kern_mutex.c revision 170441
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 170441 2007-06-08 21:36:52Z 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 87#ifdef DDB 88static void db_show_mtx(struct lock_object *lock); 89#endif 90static void lock_mtx(struct lock_object *lock, int how); 91static void lock_spin(struct lock_object *lock, int how); 92static int unlock_mtx(struct lock_object *lock); 93static int unlock_spin(struct lock_object *lock); 94 95/* 96 * Lock classes for sleep and spin mutexes. 97 */ 98struct lock_class lock_class_mtx_sleep = { 99 .lc_name = "sleep mutex", 100 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 101#ifdef DDB 102 .lc_ddb_show = db_show_mtx, 103#endif 104 .lc_lock = lock_mtx, 105 .lc_unlock = unlock_mtx, 106}; 107struct lock_class lock_class_mtx_spin = { 108 .lc_name = "spin mutex", 109 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 110#ifdef DDB 111 .lc_ddb_show = db_show_mtx, 112#endif 113 .lc_lock = lock_spin, 114 .lc_unlock = unlock_spin, 115}; 116 117/* 118 * System-wide mutexes 119 */ 120struct mtx blocked_lock; 121struct mtx sched_lock; 122struct mtx Giant; 123 124#ifdef LOCK_PROFILING 125static inline void lock_profile_init(void) 126{ 127 int i; 128 /* Initialize the mutex profiling locks */ 129 for (i = 0; i < LPROF_LOCK_SIZE; i++) { 130 mtx_init(&lprof_locks[i], "mprof lock", 131 NULL, MTX_SPIN|MTX_QUIET|MTX_NOPROFILE); 132 } 133} 134#else 135static inline void lock_profile_init(void) {;} 136#endif 137 138void 139lock_mtx(struct lock_object *lock, int how) 140{ 141 142 mtx_lock((struct mtx *)lock); 143} 144 145void 146lock_spin(struct lock_object *lock, int how) 147{ 148 149 panic("spin locks can only use msleep_spin"); 150} 151 152int 153unlock_mtx(struct lock_object *lock) 154{ 155 struct mtx *m; 156 157 m = (struct mtx *)lock; 158 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 159 mtx_unlock(m); 160 return (0); 161} 162 163int 164unlock_spin(struct lock_object *lock) 165{ 166 167 panic("spin locks can only use msleep_spin"); 168} 169 170/* 171 * Function versions of the inlined __mtx_* macros. These are used by 172 * modules and can also be called from assembly language if needed. 173 */ 174void 175_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 176{ 177 178 MPASS(curthread != NULL); 179 KASSERT(m->mtx_lock != MTX_DESTROYED, 180 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 181 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 182 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 183 file, line)); 184 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 185 file, line); 186 187 _get_sleep_lock(m, curthread, opts, file, line); 188 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 189 line); 190 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 191 curthread->td_locks++; 192} 193 194void 195_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 196{ 197 MPASS(curthread != NULL); 198 KASSERT(m->mtx_lock != MTX_DESTROYED, 199 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 200 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 201 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 202 file, line)); 203 curthread->td_locks--; 204 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 205 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 206 line); 207 mtx_assert(m, MA_OWNED); 208 209 if (m->mtx_recurse == 0) 210 lock_profile_release_lock(&m->lock_object); 211 _rel_sleep_lock(m, curthread, opts, file, line); 212} 213 214void 215_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 216{ 217 218 MPASS(curthread != NULL); 219 KASSERT(m->mtx_lock != MTX_DESTROYED, 220 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 221 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 222 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 223 m->lock_object.lo_name, file, line)); 224 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 225 file, line); 226 _get_spin_lock(m, curthread, opts, file, line); 227 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 228 line); 229 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 230} 231 232void 233_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 234{ 235 236 MPASS(curthread != NULL); 237 KASSERT(m->mtx_lock != MTX_DESTROYED, 238 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 239 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 240 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 241 m->lock_object.lo_name, file, line)); 242 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 243 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 244 line); 245 mtx_assert(m, MA_OWNED); 246 247 _rel_spin_lock(m); 248} 249 250/* 251 * The important part of mtx_trylock{,_flags}() 252 * Tries to acquire lock `m.' If this function is called on a mutex that 253 * is already owned, it will recursively acquire the lock. 254 */ 255int 256_mtx_trylock(struct mtx *m, int opts, const char *file, int line) 257{ 258 int rval, contested = 0; 259 uint64_t waittime = 0; 260 261 MPASS(curthread != NULL); 262 KASSERT(m->mtx_lock != MTX_DESTROYED, 263 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 264 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 265 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 266 file, line)); 267 268 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 269 m->mtx_recurse++; 270 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 271 rval = 1; 272 } else 273 rval = _obtain_lock(m, (uintptr_t)curthread); 274 275 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 276 if (rval) { 277 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 278 file, line); 279 curthread->td_locks++; 280 if (m->mtx_recurse == 0) 281 lock_profile_obtain_lock_success(&m->lock_object, contested, 282 waittime, file, line); 283 284 } 285 286 return (rval); 287} 288 289/* 290 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 291 * 292 * We call this if the lock is either contested (i.e. we need to go to 293 * sleep waiting for it), or if we need to recurse on it. 294 */ 295void 296_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 297 int line) 298{ 299 struct turnstile *ts; 300#ifdef ADAPTIVE_MUTEXES 301 volatile struct thread *owner; 302#endif 303#ifdef KTR 304 int cont_logged = 0; 305#endif 306 int contested = 0; 307 uint64_t waittime = 0; 308 uintptr_t v; 309 310 if (mtx_owned(m)) { 311 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 312 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 313 m->lock_object.lo_name, file, line)); 314 m->mtx_recurse++; 315 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 316 if (LOCK_LOG_TEST(&m->lock_object, opts)) 317 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 318 return; 319 } 320 321 lock_profile_obtain_lock_failed(&m->lock_object, 322 &contested, &waittime); 323 if (LOCK_LOG_TEST(&m->lock_object, opts)) 324 CTR4(KTR_LOCK, 325 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 326 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 327 328 while (!_obtain_lock(m, tid)) { 329 ts = turnstile_trywait(&m->lock_object); 330 v = m->mtx_lock; 331 332 /* 333 * Check if the lock has been released while spinning for 334 * the turnstile chain lock. 335 */ 336 if (v == MTX_UNOWNED) { 337 turnstile_cancel(ts); 338 cpu_spinwait(); 339 continue; 340 } 341 342 MPASS(v != MTX_CONTESTED); 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, v, v | MTX_CONTESTED)) { 351 turnstile_cancel(ts); 352 cpu_spinwait(); 353 continue; 354 } 355 356#ifdef ADAPTIVE_MUTEXES 357 /* 358 * If the current owner of the lock is executing on another 359 * CPU, spin instead of blocking. 360 */ 361 owner = (struct thread *)(v & ~MTX_FLAGMASK); 362#ifdef ADAPTIVE_GIANT 363 if (TD_IS_RUNNING(owner)) 364#else 365 if (m != &Giant && TD_IS_RUNNING(owner)) 366#endif 367 { 368 turnstile_cancel(ts); 369 while (mtx_owner(m) == owner && TD_IS_RUNNING(owner)) { 370 cpu_spinwait(); 371 } 372 continue; 373 } 374#endif /* ADAPTIVE_MUTEXES */ 375 376 /* 377 * We definitely must sleep for this lock. 378 */ 379 mtx_assert(m, MA_NOTOWNED); 380 381#ifdef KTR 382 if (!cont_logged) { 383 CTR6(KTR_CONTENTION, 384 "contention: %p at %s:%d wants %s, taken by %s:%d", 385 (void *)tid, file, line, m->lock_object.lo_name, 386 WITNESS_FILE(&m->lock_object), 387 WITNESS_LINE(&m->lock_object)); 388 cont_logged = 1; 389 } 390#endif 391 392 /* 393 * Block on the turnstile. 394 */ 395 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 396 } 397#ifdef KTR 398 if (cont_logged) { 399 CTR4(KTR_CONTENTION, 400 "contention end: %s acquired by %p at %s:%d", 401 m->lock_object.lo_name, (void *)tid, file, line); 402 } 403#endif 404 lock_profile_obtain_lock_success(&m->lock_object, contested, 405 waittime, (file), (line)); 406} 407 408static void 409_mtx_lock_spin_failed(struct mtx *m) 410{ 411 struct thread *td; 412 413 td = mtx_owner(m); 414 415 /* If the mutex is unlocked, try again. */ 416 if (td == NULL) 417 return; 418 419 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 420 m, m->lock_object.lo_name, td, td->td_tid); 421#ifdef WITNESS 422 witness_display_spinlock(&m->lock_object, td); 423#endif 424 panic("spin lock held too long"); 425} 426 427#ifdef SMP 428/* 429 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 430 * 431 * This is only called if we need to actually spin for the lock. Recursion 432 * is handled inline. 433 */ 434void 435_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 436 int line) 437{ 438 int i = 0, contested = 0; 439 uint64_t waittime = 0; 440 441 if (LOCK_LOG_TEST(&m->lock_object, opts)) 442 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 443 444 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 445 while (!_obtain_lock(m, tid)) { 446 447 /* Give interrupts a chance while we spin. */ 448 spinlock_exit(); 449 while (m->mtx_lock != MTX_UNOWNED) { 450 if (i++ < 10000000) { 451 cpu_spinwait(); 452 continue; 453 } 454 if (i < 60000000 || kdb_active || panicstr != NULL) 455 DELAY(1); 456 else 457 _mtx_lock_spin_failed(m); 458 cpu_spinwait(); 459 } 460 spinlock_enter(); 461 } 462 463 if (LOCK_LOG_TEST(&m->lock_object, opts)) 464 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 465 466 lock_profile_obtain_lock_success(&m->lock_object, contested, 467 waittime, (file), (line)); 468} 469#endif /* SMP */ 470 471void 472_thread_lock_flags(struct thread *td, int opts, const char *file, int line) 473{ 474 struct mtx *m; 475 uintptr_t tid; 476 int i; 477 478 i = 0; 479 tid = (uintptr_t)curthread; 480 for (;;) { 481retry: 482 spinlock_enter(); 483 m = td->td_lock; 484 WITNESS_CHECKORDER(&m->lock_object, 485 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line); 486 while (!_obtain_lock(m, tid)) { 487 if (m->mtx_lock == tid) { 488 m->mtx_recurse++; 489 break; 490 } 491 /* Give interrupts a chance while we spin. */ 492 spinlock_exit(); 493 while (m->mtx_lock != MTX_UNOWNED) { 494 if (i++ < 10000000) 495 cpu_spinwait(); 496 else if (i < 60000000 || 497 kdb_active || panicstr != NULL) 498 DELAY(1); 499 else 500 _mtx_lock_spin_failed(m); 501 cpu_spinwait(); 502 if (m != td->td_lock) 503 goto retry; 504 } 505 spinlock_enter(); 506 } 507 if (m == td->td_lock) 508 break; 509 _rel_spin_lock(m); /* does spinlock_exit() */ 510 } 511 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 512} 513 514struct mtx * 515thread_lock_block(struct thread *td) 516{ 517 struct mtx *lock; 518 519 spinlock_enter(); 520 THREAD_LOCK_ASSERT(td, MA_OWNED); 521 lock = td->td_lock; 522 td->td_lock = &blocked_lock; 523 mtx_unlock_spin(lock); 524 525 return (lock); 526} 527 528void 529thread_lock_unblock(struct thread *td, struct mtx *new) 530{ 531 mtx_assert(new, MA_OWNED); 532 MPASS(td->td_lock == &blocked_lock); 533 atomic_store_rel_ptr((void *)&td->td_lock, (uintptr_t)new); 534 spinlock_exit(); 535} 536 537void 538thread_lock_set(struct thread *td, struct mtx *new) 539{ 540 struct mtx *lock; 541 542 mtx_assert(new, MA_OWNED); 543 THREAD_LOCK_ASSERT(td, MA_OWNED); 544 lock = td->td_lock; 545 td->td_lock = new; 546 mtx_unlock_spin(lock); 547} 548 549/* 550 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 551 * 552 * We are only called here if the lock is recursed or contested (i.e. we 553 * need to wake up a blocked thread). 554 */ 555void 556_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 557{ 558 struct turnstile *ts; 559 560 if (mtx_recursed(m)) { 561 if (--(m->mtx_recurse) == 0) 562 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 563 if (LOCK_LOG_TEST(&m->lock_object, opts)) 564 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 565 return; 566 } 567 568 /* 569 * We have to lock the chain before the turnstile so this turnstile 570 * can be removed from the hash list if it is empty. 571 */ 572 turnstile_chain_lock(&m->lock_object); 573 ts = turnstile_lookup(&m->lock_object); 574 if (LOCK_LOG_TEST(&m->lock_object, opts)) 575 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 576 577#ifdef ADAPTIVE_MUTEXES 578 if (ts == NULL) { 579 _release_lock_quick(m); 580 if (LOCK_LOG_TEST(&m->lock_object, opts)) 581 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m); 582 turnstile_chain_unlock(&m->lock_object); 583 return; 584 } 585#else 586 MPASS(ts != NULL); 587#endif 588 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 589 _release_lock_quick(m); 590 /* 591 * This turnstile is now no longer associated with the mutex. We can 592 * unlock the chain lock so a new turnstile may take it's place. 593 */ 594 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 595 turnstile_chain_unlock(&m->lock_object); 596} 597 598/* 599 * All the unlocking of MTX_SPIN locks is done inline. 600 * See the _rel_spin_lock() macro for the details. 601 */ 602 603/* 604 * The backing function for the INVARIANTS-enabled mtx_assert() 605 */ 606#ifdef INVARIANT_SUPPORT 607void 608_mtx_assert(struct mtx *m, int what, const char *file, int line) 609{ 610 611 if (panicstr != NULL || dumping) 612 return; 613 switch (what) { 614 case MA_OWNED: 615 case MA_OWNED | MA_RECURSED: 616 case MA_OWNED | MA_NOTRECURSED: 617 if (!mtx_owned(m)) 618 panic("mutex %s not owned at %s:%d", 619 m->lock_object.lo_name, file, line); 620 if (mtx_recursed(m)) { 621 if ((what & MA_NOTRECURSED) != 0) 622 panic("mutex %s recursed at %s:%d", 623 m->lock_object.lo_name, file, line); 624 } else if ((what & MA_RECURSED) != 0) { 625 panic("mutex %s unrecursed at %s:%d", 626 m->lock_object.lo_name, file, line); 627 } 628 break; 629 case MA_NOTOWNED: 630 if (mtx_owned(m)) 631 panic("mutex %s owned at %s:%d", 632 m->lock_object.lo_name, file, line); 633 break; 634 default: 635 panic("unknown mtx_assert at %s:%d", file, line); 636 } 637} 638#endif 639 640/* 641 * The MUTEX_DEBUG-enabled mtx_validate() 642 * 643 * Most of these checks have been moved off into the LO_INITIALIZED flag 644 * maintained by the witness code. 645 */ 646#ifdef MUTEX_DEBUG 647 648void mtx_validate(struct mtx *); 649 650void 651mtx_validate(struct mtx *m) 652{ 653 654/* 655 * XXX: When kernacc() does not require Giant we can reenable this check 656 */ 657#ifdef notyet 658 /* 659 * Can't call kernacc() from early init386(), especially when 660 * initializing Giant mutex, because some stuff in kernacc() 661 * requires Giant itself. 662 */ 663 if (!cold) 664 if (!kernacc((caddr_t)m, sizeof(m), 665 VM_PROT_READ | VM_PROT_WRITE)) 666 panic("Can't read and write to mutex %p", m); 667#endif 668} 669#endif 670 671/* 672 * General init routine used by the MTX_SYSINIT() macro. 673 */ 674void 675mtx_sysinit(void *arg) 676{ 677 struct mtx_args *margs = arg; 678 679 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 680} 681 682/* 683 * Mutex initialization routine; initialize lock `m' of type contained in 684 * `opts' with options contained in `opts' and name `name.' The optional 685 * lock type `type' is used as a general lock category name for use with 686 * witness. 687 */ 688void 689mtx_init(struct mtx *m, const char *name, const char *type, int opts) 690{ 691 struct lock_class *class; 692 int flags; 693 694 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 695 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 696 697#ifdef MUTEX_DEBUG 698 /* Diagnostic and error correction */ 699 mtx_validate(m); 700#endif 701 702 /* Determine lock class and lock flags. */ 703 if (opts & MTX_SPIN) 704 class = &lock_class_mtx_spin; 705 else 706 class = &lock_class_mtx_sleep; 707 flags = 0; 708 if (opts & MTX_QUIET) 709 flags |= LO_QUIET; 710 if (opts & MTX_RECURSE) 711 flags |= LO_RECURSABLE; 712 if ((opts & MTX_NOWITNESS) == 0) 713 flags |= LO_WITNESS; 714 if (opts & MTX_DUPOK) 715 flags |= LO_DUPOK; 716 if (opts & MTX_NOPROFILE) 717 flags |= LO_NOPROFILE; 718 719 /* Initialize mutex. */ 720 m->mtx_lock = MTX_UNOWNED; 721 m->mtx_recurse = 0; 722 723 lock_init(&m->lock_object, class, name, type, flags); 724} 725 726/* 727 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 728 * passed in as a flag here because if the corresponding mtx_init() was 729 * called with MTX_QUIET set, then it will already be set in the mutex's 730 * flags. 731 */ 732void 733mtx_destroy(struct mtx *m) 734{ 735 736 if (!mtx_owned(m)) 737 MPASS(mtx_unowned(m)); 738 else { 739 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 740 741 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 742 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 743 spinlock_exit(); 744 else 745 curthread->td_locks--; 746 747 /* Tell witness this isn't locked to make it happy. */ 748 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 749 __LINE__); 750 } 751 752 m->mtx_lock = MTX_DESTROYED; 753 lock_destroy(&m->lock_object); 754} 755 756/* 757 * Intialize the mutex code and system mutexes. This is called from the MD 758 * startup code prior to mi_startup(). The per-CPU data space needs to be 759 * setup before this is called. 760 */ 761void 762mutex_init(void) 763{ 764 765 /* Setup turnstiles so that sleep mutexes work. */ 766 init_turnstiles(); 767 768 /* 769 * Initialize mutexes. 770 */ 771 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 772 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 773 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 774 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 775 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 776 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 777 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 778 mtx_lock(&Giant); 779 780 lock_profile_init(); 781} 782 783#ifdef DDB 784void 785db_show_mtx(struct lock_object *lock) 786{ 787 struct thread *td; 788 struct mtx *m; 789 790 m = (struct mtx *)lock; 791 792 db_printf(" flags: {"); 793 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 794 db_printf("SPIN"); 795 else 796 db_printf("DEF"); 797 if (m->lock_object.lo_flags & LO_RECURSABLE) 798 db_printf(", RECURSE"); 799 if (m->lock_object.lo_flags & LO_DUPOK) 800 db_printf(", DUPOK"); 801 db_printf("}\n"); 802 db_printf(" state: {"); 803 if (mtx_unowned(m)) 804 db_printf("UNOWNED"); 805 else if (mtx_destroyed(m)) 806 db_printf("DESTROYED"); 807 else { 808 db_printf("OWNED"); 809 if (m->mtx_lock & MTX_CONTESTED) 810 db_printf(", CONTESTED"); 811 if (m->mtx_lock & MTX_RECURSED) 812 db_printf(", RECURSED"); 813 } 814 db_printf("}\n"); 815 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 816 td = mtx_owner(m); 817 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 818 td->td_tid, td->td_proc->p_pid, td->td_proc->p_comm); 819 if (mtx_recursed(m)) 820 db_printf(" recursed: %d\n", m->mtx_recurse); 821 } 822} 823#endif 824