kern_mutex.c revision 196969
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 196969 2009-09-08 13:16:55Z phk $"); 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 136static void 137assert_mtx(struct lock_object *lock, int what) 138{ 139 140 mtx_assert((struct mtx *)lock, what); 141} 142 143static void 144lock_mtx(struct lock_object *lock, int how) 145{ 146 147 mtx_lock((struct mtx *)lock); 148} 149 150static void 151lock_spin(struct lock_object *lock, int how) 152{ 153 154 panic("spin locks can only use msleep_spin"); 155} 156 157static int 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} 167 168/* XXX: FlexeLint retval */ 169static int 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(struct lock_object *lock, struct thread **owner) 179{ 180 struct mtx *m = (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 MPASS(curthread != NULL); 196 KASSERT(m->mtx_lock != MTX_DESTROYED, 197 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 198 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 199 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 200 file, line)); 201 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 202 file, line, NULL); 203 204 _get_sleep_lock(m, curthread, opts, file, line); 205 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 206 line); 207 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 208 curthread->td_locks++; 209} 210 211void 212_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 213{ 214 MPASS(curthread != NULL); 215 KASSERT(m->mtx_lock != MTX_DESTROYED, 216 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 217 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 218 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 219 file, line)); 220 curthread->td_locks--; 221 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 222 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 223 line); 224 mtx_assert(m, MA_OWNED); 225 226 if (m->mtx_recurse == 0) 227 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m); 228 _rel_sleep_lock(m, curthread, opts, file, line); 229} 230 231void 232_mtx_lock_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_lock_spin() of destroyed mutex @ %s:%d", file, line)); 238 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 239 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 240 m->lock_object.lo_name, file, line)); 241 if (mtx_owned(m)) 242 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 243 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 244 m->lock_object.lo_name, file, line)); 245 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 246 file, line, NULL); 247 _get_spin_lock(m, curthread, opts, file, line); 248 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 249 line); 250 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 251} 252 253void 254_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 255{ 256 257 MPASS(curthread != NULL); 258 KASSERT(m->mtx_lock != MTX_DESTROYED, 259 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 260 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 261 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 262 m->lock_object.lo_name, file, line)); 263 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 264 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 265 line); 266 mtx_assert(m, MA_OWNED); 267 268 _rel_spin_lock(m); 269} 270 271/* 272 * The important part of mtx_trylock{,_flags}() 273 * Tries to acquire lock `m.' If this function is called on a mutex that 274 * is already owned, it will recursively acquire the lock. 275 */ 276int 277_mtx_trylock(struct mtx *m, int opts, const char *file, int line) 278{ 279#ifdef LOCK_PROFILING 280 uint64_t waittime = 0; 281 int contested = 0; 282#endif 283 int rval; 284 285 MPASS(curthread != NULL); 286 KASSERT(m->mtx_lock != MTX_DESTROYED, 287 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 288 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 289 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 290 file, line)); 291 292 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 293 m->mtx_recurse++; 294 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 295 rval = 1; 296 } else 297 rval = _obtain_lock(m, (uintptr_t)curthread); 298 299 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 300 if (rval) { 301 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 302 file, line); 303 curthread->td_locks++; 304 if (m->mtx_recurse == 0) 305 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, 306 m, contested, waittime, file, line); 307 308 } 309 310 return (rval); 311} 312 313/* 314 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 315 * 316 * We call this if the lock is either contested (i.e. we need to go to 317 * sleep waiting for it), or if we need to recurse on it. 318 */ 319void 320_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 321 int line) 322{ 323 struct turnstile *ts; 324 uintptr_t v; 325#ifdef ADAPTIVE_MUTEXES 326 volatile struct thread *owner; 327#endif 328#ifdef KTR 329 int cont_logged = 0; 330#endif 331#ifdef LOCK_PROFILING 332 int contested = 0; 333 uint64_t waittime = 0; 334#endif 335#ifdef KDTRACE_HOOKS 336 uint64_t spin_cnt = 0; 337 uint64_t sleep_cnt = 0; 338 int64_t sleep_time = 0; 339#endif 340 341 if (mtx_owned(m)) { 342 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 343 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 344 m->lock_object.lo_name, file, line)); 345 m->mtx_recurse++; 346 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 347 if (LOCK_LOG_TEST(&m->lock_object, opts)) 348 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 349 return; 350 } 351 352 lock_profile_obtain_lock_failed(&m->lock_object, 353 &contested, &waittime); 354 if (LOCK_LOG_TEST(&m->lock_object, opts)) 355 CTR4(KTR_LOCK, 356 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 357 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 358 359 while (!_obtain_lock(m, tid)) { 360#ifdef KDTRACE_HOOKS 361 spin_cnt++; 362#endif 363#ifdef ADAPTIVE_MUTEXES 364 /* 365 * If the owner is running on another CPU, spin until the 366 * owner stops running or the state of the lock changes. 367 */ 368 v = m->mtx_lock; 369 if (v != MTX_UNOWNED) { 370 owner = (struct thread *)(v & ~MTX_FLAGMASK); 371 if (TD_IS_RUNNING(owner)) { 372 if (LOCK_LOG_TEST(&m->lock_object, 0)) 373 CTR3(KTR_LOCK, 374 "%s: spinning on %p held by %p", 375 __func__, m, owner); 376 while (mtx_owner(m) == owner && 377 TD_IS_RUNNING(owner)) { 378 cpu_spinwait(); 379#ifdef KDTRACE_HOOKS 380 spin_cnt++; 381#endif 382 } 383 continue; 384 } 385 } 386#endif 387 388 ts = turnstile_trywait(&m->lock_object); 389 v = m->mtx_lock; 390 391 /* 392 * Check if the lock has been released while spinning for 393 * the turnstile chain lock. 394 */ 395 if (v == MTX_UNOWNED) { 396 turnstile_cancel(ts); 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 continue; 412 } 413#endif 414 415 /* 416 * If the mutex isn't already contested and a failure occurs 417 * setting the contested bit, the mutex was either released 418 * or the state of the MTX_RECURSED bit changed. 419 */ 420 if ((v & MTX_CONTESTED) == 0 && 421 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 422 turnstile_cancel(ts); 423 continue; 424 } 425 426 /* 427 * We definitely must sleep for this lock. 428 */ 429 mtx_assert(m, MA_NOTOWNED); 430 431#ifdef KTR 432 if (!cont_logged) { 433 CTR6(KTR_CONTENTION, 434 "contention: %p at %s:%d wants %s, taken by %s:%d", 435 (void *)tid, file, line, m->lock_object.lo_name, 436 WITNESS_FILE(&m->lock_object), 437 WITNESS_LINE(&m->lock_object)); 438 cont_logged = 1; 439 } 440#endif 441 442 /* 443 * Block on the turnstile. 444 */ 445#ifdef KDTRACE_HOOKS 446 sleep_time -= lockstat_nsecs(); 447#endif 448 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 449#ifdef KDTRACE_HOOKS 450 sleep_time += lockstat_nsecs(); 451 sleep_cnt++; 452#endif 453 } 454#ifdef KTR 455 if (cont_logged) { 456 CTR4(KTR_CONTENTION, 457 "contention end: %s acquired by %p at %s:%d", 458 m->lock_object.lo_name, (void *)tid, file, line); 459 } 460#endif 461 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested, 462 waittime, file, line); 463#ifdef KDTRACE_HOOKS 464 if (sleep_time) 465 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time); 466 467 /* 468 * Only record the loops spinning and not sleeping. 469 */ 470 if (spin_cnt > sleep_cnt) 471 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt)); 472#endif 473} 474 475static void 476_mtx_lock_spin_failed(struct mtx *m) 477{ 478 struct thread *td; 479 480 td = mtx_owner(m); 481 482 /* If the mutex is unlocked, try again. */ 483 if (td == NULL) 484 return; 485 486 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 487 m, m->lock_object.lo_name, td, td->td_tid); 488#ifdef WITNESS 489 witness_display_spinlock(&m->lock_object, td); 490#endif 491 panic("spin lock held too long"); 492} 493 494#ifdef SMP 495/* 496 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 497 * 498 * This is only called if we need to actually spin for the lock. Recursion 499 * is handled inline. 500 */ 501void 502_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 503 int line) 504{ 505 int i = 0; 506#ifdef LOCK_PROFILING 507 int contested = 0; 508 uint64_t waittime = 0; 509#endif 510 511 if (LOCK_LOG_TEST(&m->lock_object, opts)) 512 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 513 514 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 515 while (!_obtain_lock(m, tid)) { 516 517 /* Give interrupts a chance while we spin. */ 518 spinlock_exit(); 519 while (m->mtx_lock != MTX_UNOWNED) { 520 if (i++ < 10000000) { 521 cpu_spinwait(); 522 continue; 523 } 524 if (i < 60000000 || kdb_active || panicstr != NULL) 525 DELAY(1); 526 else 527 _mtx_lock_spin_failed(m); 528 cpu_spinwait(); 529 } 530 spinlock_enter(); 531 } 532 533 if (LOCK_LOG_TEST(&m->lock_object, opts)) 534 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 535 536 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m, 537 contested, waittime, (file), (line)); 538 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i); 539} 540#endif /* SMP */ 541 542void 543_thread_lock_flags(struct thread *td, int opts, const char *file, int line) 544{ 545 struct mtx *m; 546 uintptr_t tid; 547 int i; 548#ifdef LOCK_PROFILING 549 int contested = 0; 550 uint64_t waittime = 0; 551#endif 552#ifdef KDTRACE_HOOKS 553 uint64_t spin_cnt = 0; 554#endif 555 556 i = 0; 557 tid = (uintptr_t)curthread; 558 for (;;) { 559retry: 560 spinlock_enter(); 561 m = td->td_lock; 562 KASSERT(m->mtx_lock != MTX_DESTROYED, 563 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 564 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 565 ("thread_lock() of sleep mutex %s @ %s:%d", 566 m->lock_object.lo_name, file, line)); 567 if (mtx_owned(m)) 568 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 569 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 570 m->lock_object.lo_name, file, line)); 571 WITNESS_CHECKORDER(&m->lock_object, 572 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 573 while (!_obtain_lock(m, tid)) { 574#ifdef KDTRACE_HOOKS 575 spin_cnt++; 576#endif 577 if (m->mtx_lock == tid) { 578 m->mtx_recurse++; 579 break; 580 } 581 lock_profile_obtain_lock_failed(&m->lock_object, 582 &contested, &waittime); 583 /* Give interrupts a chance while we spin. */ 584 spinlock_exit(); 585 while (m->mtx_lock != MTX_UNOWNED) { 586 if (i++ < 10000000) 587 cpu_spinwait(); 588 else if (i < 60000000 || 589 kdb_active || panicstr != NULL) 590 DELAY(1); 591 else 592 _mtx_lock_spin_failed(m); 593 cpu_spinwait(); 594 if (m != td->td_lock) 595 goto retry; 596 } 597 spinlock_enter(); 598 } 599 if (m == td->td_lock) 600 break; 601 _rel_spin_lock(m); /* does spinlock_exit() */ 602#ifdef KDTRACE_HOOKS 603 spin_cnt++; 604#endif 605 } 606 if (m->mtx_recurse == 0) 607 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, 608 m, contested, waittime, (file), (line)); 609 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 610 line); 611 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 612 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt); 613} 614 615struct mtx * 616thread_lock_block(struct thread *td) 617{ 618 struct mtx *lock; 619 620 spinlock_enter(); 621 THREAD_LOCK_ASSERT(td, MA_OWNED); 622 lock = td->td_lock; 623 td->td_lock = &blocked_lock; 624 mtx_unlock_spin(lock); 625 626 return (lock); 627} 628 629void 630thread_lock_unblock(struct thread *td, struct mtx *new) 631{ 632 mtx_assert(new, MA_OWNED); 633 MPASS(td->td_lock == &blocked_lock); 634 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 635 spinlock_exit(); 636} 637 638void 639thread_lock_set(struct thread *td, struct mtx *new) 640{ 641 struct mtx *lock; 642 643 mtx_assert(new, MA_OWNED); 644 THREAD_LOCK_ASSERT(td, MA_OWNED); 645 lock = td->td_lock; 646 td->td_lock = new; 647 mtx_unlock_spin(lock); 648} 649 650/* 651 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 652 * 653 * We are only called here if the lock is recursed or contested (i.e. we 654 * need to wake up a blocked thread). 655 */ 656void 657_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 658{ 659 struct turnstile *ts; 660 661 if (mtx_recursed(m)) { 662 if (--(m->mtx_recurse) == 0) 663 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 664 if (LOCK_LOG_TEST(&m->lock_object, opts)) 665 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 666 return; 667 } 668 669 /* 670 * We have to lock the chain before the turnstile so this turnstile 671 * can be removed from the hash list if it is empty. 672 */ 673 turnstile_chain_lock(&m->lock_object); 674 ts = turnstile_lookup(&m->lock_object); 675 if (LOCK_LOG_TEST(&m->lock_object, opts)) 676 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 677 MPASS(ts != NULL); 678 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 679 _release_lock_quick(m); 680 681 /* 682 * This turnstile is now no longer associated with the mutex. We can 683 * unlock the chain lock so a new turnstile may take it's place. 684 */ 685 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 686 turnstile_chain_unlock(&m->lock_object); 687} 688 689/* 690 * All the unlocking of MTX_SPIN locks is done inline. 691 * See the _rel_spin_lock() macro for the details. 692 */ 693 694/* 695 * The backing function for the INVARIANTS-enabled mtx_assert() 696 */ 697#ifdef INVARIANT_SUPPORT 698void 699_mtx_assert(struct mtx *m, int what, const char *file, int line) 700{ 701 702 if (panicstr != NULL || dumping) 703 return; 704 switch (what) { 705 case MA_OWNED: 706 case MA_OWNED | MA_RECURSED: 707 case MA_OWNED | MA_NOTRECURSED: 708 if (!mtx_owned(m)) 709 panic("mutex %s not owned at %s:%d", 710 m->lock_object.lo_name, file, line); 711 if (mtx_recursed(m)) { 712 if ((what & MA_NOTRECURSED) != 0) 713 panic("mutex %s recursed at %s:%d", 714 m->lock_object.lo_name, file, line); 715 } else if ((what & MA_RECURSED) != 0) { 716 panic("mutex %s unrecursed at %s:%d", 717 m->lock_object.lo_name, file, line); 718 } 719 break; 720 case MA_NOTOWNED: 721 if (mtx_owned(m)) 722 panic("mutex %s owned at %s:%d", 723 m->lock_object.lo_name, file, line); 724 break; 725 default: 726 panic("unknown mtx_assert at %s:%d", file, line); 727 } 728} 729#endif 730 731/* 732 * The MUTEX_DEBUG-enabled mtx_validate() 733 * 734 * Most of these checks have been moved off into the LO_INITIALIZED flag 735 * maintained by the witness code. 736 */ 737#ifdef MUTEX_DEBUG 738 739void mtx_validate(struct mtx *); 740 741void 742mtx_validate(struct mtx *m) 743{ 744 745/* 746 * XXX: When kernacc() does not require Giant we can reenable this check 747 */ 748#ifdef notyet 749 /* 750 * Can't call kernacc() from early init386(), especially when 751 * initializing Giant mutex, because some stuff in kernacc() 752 * requires Giant itself. 753 */ 754 if (!cold) 755 if (!kernacc((caddr_t)m, sizeof(m), 756 VM_PROT_READ | VM_PROT_WRITE)) 757 panic("Can't read and write to mutex %p", m); 758#endif 759} 760#endif 761 762/* 763 * General init routine used by the MTX_SYSINIT() macro. 764 */ 765void 766mtx_sysinit(void *arg) 767{ 768 struct mtx_args *margs = arg; 769 770 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 771} 772 773/* 774 * Mutex initialization routine; initialize lock `m' of type contained in 775 * `opts' with options contained in `opts' and name `name.' The optional 776 * lock type `type' is used as a general lock category name for use with 777 * witness. 778 */ 779void 780mtx_init(struct mtx *m, const char *name, const char *type, int opts) 781{ 782 struct lock_class *class; 783 int flags; 784 785 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 786 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 787 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 788 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 789 &m->mtx_lock)); 790 791#ifdef MUTEX_DEBUG 792 /* Diagnostic and error correction */ 793 mtx_validate(m); 794#endif 795 796 /* Determine lock class and lock flags. */ 797 if (opts & MTX_SPIN) 798 class = &lock_class_mtx_spin; 799 else 800 class = &lock_class_mtx_sleep; 801 flags = 0; 802 if (opts & MTX_QUIET) 803 flags |= LO_QUIET; 804 if (opts & MTX_RECURSE) 805 flags |= LO_RECURSABLE; 806 if ((opts & MTX_NOWITNESS) == 0) 807 flags |= LO_WITNESS; 808 if (opts & MTX_DUPOK) 809 flags |= LO_DUPOK; 810 if (opts & MTX_NOPROFILE) 811 flags |= LO_NOPROFILE; 812 813 /* Initialize mutex. */ 814 m->mtx_lock = MTX_UNOWNED; 815 m->mtx_recurse = 0; 816 817 lock_init(&m->lock_object, class, name, type, flags); 818} 819 820/* 821 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 822 * passed in as a flag here because if the corresponding mtx_init() was 823 * called with MTX_QUIET set, then it will already be set in the mutex's 824 * flags. 825 */ 826void 827mtx_destroy(struct mtx *m) 828{ 829 830 if (!mtx_owned(m)) 831 MPASS(mtx_unowned(m)); 832 else { 833 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 834 835 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 836 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 837 spinlock_exit(); 838 else 839 curthread->td_locks--; 840 841 lock_profile_release_lock(&m->lock_object); 842 /* Tell witness this isn't locked to make it happy. */ 843 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 844 __LINE__); 845 } 846 847 m->mtx_lock = MTX_DESTROYED; 848 lock_destroy(&m->lock_object); 849} 850 851/* 852 * Intialize the mutex code and system mutexes. This is called from the MD 853 * startup code prior to mi_startup(). The per-CPU data space needs to be 854 * setup before this is called. 855 */ 856void 857mutex_init(void) 858{ 859 860 /* Setup turnstiles so that sleep mutexes work. */ 861 init_turnstiles(); 862 863 /* 864 * Initialize mutexes. 865 */ 866 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 867 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 868 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 869 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 870 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 871 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 872 mtx_lock(&Giant); 873} 874 875#ifdef DDB 876void 877db_show_mtx(struct lock_object *lock) 878{ 879 struct thread *td; 880 struct mtx *m; 881 882 m = (struct mtx *)lock; 883 884 db_printf(" flags: {"); 885 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 886 db_printf("SPIN"); 887 else 888 db_printf("DEF"); 889 if (m->lock_object.lo_flags & LO_RECURSABLE) 890 db_printf(", RECURSE"); 891 if (m->lock_object.lo_flags & LO_DUPOK) 892 db_printf(", DUPOK"); 893 db_printf("}\n"); 894 db_printf(" state: {"); 895 if (mtx_unowned(m)) 896 db_printf("UNOWNED"); 897 else if (mtx_destroyed(m)) 898 db_printf("DESTROYED"); 899 else { 900 db_printf("OWNED"); 901 if (m->mtx_lock & MTX_CONTESTED) 902 db_printf(", CONTESTED"); 903 if (m->mtx_lock & MTX_RECURSED) 904 db_printf(", RECURSED"); 905 } 906 db_printf("}\n"); 907 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 908 td = mtx_owner(m); 909 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 910 td->td_tid, td->td_proc->p_pid, td->td_name); 911 if (mtx_recursed(m)) 912 db_printf(" recursed: %d\n", m->mtx_recurse); 913 } 914} 915#endif 916