kern_mutex.c revision 228424
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 228424 2011-12-11 21:02:01Z avg $"); 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(const struct lock_object *lock, int what); 89#ifdef DDB 90static void db_show_mtx(const 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(const struct lock_object *lock, 96 struct thread **owner); 97#endif 98static int unlock_mtx(struct lock_object *lock); 99static int unlock_spin(struct lock_object *lock); 100 101/* 102 * Lock classes for sleep and spin mutexes. 103 */ 104struct lock_class lock_class_mtx_sleep = { 105 .lc_name = "sleep mutex", 106 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 107 .lc_assert = assert_mtx, 108#ifdef DDB 109 .lc_ddb_show = db_show_mtx, 110#endif 111 .lc_lock = lock_mtx, 112 .lc_unlock = unlock_mtx, 113#ifdef KDTRACE_HOOKS 114 .lc_owner = owner_mtx, 115#endif 116}; 117struct lock_class lock_class_mtx_spin = { 118 .lc_name = "spin mutex", 119 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 120 .lc_assert = assert_mtx, 121#ifdef DDB 122 .lc_ddb_show = db_show_mtx, 123#endif 124 .lc_lock = lock_spin, 125 .lc_unlock = unlock_spin, 126#ifdef KDTRACE_HOOKS 127 .lc_owner = owner_mtx, 128#endif 129}; 130 131/* 132 * System-wide mutexes 133 */ 134struct mtx blocked_lock; 135struct mtx Giant; 136 137void 138assert_mtx(const struct lock_object *lock, int what) 139{ 140 141 mtx_assert((const struct mtx *)lock, what); 142} 143 144void 145lock_mtx(struct lock_object *lock, int how) 146{ 147 148 mtx_lock((struct mtx *)lock); 149} 150 151void 152lock_spin(struct lock_object *lock, int how) 153{ 154 155 panic("spin locks can only use msleep_spin"); 156} 157 158int 159unlock_mtx(struct lock_object *lock) 160{ 161 struct mtx *m; 162 163 m = (struct mtx *)lock; 164 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 165 mtx_unlock(m); 166 return (0); 167} 168 169int 170unlock_spin(struct lock_object *lock) 171{ 172 173 panic("spin locks can only use msleep_spin"); 174} 175 176#ifdef KDTRACE_HOOKS 177int 178owner_mtx(const struct lock_object *lock, struct thread **owner) 179{ 180 const struct mtx *m = (const struct mtx *)lock; 181 182 *owner = mtx_owner(m); 183 return (mtx_unowned(m) == 0); 184} 185#endif 186 187/* 188 * Function versions of the inlined __mtx_* macros. These are used by 189 * modules and can also be called from assembly language if needed. 190 */ 191void 192_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 193{ 194 195 if (SCHEDULER_STOPPED()) 196 return; 197 MPASS(curthread != NULL); 198 KASSERT(m->mtx_lock != MTX_DESTROYED, 199 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 200 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 201 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 202 file, line)); 203 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 204 file, line, NULL); 205 206 __mtx_lock(m, curthread, opts, file, line); 207 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 208 line); 209 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 210 curthread->td_locks++; 211} 212 213void 214_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 215{ 216 217 if (SCHEDULER_STOPPED()) 218 return; 219 MPASS(curthread != NULL); 220 KASSERT(m->mtx_lock != MTX_DESTROYED, 221 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 222 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 223 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 224 file, line)); 225 curthread->td_locks--; 226 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 227 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 228 line); 229 mtx_assert(m, MA_OWNED); 230 231 if (m->mtx_recurse == 0) 232 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m); 233 __mtx_unlock(m, curthread, opts, file, line); 234} 235 236void 237_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 238{ 239 240 if (SCHEDULER_STOPPED()) 241 return; 242 MPASS(curthread != NULL); 243 KASSERT(m->mtx_lock != MTX_DESTROYED, 244 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 245 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 246 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 247 m->lock_object.lo_name, file, line)); 248 if (mtx_owned(m)) 249 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 250 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 251 m->lock_object.lo_name, file, line)); 252 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 253 file, line, NULL); 254 __mtx_lock_spin(m, curthread, opts, file, line); 255 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 256 line); 257 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 258} 259 260void 261_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 262{ 263 264 if (SCHEDULER_STOPPED()) 265 return; 266 MPASS(curthread != NULL); 267 KASSERT(m->mtx_lock != MTX_DESTROYED, 268 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 269 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 270 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 271 m->lock_object.lo_name, file, line)); 272 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 273 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 274 line); 275 mtx_assert(m, MA_OWNED); 276 277 __mtx_unlock_spin(m); 278} 279 280/* 281 * The important part of mtx_trylock{,_flags}() 282 * Tries to acquire lock `m.' If this function is called on a mutex that 283 * is already owned, it will recursively acquire the lock. 284 */ 285int 286mtx_trylock_flags_(struct mtx *m, int opts, const char *file, int line) 287{ 288#ifdef LOCK_PROFILING 289 uint64_t waittime = 0; 290 int contested = 0; 291#endif 292 int rval; 293 294 if (SCHEDULER_STOPPED()) 295 return (1); 296 297 MPASS(curthread != NULL); 298 KASSERT(m->mtx_lock != MTX_DESTROYED, 299 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 300 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 301 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 302 file, line)); 303 304 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 305 m->mtx_recurse++; 306 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 307 rval = 1; 308 } else 309 rval = _mtx_obtain_lock(m, (uintptr_t)curthread); 310 311 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 312 if (rval) { 313 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 314 file, line); 315 curthread->td_locks++; 316 if (m->mtx_recurse == 0) 317 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, 318 m, contested, waittime, file, line); 319 320 } 321 322 return (rval); 323} 324 325/* 326 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 327 * 328 * We call this if the lock is either contested (i.e. we need to go to 329 * sleep waiting for it), or if we need to recurse on it. 330 */ 331void 332_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 333 int line) 334{ 335 struct turnstile *ts; 336 uintptr_t v; 337#ifdef ADAPTIVE_MUTEXES 338 volatile struct thread *owner; 339#endif 340#ifdef KTR 341 int cont_logged = 0; 342#endif 343#ifdef LOCK_PROFILING 344 int contested = 0; 345 uint64_t waittime = 0; 346#endif 347#ifdef KDTRACE_HOOKS 348 uint64_t spin_cnt = 0; 349 uint64_t sleep_cnt = 0; 350 int64_t sleep_time = 0; 351#endif 352 353 if (SCHEDULER_STOPPED()) 354 return; 355 356 if (mtx_owned(m)) { 357 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 358 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 359 m->lock_object.lo_name, file, line)); 360 m->mtx_recurse++; 361 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 362 if (LOCK_LOG_TEST(&m->lock_object, opts)) 363 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 364 return; 365 } 366 367 lock_profile_obtain_lock_failed(&m->lock_object, 368 &contested, &waittime); 369 if (LOCK_LOG_TEST(&m->lock_object, opts)) 370 CTR4(KTR_LOCK, 371 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 372 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 373 374 while (!_mtx_obtain_lock(m, tid)) { 375#ifdef KDTRACE_HOOKS 376 spin_cnt++; 377#endif 378#ifdef ADAPTIVE_MUTEXES 379 /* 380 * If the owner is running on another CPU, spin until the 381 * owner stops running or the state of the lock changes. 382 */ 383 v = m->mtx_lock; 384 if (v != MTX_UNOWNED) { 385 owner = (struct thread *)(v & ~MTX_FLAGMASK); 386 if (TD_IS_RUNNING(owner)) { 387 if (LOCK_LOG_TEST(&m->lock_object, 0)) 388 CTR3(KTR_LOCK, 389 "%s: spinning on %p held by %p", 390 __func__, m, owner); 391 while (mtx_owner(m) == owner && 392 TD_IS_RUNNING(owner)) { 393 cpu_spinwait(); 394#ifdef KDTRACE_HOOKS 395 spin_cnt++; 396#endif 397 } 398 continue; 399 } 400 } 401#endif 402 403 ts = turnstile_trywait(&m->lock_object); 404 v = m->mtx_lock; 405 406 /* 407 * Check if the lock has been released while spinning for 408 * the turnstile chain lock. 409 */ 410 if (v == MTX_UNOWNED) { 411 turnstile_cancel(ts); 412 continue; 413 } 414 415#ifdef ADAPTIVE_MUTEXES 416 /* 417 * The current lock owner might have started executing 418 * on another CPU (or the lock could have changed 419 * owners) while we were waiting on the turnstile 420 * chain lock. If so, drop the turnstile lock and try 421 * again. 422 */ 423 owner = (struct thread *)(v & ~MTX_FLAGMASK); 424 if (TD_IS_RUNNING(owner)) { 425 turnstile_cancel(ts); 426 continue; 427 } 428#endif 429 430 /* 431 * If the mutex isn't already contested and a failure occurs 432 * setting the contested bit, the mutex was either released 433 * or the state of the MTX_RECURSED bit changed. 434 */ 435 if ((v & MTX_CONTESTED) == 0 && 436 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 437 turnstile_cancel(ts); 438 continue; 439 } 440 441 /* 442 * We definitely must sleep for this lock. 443 */ 444 mtx_assert(m, MA_NOTOWNED); 445 446#ifdef KTR 447 if (!cont_logged) { 448 CTR6(KTR_CONTENTION, 449 "contention: %p at %s:%d wants %s, taken by %s:%d", 450 (void *)tid, file, line, m->lock_object.lo_name, 451 WITNESS_FILE(&m->lock_object), 452 WITNESS_LINE(&m->lock_object)); 453 cont_logged = 1; 454 } 455#endif 456 457 /* 458 * Block on the turnstile. 459 */ 460#ifdef KDTRACE_HOOKS 461 sleep_time -= lockstat_nsecs(); 462#endif 463 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 464#ifdef KDTRACE_HOOKS 465 sleep_time += lockstat_nsecs(); 466 sleep_cnt++; 467#endif 468 } 469#ifdef KTR 470 if (cont_logged) { 471 CTR4(KTR_CONTENTION, 472 "contention end: %s acquired by %p at %s:%d", 473 m->lock_object.lo_name, (void *)tid, file, line); 474 } 475#endif 476 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested, 477 waittime, file, line); 478#ifdef KDTRACE_HOOKS 479 if (sleep_time) 480 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time); 481 482 /* 483 * Only record the loops spinning and not sleeping. 484 */ 485 if (spin_cnt > sleep_cnt) 486 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt)); 487#endif 488} 489 490static void 491_mtx_lock_spin_failed(struct mtx *m) 492{ 493 struct thread *td; 494 495 td = mtx_owner(m); 496 497 /* If the mutex is unlocked, try again. */ 498 if (td == NULL) 499 return; 500 501 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 502 m, m->lock_object.lo_name, td, td->td_tid); 503#ifdef WITNESS 504 witness_display_spinlock(&m->lock_object, td, printf); 505#endif 506 panic("spin lock held too long"); 507} 508 509#ifdef SMP 510/* 511 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 512 * 513 * This is only called if we need to actually spin for the lock. Recursion 514 * is handled inline. 515 */ 516void 517_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 518 int line) 519{ 520 int i = 0; 521#ifdef LOCK_PROFILING 522 int contested = 0; 523 uint64_t waittime = 0; 524#endif 525 526 if (SCHEDULER_STOPPED()) 527 return; 528 529 if (LOCK_LOG_TEST(&m->lock_object, opts)) 530 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 531 532 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 533 while (!_mtx_obtain_lock(m, tid)) { 534 535 /* Give interrupts a chance while we spin. */ 536 spinlock_exit(); 537 while (m->mtx_lock != MTX_UNOWNED) { 538 if (i++ < 10000000) { 539 cpu_spinwait(); 540 continue; 541 } 542 if (i < 60000000 || kdb_active || panicstr != NULL) 543 DELAY(1); 544 else 545 _mtx_lock_spin_failed(m); 546 cpu_spinwait(); 547 } 548 spinlock_enter(); 549 } 550 551 if (LOCK_LOG_TEST(&m->lock_object, opts)) 552 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 553 554 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m, 555 contested, waittime, (file), (line)); 556 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i); 557} 558#endif /* SMP */ 559 560void 561thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 562{ 563 struct mtx *m; 564 uintptr_t tid; 565 int i; 566#ifdef LOCK_PROFILING 567 int contested = 0; 568 uint64_t waittime = 0; 569#endif 570#ifdef KDTRACE_HOOKS 571 uint64_t spin_cnt = 0; 572#endif 573 574 i = 0; 575 tid = (uintptr_t)curthread; 576 577 if (SCHEDULER_STOPPED()) 578 return; 579 580 for (;;) { 581retry: 582 spinlock_enter(); 583 m = td->td_lock; 584 KASSERT(m->mtx_lock != MTX_DESTROYED, 585 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 586 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 587 ("thread_lock() of sleep mutex %s @ %s:%d", 588 m->lock_object.lo_name, file, line)); 589 if (mtx_owned(m)) 590 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 591 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 592 m->lock_object.lo_name, file, line)); 593 WITNESS_CHECKORDER(&m->lock_object, 594 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 595 while (!_mtx_obtain_lock(m, tid)) { 596#ifdef KDTRACE_HOOKS 597 spin_cnt++; 598#endif 599 if (m->mtx_lock == tid) { 600 m->mtx_recurse++; 601 break; 602 } 603 lock_profile_obtain_lock_failed(&m->lock_object, 604 &contested, &waittime); 605 /* Give interrupts a chance while we spin. */ 606 spinlock_exit(); 607 while (m->mtx_lock != MTX_UNOWNED) { 608 if (i++ < 10000000) 609 cpu_spinwait(); 610 else if (i < 60000000 || 611 kdb_active || panicstr != NULL) 612 DELAY(1); 613 else 614 _mtx_lock_spin_failed(m); 615 cpu_spinwait(); 616 if (m != td->td_lock) 617 goto retry; 618 } 619 spinlock_enter(); 620 } 621 if (m == td->td_lock) 622 break; 623 __mtx_unlock_spin(m); /* does spinlock_exit() */ 624#ifdef KDTRACE_HOOKS 625 spin_cnt++; 626#endif 627 } 628 if (m->mtx_recurse == 0) 629 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, 630 m, contested, waittime, (file), (line)); 631 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 632 line); 633 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 634 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt); 635} 636 637struct mtx * 638thread_lock_block(struct thread *td) 639{ 640 struct mtx *lock; 641 642 THREAD_LOCK_ASSERT(td, MA_OWNED); 643 lock = td->td_lock; 644 td->td_lock = &blocked_lock; 645 mtx_unlock_spin(lock); 646 647 return (lock); 648} 649 650void 651thread_lock_unblock(struct thread *td, struct mtx *new) 652{ 653 mtx_assert(new, MA_OWNED); 654 MPASS(td->td_lock == &blocked_lock); 655 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 656} 657 658void 659thread_lock_set(struct thread *td, struct mtx *new) 660{ 661 struct mtx *lock; 662 663 mtx_assert(new, MA_OWNED); 664 THREAD_LOCK_ASSERT(td, MA_OWNED); 665 lock = td->td_lock; 666 td->td_lock = new; 667 mtx_unlock_spin(lock); 668} 669 670/* 671 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 672 * 673 * We are only called here if the lock is recursed or contested (i.e. we 674 * need to wake up a blocked thread). 675 */ 676void 677_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 678{ 679 struct turnstile *ts; 680 681 if (SCHEDULER_STOPPED()) 682 return; 683 684 if (mtx_recursed(m)) { 685 if (--(m->mtx_recurse) == 0) 686 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 687 if (LOCK_LOG_TEST(&m->lock_object, opts)) 688 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 689 return; 690 } 691 692 /* 693 * We have to lock the chain before the turnstile so this turnstile 694 * can be removed from the hash list if it is empty. 695 */ 696 turnstile_chain_lock(&m->lock_object); 697 ts = turnstile_lookup(&m->lock_object); 698 if (LOCK_LOG_TEST(&m->lock_object, opts)) 699 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 700 MPASS(ts != NULL); 701 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 702 _mtx_release_lock_quick(m); 703 704 /* 705 * This turnstile is now no longer associated with the mutex. We can 706 * unlock the chain lock so a new turnstile may take it's place. 707 */ 708 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 709 turnstile_chain_unlock(&m->lock_object); 710} 711 712/* 713 * All the unlocking of MTX_SPIN locks is done inline. 714 * See the __mtx_unlock_spin() macro for the details. 715 */ 716 717/* 718 * The backing function for the INVARIANTS-enabled mtx_assert() 719 */ 720#ifdef INVARIANT_SUPPORT 721void 722_mtx_assert(const struct mtx *m, int what, const char *file, int line) 723{ 724 725 if (panicstr != NULL || dumping) 726 return; 727 switch (what) { 728 case MA_OWNED: 729 case MA_OWNED | MA_RECURSED: 730 case MA_OWNED | MA_NOTRECURSED: 731 if (!mtx_owned(m)) 732 panic("mutex %s not owned at %s:%d", 733 m->lock_object.lo_name, file, line); 734 if (mtx_recursed(m)) { 735 if ((what & MA_NOTRECURSED) != 0) 736 panic("mutex %s recursed at %s:%d", 737 m->lock_object.lo_name, file, line); 738 } else if ((what & MA_RECURSED) != 0) { 739 panic("mutex %s unrecursed at %s:%d", 740 m->lock_object.lo_name, file, line); 741 } 742 break; 743 case MA_NOTOWNED: 744 if (mtx_owned(m)) 745 panic("mutex %s owned at %s:%d", 746 m->lock_object.lo_name, file, line); 747 break; 748 default: 749 panic("unknown mtx_assert at %s:%d", file, line); 750 } 751} 752#endif 753 754/* 755 * The MUTEX_DEBUG-enabled mtx_validate() 756 * 757 * Most of these checks have been moved off into the LO_INITIALIZED flag 758 * maintained by the witness code. 759 */ 760#ifdef MUTEX_DEBUG 761 762void mtx_validate(struct mtx *); 763 764void 765mtx_validate(struct mtx *m) 766{ 767 768/* 769 * XXX: When kernacc() does not require Giant we can reenable this check 770 */ 771#ifdef notyet 772 /* 773 * Can't call kernacc() from early init386(), especially when 774 * initializing Giant mutex, because some stuff in kernacc() 775 * requires Giant itself. 776 */ 777 if (!cold) 778 if (!kernacc((caddr_t)m, sizeof(m), 779 VM_PROT_READ | VM_PROT_WRITE)) 780 panic("Can't read and write to mutex %p", m); 781#endif 782} 783#endif 784 785/* 786 * General init routine used by the MTX_SYSINIT() macro. 787 */ 788void 789mtx_sysinit(void *arg) 790{ 791 struct mtx_args *margs = arg; 792 793 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 794} 795 796/* 797 * Mutex initialization routine; initialize lock `m' of type contained in 798 * `opts' with options contained in `opts' and name `name.' The optional 799 * lock type `type' is used as a general lock category name for use with 800 * witness. 801 */ 802void 803mtx_init(struct mtx *m, const char *name, const char *type, int opts) 804{ 805 struct lock_class *class; 806 int flags; 807 808 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 809 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 810 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 811 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 812 &m->mtx_lock)); 813 814#ifdef MUTEX_DEBUG 815 /* Diagnostic and error correction */ 816 mtx_validate(m); 817#endif 818 819 /* Determine lock class and lock flags. */ 820 if (opts & MTX_SPIN) 821 class = &lock_class_mtx_spin; 822 else 823 class = &lock_class_mtx_sleep; 824 flags = 0; 825 if (opts & MTX_QUIET) 826 flags |= LO_QUIET; 827 if (opts & MTX_RECURSE) 828 flags |= LO_RECURSABLE; 829 if ((opts & MTX_NOWITNESS) == 0) 830 flags |= LO_WITNESS; 831 if (opts & MTX_DUPOK) 832 flags |= LO_DUPOK; 833 if (opts & MTX_NOPROFILE) 834 flags |= LO_NOPROFILE; 835 836 /* Initialize mutex. */ 837 m->mtx_lock = MTX_UNOWNED; 838 m->mtx_recurse = 0; 839 840 lock_init(&m->lock_object, class, name, type, flags); 841} 842 843/* 844 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 845 * passed in as a flag here because if the corresponding mtx_init() was 846 * called with MTX_QUIET set, then it will already be set in the mutex's 847 * flags. 848 */ 849void 850mtx_destroy(struct mtx *m) 851{ 852 853 if (!mtx_owned(m)) 854 MPASS(mtx_unowned(m)); 855 else { 856 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 857 858 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 859 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 860 spinlock_exit(); 861 else 862 curthread->td_locks--; 863 864 lock_profile_release_lock(&m->lock_object); 865 /* Tell witness this isn't locked to make it happy. */ 866 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 867 __LINE__); 868 } 869 870 m->mtx_lock = MTX_DESTROYED; 871 lock_destroy(&m->lock_object); 872} 873 874/* 875 * Intialize the mutex code and system mutexes. This is called from the MD 876 * startup code prior to mi_startup(). The per-CPU data space needs to be 877 * setup before this is called. 878 */ 879void 880mutex_init(void) 881{ 882 883 /* Setup turnstiles so that sleep mutexes work. */ 884 init_turnstiles(); 885 886 /* 887 * Initialize mutexes. 888 */ 889 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 890 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 891 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 892 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 893 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 894 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 895 mtx_lock(&Giant); 896} 897 898#ifdef DDB 899void 900db_show_mtx(const struct lock_object *lock) 901{ 902 struct thread *td; 903 const struct mtx *m; 904 905 m = (const struct mtx *)lock; 906 907 db_printf(" flags: {"); 908 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 909 db_printf("SPIN"); 910 else 911 db_printf("DEF"); 912 if (m->lock_object.lo_flags & LO_RECURSABLE) 913 db_printf(", RECURSE"); 914 if (m->lock_object.lo_flags & LO_DUPOK) 915 db_printf(", DUPOK"); 916 db_printf("}\n"); 917 db_printf(" state: {"); 918 if (mtx_unowned(m)) 919 db_printf("UNOWNED"); 920 else if (mtx_destroyed(m)) 921 db_printf("DESTROYED"); 922 else { 923 db_printf("OWNED"); 924 if (m->mtx_lock & MTX_CONTESTED) 925 db_printf(", CONTESTED"); 926 if (m->mtx_lock & MTX_RECURSED) 927 db_printf(", RECURSED"); 928 } 929 db_printf("}\n"); 930 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 931 td = mtx_owner(m); 932 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 933 td->td_tid, td->td_proc->p_pid, td->td_name); 934 if (mtx_recursed(m)) 935 db_printf(" recursed: %d\n", m->mtx_recurse); 936 } 937} 938#endif 939