uint64_t waittime = 0; 269 270 MPASS(curthread != NULL); 271 KASSERT(m->mtx_lock != MTX_DESTROYED, 272 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 273 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 274 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 275 file, line)); 276 277 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 278 m->mtx_recurse++; 279 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 280 rval = 1; 281 } else 282 rval = _obtain_lock(m, (uintptr_t)curthread); 283 284 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 285 if (rval) { 286 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 287 file, line); 288 curthread->td_locks++; 289 if (m->mtx_recurse == 0) 290 lock_profile_obtain_lock_success(&m->lock_object, contested, 291 waittime, file, line); 292 293 } 294 295 return (rval); 296} 297 298/* 299 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 300 * 301 * We call this if the lock is either contested (i.e. we need to go to 302 * sleep waiting for it), or if we need to recurse on it. 303 */ 304void 305_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 306 int line) 307{ 308 struct turnstile *ts; 309#ifdef ADAPTIVE_MUTEXES 310 volatile struct thread *owner; 311#endif 312#ifdef KTR 313 int cont_logged = 0; 314#endif 315 int contested = 0; 316 uint64_t waittime = 0; 317 uintptr_t v; 318 319 if (mtx_owned(m)) { 320 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 321 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 322 m->lock_object.lo_name, file, line)); 323 m->mtx_recurse++; 324 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 325 if (LOCK_LOG_TEST(&m->lock_object, opts)) 326 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 327 return; 328 } 329 330 lock_profile_obtain_lock_failed(&m->lock_object, 331 &contested, &waittime); 332 if (LOCK_LOG_TEST(&m->lock_object, opts)) 333 CTR4(KTR_LOCK, 334 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 335 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 336 337 while (!_obtain_lock(m, tid)) { 338#ifdef ADAPTIVE_MUTEXES 339 /* 340 * If the owner is running on another CPU, spin until the 341 * owner stops running or the state of the lock changes. 342 */ 343 v = m->mtx_lock; 344 if (v != MTX_UNOWNED) { 345 owner = (struct thread *)(v & ~MTX_FLAGMASK); 346 if (TD_IS_RUNNING(owner)) { 347 if (LOCK_LOG_TEST(&m->lock_object, 0)) 348 CTR3(KTR_LOCK, 349 "%s: spinning on %p held by %p", 350 __func__, m, owner); 351 while (mtx_owner(m) == owner && 352 TD_IS_RUNNING(owner)) 353 cpu_spinwait(); 354 continue; 355 } 356 } 357#endif 358 359 ts = turnstile_trywait(&m->lock_object); 360 v = m->mtx_lock; 361 362 /* 363 * Check if the lock has been released while spinning for 364 * the turnstile chain lock. 365 */ 366 if (v == MTX_UNOWNED) { 367 turnstile_cancel(ts); 368 cpu_spinwait(); 369 continue; 370 } 371 372 MPASS(v != MTX_CONTESTED); 373 374#ifdef ADAPTIVE_MUTEXES 375 /* 376 * If the current owner of the lock is executing on another 377 * CPU quit the hard path and try to spin. 378 */ 379 owner = (struct thread *)(v & ~MTX_FLAGMASK); 380 if (TD_IS_RUNNING(owner)) { 381 turnstile_cancel(ts); 382 cpu_spinwait(); 383 continue; 384 } 385#endif 386 387 /* 388 * If the mutex isn't already contested and a failure occurs 389 * setting the contested bit, the mutex was either released 390 * or the state of the MTX_RECURSED bit changed. 391 */ 392 if ((v & MTX_CONTESTED) == 0 && 393 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 394 turnstile_cancel(ts); 395 cpu_spinwait(); 396 continue; 397 } 398 399 /* 400 * We definitely must sleep for this lock. 401 */ 402 mtx_assert(m, MA_NOTOWNED); 403 404#ifdef KTR 405 if (!cont_logged) { 406 CTR6(KTR_CONTENTION, 407 "contention: %p at %s:%d wants %s, taken by %s:%d", 408 (void *)tid, file, line, m->lock_object.lo_name, 409 WITNESS_FILE(&m->lock_object), 410 WITNESS_LINE(&m->lock_object)); 411 cont_logged = 1; 412 } 413#endif 414 415 /* 416 * Block on the turnstile. 417 */ 418 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 419 } 420#ifdef KTR 421 if (cont_logged) { 422 CTR4(KTR_CONTENTION, 423 "contention end: %s acquired by %p at %s:%d", 424 m->lock_object.lo_name, (void *)tid, file, line); 425 } 426#endif 427 lock_profile_obtain_lock_success(&m->lock_object, contested, 428 waittime, (file), (line)); 429} 430 431static void 432_mtx_lock_spin_failed(struct mtx *m) 433{ 434 struct thread *td; 435 436 td = mtx_owner(m); 437 438 /* If the mutex is unlocked, try again. */ 439 if (td == NULL) 440 return; 441 442 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 443 m, m->lock_object.lo_name, td, td->td_tid); 444#ifdef WITNESS 445 witness_display_spinlock(&m->lock_object, td); 446#endif 447 panic("spin lock held too long"); 448} 449 450#ifdef SMP 451/* 452 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 453 * 454 * This is only called if we need to actually spin for the lock. Recursion 455 * is handled inline. 456 */ 457void 458_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 459 int line) 460{ 461 int i = 0, contested = 0; 462 uint64_t waittime = 0; 463 464 if (LOCK_LOG_TEST(&m->lock_object, opts)) 465 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 466 467 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 468 while (!_obtain_lock(m, tid)) { 469 470 /* Give interrupts a chance while we spin. */ 471 spinlock_exit(); 472 while (m->mtx_lock != MTX_UNOWNED) { 473 if (i++ < 10000000) { 474 cpu_spinwait(); 475 continue; 476 } 477 if (i < 60000000 || kdb_active || panicstr != NULL) 478 DELAY(1); 479 else 480 _mtx_lock_spin_failed(m); 481 cpu_spinwait(); 482 } 483 spinlock_enter(); 484 } 485 486 if (LOCK_LOG_TEST(&m->lock_object, opts)) 487 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 488 489 lock_profile_obtain_lock_success(&m->lock_object, contested, 490 waittime, (file), (line)); 491} 492#endif /* SMP */ 493 494void 495_thread_lock_flags(struct thread *td, int opts, const char *file, int line) 496{ 497 struct mtx *m; 498 uintptr_t tid; 499 int i, contested; 500 uint64_t waittime; 501 502 503 contested = i = 0; 504 waittime = 0; 505 tid = (uintptr_t)curthread; 506 for (;;) { 507retry: 508 spinlock_enter(); 509 m = td->td_lock; 510 WITNESS_CHECKORDER(&m->lock_object, 511 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line); 512 while (!_obtain_lock(m, tid)) { 513 if (m->mtx_lock == tid) { 514 m->mtx_recurse++; 515 break; 516 } 517 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 518 /* Give interrupts a chance while we spin. */ 519 spinlock_exit(); 520 while (m->mtx_lock != MTX_UNOWNED) { 521 if (i++ < 10000000) 522 cpu_spinwait(); 523 else if (i < 60000000 || 524 kdb_active || panicstr != NULL) 525 DELAY(1); 526 else 527 _mtx_lock_spin_failed(m); 528 cpu_spinwait(); 529 if (m != td->td_lock) 530 goto retry; 531 } 532 spinlock_enter(); 533 } 534 if (m == td->td_lock) 535 break; 536 _rel_spin_lock(m); /* does spinlock_exit() */ 537 } 538 lock_profile_obtain_lock_success(&m->lock_object, contested, 539 waittime, (file), (line)); 540 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 541} 542 543struct mtx * 544thread_lock_block(struct thread *td) 545{ 546 struct mtx *lock; 547 548 spinlock_enter(); 549 THREAD_LOCK_ASSERT(td, MA_OWNED); 550 lock = td->td_lock; 551 td->td_lock = &blocked_lock; 552 mtx_unlock_spin(lock); 553 554 return (lock); 555} 556 557void 558thread_lock_unblock(struct thread *td, struct mtx *new) 559{ 560 mtx_assert(new, MA_OWNED); 561 MPASS(td->td_lock == &blocked_lock); 562 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 563 spinlock_exit(); 564} 565 566void 567thread_lock_set(struct thread *td, struct mtx *new) 568{ 569 struct mtx *lock; 570 571 mtx_assert(new, MA_OWNED); 572 THREAD_LOCK_ASSERT(td, MA_OWNED); 573 lock = td->td_lock; 574 td->td_lock = new; 575 mtx_unlock_spin(lock); 576} 577 578/* 579 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 580 * 581 * We are only called here if the lock is recursed or contested (i.e. we 582 * need to wake up a blocked thread). 583 */ 584void 585_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 586{ 587 struct turnstile *ts; 588 589 if (mtx_recursed(m)) { 590 if (--(m->mtx_recurse) == 0) 591 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 592 if (LOCK_LOG_TEST(&m->lock_object, opts)) 593 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 594 return; 595 } 596 597 /* 598 * We have to lock the chain before the turnstile so this turnstile 599 * can be removed from the hash list if it is empty. 600 */ 601 turnstile_chain_lock(&m->lock_object); 602 ts = turnstile_lookup(&m->lock_object); 603 if (LOCK_LOG_TEST(&m->lock_object, opts)) 604 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 605 606 MPASS(ts != NULL); 607 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 608 _release_lock_quick(m); 609 /* 610 * This turnstile is now no longer associated with the mutex. We can 611 * unlock the chain lock so a new turnstile may take it's place. 612 */ 613 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 614 turnstile_chain_unlock(&m->lock_object); 615} 616 617/* 618 * All the unlocking of MTX_SPIN locks is done inline. 619 * See the _rel_spin_lock() macro for the details. 620 */ 621 622/* 623 * The backing function for the INVARIANTS-enabled mtx_assert() 624 */ 625#ifdef INVARIANT_SUPPORT 626void 627_mtx_assert(struct mtx *m, int what, const char *file, int line) 628{ 629 630 if (panicstr != NULL || dumping) 631 return; 632 switch (what) { 633 case MA_OWNED: 634 case MA_OWNED | MA_RECURSED: 635 case MA_OWNED | MA_NOTRECURSED: 636 if (!mtx_owned(m)) 637 panic("mutex %s not owned at %s:%d", 638 m->lock_object.lo_name, file, line); 639 if (mtx_recursed(m)) { 640 if ((what & MA_NOTRECURSED) != 0) 641 panic("mutex %s recursed at %s:%d", 642 m->lock_object.lo_name, file, line); 643 } else if ((what & MA_RECURSED) != 0) { 644 panic("mutex %s unrecursed at %s:%d", 645 m->lock_object.lo_name, file, line); 646 } 647 break; 648 case MA_NOTOWNED: 649 if (mtx_owned(m)) 650 panic("mutex %s owned at %s:%d", 651 m->lock_object.lo_name, file, line); 652 break; 653 default: 654 panic("unknown mtx_assert at %s:%d", file, line); 655 } 656} 657#endif 658 659/* 660 * The MUTEX_DEBUG-enabled mtx_validate() 661 * 662 * Most of these checks have been moved off into the LO_INITIALIZED flag 663 * maintained by the witness code. 664 */ 665#ifdef MUTEX_DEBUG 666 667void mtx_validate(struct mtx *); 668 669void 670mtx_validate(struct mtx *m) 671{ 672 673/* 674 * XXX: When kernacc() does not require Giant we can reenable this check 675 */ 676#ifdef notyet 677 /* 678 * Can't call kernacc() from early init386(), especially when 679 * initializing Giant mutex, because some stuff in kernacc() 680 * requires Giant itself. 681 */ 682 if (!cold) 683 if (!kernacc((caddr_t)m, sizeof(m), 684 VM_PROT_READ | VM_PROT_WRITE)) 685 panic("Can't read and write to mutex %p", m); 686#endif 687} 688#endif 689 690/* 691 * General init routine used by the MTX_SYSINIT() macro. 692 */ 693void 694mtx_sysinit(void *arg) 695{ 696 struct mtx_args *margs = arg; 697 698 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 699} 700 701/* 702 * Mutex initialization routine; initialize lock `m' of type contained in 703 * `opts' with options contained in `opts' and name `name.' The optional 704 * lock type `type' is used as a general lock category name for use with 705 * witness. 706 */ 707void 708mtx_init(struct mtx *m, const char *name, const char *type, int opts) 709{ 710 struct lock_class *class; 711 int flags; 712 713 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 714 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 715 716#ifdef MUTEX_DEBUG 717 /* Diagnostic and error correction */ 718 mtx_validate(m); 719#endif 720 721 /* Determine lock class and lock flags. */ 722 if (opts & MTX_SPIN) 723 class = &lock_class_mtx_spin; 724 else 725 class = &lock_class_mtx_sleep; 726 flags = 0; 727 if (opts & MTX_QUIET) 728 flags |= LO_QUIET; 729 if (opts & MTX_RECURSE) 730 flags |= LO_RECURSABLE; 731 if ((opts & MTX_NOWITNESS) == 0) 732 flags |= LO_WITNESS; 733 if (opts & MTX_DUPOK) 734 flags |= LO_DUPOK; 735 if (opts & MTX_NOPROFILE) 736 flags |= LO_NOPROFILE; 737 738 /* Initialize mutex. */ 739 m->mtx_lock = MTX_UNOWNED; 740 m->mtx_recurse = 0; 741 742 lock_init(&m->lock_object, class, name, type, flags); 743} 744 745/* 746 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 747 * passed in as a flag here because if the corresponding mtx_init() was 748 * called with MTX_QUIET set, then it will already be set in the mutex's 749 * flags. 750 */ 751void 752mtx_destroy(struct mtx *m) 753{ 754 755 if (!mtx_owned(m)) 756 MPASS(mtx_unowned(m)); 757 else { 758 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 759 760 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 761 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 762 spinlock_exit(); 763 else 764 curthread->td_locks--; 765 766 /* Tell witness this isn't locked to make it happy. */ 767 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 768 __LINE__); 769 } 770 771 m->mtx_lock = MTX_DESTROYED; 772 lock_destroy(&m->lock_object); 773} 774 775/* 776 * Intialize the mutex code and system mutexes. This is called from the MD 777 * startup code prior to mi_startup(). The per-CPU data space needs to be 778 * setup before this is called. 779 */ 780void 781mutex_init(void) 782{ 783 784 /* Setup turnstiles so that sleep mutexes work. */ 785 init_turnstiles(); 786 787 /* 788 * Initialize mutexes. 789 */ 790 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 791 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 792 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 793 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 794 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 795 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 796 mtx_lock(&Giant); 797 798 lock_profile_init(); 799} 800 801#ifdef DDB 802void 803db_show_mtx(struct lock_object *lock) 804{ 805 struct thread *td; 806 struct mtx *m; 807 808 m = (struct mtx *)lock; 809 810 db_printf(" flags: {"); 811 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 812 db_printf("SPIN"); 813 else 814 db_printf("DEF"); 815 if (m->lock_object.lo_flags & LO_RECURSABLE) 816 db_printf(", RECURSE"); 817 if (m->lock_object.lo_flags & LO_DUPOK) 818 db_printf(", DUPOK"); 819 db_printf("}\n"); 820 db_printf(" state: {"); 821 if (mtx_unowned(m)) 822 db_printf("UNOWNED"); 823 else if (mtx_destroyed(m)) 824 db_printf("DESTROYED"); 825 else { 826 db_printf("OWNED"); 827 if (m->mtx_lock & MTX_CONTESTED) 828 db_printf(", CONTESTED"); 829 if (m->mtx_lock & MTX_RECURSED) 830 db_printf(", RECURSED"); 831 } 832 db_printf("}\n"); 833 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 834 td = mtx_owner(m); 835 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 836 td->td_tid, td->td_proc->p_pid, td->td_name); 837 if (mtx_recursed(m)) 838 db_printf(" recursed: %d\n", m->mtx_recurse); 839 } 840} 841#endif 842