kern_mutex.c revision 170327
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 170327 2007-06-05 14:20:13Z kib $"); 38 39#include "opt_adaptive_mutexes.h" 40#include "opt_ddb.h" 41#include "opt_global.h" 42#include "opt_mutex_wake_all.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/* 76 * Force MUTEX_WAKE_ALL for now. 77 * single thread wakeup needs fixes to avoid race conditions with 78 * priority inheritance. 79 */ 80#ifndef MUTEX_WAKE_ALL 81#define MUTEX_WAKE_ALL 82#endif 83 84#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 85#define ADAPTIVE_MUTEXES 86#endif 87 88/* 89 * Internal utility macros. 90 */ 91#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 92 93#define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 94 95#define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 96 97#ifdef DDB 98static void db_show_mtx(struct lock_object *lock); 99#endif 100static void lock_mtx(struct lock_object *lock, int how); 101static void lock_spin(struct lock_object *lock, int how); 102static int unlock_mtx(struct lock_object *lock); 103static int unlock_spin(struct lock_object *lock); 104 105/* 106 * Lock classes for sleep and spin mutexes. 107 */ 108struct lock_class lock_class_mtx_sleep = { 109 .lc_name = "sleep mutex", 110 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 111#ifdef DDB 112 .lc_ddb_show = db_show_mtx, 113#endif 114 .lc_lock = lock_mtx, 115 .lc_unlock = unlock_mtx, 116}; 117struct lock_class lock_class_mtx_spin = { 118 .lc_name = "spin mutex", 119 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 120#ifdef DDB 121 .lc_ddb_show = db_show_mtx, 122#endif 123 .lc_lock = lock_spin, 124 .lc_unlock = unlock_spin, 125}; 126 127/* 128 * 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#ifndef PREEMPTION 584 struct thread *td, *td1; 585#endif 586 587 if (mtx_recursed(m)) { 588 if (--(m->mtx_recurse) == 0) 589 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 590 if (LOCK_LOG_TEST(&m->lock_object, opts)) 591 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 592 return; 593 } 594 595 /* 596 * We have to lock the chain before the turnstile so this turnstile 597 * can be removed from the hash list if it is empty. 598 */ 599 turnstile_chain_lock(&m->lock_object); 600 ts = turnstile_lookup(&m->lock_object); 601 if (LOCK_LOG_TEST(&m->lock_object, opts)) 602 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 603 604#ifdef ADAPTIVE_MUTEXES 605 if (ts == NULL) { 606 _release_lock_quick(m); 607 if (LOCK_LOG_TEST(&m->lock_object, opts)) 608 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m); 609 turnstile_chain_unlock(&m->lock_object); 610 return; 611 } 612#else 613 MPASS(ts != NULL); 614#endif 615#ifndef PREEMPTION 616 /* XXX */ 617 td1 = turnstile_head(ts, TS_EXCLUSIVE_QUEUE); 618#endif 619#ifdef MUTEX_WAKE_ALL 620 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 621 _release_lock_quick(m); 622#else 623 if (turnstile_signal(ts, TS_EXCLUSIVE_QUEUE)) { 624 _release_lock_quick(m); 625 if (LOCK_LOG_TEST(&m->lock_object, opts)) 626 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); 627 } else { 628 m->mtx_lock = MTX_CONTESTED; 629 if (LOCK_LOG_TEST(&m->lock_object, opts)) 630 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p still contested", 631 m); 632 } 633#endif 634 /* 635 * This turnstile is now no longer associated with the mutex. We can 636 * unlock the chain lock so a new turnstile may take it's place. 637 */ 638 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 639 turnstile_chain_unlock(&m->lock_object); 640 641#ifndef PREEMPTION 642 /* 643 * XXX: This is just a hack until preemption is done. However, 644 * once preemption is done we need to either wrap the 645 * turnstile_signal() and release of the actual lock in an 646 * extra critical section or change the preemption code to 647 * always just set a flag and never do instant-preempts. 648 */ 649 td = curthread; 650 if (td->td_critnest > 0 || td1->td_priority >= td->td_priority) 651 return; 652 653 thread_lock(td1); 654 if (!TD_IS_RUNNING(td1)) { 655#ifdef notyet 656 if (td->td_ithd != NULL) { 657 struct ithd *it = td->td_ithd; 658 659 if (it->it_interrupted) { 660 if (LOCK_LOG_TEST(&m->lock_object, opts)) 661 CTR2(KTR_LOCK, 662 "_mtx_unlock_sleep: %p interrupted %p", 663 it, it->it_interrupted); 664 intr_thd_fixup(it); 665 } 666 } 667#endif 668 if (LOCK_LOG_TEST(&m->lock_object, opts)) 669 CTR2(KTR_LOCK, 670 "_mtx_unlock_sleep: %p switching out lock=%p", m, 671 (void *)m->mtx_lock); 672 673 mi_switch(SW_INVOL, NULL); 674 if (LOCK_LOG_TEST(&m->lock_object, opts)) 675 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p", 676 m, (void *)m->mtx_lock); 677 } 678 thread_unlock(td1); 679#endif 680} 681 682/* 683 * All the unlocking of MTX_SPIN locks is done inline. 684 * See the _rel_spin_lock() macro for the details. 685 */ 686 687/* 688 * The backing function for the INVARIANTS-enabled mtx_assert() 689 */ 690#ifdef INVARIANT_SUPPORT 691void 692_mtx_assert(struct mtx *m, int what, const char *file, int line) 693{ 694 695 if (panicstr != NULL || dumping) 696 return; 697 switch (what) { 698 case MA_OWNED: 699 case MA_OWNED | MA_RECURSED: 700 case MA_OWNED | MA_NOTRECURSED: 701 if (!mtx_owned(m)) 702 panic("mutex %s not owned at %s:%d", 703 m->lock_object.lo_name, file, line); 704 if (mtx_recursed(m)) { 705 if ((what & MA_NOTRECURSED) != 0) 706 panic("mutex %s recursed at %s:%d", 707 m->lock_object.lo_name, file, line); 708 } else if ((what & MA_RECURSED) != 0) { 709 panic("mutex %s unrecursed at %s:%d", 710 m->lock_object.lo_name, file, line); 711 } 712 break; 713 case MA_NOTOWNED: 714 if (mtx_owned(m)) 715 panic("mutex %s owned at %s:%d", 716 m->lock_object.lo_name, file, line); 717 break; 718 default: 719 panic("unknown mtx_assert at %s:%d", file, line); 720 } 721} 722#endif 723 724/* 725 * The MUTEX_DEBUG-enabled mtx_validate() 726 * 727 * Most of these checks have been moved off into the LO_INITIALIZED flag 728 * maintained by the witness code. 729 */ 730#ifdef MUTEX_DEBUG 731 732void mtx_validate(struct mtx *); 733 734void 735mtx_validate(struct mtx *m) 736{ 737 738/* 739 * XXX: When kernacc() does not require Giant we can reenable this check 740 */ 741#ifdef notyet 742 /* 743 * Can't call kernacc() from early init386(), especially when 744 * initializing Giant mutex, because some stuff in kernacc() 745 * requires Giant itself. 746 */ 747 if (!cold) 748 if (!kernacc((caddr_t)m, sizeof(m), 749 VM_PROT_READ | VM_PROT_WRITE)) 750 panic("Can't read and write to mutex %p", m); 751#endif 752} 753#endif 754 755/* 756 * General init routine used by the MTX_SYSINIT() macro. 757 */ 758void 759mtx_sysinit(void *arg) 760{ 761 struct mtx_args *margs = arg; 762 763 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 764} 765 766/* 767 * Mutex initialization routine; initialize lock `m' of type contained in 768 * `opts' with options contained in `opts' and name `name.' The optional 769 * lock type `type' is used as a general lock category name for use with 770 * witness. 771 */ 772void 773mtx_init(struct mtx *m, const char *name, const char *type, int opts) 774{ 775 struct lock_class *class; 776 int flags; 777 778 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 779 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 780 781#ifdef MUTEX_DEBUG 782 /* Diagnostic and error correction */ 783 mtx_validate(m); 784#endif 785 786 /* Determine lock class and lock flags. */ 787 if (opts & MTX_SPIN) 788 class = &lock_class_mtx_spin; 789 else 790 class = &lock_class_mtx_sleep; 791 flags = 0; 792 if (opts & MTX_QUIET) 793 flags |= LO_QUIET; 794 if (opts & MTX_RECURSE) 795 flags |= LO_RECURSABLE; 796 if ((opts & MTX_NOWITNESS) == 0) 797 flags |= LO_WITNESS; 798 if (opts & MTX_DUPOK) 799 flags |= LO_DUPOK; 800 if (opts & MTX_NOPROFILE) 801 flags |= LO_NOPROFILE; 802 803 /* Initialize mutex. */ 804 m->mtx_lock = MTX_UNOWNED; 805 m->mtx_recurse = 0; 806 807 lock_init(&m->lock_object, class, name, type, flags); 808} 809 810/* 811 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 812 * passed in as a flag here because if the corresponding mtx_init() was 813 * called with MTX_QUIET set, then it will already be set in the mutex's 814 * flags. 815 */ 816void 817mtx_destroy(struct mtx *m) 818{ 819 820 if (!mtx_owned(m)) 821 MPASS(mtx_unowned(m)); 822 else { 823 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 824 825 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 826 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 827 spinlock_exit(); 828 else 829 curthread->td_locks--; 830 831 /* Tell witness this isn't locked to make it happy. */ 832 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 833 __LINE__); 834 } 835 836 m->mtx_lock = MTX_DESTROYED; 837 lock_destroy(&m->lock_object); 838} 839 840/* 841 * Intialize the mutex code and system mutexes. This is called from the MD 842 * startup code prior to mi_startup(). The per-CPU data space needs to be 843 * setup before this is called. 844 */ 845void 846mutex_init(void) 847{ 848 849 /* Setup turnstiles so that sleep mutexes work. */ 850 init_turnstiles(); 851 852 /* 853 * Initialize mutexes. 854 */ 855 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 856 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 857 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 858 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 859 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 860 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 861 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 862 mtx_lock(&Giant); 863 864 lock_profile_init(); 865} 866 867#ifdef DDB 868void 869db_show_mtx(struct lock_object *lock) 870{ 871 struct thread *td; 872 struct mtx *m; 873 874 m = (struct mtx *)lock; 875 876 db_printf(" flags: {"); 877 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 878 db_printf("SPIN"); 879 else 880 db_printf("DEF"); 881 if (m->lock_object.lo_flags & LO_RECURSABLE) 882 db_printf(", RECURSE"); 883 if (m->lock_object.lo_flags & LO_DUPOK) 884 db_printf(", DUPOK"); 885 db_printf("}\n"); 886 db_printf(" state: {"); 887 if (mtx_unowned(m)) 888 db_printf("UNOWNED"); 889 else if (mtx_destroyed(m)) 890 db_printf("DESTROYED"); 891 else { 892 db_printf("OWNED"); 893 if (m->mtx_lock & MTX_CONTESTED) 894 db_printf(", CONTESTED"); 895 if (m->mtx_lock & MTX_RECURSED) 896 db_printf(", RECURSED"); 897 } 898 db_printf("}\n"); 899 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 900 td = mtx_owner(m); 901 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 902 td->td_tid, td->td_proc->p_pid, td->td_proc->p_comm); 903 if (mtx_recursed(m)) 904 db_printf(" recursed: %d\n", m->mtx_recurse); 905 } 906} 907#endif 908