kern_mutex.c revision 193035
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 193035 2009-05-29 13:56:34Z jhb $"); 38 39#include "opt_adaptive_mutexes.h" 40#include "opt_ddb.h" 41#include "opt_global.h" 42#include "opt_kdtrace.h" 43#include "opt_sched.h" 44 45#include <sys/param.h> 46#include <sys/systm.h> 47#include <sys/bus.h> 48#include <sys/conf.h> 49#include <sys/kdb.h> 50#include <sys/kernel.h> 51#include <sys/ktr.h> 52#include <sys/lock.h> 53#include <sys/malloc.h> 54#include <sys/mutex.h> 55#include <sys/proc.h> 56#include <sys/resourcevar.h> 57#include <sys/sched.h> 58#include <sys/sbuf.h> 59#include <sys/sysctl.h> 60#include <sys/turnstile.h> 61#include <sys/vmmeter.h> 62#include <sys/lock_profile.h> 63 64#include <machine/atomic.h> 65#include <machine/bus.h> 66#include <machine/cpu.h> 67 68#include <ddb/ddb.h> 69 70#include <fs/devfs/devfs_int.h> 71 72#include <vm/vm.h> 73#include <vm/vm_extern.h> 74 75#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 76#define ADAPTIVE_MUTEXES 77#endif 78 79/* 80 * Internal utility macros. 81 */ 82#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 83 84#define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 85 86#define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 87 88static void assert_mtx(struct lock_object *lock, int what); 89#ifdef DDB 90static void db_show_mtx(struct lock_object *lock); 91#endif 92static void lock_mtx(struct lock_object *lock, int how); 93static void lock_spin(struct lock_object *lock, int how); 94#ifdef KDTRACE_HOOKS 95static int owner_mtx(struct lock_object *lock, struct thread **owner); 96#endif 97static int unlock_mtx(struct lock_object *lock); 98static int unlock_spin(struct lock_object *lock); 99 100/* 101 * Lock classes for sleep and spin mutexes. 102 */ 103struct lock_class lock_class_mtx_sleep = { 104 .lc_name = "sleep mutex", 105 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 106 .lc_assert = assert_mtx, 107#ifdef DDB 108 .lc_ddb_show = db_show_mtx, 109#endif 110 .lc_lock = lock_mtx, 111 .lc_unlock = unlock_mtx, 112#ifdef KDTRACE_HOOKS 113 .lc_owner = owner_mtx, 114#endif 115}; 116struct lock_class lock_class_mtx_spin = { 117 .lc_name = "spin mutex", 118 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 119 .lc_assert = assert_mtx, 120#ifdef DDB 121 .lc_ddb_show = db_show_mtx, 122#endif 123 .lc_lock = lock_spin, 124 .lc_unlock = unlock_spin, 125#ifdef KDTRACE_HOOKS 126 .lc_owner = owner_mtx, 127#endif 128}; 129 130/* 131 * System-wide mutexes 132 */ 133struct mtx blocked_lock; 134struct mtx Giant; 135 136void 137assert_mtx(struct lock_object *lock, int what) 138{ 139 140 mtx_assert((struct mtx *)lock, what); 141} 142 143void 144lock_mtx(struct lock_object *lock, int how) 145{ 146 147 mtx_lock((struct mtx *)lock); 148} 149 150void 151lock_spin(struct lock_object *lock, int how) 152{ 153 154 panic("spin locks can only use msleep_spin"); 155} 156 157int 158unlock_mtx(struct lock_object *lock) 159{ 160 struct mtx *m; 161 162 m = (struct mtx *)lock; 163 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 164 mtx_unlock(m); 165 return (0); 166} 167 168int 169unlock_spin(struct lock_object *lock) 170{ 171 172 panic("spin locks can only use msleep_spin"); 173} 174 175#ifdef KDTRACE_HOOKS 176int 177owner_mtx(struct lock_object *lock, struct thread **owner) 178{ 179 struct mtx *m = (struct mtx *)lock; 180 181 *owner = mtx_owner(m); 182 return (mtx_unowned(m) == 0); 183} 184#endif 185 186/* 187 * Function versions of the inlined __mtx_* macros. These are used by 188 * modules and can also be called from assembly language if needed. 189 */ 190void 191_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 192{ 193 194 MPASS(curthread != NULL); 195 KASSERT(m->mtx_lock != MTX_DESTROYED, 196 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 197 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 198 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 199 file, line)); 200 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 201 file, line, NULL); 202 203 _get_sleep_lock(m, curthread, opts, file, line); 204 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 205 line); 206 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 207 curthread->td_locks++; 208} 209 210void 211_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 212{ 213 MPASS(curthread != NULL); 214 KASSERT(m->mtx_lock != MTX_DESTROYED, 215 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 216 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 217 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 218 file, line)); 219 curthread->td_locks--; 220 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 221 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 222 line); 223 mtx_assert(m, MA_OWNED); 224 225 if (m->mtx_recurse == 0) 226 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m); 227 _rel_sleep_lock(m, curthread, opts, file, line); 228} 229 230void 231_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 232{ 233 234 MPASS(curthread != NULL); 235 KASSERT(m->mtx_lock != MTX_DESTROYED, 236 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 237 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 238 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 239 m->lock_object.lo_name, file, line)); 240 if (mtx_owned(m)) 241 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 242 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 243 m->lock_object.lo_name, file, line)); 244 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 245 file, line, NULL); 246 _get_spin_lock(m, curthread, opts, file, line); 247 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 248 line); 249 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 250} 251 252void 253_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 254{ 255 256 MPASS(curthread != NULL); 257 KASSERT(m->mtx_lock != MTX_DESTROYED, 258 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 259 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 260 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 261 m->lock_object.lo_name, file, line)); 262 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 263 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 264 line); 265 mtx_assert(m, MA_OWNED); 266 267 _rel_spin_lock(m); 268} 269 270/* 271 * The important part of mtx_trylock{,_flags}() 272 * Tries to acquire lock `m.' If this function is called on a mutex that 273 * is already owned, it will recursively acquire the lock. 274 */ 275int 276_mtx_trylock(struct mtx *m, int opts, const char *file, int line) 277{ 278#ifdef LOCK_PROFILING 279 uint64_t waittime = 0; 280 int contested = 0; 281#endif 282 int rval; 283 284 MPASS(curthread != NULL); 285 KASSERT(m->mtx_lock != MTX_DESTROYED, 286 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 287 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 288 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 289 file, line)); 290 291 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 292 m->mtx_recurse++; 293 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 294 rval = 1; 295 } else 296 rval = _obtain_lock(m, (uintptr_t)curthread); 297 298 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 299 if (rval) { 300 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 301 file, line); 302 curthread->td_locks++; 303 if (m->mtx_recurse == 0) 304 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, 305 m, contested, waittime, file, line); 306 307 } 308 309 return (rval); 310} 311 312/* 313 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 314 * 315 * We call this if the lock is either contested (i.e. we need to go to 316 * sleep waiting for it), or if we need to recurse on it. 317 */ 318void 319_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 320 int line) 321{ 322 struct turnstile *ts; 323 uintptr_t v; 324#ifdef ADAPTIVE_MUTEXES 325 volatile struct thread *owner; 326#endif 327#ifdef KTR 328 int cont_logged = 0; 329#endif 330#ifdef LOCK_PROFILING 331 int contested = 0; 332 uint64_t waittime = 0; 333#endif 334#ifdef KDTRACE_HOOKS 335 uint64_t spin_cnt = 0; 336 uint64_t sleep_cnt = 0; 337 int64_t sleep_time = 0; 338#endif 339 340 if (mtx_owned(m)) { 341 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 342 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 343 m->lock_object.lo_name, file, line)); 344 m->mtx_recurse++; 345 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 346 if (LOCK_LOG_TEST(&m->lock_object, opts)) 347 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 348 return; 349 } 350 351 lock_profile_obtain_lock_failed(&m->lock_object, 352 &contested, &waittime); 353 if (LOCK_LOG_TEST(&m->lock_object, opts)) 354 CTR4(KTR_LOCK, 355 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 356 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 357 358 while (!_obtain_lock(m, tid)) { 359#ifdef KDTRACE_HOOKS 360 spin_cnt++; 361#endif 362#ifdef ADAPTIVE_MUTEXES 363 /* 364 * If the owner is running on another CPU, spin until the 365 * owner stops running or the state of the lock changes. 366 */ 367 v = m->mtx_lock; 368 if (v != MTX_UNOWNED) { 369 owner = (struct thread *)(v & ~MTX_FLAGMASK); 370 if (TD_IS_RUNNING(owner)) { 371 if (LOCK_LOG_TEST(&m->lock_object, 0)) 372 CTR3(KTR_LOCK, 373 "%s: spinning on %p held by %p", 374 __func__, m, owner); 375 while (mtx_owner(m) == owner && 376 TD_IS_RUNNING(owner)) { 377 cpu_spinwait(); 378#ifdef KDTRACE_HOOKS 379 spin_cnt++; 380#endif 381 } 382 continue; 383 } 384 } 385#endif 386 387 ts = turnstile_trywait(&m->lock_object); 388 v = m->mtx_lock; 389 390 /* 391 * Check if the lock has been released while spinning for 392 * the turnstile chain lock. 393 */ 394 if (v == MTX_UNOWNED) { 395 turnstile_cancel(ts); 396 cpu_spinwait(); 397 continue; 398 } 399 400#ifdef ADAPTIVE_MUTEXES 401 /* 402 * The current lock owner might have started executing 403 * on another CPU (or the lock could have changed 404 * owners) while we were waiting on the turnstile 405 * chain lock. If so, drop the turnstile lock and try 406 * again. 407 */ 408 owner = (struct thread *)(v & ~MTX_FLAGMASK); 409 if (TD_IS_RUNNING(owner)) { 410 turnstile_cancel(ts); 411 cpu_spinwait(); 412 continue; 413 } 414#endif 415 416 /* 417 * If the mutex isn't already contested and a failure occurs 418 * setting the contested bit, the mutex was either released 419 * or the state of the MTX_RECURSED bit changed. 420 */ 421 if ((v & MTX_CONTESTED) == 0 && 422 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 423 turnstile_cancel(ts); 424 cpu_spinwait(); 425 continue; 426 } 427 428 /* 429 * We definitely must sleep for this lock. 430 */ 431 mtx_assert(m, MA_NOTOWNED); 432 433#ifdef KTR 434 if (!cont_logged) { 435 CTR6(KTR_CONTENTION, 436 "contention: %p at %s:%d wants %s, taken by %s:%d", 437 (void *)tid, file, line, m->lock_object.lo_name, 438 WITNESS_FILE(&m->lock_object), 439 WITNESS_LINE(&m->lock_object)); 440 cont_logged = 1; 441 } 442#endif 443 444 /* 445 * Block on the turnstile. 446 */ 447#ifdef KDTRACE_HOOKS 448 sleep_time -= lockstat_nsecs(); 449#endif 450 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 451#ifdef KDTRACE_HOOKS 452 sleep_time += lockstat_nsecs(); 453 sleep_cnt++; 454#endif 455 } 456#ifdef KTR 457 if (cont_logged) { 458 CTR4(KTR_CONTENTION, 459 "contention end: %s acquired by %p at %s:%d", 460 m->lock_object.lo_name, (void *)tid, file, line); 461 } 462#endif 463 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested, 464 waittime, file, line); 465#ifdef KDTRACE_HOOKS 466 if (sleep_time) 467 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time); 468 469 /* 470 * Only record the loops spinning and not sleeping. 471 */ 472 if (spin_cnt > sleep_cnt) 473 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt)); 474#endif 475} 476 477static void 478_mtx_lock_spin_failed(struct mtx *m) 479{ 480 struct thread *td; 481 482 td = mtx_owner(m); 483 484 /* If the mutex is unlocked, try again. */ 485 if (td == NULL) 486 return; 487 488 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 489 m, m->lock_object.lo_name, td, td->td_tid); 490#ifdef WITNESS 491 witness_display_spinlock(&m->lock_object, td); 492#endif 493 panic("spin lock held too long"); 494} 495 496#ifdef SMP 497/* 498 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 499 * 500 * This is only called if we need to actually spin for the lock. Recursion 501 * is handled inline. 502 */ 503void 504_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 505 int line) 506{ 507 int i = 0; 508#ifdef LOCK_PROFILING 509 int contested = 0; 510 uint64_t waittime = 0; 511#endif 512 513 if (LOCK_LOG_TEST(&m->lock_object, opts)) 514 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 515 516 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 517 while (!_obtain_lock(m, tid)) { 518 519 /* Give interrupts a chance while we spin. */ 520 spinlock_exit(); 521 while (m->mtx_lock != MTX_UNOWNED) { 522 if (i++ < 10000000) { 523 cpu_spinwait(); 524 continue; 525 } 526 if (i < 60000000 || kdb_active || panicstr != NULL) 527 DELAY(1); 528 else 529 _mtx_lock_spin_failed(m); 530 cpu_spinwait(); 531 } 532 spinlock_enter(); 533 } 534 535 if (LOCK_LOG_TEST(&m->lock_object, opts)) 536 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 537 538 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m, 539 contested, waittime, (file), (line)); 540 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i); 541} 542#endif /* SMP */ 543 544void 545_thread_lock_flags(struct thread *td, int opts, const char *file, int line) 546{ 547 struct mtx *m; 548 uintptr_t tid; 549 int i; 550#ifdef LOCK_PROFILING 551 int contested = 0; 552 uint64_t waittime = 0; 553#endif 554#ifdef KDTRACE_HOOKS 555 uint64_t spin_cnt = 0; 556#endif 557 558 i = 0; 559 tid = (uintptr_t)curthread; 560 for (;;) { 561retry: 562 spinlock_enter(); 563 m = td->td_lock; 564 KASSERT(m->mtx_lock != MTX_DESTROYED, 565 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 566 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 567 ("thread_lock() of sleep mutex %s @ %s:%d", 568 m->lock_object.lo_name, file, line)); 569 if (mtx_owned(m)) 570 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 571 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 572 m->lock_object.lo_name, file, line)); 573 WITNESS_CHECKORDER(&m->lock_object, 574 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 575 while (!_obtain_lock(m, tid)) { 576#ifdef KDTRACE_HOOKS 577 spin_cnt++; 578#endif 579 if (m->mtx_lock == tid) { 580 m->mtx_recurse++; 581 break; 582 } 583 lock_profile_obtain_lock_failed(&m->lock_object, 584 &contested, &waittime); 585 /* Give interrupts a chance while we spin. */ 586 spinlock_exit(); 587 while (m->mtx_lock != MTX_UNOWNED) { 588 if (i++ < 10000000) 589 cpu_spinwait(); 590 else if (i < 60000000 || 591 kdb_active || panicstr != NULL) 592 DELAY(1); 593 else 594 _mtx_lock_spin_failed(m); 595 cpu_spinwait(); 596 if (m != td->td_lock) 597 goto retry; 598 } 599 spinlock_enter(); 600 } 601 if (m == td->td_lock) 602 break; 603 _rel_spin_lock(m); /* does spinlock_exit() */ 604#ifdef KDTRACE_HOOKS 605 spin_cnt++; 606#endif 607 } 608 if (m->mtx_recurse == 0) 609 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, 610 m, contested, waittime, (file), (line)); 611 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 612 line); 613 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 614 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt); 615} 616 617struct mtx * 618thread_lock_block(struct thread *td) 619{ 620 struct mtx *lock; 621 622 spinlock_enter(); 623 THREAD_LOCK_ASSERT(td, MA_OWNED); 624 lock = td->td_lock; 625 td->td_lock = &blocked_lock; 626 mtx_unlock_spin(lock); 627 628 return (lock); 629} 630 631void 632thread_lock_unblock(struct thread *td, struct mtx *new) 633{ 634 mtx_assert(new, MA_OWNED); 635 MPASS(td->td_lock == &blocked_lock); 636 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 637 spinlock_exit(); 638} 639 640void 641thread_lock_set(struct thread *td, struct mtx *new) 642{ 643 struct mtx *lock; 644 645 mtx_assert(new, MA_OWNED); 646 THREAD_LOCK_ASSERT(td, MA_OWNED); 647 lock = td->td_lock; 648 td->td_lock = new; 649 mtx_unlock_spin(lock); 650} 651 652/* 653 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 654 * 655 * We are only called here if the lock is recursed or contested (i.e. we 656 * need to wake up a blocked thread). 657 */ 658void 659_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 660{ 661 struct turnstile *ts; 662 663 if (mtx_recursed(m)) { 664 if (--(m->mtx_recurse) == 0) 665 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 666 if (LOCK_LOG_TEST(&m->lock_object, opts)) 667 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 668 return; 669 } 670 671 /* 672 * We have to lock the chain before the turnstile so this turnstile 673 * can be removed from the hash list if it is empty. 674 */ 675 turnstile_chain_lock(&m->lock_object); 676 ts = turnstile_lookup(&m->lock_object); 677 if (LOCK_LOG_TEST(&m->lock_object, opts)) 678 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 679 MPASS(ts != NULL); 680 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 681 _release_lock_quick(m); 682 683 /* 684 * This turnstile is now no longer associated with the mutex. We can 685 * unlock the chain lock so a new turnstile may take it's place. 686 */ 687 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 688 turnstile_chain_unlock(&m->lock_object); 689} 690 691/* 692 * All the unlocking of MTX_SPIN locks is done inline. 693 * See the _rel_spin_lock() macro for the details. 694 */ 695 696/* 697 * The backing function for the INVARIANTS-enabled mtx_assert() 698 */ 699#ifdef INVARIANT_SUPPORT 700void 701_mtx_assert(struct mtx *m, int what, const char *file, int line) 702{ 703 704 if (panicstr != NULL || dumping) 705 return; 706 switch (what) { 707 case MA_OWNED: 708 case MA_OWNED | MA_RECURSED: 709 case MA_OWNED | MA_NOTRECURSED: 710 if (!mtx_owned(m)) 711 panic("mutex %s not owned at %s:%d", 712 m->lock_object.lo_name, file, line); 713 if (mtx_recursed(m)) { 714 if ((what & MA_NOTRECURSED) != 0) 715 panic("mutex %s recursed at %s:%d", 716 m->lock_object.lo_name, file, line); 717 } else if ((what & MA_RECURSED) != 0) { 718 panic("mutex %s unrecursed at %s:%d", 719 m->lock_object.lo_name, file, line); 720 } 721 break; 722 case MA_NOTOWNED: 723 if (mtx_owned(m)) 724 panic("mutex %s owned at %s:%d", 725 m->lock_object.lo_name, file, line); 726 break; 727 default: 728 panic("unknown mtx_assert at %s:%d", file, line); 729 } 730} 731#endif 732 733/* 734 * The MUTEX_DEBUG-enabled mtx_validate() 735 * 736 * Most of these checks have been moved off into the LO_INITIALIZED flag 737 * maintained by the witness code. 738 */ 739#ifdef MUTEX_DEBUG 740 741void mtx_validate(struct mtx *); 742 743void 744mtx_validate(struct mtx *m) 745{ 746 747/* 748 * XXX: When kernacc() does not require Giant we can reenable this check 749 */ 750#ifdef notyet 751 /* 752 * Can't call kernacc() from early init386(), especially when 753 * initializing Giant mutex, because some stuff in kernacc() 754 * requires Giant itself. 755 */ 756 if (!cold) 757 if (!kernacc((caddr_t)m, sizeof(m), 758 VM_PROT_READ | VM_PROT_WRITE)) 759 panic("Can't read and write to mutex %p", m); 760#endif 761} 762#endif 763 764/* 765 * General init routine used by the MTX_SYSINIT() macro. 766 */ 767void 768mtx_sysinit(void *arg) 769{ 770 struct mtx_args *margs = arg; 771 772 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 773} 774 775/* 776 * Mutex initialization routine; initialize lock `m' of type contained in 777 * `opts' with options contained in `opts' and name `name.' The optional 778 * lock type `type' is used as a general lock category name for use with 779 * witness. 780 */ 781void 782mtx_init(struct mtx *m, const char *name, const char *type, int opts) 783{ 784 struct lock_class *class; 785 int flags; 786 787 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 788 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 789 790#ifdef MUTEX_DEBUG 791 /* Diagnostic and error correction */ 792 mtx_validate(m); 793#endif 794 795 /* Determine lock class and lock flags. */ 796 if (opts & MTX_SPIN) 797 class = &lock_class_mtx_spin; 798 else 799 class = &lock_class_mtx_sleep; 800 flags = 0; 801 if (opts & MTX_QUIET) 802 flags |= LO_QUIET; 803 if (opts & MTX_RECURSE) 804 flags |= LO_RECURSABLE; 805 if ((opts & MTX_NOWITNESS) == 0) 806 flags |= LO_WITNESS; 807 if (opts & MTX_DUPOK) 808 flags |= LO_DUPOK; 809 if (opts & MTX_NOPROFILE) 810 flags |= LO_NOPROFILE; 811 812 /* Initialize mutex. */ 813 m->mtx_lock = MTX_UNOWNED; 814 m->mtx_recurse = 0; 815 816 lock_init(&m->lock_object, class, name, type, flags); 817} 818 819/* 820 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 821 * passed in as a flag here because if the corresponding mtx_init() was 822 * called with MTX_QUIET set, then it will already be set in the mutex's 823 * flags. 824 */ 825void 826mtx_destroy(struct mtx *m) 827{ 828 829 if (!mtx_owned(m)) 830 MPASS(mtx_unowned(m)); 831 else { 832 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 833 834 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 835 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 836 spinlock_exit(); 837 else 838 curthread->td_locks--; 839 840 lock_profile_release_lock(&m->lock_object); 841 /* Tell witness this isn't locked to make it happy. */ 842 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 843 __LINE__); 844 } 845 846 m->mtx_lock = MTX_DESTROYED; 847 lock_destroy(&m->lock_object); 848} 849 850/* 851 * Intialize the mutex code and system mutexes. This is called from the MD 852 * startup code prior to mi_startup(). The per-CPU data space needs to be 853 * setup before this is called. 854 */ 855void 856mutex_init(void) 857{ 858 859 /* Setup turnstiles so that sleep mutexes work. */ 860 init_turnstiles(); 861 862 /* 863 * Initialize mutexes. 864 */ 865 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 866 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 867 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 868 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 869 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 870 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 871 mtx_lock(&Giant); 872} 873 874#ifdef DDB 875void 876db_show_mtx(struct lock_object *lock) 877{ 878 struct thread *td; 879 struct mtx *m; 880 881 m = (struct mtx *)lock; 882 883 db_printf(" flags: {"); 884 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 885 db_printf("SPIN"); 886 else 887 db_printf("DEF"); 888 if (m->lock_object.lo_flags & LO_RECURSABLE) 889 db_printf(", RECURSE"); 890 if (m->lock_object.lo_flags & LO_DUPOK) 891 db_printf(", DUPOK"); 892 db_printf("}\n"); 893 db_printf(" state: {"); 894 if (mtx_unowned(m)) 895 db_printf("UNOWNED"); 896 else if (mtx_destroyed(m)) 897 db_printf("DESTROYED"); 898 else { 899 db_printf("OWNED"); 900 if (m->mtx_lock & MTX_CONTESTED) 901 db_printf(", CONTESTED"); 902 if (m->mtx_lock & MTX_RECURSED) 903 db_printf(", RECURSED"); 904 } 905 db_printf("}\n"); 906 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 907 td = mtx_owner(m); 908 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 909 td->td_tid, td->td_proc->p_pid, td->td_name); 910 if (mtx_recursed(m)) 911 db_printf(" recursed: %d\n", m->mtx_recurse); 912 } 913} 914#endif 915