kern_mutex.c revision 240424
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 240424 2012-09-12 22:10:53Z attilio $"); 38 39#include "opt_adaptive_mutexes.h" 40#include "opt_ddb.h" 41#include "opt_global.h" 42#include "opt_hwpmc_hooks.h" 43#include "opt_kdtrace.h" 44#include "opt_sched.h" 45 46#include <sys/param.h> 47#include <sys/systm.h> 48#include <sys/bus.h> 49#include <sys/conf.h> 50#include <sys/kdb.h> 51#include <sys/kernel.h> 52#include <sys/ktr.h> 53#include <sys/lock.h> 54#include <sys/malloc.h> 55#include <sys/mutex.h> 56#include <sys/proc.h> 57#include <sys/resourcevar.h> 58#include <sys/sched.h> 59#include <sys/sbuf.h> 60#include <sys/sysctl.h> 61#include <sys/turnstile.h> 62#include <sys/vmmeter.h> 63#include <sys/lock_profile.h> 64 65#include <machine/atomic.h> 66#include <machine/bus.h> 67#include <machine/cpu.h> 68 69#include <ddb/ddb.h> 70 71#include <fs/devfs/devfs_int.h> 72 73#include <vm/vm.h> 74#include <vm/vm_extern.h> 75 76#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 77#define ADAPTIVE_MUTEXES 78#endif 79 80#ifdef HWPMC_HOOKS 81#include <sys/pmckern.h> 82PMC_SOFT_DEFINE( , , lock, failed); 83#endif 84 85/* 86 * Internal utility macros. 87 */ 88#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 89 90#define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 91 92#define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 93 94static void assert_mtx(const struct lock_object *lock, int what); 95#ifdef DDB 96static void db_show_mtx(const struct lock_object *lock); 97#endif 98static void lock_mtx(struct lock_object *lock, int how); 99static void lock_spin(struct lock_object *lock, int how); 100#ifdef KDTRACE_HOOKS 101static int owner_mtx(const struct lock_object *lock, 102 struct thread **owner); 103#endif 104static int unlock_mtx(struct lock_object *lock); 105static int unlock_spin(struct lock_object *lock); 106 107/* 108 * Lock classes for sleep and spin mutexes. 109 */ 110struct lock_class lock_class_mtx_sleep = { 111 .lc_name = "sleep mutex", 112 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 113 .lc_assert = assert_mtx, 114#ifdef DDB 115 .lc_ddb_show = db_show_mtx, 116#endif 117 .lc_lock = lock_mtx, 118 .lc_unlock = unlock_mtx, 119#ifdef KDTRACE_HOOKS 120 .lc_owner = owner_mtx, 121#endif 122}; 123struct lock_class lock_class_mtx_spin = { 124 .lc_name = "spin mutex", 125 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 126 .lc_assert = assert_mtx, 127#ifdef DDB 128 .lc_ddb_show = db_show_mtx, 129#endif 130 .lc_lock = lock_spin, 131 .lc_unlock = unlock_spin, 132#ifdef KDTRACE_HOOKS 133 .lc_owner = owner_mtx, 134#endif 135}; 136 137/* 138 * System-wide mutexes 139 */ 140struct mtx blocked_lock; 141struct mtx Giant; 142 143void 144assert_mtx(const struct lock_object *lock, int what) 145{ 146 147 mtx_assert((const struct mtx *)lock, what); 148} 149 150void 151lock_mtx(struct lock_object *lock, int how) 152{ 153 154 mtx_lock((struct mtx *)lock); 155} 156 157void 158lock_spin(struct lock_object *lock, int how) 159{ 160 161 panic("spin locks can only use msleep_spin"); 162} 163 164int 165unlock_mtx(struct lock_object *lock) 166{ 167 struct mtx *m; 168 169 m = (struct mtx *)lock; 170 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 171 mtx_unlock(m); 172 return (0); 173} 174 175int 176unlock_spin(struct lock_object *lock) 177{ 178 179 panic("spin locks can only use msleep_spin"); 180} 181 182#ifdef KDTRACE_HOOKS 183int 184owner_mtx(const struct lock_object *lock, struct thread **owner) 185{ 186 const struct mtx *m = (const struct mtx *)lock; 187 188 *owner = mtx_owner(m); 189 return (mtx_unowned(m) == 0); 190} 191#endif 192 193/* 194 * Function versions of the inlined __mtx_* macros. These are used by 195 * modules and can also be called from assembly language if needed. 196 */ 197void 198_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 199{ 200 201 if (SCHEDULER_STOPPED()) 202 return; 203 MPASS(curthread != NULL); 204 KASSERT(!TD_IS_IDLETHREAD(curthread), 205 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d", 206 curthread, m->lock_object.lo_name, file, line)); 207 KASSERT(m->mtx_lock != MTX_DESTROYED, 208 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 209 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 210 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 211 file, line)); 212 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 213 file, line, NULL); 214 215 __mtx_lock(m, curthread, opts, file, line); 216 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 217 line); 218 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 219 curthread->td_locks++; 220} 221 222void 223_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 224{ 225 226 if (SCHEDULER_STOPPED()) 227 return; 228 MPASS(curthread != NULL); 229 KASSERT(m->mtx_lock != MTX_DESTROYED, 230 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 231 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 232 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 233 file, line)); 234 curthread->td_locks--; 235 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 236 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 237 line); 238 mtx_assert(m, MA_OWNED); 239 240 if (m->mtx_recurse == 0) 241 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m); 242 __mtx_unlock(m, curthread, opts, file, line); 243} 244 245void 246_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 247{ 248 249 if (SCHEDULER_STOPPED()) 250 return; 251 MPASS(curthread != NULL); 252 KASSERT(m->mtx_lock != MTX_DESTROYED, 253 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 254 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 255 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 256 m->lock_object.lo_name, file, line)); 257 if (mtx_owned(m)) 258 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 259 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 260 m->lock_object.lo_name, file, line)); 261 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 262 file, line, NULL); 263 __mtx_lock_spin(m, curthread, opts, file, line); 264 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 265 line); 266 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 267} 268 269void 270_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 271{ 272 273 if (SCHEDULER_STOPPED()) 274 return; 275 MPASS(curthread != NULL); 276 KASSERT(m->mtx_lock != MTX_DESTROYED, 277 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 278 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 279 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 280 m->lock_object.lo_name, file, line)); 281 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 282 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 283 line); 284 mtx_assert(m, MA_OWNED); 285 286 __mtx_unlock_spin(m); 287} 288 289/* 290 * The important part of mtx_trylock{,_flags}() 291 * Tries to acquire lock `m.' If this function is called on a mutex that 292 * is already owned, it will recursively acquire the lock. 293 */ 294int 295mtx_trylock_flags_(struct mtx *m, int opts, const char *file, int line) 296{ 297#ifdef LOCK_PROFILING 298 uint64_t waittime = 0; 299 int contested = 0; 300#endif 301 int rval; 302 303 if (SCHEDULER_STOPPED()) 304 return (1); 305 306 MPASS(curthread != NULL); 307 KASSERT(!TD_IS_IDLETHREAD(curthread), 308 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", 309 curthread, m->lock_object.lo_name, file, line)); 310 KASSERT(m->mtx_lock != MTX_DESTROYED, 311 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 312 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 313 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 314 file, line)); 315 316 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 317 m->mtx_recurse++; 318 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 319 rval = 1; 320 } else 321 rval = _mtx_obtain_lock(m, (uintptr_t)curthread); 322 323 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 324 if (rval) { 325 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 326 file, line); 327 curthread->td_locks++; 328 if (m->mtx_recurse == 0) 329 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, 330 m, contested, waittime, file, line); 331 332 } 333 334 return (rval); 335} 336 337/* 338 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 339 * 340 * We call this if the lock is either contested (i.e. we need to go to 341 * sleep waiting for it), or if we need to recurse on it. 342 */ 343void 344_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 345 int line) 346{ 347 struct turnstile *ts; 348 uintptr_t v; 349#ifdef ADAPTIVE_MUTEXES 350 volatile struct thread *owner; 351#endif 352#ifdef KTR 353 int cont_logged = 0; 354#endif 355#ifdef LOCK_PROFILING 356 int contested = 0; 357 uint64_t waittime = 0; 358#endif 359#ifdef KDTRACE_HOOKS 360 uint64_t spin_cnt = 0; 361 uint64_t sleep_cnt = 0; 362 int64_t sleep_time = 0; 363#endif 364 365 if (SCHEDULER_STOPPED()) 366 return; 367 368 if (mtx_owned(m)) { 369 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 370 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 371 m->lock_object.lo_name, file, line)); 372 m->mtx_recurse++; 373 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 374 if (LOCK_LOG_TEST(&m->lock_object, opts)) 375 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 376 return; 377 } 378 379#ifdef HWPMC_HOOKS 380 PMC_SOFT_CALL( , , lock, failed); 381#endif 382 lock_profile_obtain_lock_failed(&m->lock_object, 383 &contested, &waittime); 384 if (LOCK_LOG_TEST(&m->lock_object, opts)) 385 CTR4(KTR_LOCK, 386 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 387 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 388 389 while (!_mtx_obtain_lock(m, tid)) { 390#ifdef KDTRACE_HOOKS 391 spin_cnt++; 392#endif 393#ifdef ADAPTIVE_MUTEXES 394 /* 395 * If the owner is running on another CPU, spin until the 396 * owner stops running or the state of the lock changes. 397 */ 398 v = m->mtx_lock; 399 if (v != MTX_UNOWNED) { 400 owner = (struct thread *)(v & ~MTX_FLAGMASK); 401 if (TD_IS_RUNNING(owner)) { 402 if (LOCK_LOG_TEST(&m->lock_object, 0)) 403 CTR3(KTR_LOCK, 404 "%s: spinning on %p held by %p", 405 __func__, m, owner); 406 while (mtx_owner(m) == owner && 407 TD_IS_RUNNING(owner)) { 408 cpu_spinwait(); 409#ifdef KDTRACE_HOOKS 410 spin_cnt++; 411#endif 412 } 413 continue; 414 } 415 } 416#endif 417 418 ts = turnstile_trywait(&m->lock_object); 419 v = m->mtx_lock; 420 421 /* 422 * Check if the lock has been released while spinning for 423 * the turnstile chain lock. 424 */ 425 if (v == MTX_UNOWNED) { 426 turnstile_cancel(ts); 427 continue; 428 } 429 430#ifdef ADAPTIVE_MUTEXES 431 /* 432 * The current lock owner might have started executing 433 * on another CPU (or the lock could have changed 434 * owners) while we were waiting on the turnstile 435 * chain lock. If so, drop the turnstile lock and try 436 * again. 437 */ 438 owner = (struct thread *)(v & ~MTX_FLAGMASK); 439 if (TD_IS_RUNNING(owner)) { 440 turnstile_cancel(ts); 441 continue; 442 } 443#endif 444 445 /* 446 * If the mutex isn't already contested and a failure occurs 447 * setting the contested bit, the mutex was either released 448 * or the state of the MTX_RECURSED bit changed. 449 */ 450 if ((v & MTX_CONTESTED) == 0 && 451 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 452 turnstile_cancel(ts); 453 continue; 454 } 455 456 /* 457 * We definitely must sleep for this lock. 458 */ 459 mtx_assert(m, MA_NOTOWNED); 460 461#ifdef KTR 462 if (!cont_logged) { 463 CTR6(KTR_CONTENTION, 464 "contention: %p at %s:%d wants %s, taken by %s:%d", 465 (void *)tid, file, line, m->lock_object.lo_name, 466 WITNESS_FILE(&m->lock_object), 467 WITNESS_LINE(&m->lock_object)); 468 cont_logged = 1; 469 } 470#endif 471 472 /* 473 * Block on the turnstile. 474 */ 475#ifdef KDTRACE_HOOKS 476 sleep_time -= lockstat_nsecs(); 477#endif 478 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 479#ifdef KDTRACE_HOOKS 480 sleep_time += lockstat_nsecs(); 481 sleep_cnt++; 482#endif 483 } 484#ifdef KTR 485 if (cont_logged) { 486 CTR4(KTR_CONTENTION, 487 "contention end: %s acquired by %p at %s:%d", 488 m->lock_object.lo_name, (void *)tid, file, line); 489 } 490#endif 491 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested, 492 waittime, file, line); 493#ifdef KDTRACE_HOOKS 494 if (sleep_time) 495 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time); 496 497 /* 498 * Only record the loops spinning and not sleeping. 499 */ 500 if (spin_cnt > sleep_cnt) 501 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt)); 502#endif 503} 504 505static void 506_mtx_lock_spin_failed(struct mtx *m) 507{ 508 struct thread *td; 509 510 td = mtx_owner(m); 511 512 /* If the mutex is unlocked, try again. */ 513 if (td == NULL) 514 return; 515 516 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 517 m, m->lock_object.lo_name, td, td->td_tid); 518#ifdef WITNESS 519 witness_display_spinlock(&m->lock_object, td, printf); 520#endif 521 panic("spin lock held too long"); 522} 523 524#ifdef SMP 525/* 526 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 527 * 528 * This is only called if we need to actually spin for the lock. Recursion 529 * is handled inline. 530 */ 531void 532_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 533 int line) 534{ 535 int i = 0; 536#ifdef LOCK_PROFILING 537 int contested = 0; 538 uint64_t waittime = 0; 539#endif 540 541 if (SCHEDULER_STOPPED()) 542 return; 543 544 if (LOCK_LOG_TEST(&m->lock_object, opts)) 545 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 546 547#ifdef HWPMC_HOOKS 548 PMC_SOFT_CALL( , , lock, failed); 549#endif 550 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 551 while (!_mtx_obtain_lock(m, tid)) { 552 553 /* Give interrupts a chance while we spin. */ 554 spinlock_exit(); 555 while (m->mtx_lock != MTX_UNOWNED) { 556 if (i++ < 10000000) { 557 cpu_spinwait(); 558 continue; 559 } 560 if (i < 60000000 || kdb_active || panicstr != NULL) 561 DELAY(1); 562 else 563 _mtx_lock_spin_failed(m); 564 cpu_spinwait(); 565 } 566 spinlock_enter(); 567 } 568 569 if (LOCK_LOG_TEST(&m->lock_object, opts)) 570 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 571 572 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m, 573 contested, waittime, (file), (line)); 574 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i); 575} 576#endif /* SMP */ 577 578void 579thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 580{ 581 struct mtx *m; 582 uintptr_t tid; 583 int i; 584#ifdef LOCK_PROFILING 585 int contested = 0; 586 uint64_t waittime = 0; 587#endif 588#ifdef KDTRACE_HOOKS 589 uint64_t spin_cnt = 0; 590#endif 591 592 i = 0; 593 tid = (uintptr_t)curthread; 594 595 if (SCHEDULER_STOPPED()) 596 return; 597 598 for (;;) { 599retry: 600 spinlock_enter(); 601 m = td->td_lock; 602 KASSERT(m->mtx_lock != MTX_DESTROYED, 603 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 604 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 605 ("thread_lock() of sleep mutex %s @ %s:%d", 606 m->lock_object.lo_name, file, line)); 607 if (mtx_owned(m)) 608 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 609 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 610 m->lock_object.lo_name, file, line)); 611 WITNESS_CHECKORDER(&m->lock_object, 612 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 613 while (!_mtx_obtain_lock(m, tid)) { 614#ifdef KDTRACE_HOOKS 615 spin_cnt++; 616#endif 617 if (m->mtx_lock == tid) { 618 m->mtx_recurse++; 619 break; 620 } 621#ifdef HWPMC_HOOKS 622 PMC_SOFT_CALL( , , lock, failed); 623#endif 624 lock_profile_obtain_lock_failed(&m->lock_object, 625 &contested, &waittime); 626 /* Give interrupts a chance while we spin. */ 627 spinlock_exit(); 628 while (m->mtx_lock != MTX_UNOWNED) { 629 if (i++ < 10000000) 630 cpu_spinwait(); 631 else if (i < 60000000 || 632 kdb_active || panicstr != NULL) 633 DELAY(1); 634 else 635 _mtx_lock_spin_failed(m); 636 cpu_spinwait(); 637 if (m != td->td_lock) 638 goto retry; 639 } 640 spinlock_enter(); 641 } 642 if (m == td->td_lock) 643 break; 644 __mtx_unlock_spin(m); /* does spinlock_exit() */ 645#ifdef KDTRACE_HOOKS 646 spin_cnt++; 647#endif 648 } 649 if (m->mtx_recurse == 0) 650 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, 651 m, contested, waittime, (file), (line)); 652 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 653 line); 654 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 655 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt); 656} 657 658struct mtx * 659thread_lock_block(struct thread *td) 660{ 661 struct mtx *lock; 662 663 THREAD_LOCK_ASSERT(td, MA_OWNED); 664 lock = td->td_lock; 665 td->td_lock = &blocked_lock; 666 mtx_unlock_spin(lock); 667 668 return (lock); 669} 670 671void 672thread_lock_unblock(struct thread *td, struct mtx *new) 673{ 674 mtx_assert(new, MA_OWNED); 675 MPASS(td->td_lock == &blocked_lock); 676 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 677} 678 679void 680thread_lock_set(struct thread *td, struct mtx *new) 681{ 682 struct mtx *lock; 683 684 mtx_assert(new, MA_OWNED); 685 THREAD_LOCK_ASSERT(td, MA_OWNED); 686 lock = td->td_lock; 687 td->td_lock = new; 688 mtx_unlock_spin(lock); 689} 690 691/* 692 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 693 * 694 * We are only called here if the lock is recursed or contested (i.e. we 695 * need to wake up a blocked thread). 696 */ 697void 698_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 699{ 700 struct turnstile *ts; 701 702 if (SCHEDULER_STOPPED()) 703 return; 704 705 if (mtx_recursed(m)) { 706 if (--(m->mtx_recurse) == 0) 707 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 708 if (LOCK_LOG_TEST(&m->lock_object, opts)) 709 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 710 return; 711 } 712 713 /* 714 * We have to lock the chain before the turnstile so this turnstile 715 * can be removed from the hash list if it is empty. 716 */ 717 turnstile_chain_lock(&m->lock_object); 718 ts = turnstile_lookup(&m->lock_object); 719 if (LOCK_LOG_TEST(&m->lock_object, opts)) 720 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 721 MPASS(ts != NULL); 722 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 723 _mtx_release_lock_quick(m); 724 725 /* 726 * This turnstile is now no longer associated with the mutex. We can 727 * unlock the chain lock so a new turnstile may take it's place. 728 */ 729 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 730 turnstile_chain_unlock(&m->lock_object); 731} 732 733/* 734 * All the unlocking of MTX_SPIN locks is done inline. 735 * See the __mtx_unlock_spin() macro for the details. 736 */ 737 738/* 739 * The backing function for the INVARIANTS-enabled mtx_assert() 740 */ 741#ifdef INVARIANT_SUPPORT 742void 743_mtx_assert(const struct mtx *m, int what, const char *file, int line) 744{ 745 746 if (panicstr != NULL || dumping) 747 return; 748 switch (what) { 749 case MA_OWNED: 750 case MA_OWNED | MA_RECURSED: 751 case MA_OWNED | MA_NOTRECURSED: 752 if (!mtx_owned(m)) 753 panic("mutex %s not owned at %s:%d", 754 m->lock_object.lo_name, file, line); 755 if (mtx_recursed(m)) { 756 if ((what & MA_NOTRECURSED) != 0) 757 panic("mutex %s recursed at %s:%d", 758 m->lock_object.lo_name, file, line); 759 } else if ((what & MA_RECURSED) != 0) { 760 panic("mutex %s unrecursed at %s:%d", 761 m->lock_object.lo_name, file, line); 762 } 763 break; 764 case MA_NOTOWNED: 765 if (mtx_owned(m)) 766 panic("mutex %s owned at %s:%d", 767 m->lock_object.lo_name, file, line); 768 break; 769 default: 770 panic("unknown mtx_assert at %s:%d", file, line); 771 } 772} 773#endif 774 775/* 776 * The MUTEX_DEBUG-enabled mtx_validate() 777 * 778 * Most of these checks have been moved off into the LO_INITIALIZED flag 779 * maintained by the witness code. 780 */ 781#ifdef MUTEX_DEBUG 782 783void mtx_validate(struct mtx *); 784 785void 786mtx_validate(struct mtx *m) 787{ 788 789/* 790 * XXX: When kernacc() does not require Giant we can reenable this check 791 */ 792#ifdef notyet 793 /* 794 * Can't call kernacc() from early init386(), especially when 795 * initializing Giant mutex, because some stuff in kernacc() 796 * requires Giant itself. 797 */ 798 if (!cold) 799 if (!kernacc((caddr_t)m, sizeof(m), 800 VM_PROT_READ | VM_PROT_WRITE)) 801 panic("Can't read and write to mutex %p", m); 802#endif 803} 804#endif 805 806/* 807 * General init routine used by the MTX_SYSINIT() macro. 808 */ 809void 810mtx_sysinit(void *arg) 811{ 812 struct mtx_args *margs = arg; 813 814 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 815} 816 817/* 818 * Mutex initialization routine; initialize lock `m' of type contained in 819 * `opts' with options contained in `opts' and name `name.' The optional 820 * lock type `type' is used as a general lock category name for use with 821 * witness. 822 */ 823void 824mtx_init(struct mtx *m, const char *name, const char *type, int opts) 825{ 826 struct lock_class *class; 827 int flags; 828 829 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 830 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 831 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 832 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 833 &m->mtx_lock)); 834 835#ifdef MUTEX_DEBUG 836 /* Diagnostic and error correction */ 837 mtx_validate(m); 838#endif 839 840 /* Determine lock class and lock flags. */ 841 if (opts & MTX_SPIN) 842 class = &lock_class_mtx_spin; 843 else 844 class = &lock_class_mtx_sleep; 845 flags = 0; 846 if (opts & MTX_QUIET) 847 flags |= LO_QUIET; 848 if (opts & MTX_RECURSE) 849 flags |= LO_RECURSABLE; 850 if ((opts & MTX_NOWITNESS) == 0) 851 flags |= LO_WITNESS; 852 if (opts & MTX_DUPOK) 853 flags |= LO_DUPOK; 854 if (opts & MTX_NOPROFILE) 855 flags |= LO_NOPROFILE; 856 857 /* Initialize mutex. */ 858 m->mtx_lock = MTX_UNOWNED; 859 m->mtx_recurse = 0; 860 861 lock_init(&m->lock_object, class, name, type, flags); 862} 863 864/* 865 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 866 * passed in as a flag here because if the corresponding mtx_init() was 867 * called with MTX_QUIET set, then it will already be set in the mutex's 868 * flags. 869 */ 870void 871mtx_destroy(struct mtx *m) 872{ 873 874 if (!mtx_owned(m)) 875 MPASS(mtx_unowned(m)); 876 else { 877 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 878 879 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 880 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 881 spinlock_exit(); 882 else 883 curthread->td_locks--; 884 885 lock_profile_release_lock(&m->lock_object); 886 /* Tell witness this isn't locked to make it happy. */ 887 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 888 __LINE__); 889 } 890 891 m->mtx_lock = MTX_DESTROYED; 892 lock_destroy(&m->lock_object); 893} 894 895/* 896 * Intialize the mutex code and system mutexes. This is called from the MD 897 * startup code prior to mi_startup(). The per-CPU data space needs to be 898 * setup before this is called. 899 */ 900void 901mutex_init(void) 902{ 903 904 /* Setup turnstiles so that sleep mutexes work. */ 905 init_turnstiles(); 906 907 /* 908 * Initialize mutexes. 909 */ 910 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 911 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 912 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 913 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 914 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 915 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 916 mtx_lock(&Giant); 917} 918 919#ifdef DDB 920void 921db_show_mtx(const struct lock_object *lock) 922{ 923 struct thread *td; 924 const struct mtx *m; 925 926 m = (const struct mtx *)lock; 927 928 db_printf(" flags: {"); 929 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 930 db_printf("SPIN"); 931 else 932 db_printf("DEF"); 933 if (m->lock_object.lo_flags & LO_RECURSABLE) 934 db_printf(", RECURSE"); 935 if (m->lock_object.lo_flags & LO_DUPOK) 936 db_printf(", DUPOK"); 937 db_printf("}\n"); 938 db_printf(" state: {"); 939 if (mtx_unowned(m)) 940 db_printf("UNOWNED"); 941 else if (mtx_destroyed(m)) 942 db_printf("DESTROYED"); 943 else { 944 db_printf("OWNED"); 945 if (m->mtx_lock & MTX_CONTESTED) 946 db_printf(", CONTESTED"); 947 if (m->mtx_lock & MTX_RECURSED) 948 db_printf(", RECURSED"); 949 } 950 db_printf("}\n"); 951 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 952 td = mtx_owner(m); 953 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 954 td->td_tid, td->td_proc->p_pid, td->td_name); 955 if (mtx_recursed(m)) 956 db_printf(" recursed: %d\n", m->mtx_recurse); 957 } 958} 959#endif 960