kern_mutex.c revision 173600
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 173600 2007-11-14 06:21:24Z julian $"); 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 Giant; 122 123#ifdef LOCK_PROFILING 124static inline void lock_profile_init(void) 125{ 126 int i; 127 /* Initialize the mutex profiling locks */ 128 for (i = 0; i < LPROF_LOCK_SIZE; i++) { 129 mtx_init(&lprof_locks[i], "mprof lock", 130 NULL, MTX_SPIN|MTX_QUIET|MTX_NOPROFILE); 131 } 132} 133#else 134static inline void lock_profile_init(void) {;} 135#endif 136 137void 138lock_mtx(struct lock_object *lock, int how) 139{ 140 141 mtx_lock((struct mtx *)lock); 142} 143 144void 145lock_spin(struct lock_object *lock, int how) 146{ 147 148 panic("spin locks can only use msleep_spin"); 149} 150 151int 152unlock_mtx(struct lock_object *lock) 153{ 154 struct mtx *m; 155 156 m = (struct mtx *)lock; 157 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 158 mtx_unlock(m); 159 return (0); 160} 161 162int 163unlock_spin(struct lock_object *lock) 164{ 165 166 panic("spin locks can only use msleep_spin"); 167} 168 169/* 170 * Function versions of the inlined __mtx_* macros. These are used by 171 * modules and can also be called from assembly language if needed. 172 */ 173void 174_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 175{ 176 177 MPASS(curthread != NULL); 178 KASSERT(m->mtx_lock != MTX_DESTROYED, 179 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 180 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 181 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 182 file, line)); 183 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 184 file, line); 185 186 _get_sleep_lock(m, curthread, opts, file, line); 187 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 188 line); 189 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 190 curthread->td_locks++; 191} 192 193void 194_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 195{ 196 MPASS(curthread != NULL); 197 KASSERT(m->mtx_lock != MTX_DESTROYED, 198 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 199 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 200 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 201 file, line)); 202 curthread->td_locks--; 203 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 204 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 205 line); 206 mtx_assert(m, MA_OWNED); 207 208 if (m->mtx_recurse == 0) 209 lock_profile_release_lock(&m->lock_object); 210 _rel_sleep_lock(m, curthread, opts, file, line); 211} 212 213void 214_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 215{ 216 217 MPASS(curthread != NULL); 218 KASSERT(m->mtx_lock != MTX_DESTROYED, 219 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 220 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 221 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 222 m->lock_object.lo_name, file, line)); 223 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 224 file, line); 225 _get_spin_lock(m, curthread, opts, file, line); 226 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 227 line); 228 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 229} 230 231void 232_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 233{ 234 235 MPASS(curthread != NULL); 236 KASSERT(m->mtx_lock != MTX_DESTROYED, 237 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 238 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 239 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 240 m->lock_object.lo_name, file, line)); 241 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 242 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 243 line); 244 mtx_assert(m, MA_OWNED); 245 246 _rel_spin_lock(m); 247} 248 249/* 250 * The important part of mtx_trylock{,_flags}() 251 * Tries to acquire lock `m.' If this function is called on a mutex that 252 * is already owned, it will recursively acquire the lock. 253 */ 254int 255_mtx_trylock(struct mtx *m, int opts, const char *file, int line) 256{ 257 int rval, contested = 0; 258 uint64_t waittime = 0; 259 260 MPASS(curthread != NULL); 261 KASSERT(m->mtx_lock != MTX_DESTROYED, 262 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 263 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 264 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 265 file, line)); 266 267 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 268 m->mtx_recurse++; 269 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 270 rval = 1; 271 } else 272 rval = _obtain_lock(m, (uintptr_t)curthread); 273 274 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 275 if (rval) { 276 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 277 file, line); 278 curthread->td_locks++; 279 if (m->mtx_recurse == 0) 280 lock_profile_obtain_lock_success(&m->lock_object, contested, 281 waittime, file, line); 282 283 } 284 285 return (rval); 286} 287 288/* 289 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 290 * 291 * We call this if the lock is either contested (i.e. we need to go to 292 * sleep waiting for it), or if we need to recurse on it. 293 */ 294void 295_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 296 int line) 297{ 298 struct turnstile *ts; 299#ifdef ADAPTIVE_MUTEXES 300 volatile struct thread *owner; 301#endif 302#ifdef KTR 303 int cont_logged = 0; 304#endif 305 int contested = 0; 306 uint64_t waittime = 0; 307 uintptr_t v; 308 309 if (mtx_owned(m)) { 310 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 311 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 312 m->lock_object.lo_name, file, line)); 313 m->mtx_recurse++; 314 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 315 if (LOCK_LOG_TEST(&m->lock_object, opts)) 316 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 317 return; 318 } 319 320 lock_profile_obtain_lock_failed(&m->lock_object, 321 &contested, &waittime); 322 if (LOCK_LOG_TEST(&m->lock_object, opts)) 323 CTR4(KTR_LOCK, 324 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 325 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 326 327 while (!_obtain_lock(m, tid)) { 328 ts = turnstile_trywait(&m->lock_object); 329 v = m->mtx_lock; 330 331 /* 332 * Check if the lock has been released while spinning for 333 * the turnstile chain lock. 334 */ 335 if (v == MTX_UNOWNED) { 336 turnstile_cancel(ts); 337 cpu_spinwait(); 338 continue; 339 } 340 341 MPASS(v != MTX_CONTESTED); 342 343 /* 344 * If the mutex isn't already contested and a failure occurs 345 * setting the contested bit, the mutex was either released 346 * or the state of the MTX_RECURSED bit changed. 347 */ 348 if ((v & MTX_CONTESTED) == 0 && 349 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 350 turnstile_cancel(ts); 351 cpu_spinwait(); 352 continue; 353 } 354 355#ifdef ADAPTIVE_MUTEXES 356 /* 357 * If the current owner of the lock is executing on another 358 * CPU, spin instead of blocking. 359 */ 360 owner = (struct thread *)(v & ~MTX_FLAGMASK); 361#ifdef ADAPTIVE_GIANT 362 if (TD_IS_RUNNING(owner)) 363#else 364 if (m != &Giant && TD_IS_RUNNING(owner)) 365#endif 366 { 367 turnstile_cancel(ts); 368 while (mtx_owner(m) == owner && TD_IS_RUNNING(owner)) { 369 cpu_spinwait(); 370 } 371 continue; 372 } 373#endif /* ADAPTIVE_MUTEXES */ 374 375 /* 376 * We definitely must sleep for this lock. 377 */ 378 mtx_assert(m, MA_NOTOWNED); 379 380#ifdef KTR 381 if (!cont_logged) { 382 CTR6(KTR_CONTENTION, 383 "contention: %p at %s:%d wants %s, taken by %s:%d", 384 (void *)tid, file, line, m->lock_object.lo_name, 385 WITNESS_FILE(&m->lock_object), 386 WITNESS_LINE(&m->lock_object)); 387 cont_logged = 1; 388 } 389#endif 390 391 /* 392 * Block on the turnstile. 393 */ 394 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 395 } 396#ifdef KTR 397 if (cont_logged) { 398 CTR4(KTR_CONTENTION, 399 "contention end: %s acquired by %p at %s:%d", 400 m->lock_object.lo_name, (void *)tid, file, line); 401 } 402#endif 403 lock_profile_obtain_lock_success(&m->lock_object, contested, 404 waittime, (file), (line)); 405} 406 407static void 408_mtx_lock_spin_failed(struct mtx *m) 409{ 410 struct thread *td; 411 412 td = mtx_owner(m); 413 414 /* If the mutex is unlocked, try again. */ 415 if (td == NULL) 416 return; 417 418 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 419 m, m->lock_object.lo_name, td, td->td_tid); 420#ifdef WITNESS 421 witness_display_spinlock(&m->lock_object, td); 422#endif 423 panic("spin lock held too long"); 424} 425 426#ifdef SMP 427/* 428 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 429 * 430 * This is only called if we need to actually spin for the lock. Recursion 431 * is handled inline. 432 */ 433void 434_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 435 int line) 436{ 437 int i = 0, contested = 0; 438 uint64_t waittime = 0; 439 440 if (LOCK_LOG_TEST(&m->lock_object, opts)) 441 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 442 443 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 444 while (!_obtain_lock(m, tid)) { 445 446 /* Give interrupts a chance while we spin. */ 447 spinlock_exit(); 448 while (m->mtx_lock != MTX_UNOWNED) { 449 if (i++ < 10000000) { 450 cpu_spinwait(); 451 continue; 452 } 453 if (i < 60000000 || kdb_active || panicstr != NULL) 454 DELAY(1); 455 else 456 _mtx_lock_spin_failed(m); 457 cpu_spinwait(); 458 } 459 spinlock_enter(); 460 } 461 462 if (LOCK_LOG_TEST(&m->lock_object, opts)) 463 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 464 465 lock_profile_obtain_lock_success(&m->lock_object, contested, 466 waittime, (file), (line)); 467} 468#endif /* SMP */ 469 470void 471_thread_lock_flags(struct thread *td, int opts, const char *file, int line) 472{ 473 struct mtx *m; 474 uintptr_t tid; 475 int i, contested; 476 uint64_t waittime; 477 478 479 contested = i = 0; 480 waittime = 0; 481 tid = (uintptr_t)curthread; 482 for (;;) { 483retry: 484 spinlock_enter(); 485 m = td->td_lock; 486 WITNESS_CHECKORDER(&m->lock_object, 487 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line); 488 while (!_obtain_lock(m, tid)) { 489 if (m->mtx_lock == tid) { 490 m->mtx_recurse++; 491 break; 492 } 493 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 494 /* Give interrupts a chance while we spin. */ 495 spinlock_exit(); 496 while (m->mtx_lock != MTX_UNOWNED) { 497 if (i++ < 10000000) 498 cpu_spinwait(); 499 else if (i < 60000000 || 500 kdb_active || panicstr != NULL) 501 DELAY(1); 502 else 503 _mtx_lock_spin_failed(m); 504 cpu_spinwait(); 505 if (m != td->td_lock) 506 goto retry; 507 } 508 spinlock_enter(); 509 } 510 if (m == td->td_lock) 511 break; 512 _rel_spin_lock(m); /* does spinlock_exit() */ 513 } 514 lock_profile_obtain_lock_success(&m->lock_object, contested, 515 waittime, (file), (line)); 516 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 517} 518 519struct mtx * 520thread_lock_block(struct thread *td) 521{ 522 struct mtx *lock; 523 524 spinlock_enter(); 525 THREAD_LOCK_ASSERT(td, MA_OWNED); 526 lock = td->td_lock; 527 td->td_lock = &blocked_lock; 528 mtx_unlock_spin(lock); 529 530 return (lock); 531} 532 533void 534thread_lock_unblock(struct thread *td, struct mtx *new) 535{ 536 mtx_assert(new, MA_OWNED); 537 MPASS(td->td_lock == &blocked_lock); 538 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 539 spinlock_exit(); 540} 541 542void 543thread_lock_set(struct thread *td, struct mtx *new) 544{ 545 struct mtx *lock; 546 547 mtx_assert(new, MA_OWNED); 548 THREAD_LOCK_ASSERT(td, MA_OWNED); 549 lock = td->td_lock; 550 td->td_lock = new; 551 mtx_unlock_spin(lock); 552} 553 554/* 555 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 556 * 557 * We are only called here if the lock is recursed or contested (i.e. we 558 * need to wake up a blocked thread). 559 */ 560void 561_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 562{ 563 struct turnstile *ts; 564 565 if (mtx_recursed(m)) { 566 if (--(m->mtx_recurse) == 0) 567 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 568 if (LOCK_LOG_TEST(&m->lock_object, opts)) 569 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 570 return; 571 } 572 573 /* 574 * We have to lock the chain before the turnstile so this turnstile 575 * can be removed from the hash list if it is empty. 576 */ 577 turnstile_chain_lock(&m->lock_object); 578 ts = turnstile_lookup(&m->lock_object); 579 if (LOCK_LOG_TEST(&m->lock_object, opts)) 580 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 581 582#ifdef ADAPTIVE_MUTEXES 583 if (ts == NULL) { 584 _release_lock_quick(m); 585 if (LOCK_LOG_TEST(&m->lock_object, opts)) 586 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m); 587 turnstile_chain_unlock(&m->lock_object); 588 return; 589 } 590#else 591 MPASS(ts != NULL); 592#endif 593 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 594 _release_lock_quick(m); 595 /* 596 * This turnstile is now no longer associated with the mutex. We can 597 * unlock the chain lock so a new turnstile may take it's place. 598 */ 599 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 600 turnstile_chain_unlock(&m->lock_object); 601} 602 603/* 604 * All the unlocking of MTX_SPIN locks is done inline. 605 * See the _rel_spin_lock() macro for the details. 606 */ 607 608/* 609 * The backing function for the INVARIANTS-enabled mtx_assert() 610 */ 611#ifdef INVARIANT_SUPPORT 612void 613_mtx_assert(struct mtx *m, int what, const char *file, int line) 614{ 615 616 if (panicstr != NULL || dumping) 617 return; 618 switch (what) { 619 case MA_OWNED: 620 case MA_OWNED | MA_RECURSED: 621 case MA_OWNED | MA_NOTRECURSED: 622 if (!mtx_owned(m)) 623 panic("mutex %s not owned at %s:%d", 624 m->lock_object.lo_name, file, line); 625 if (mtx_recursed(m)) { 626 if ((what & MA_NOTRECURSED) != 0) 627 panic("mutex %s recursed at %s:%d", 628 m->lock_object.lo_name, file, line); 629 } else if ((what & MA_RECURSED) != 0) { 630 panic("mutex %s unrecursed at %s:%d", 631 m->lock_object.lo_name, file, line); 632 } 633 break; 634 case MA_NOTOWNED: 635 if (mtx_owned(m)) 636 panic("mutex %s owned at %s:%d", 637 m->lock_object.lo_name, file, line); 638 break; 639 default: 640 panic("unknown mtx_assert at %s:%d", file, line); 641 } 642} 643#endif 644 645/* 646 * The MUTEX_DEBUG-enabled mtx_validate() 647 * 648 * Most of these checks have been moved off into the LO_INITIALIZED flag 649 * maintained by the witness code. 650 */ 651#ifdef MUTEX_DEBUG 652 653void mtx_validate(struct mtx *); 654 655void 656mtx_validate(struct mtx *m) 657{ 658 659/* 660 * XXX: When kernacc() does not require Giant we can reenable this check 661 */ 662#ifdef notyet 663 /* 664 * Can't call kernacc() from early init386(), especially when 665 * initializing Giant mutex, because some stuff in kernacc() 666 * requires Giant itself. 667 */ 668 if (!cold) 669 if (!kernacc((caddr_t)m, sizeof(m), 670 VM_PROT_READ | VM_PROT_WRITE)) 671 panic("Can't read and write to mutex %p", m); 672#endif 673} 674#endif 675 676/* 677 * General init routine used by the MTX_SYSINIT() macro. 678 */ 679void 680mtx_sysinit(void *arg) 681{ 682 struct mtx_args *margs = arg; 683 684 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 685} 686 687/* 688 * Mutex initialization routine; initialize lock `m' of type contained in 689 * `opts' with options contained in `opts' and name `name.' The optional 690 * lock type `type' is used as a general lock category name for use with 691 * witness. 692 */ 693void 694mtx_init(struct mtx *m, const char *name, const char *type, int opts) 695{ 696 struct lock_class *class; 697 int flags; 698 699 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 700 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 701 702#ifdef MUTEX_DEBUG 703 /* Diagnostic and error correction */ 704 mtx_validate(m); 705#endif 706 707 /* Determine lock class and lock flags. */ 708 if (opts & MTX_SPIN) 709 class = &lock_class_mtx_spin; 710 else 711 class = &lock_class_mtx_sleep; 712 flags = 0; 713 if (opts & MTX_QUIET) 714 flags |= LO_QUIET; 715 if (opts & MTX_RECURSE) 716 flags |= LO_RECURSABLE; 717 if ((opts & MTX_NOWITNESS) == 0) 718 flags |= LO_WITNESS; 719 if (opts & MTX_DUPOK) 720 flags |= LO_DUPOK; 721 if (opts & MTX_NOPROFILE) 722 flags |= LO_NOPROFILE; 723 724 /* Initialize mutex. */ 725 m->mtx_lock = MTX_UNOWNED; 726 m->mtx_recurse = 0; 727 728 lock_init(&m->lock_object, class, name, type, flags); 729} 730 731/* 732 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 733 * passed in as a flag here because if the corresponding mtx_init() was 734 * called with MTX_QUIET set, then it will already be set in the mutex's 735 * flags. 736 */ 737void 738mtx_destroy(struct mtx *m) 739{ 740 741 if (!mtx_owned(m)) 742 MPASS(mtx_unowned(m)); 743 else { 744 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 745 746 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 747 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 748 spinlock_exit(); 749 else 750 curthread->td_locks--; 751 752 /* Tell witness this isn't locked to make it happy. */ 753 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 754 __LINE__); 755 } 756 757 m->mtx_lock = MTX_DESTROYED; 758 lock_destroy(&m->lock_object); 759} 760 761/* 762 * Intialize the mutex code and system mutexes. This is called from the MD 763 * startup code prior to mi_startup(). The per-CPU data space needs to be 764 * setup before this is called. 765 */ 766void 767mutex_init(void) 768{ 769 770 /* Setup turnstiles so that sleep mutexes work. */ 771 init_turnstiles(); 772 773 /* 774 * Initialize mutexes. 775 */ 776 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 777 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 778 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 779 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 780 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 781 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 782 mtx_lock(&Giant); 783 784 lock_profile_init(); 785} 786 787#ifdef DDB 788void 789db_show_mtx(struct lock_object *lock) 790{ 791 struct thread *td; 792 struct mtx *m; 793 794 m = (struct mtx *)lock; 795 796 db_printf(" flags: {"); 797 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 798 db_printf("SPIN"); 799 else 800 db_printf("DEF"); 801 if (m->lock_object.lo_flags & LO_RECURSABLE) 802 db_printf(", RECURSE"); 803 if (m->lock_object.lo_flags & LO_DUPOK) 804 db_printf(", DUPOK"); 805 db_printf("}\n"); 806 db_printf(" state: {"); 807 if (mtx_unowned(m)) 808 db_printf("UNOWNED"); 809 else if (mtx_destroyed(m)) 810 db_printf("DESTROYED"); 811 else { 812 db_printf("OWNED"); 813 if (m->mtx_lock & MTX_CONTESTED) 814 db_printf(", CONTESTED"); 815 if (m->mtx_lock & MTX_RECURSED) 816 db_printf(", RECURSED"); 817 } 818 db_printf("}\n"); 819 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 820 td = mtx_owner(m); 821 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 822 td->td_tid, td->td_proc->p_pid, td->td_name); 823 if (mtx_recursed(m)) 824 db_printf(" recursed: %d\n", m->mtx_recurse); 825 } 826} 827#endif 828