kern_mutex.c revision 170339
1193242Ssam/*- 2193242Ssam * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved. 3193242Ssam * 4193242Ssam * Redistribution and use in source and binary forms, with or without 5193242Ssam * modification, are permitted provided that the following conditions 6193242Ssam * are met: 7193242Ssam * 1. Redistributions of source code must retain the above copyright 8193242Ssam * notice, this list of conditions and the following disclaimer. 9193242Ssam * 2. Redistributions in binary form must reproduce the above copyright 10193242Ssam * notice, this list of conditions and the following disclaimer in the 11193242Ssam * documentation and/or other materials provided with the distribution. 12193242Ssam * 3. Berkeley Software Design Inc's name may not be used to endorse or 13193242Ssam * promote products derived from this software without specific prior 14193242Ssam * written permission. 15193242Ssam * 16193242Ssam * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 17193242Ssam * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18193242Ssam * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19193242Ssam * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 20193242Ssam * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21193242Ssam * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22193242Ssam * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23193242Ssam * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24193242Ssam * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25193242Ssam * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26193242Ssam * SUCH DAMAGE. 27193242Ssam * 28193242Ssam * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 29193242Ssam * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 30193242Ssam */ 31193242Ssam 32193242Ssam/* 33193242Ssam * Machine independent bits of mutex implementation. 34193242Ssam */ 35193242Ssam 36193242Ssam#include <sys/cdefs.h> 37193242Ssam__FBSDID("$FreeBSD: head/sys/kern/kern_mutex.c 170339 2007-06-05 18:57:09Z attilio $"); 38193242Ssam 39193242Ssam#include "opt_adaptive_mutexes.h" 40193242Ssam#include "opt_ddb.h" 41193242Ssam#include "opt_global.h" 42193242Ssam#include "opt_mutex_wake_all.h" 43193242Ssam#include "opt_sched.h" 44193242Ssam 45193242Ssam#include <sys/param.h> 46193242Ssam#include <sys/systm.h> 47193242Ssam#include <sys/bus.h> 48193242Ssam#include <sys/conf.h> 49193242Ssam#include <sys/kdb.h> 50193242Ssam#include <sys/kernel.h> 51193242Ssam#include <sys/ktr.h> 52193242Ssam#include <sys/lock.h> 53193242Ssam#include <sys/malloc.h> 54193242Ssam#include <sys/mutex.h> 55193242Ssam#include <sys/proc.h> 56193242Ssam#include <sys/resourcevar.h> 57193242Ssam#include <sys/sched.h> 58193242Ssam#include <sys/sbuf.h> 59193242Ssam#include <sys/sysctl.h> 60193242Ssam#include <sys/turnstile.h> 61193242Ssam#include <sys/vmmeter.h> 62193242Ssam#include <sys/lock_profile.h> 63193242Ssam 64193242Ssam#include <machine/atomic.h> 65193242Ssam#include <machine/bus.h> 66193242Ssam#include <machine/cpu.h> 67193242Ssam 68193242Ssam#include <ddb/ddb.h> 69193242Ssam 70193242Ssam#include <fs/devfs/devfs_int.h> 71193242Ssam 72193242Ssam#include <vm/vm.h> 73193242Ssam#include <vm/vm_extern.h> 74193242Ssam 75193242Ssam/* 76193242Ssam * Force MUTEX_WAKE_ALL for now. 77193242Ssam * single thread wakeup needs fixes to avoid race conditions with 78193242Ssam * priority inheritance. 79193242Ssam */ 80193242Ssam#ifndef MUTEX_WAKE_ALL 81193242Ssam#define MUTEX_WAKE_ALL 82193242Ssam#endif 83193242Ssam 84193242Ssam#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 85193242Ssam#define ADAPTIVE_MUTEXES 86193242Ssam#endif 87193242Ssam 88193242Ssam/* 89193242Ssam * Internal utility macros. 90193242Ssam */ 91193242Ssam#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 92193242Ssam 93193242Ssam#define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 94193242Ssam 95193242Ssam#define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 96193242Ssam 97193242Ssam#ifdef DDB 98193242Ssamstatic void db_show_mtx(struct lock_object *lock); 99193242Ssam#endif 100193242Ssamstatic void lock_mtx(struct lock_object *lock, int how); 101193242Ssamstatic void lock_spin(struct lock_object *lock, int how); 102193242Ssamstatic int unlock_mtx(struct lock_object *lock); 103193242Ssamstatic int unlock_spin(struct lock_object *lock); 104193242Ssam 105193242Ssam/* 106193242Ssam * Lock classes for sleep and spin mutexes. 107193242Ssam */ 108193242Ssamstruct lock_class lock_class_mtx_sleep = { 109193242Ssam .lc_name = "sleep mutex", 110193242Ssam .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 111193242Ssam#ifdef DDB 112193242Ssam .lc_ddb_show = db_show_mtx, 113193242Ssam#endif 114193242Ssam .lc_lock = lock_mtx, 115193242Ssam .lc_unlock = unlock_mtx, 116193242Ssam}; 117193242Ssamstruct lock_class lock_class_mtx_spin = { 118193242Ssam .lc_name = "spin mutex", 119193242Ssam .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 120193242Ssam#ifdef DDB 121193242Ssam .lc_ddb_show = db_show_mtx, 122193242Ssam#endif 123193242Ssam .lc_lock = lock_spin, 124193242Ssam .lc_unlock = unlock_spin, 125193242Ssam}; 126193242Ssam 127193242Ssam/* 128193242Ssam * System-wide mutexes 129 */ 130struct mtx blocked_lock; 131struct mtx sched_lock; 132struct mtx Giant; 133 134#ifdef LOCK_PROFILING 135static inline void lock_profile_init(void) 136{ 137 int i; 138 /* Initialize the mutex profiling locks */ 139 for (i = 0; i < LPROF_LOCK_SIZE; i++) { 140 mtx_init(&lprof_locks[i], "mprof lock", 141 NULL, MTX_SPIN|MTX_QUIET|MTX_NOPROFILE); 142 } 143} 144#else 145static inline void lock_profile_init(void) {;} 146#endif 147 148void 149lock_mtx(struct lock_object *lock, int how) 150{ 151 152 mtx_lock((struct mtx *)lock); 153} 154 155void 156lock_spin(struct lock_object *lock, int how) 157{ 158 159 panic("spin locks can only use msleep_spin"); 160} 161 162int 163unlock_mtx(struct lock_object *lock) 164{ 165 struct mtx *m; 166 167 m = (struct mtx *)lock; 168 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 169 mtx_unlock(m); 170 return (0); 171} 172 173int 174unlock_spin(struct lock_object *lock) 175{ 176 177 panic("spin locks can only use msleep_spin"); 178} 179 180/* 181 * Function versions of the inlined __mtx_* macros. These are used by 182 * modules and can also be called from assembly language if needed. 183 */ 184void 185_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 186{ 187 188 MPASS(curthread != NULL); 189 KASSERT(m->mtx_lock != MTX_DESTROYED, 190 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 191 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 192 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 193 file, line)); 194 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 195 file, line); 196 197 _get_sleep_lock(m, curthread, opts, file, line); 198 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 199 line); 200 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 201 curthread->td_locks++; 202} 203 204void 205_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 206{ 207 MPASS(curthread != NULL); 208 KASSERT(m->mtx_lock != MTX_DESTROYED, 209 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 210 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 211 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 212 file, line)); 213 curthread->td_locks--; 214 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 215 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 216 line); 217 mtx_assert(m, MA_OWNED); 218 219 if (m->mtx_recurse == 0) 220 lock_profile_release_lock(&m->lock_object); 221 _rel_sleep_lock(m, curthread, opts, file, line); 222} 223 224void 225_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 226{ 227 228 MPASS(curthread != NULL); 229 KASSERT(m->mtx_lock != MTX_DESTROYED, 230 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 231 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 232 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 233 m->lock_object.lo_name, file, line)); 234 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 235 file, line); 236 _get_spin_lock(m, curthread, opts, file, line); 237 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 238 line); 239 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 240} 241 242void 243_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 244{ 245 246 MPASS(curthread != NULL); 247 KASSERT(m->mtx_lock != MTX_DESTROYED, 248 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 249 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 250 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 251 m->lock_object.lo_name, file, line)); 252 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 253 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 254 line); 255 mtx_assert(m, MA_OWNED); 256 257 _rel_spin_lock(m); 258} 259 260/* 261 * The important part of mtx_trylock{,_flags}() 262 * Tries to acquire lock `m.' If this function is called on a mutex that 263 * is already owned, it will recursively acquire the lock. 264 */ 265int 266_mtx_trylock(struct mtx *m, int opts, const char *file, int line) 267{ 268 int rval, contested = 0; 269 uint64_t waittime = 0; 270 271 MPASS(curthread != NULL); 272 KASSERT(m->mtx_lock != MTX_DESTROYED, 273 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 274 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 275 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 276 file, line)); 277 278 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 279 m->mtx_recurse++; 280 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 281 rval = 1; 282 } else 283 rval = _obtain_lock(m, (uintptr_t)curthread); 284 285 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 286 if (rval) { 287 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 288 file, line); 289 curthread->td_locks++; 290 if (m->mtx_recurse == 0) 291 lock_profile_obtain_lock_success(&m->lock_object, contested, 292 waittime, file, line); 293 294 } 295 296 return (rval); 297} 298 299/* 300 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 301 * 302 * We call this if the lock is either contested (i.e. we need to go to 303 * sleep waiting for it), or if we need to recurse on it. 304 */ 305void 306_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 307 int line) 308{ 309 struct turnstile *ts; 310#ifdef ADAPTIVE_MUTEXES 311 volatile struct thread *owner; 312#endif 313#ifdef KTR 314 int cont_logged = 0; 315#endif 316 int contested = 0; 317 uint64_t waittime = 0; 318 uintptr_t v; 319 320 if (mtx_owned(m)) { 321 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 322 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 323 m->lock_object.lo_name, file, line)); 324 m->mtx_recurse++; 325 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 326 if (LOCK_LOG_TEST(&m->lock_object, opts)) 327 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 328 return; 329 } 330 331 lock_profile_obtain_lock_failed(&m->lock_object, 332 &contested, &waittime); 333 if (LOCK_LOG_TEST(&m->lock_object, opts)) 334 CTR4(KTR_LOCK, 335 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 336 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 337 338 while (!_obtain_lock(m, tid)) { 339 ts = turnstile_trywait(&m->lock_object); 340 v = m->mtx_lock; 341 342 /* 343 * Check if the lock has been released while spinning for 344 * the turnstile chain lock. 345 */ 346 if (v == MTX_UNOWNED) { 347 turnstile_cancel(ts); 348 cpu_spinwait(); 349 continue; 350 } 351 352#ifdef MUTEX_WAKE_ALL 353 MPASS(v != MTX_CONTESTED); 354#else 355 /* 356 * The mutex was marked contested on release. This means that 357 * there are other threads blocked on it. Grab ownership of 358 * it and propagate its priority to the current thread if 359 * necessary. 360 */ 361 if (v == MTX_CONTESTED) { 362 m->mtx_lock = tid | MTX_CONTESTED; 363 turnstile_claim(ts); 364 break; 365 } 366#endif 367 368 /* 369 * If the mutex isn't already contested and a failure occurs 370 * setting the contested bit, the mutex was either released 371 * or the state of the MTX_RECURSED bit changed. 372 */ 373 if ((v & MTX_CONTESTED) == 0 && 374 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 375 turnstile_cancel(ts); 376 cpu_spinwait(); 377 continue; 378 } 379 380#ifdef ADAPTIVE_MUTEXES 381 /* 382 * If the current owner of the lock is executing on another 383 * CPU, spin instead of blocking. 384 */ 385 owner = (struct thread *)(v & ~MTX_FLAGMASK); 386#ifdef ADAPTIVE_GIANT 387 if (TD_IS_RUNNING(owner)) 388#else 389 if (m != &Giant && TD_IS_RUNNING(owner)) 390#endif 391 { 392 turnstile_cancel(ts); 393 while (mtx_owner(m) == owner && TD_IS_RUNNING(owner)) { 394 cpu_spinwait(); 395 } 396 continue; 397 } 398#endif /* ADAPTIVE_MUTEXES */ 399 400 /* 401 * We definitely must sleep for this lock. 402 */ 403 mtx_assert(m, MA_NOTOWNED); 404 405#ifdef KTR 406 if (!cont_logged) { 407 CTR6(KTR_CONTENTION, 408 "contention: %p at %s:%d wants %s, taken by %s:%d", 409 (void *)tid, file, line, m->lock_object.lo_name, 410 WITNESS_FILE(&m->lock_object), 411 WITNESS_LINE(&m->lock_object)); 412 cont_logged = 1; 413 } 414#endif 415 416 /* 417 * Block on the turnstile. 418 */ 419 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 420 } 421#ifdef KTR 422 if (cont_logged) { 423 CTR4(KTR_CONTENTION, 424 "contention end: %s acquired by %p at %s:%d", 425 m->lock_object.lo_name, (void *)tid, file, line); 426 } 427#endif 428 lock_profile_obtain_lock_success(&m->lock_object, contested, 429 waittime, (file), (line)); 430} 431 432static void 433_mtx_lock_spin_failed(struct mtx *m) 434{ 435 struct thread *td; 436 437 td = mtx_owner(m); 438 439 /* If the mutex is unlocked, try again. */ 440 if (td == NULL) 441 return; 442 443 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 444 m, m->lock_object.lo_name, td, td->td_tid); 445#ifdef WITNESS 446 witness_display_spinlock(&m->lock_object, td); 447#endif 448 panic("spin lock held too long"); 449} 450 451#ifdef SMP 452/* 453 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 454 * 455 * This is only called if we need to actually spin for the lock. Recursion 456 * is handled inline. 457 */ 458void 459_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 460 int line) 461{ 462 int i = 0, contested = 0; 463 uint64_t waittime = 0; 464 465 if (LOCK_LOG_TEST(&m->lock_object, opts)) 466 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 467 468 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 469 while (!_obtain_lock(m, tid)) { 470 471 /* Give interrupts a chance while we spin. */ 472 spinlock_exit(); 473 while (m->mtx_lock != MTX_UNOWNED) { 474 if (i++ < 10000000) { 475 cpu_spinwait(); 476 continue; 477 } 478 if (i < 60000000 || kdb_active || panicstr != NULL) 479 DELAY(1); 480 else 481 _mtx_lock_spin_failed(m); 482 cpu_spinwait(); 483 } 484 spinlock_enter(); 485 } 486 487 if (LOCK_LOG_TEST(&m->lock_object, opts)) 488 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 489 490 lock_profile_obtain_lock_success(&m->lock_object, contested, 491 waittime, (file), (line)); 492} 493#endif /* SMP */ 494 495void 496_thread_lock_flags(struct thread *td, int opts, const char *file, int line) 497{ 498 struct mtx *m; 499 uintptr_t tid; 500 int i; 501 502 i = 0; 503 tid = (uintptr_t)curthread; 504 for (;;) { 505retry: 506 spinlock_enter(); 507 m = __DEVOLATILE(struct mtx *, td->td_lock); 508 WITNESS_CHECKORDER(&m->lock_object, 509 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line); 510 while (!_obtain_lock(m, tid)) { 511 if (m->mtx_lock == tid) { 512 m->mtx_recurse++; 513 break; 514 } 515 /* Give interrupts a chance while we spin. */ 516 spinlock_exit(); 517 while (m->mtx_lock != MTX_UNOWNED) { 518 if (i++ < 10000000) 519 cpu_spinwait(); 520 else if (i < 60000000 || 521 kdb_active || panicstr != NULL) 522 DELAY(1); 523 else 524 _mtx_lock_spin_failed(m); 525 cpu_spinwait(); 526 if (m != td->td_lock) 527 goto retry; 528 } 529 spinlock_enter(); 530 } 531 if (m == td->td_lock) 532 break; 533 _rel_spin_lock(m); /* does spinlock_exit() */ 534 } 535 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 536} 537 538struct mtx * 539thread_lock_block(struct thread *td) 540{ 541 struct mtx *lock; 542 543 spinlock_enter(); 544 THREAD_LOCK_ASSERT(td, MA_OWNED); 545 lock = __DEVOLATILE(struct mtx *, td->td_lock); 546 td->td_lock = &blocked_lock; 547 mtx_unlock_spin(lock); 548 549 return (lock); 550} 551 552void 553thread_lock_unblock(struct thread *td, struct mtx *new) 554{ 555 mtx_assert(new, MA_OWNED); 556 MPASS(td->td_lock == &blocked_lock); 557 atomic_store_rel_ptr((void *)&td->td_lock, (uintptr_t)new); 558 spinlock_exit(); 559} 560 561void 562thread_lock_set(struct thread *td, struct mtx *new) 563{ 564 struct mtx *lock; 565 566 mtx_assert(new, MA_OWNED); 567 THREAD_LOCK_ASSERT(td, MA_OWNED); 568 lock = __DEVOLATILE(struct mtx *, td->td_lock); 569 td->td_lock = new; 570 mtx_unlock_spin(lock); 571} 572 573/* 574 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 575 * 576 * We are only called here if the lock is recursed or contested (i.e. we 577 * need to wake up a blocked thread). 578 */ 579void 580_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 581{ 582 struct turnstile *ts; 583 584 if (mtx_recursed(m)) { 585 if (--(m->mtx_recurse) == 0) 586 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 587 if (LOCK_LOG_TEST(&m->lock_object, opts)) 588 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 589 return; 590 } 591 592 /* 593 * We have to lock the chain before the turnstile so this turnstile 594 * can be removed from the hash list if it is empty. 595 */ 596 turnstile_chain_lock(&m->lock_object); 597 ts = turnstile_lookup(&m->lock_object); 598 if (LOCK_LOG_TEST(&m->lock_object, opts)) 599 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 600 601#ifdef ADAPTIVE_MUTEXES 602 if (ts == NULL) { 603 _release_lock_quick(m); 604 if (LOCK_LOG_TEST(&m->lock_object, opts)) 605 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m); 606 turnstile_chain_unlock(&m->lock_object); 607 return; 608 } 609#else 610 MPASS(ts != NULL); 611#endif 612#ifdef MUTEX_WAKE_ALL 613 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 614 _release_lock_quick(m); 615#else 616 if (turnstile_signal(ts, TS_EXCLUSIVE_QUEUE)) { 617 _release_lock_quick(m); 618 if (LOCK_LOG_TEST(&m->lock_object, opts)) 619 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); 620 } else { 621 m->mtx_lock = MTX_CONTESTED; 622 if (LOCK_LOG_TEST(&m->lock_object, opts)) 623 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p still contested", 624 m); 625 } 626#endif 627 /* 628 * This turnstile is now no longer associated with the mutex. We can 629 * unlock the chain lock so a new turnstile may take it's place. 630 */ 631 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 632 turnstile_chain_unlock(&m->lock_object); 633} 634 635/* 636 * All the unlocking of MTX_SPIN locks is done inline. 637 * See the _rel_spin_lock() macro for the details. 638 */ 639 640/* 641 * The backing function for the INVARIANTS-enabled mtx_assert() 642 */ 643#ifdef INVARIANT_SUPPORT 644void 645_mtx_assert(struct mtx *m, int what, const char *file, int line) 646{ 647 648 if (panicstr != NULL || dumping) 649 return; 650 switch (what) { 651 case MA_OWNED: 652 case MA_OWNED | MA_RECURSED: 653 case MA_OWNED | MA_NOTRECURSED: 654 if (!mtx_owned(m)) 655 panic("mutex %s not owned at %s:%d", 656 m->lock_object.lo_name, file, line); 657 if (mtx_recursed(m)) { 658 if ((what & MA_NOTRECURSED) != 0) 659 panic("mutex %s recursed at %s:%d", 660 m->lock_object.lo_name, file, line); 661 } else if ((what & MA_RECURSED) != 0) { 662 panic("mutex %s unrecursed at %s:%d", 663 m->lock_object.lo_name, file, line); 664 } 665 break; 666 case MA_NOTOWNED: 667 if (mtx_owned(m)) 668 panic("mutex %s owned at %s:%d", 669 m->lock_object.lo_name, file, line); 670 break; 671 default: 672 panic("unknown mtx_assert at %s:%d", file, line); 673 } 674} 675#endif 676 677/* 678 * The MUTEX_DEBUG-enabled mtx_validate() 679 * 680 * Most of these checks have been moved off into the LO_INITIALIZED flag 681 * maintained by the witness code. 682 */ 683#ifdef MUTEX_DEBUG 684 685void mtx_validate(struct mtx *); 686 687void 688mtx_validate(struct mtx *m) 689{ 690 691/* 692 * XXX: When kernacc() does not require Giant we can reenable this check 693 */ 694#ifdef notyet 695 /* 696 * Can't call kernacc() from early init386(), especially when 697 * initializing Giant mutex, because some stuff in kernacc() 698 * requires Giant itself. 699 */ 700 if (!cold) 701 if (!kernacc((caddr_t)m, sizeof(m), 702 VM_PROT_READ | VM_PROT_WRITE)) 703 panic("Can't read and write to mutex %p", m); 704#endif 705} 706#endif 707 708/* 709 * General init routine used by the MTX_SYSINIT() macro. 710 */ 711void 712mtx_sysinit(void *arg) 713{ 714 struct mtx_args *margs = arg; 715 716 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 717} 718 719/* 720 * Mutex initialization routine; initialize lock `m' of type contained in 721 * `opts' with options contained in `opts' and name `name.' The optional 722 * lock type `type' is used as a general lock category name for use with 723 * witness. 724 */ 725void 726mtx_init(struct mtx *m, const char *name, const char *type, int opts) 727{ 728 struct lock_class *class; 729 int flags; 730 731 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 732 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 733 734#ifdef MUTEX_DEBUG 735 /* Diagnostic and error correction */ 736 mtx_validate(m); 737#endif 738 739 /* Determine lock class and lock flags. */ 740 if (opts & MTX_SPIN) 741 class = &lock_class_mtx_spin; 742 else 743 class = &lock_class_mtx_sleep; 744 flags = 0; 745 if (opts & MTX_QUIET) 746 flags |= LO_QUIET; 747 if (opts & MTX_RECURSE) 748 flags |= LO_RECURSABLE; 749 if ((opts & MTX_NOWITNESS) == 0) 750 flags |= LO_WITNESS; 751 if (opts & MTX_DUPOK) 752 flags |= LO_DUPOK; 753 if (opts & MTX_NOPROFILE) 754 flags |= LO_NOPROFILE; 755 756 /* Initialize mutex. */ 757 m->mtx_lock = MTX_UNOWNED; 758 m->mtx_recurse = 0; 759 760 lock_init(&m->lock_object, class, name, type, flags); 761} 762 763/* 764 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 765 * passed in as a flag here because if the corresponding mtx_init() was 766 * called with MTX_QUIET set, then it will already be set in the mutex's 767 * flags. 768 */ 769void 770mtx_destroy(struct mtx *m) 771{ 772 773 if (!mtx_owned(m)) 774 MPASS(mtx_unowned(m)); 775 else { 776 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 777 778 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 779 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 780 spinlock_exit(); 781 else 782 curthread->td_locks--; 783 784 /* Tell witness this isn't locked to make it happy. */ 785 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 786 __LINE__); 787 } 788 789 m->mtx_lock = MTX_DESTROYED; 790 lock_destroy(&m->lock_object); 791} 792 793/* 794 * Intialize the mutex code and system mutexes. This is called from the MD 795 * startup code prior to mi_startup(). The per-CPU data space needs to be 796 * setup before this is called. 797 */ 798void 799mutex_init(void) 800{ 801 802 /* Setup turnstiles so that sleep mutexes work. */ 803 init_turnstiles(); 804 805 /* 806 * Initialize mutexes. 807 */ 808 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 809 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 810 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 811 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 812 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 813 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 814 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 815 mtx_lock(&Giant); 816 817 lock_profile_init(); 818} 819 820#ifdef DDB 821void 822db_show_mtx(struct lock_object *lock) 823{ 824 struct thread *td; 825 struct mtx *m; 826 827 m = (struct mtx *)lock; 828 829 db_printf(" flags: {"); 830 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 831 db_printf("SPIN"); 832 else 833 db_printf("DEF"); 834 if (m->lock_object.lo_flags & LO_RECURSABLE) 835 db_printf(", RECURSE"); 836 if (m->lock_object.lo_flags & LO_DUPOK) 837 db_printf(", DUPOK"); 838 db_printf("}\n"); 839 db_printf(" state: {"); 840 if (mtx_unowned(m)) 841 db_printf("UNOWNED"); 842 else if (mtx_destroyed(m)) 843 db_printf("DESTROYED"); 844 else { 845 db_printf("OWNED"); 846 if (m->mtx_lock & MTX_CONTESTED) 847 db_printf(", CONTESTED"); 848 if (m->mtx_lock & MTX_RECURSED) 849 db_printf(", RECURSED"); 850 } 851 db_printf("}\n"); 852 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 853 td = mtx_owner(m); 854 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 855 td->td_tid, td->td_proc->p_pid, td->td_proc->p_comm); 856 if (mtx_recursed(m)) 857 db_printf(" recursed: %d\n", m->mtx_recurse); 858 } 859} 860#endif 861