kern_mutex.c revision 192456
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 192456 2009-05-20 18:29:14Z jhb $"); 38 39#include "opt_adaptive_mutexes.h" 40#include "opt_ddb.h" 41#include "opt_global.h" 42#include "opt_sched.h" 43 44#include <sys/param.h> 45#include <sys/systm.h> 46#include <sys/bus.h> 47#include <sys/conf.h> 48#include <sys/kdb.h> 49#include <sys/kernel.h> 50#include <sys/ktr.h> 51#include <sys/lock.h> 52#include <sys/malloc.h> 53#include <sys/mutex.h> 54#include <sys/proc.h> 55#include <sys/resourcevar.h> 56#include <sys/sched.h> 57#include <sys/sbuf.h> 58#include <sys/sysctl.h> 59#include <sys/turnstile.h> 60#include <sys/vmmeter.h> 61#include <sys/lock_profile.h> 62 63#include <machine/atomic.h> 64#include <machine/bus.h> 65#include <machine/cpu.h> 66 67#include <ddb/ddb.h> 68 69#include <fs/devfs/devfs_int.h> 70 71#include <vm/vm.h> 72#include <vm/vm_extern.h> 73 74#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 75#define ADAPTIVE_MUTEXES 76#endif 77 78/* 79 * Internal utility macros. 80 */ 81#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 82 83#define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 84 85#define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 86 87static void assert_mtx(struct lock_object *lock, int what); 88#ifdef DDB 89static void db_show_mtx(struct lock_object *lock); 90#endif 91static void lock_mtx(struct lock_object *lock, int how); 92static void lock_spin(struct lock_object *lock, int how); 93static int unlock_mtx(struct lock_object *lock); 94static int unlock_spin(struct lock_object *lock); 95 96/* 97 * Lock classes for sleep and spin mutexes. 98 */ 99struct lock_class lock_class_mtx_sleep = { 100 .lc_name = "sleep mutex", 101 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 102 .lc_assert = assert_mtx, 103#ifdef DDB 104 .lc_ddb_show = db_show_mtx, 105#endif 106 .lc_lock = lock_mtx, 107 .lc_unlock = unlock_mtx, 108}; 109struct lock_class lock_class_mtx_spin = { 110 .lc_name = "spin mutex", 111 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 112 .lc_assert = assert_mtx, 113#ifdef DDB 114 .lc_ddb_show = db_show_mtx, 115#endif 116 .lc_lock = lock_spin, 117 .lc_unlock = unlock_spin, 118}; 119 120/* 121 * System-wide mutexes 122 */ 123struct mtx blocked_lock; 124struct mtx Giant; 125 126void 127assert_mtx(struct lock_object *lock, int what) 128{ 129 130 mtx_assert((struct mtx *)lock, what); 131} 132 133void 134lock_mtx(struct lock_object *lock, int how) 135{ 136 137 mtx_lock((struct mtx *)lock); 138} 139 140void 141lock_spin(struct lock_object *lock, int how) 142{ 143 144 panic("spin locks can only use msleep_spin"); 145} 146 147int 148unlock_mtx(struct lock_object *lock) 149{ 150 struct mtx *m; 151 152 m = (struct mtx *)lock; 153 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 154 mtx_unlock(m); 155 return (0); 156} 157 158int 159unlock_spin(struct lock_object *lock) 160{ 161 162 panic("spin locks can only use msleep_spin"); 163} 164 165/* 166 * Function versions of the inlined __mtx_* macros. These are used by 167 * modules and can also be called from assembly language if needed. 168 */ 169void 170_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 171{ 172 173 MPASS(curthread != NULL); 174 KASSERT(m->mtx_lock != MTX_DESTROYED, 175 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 176 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 177 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 178 file, line)); 179 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 180 file, line, NULL); 181 182 _get_sleep_lock(m, curthread, opts, file, line); 183 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 184 line); 185 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 186 curthread->td_locks++; 187} 188 189void 190_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 191{ 192 MPASS(curthread != NULL); 193 KASSERT(m->mtx_lock != MTX_DESTROYED, 194 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 195 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 196 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 197 file, line)); 198 curthread->td_locks--; 199 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 200 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 201 line); 202 mtx_assert(m, MA_OWNED); 203 204 if (m->mtx_recurse == 0) 205 lock_profile_release_lock(&m->lock_object); 206 _rel_sleep_lock(m, curthread, opts, file, line); 207} 208 209void 210_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 211{ 212 213 MPASS(curthread != NULL); 214 KASSERT(m->mtx_lock != MTX_DESTROYED, 215 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 216 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 217 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 218 m->lock_object.lo_name, file, line)); 219 if (mtx_owned(m)) 220 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 221 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 222 m->lock_object.lo_name, file, line)); 223 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 224 file, line, NULL); 225 _get_spin_lock(m, curthread, opts, file, line); 226 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 227 line); 228 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 229} 230 231void 232_mtx_unlock_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_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 238 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 239 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 240 m->lock_object.lo_name, file, line)); 241 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 242 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 243 line); 244 mtx_assert(m, MA_OWNED); 245 246 _rel_spin_lock(m); 247} 248 249/* 250 * The important part of mtx_trylock{,_flags}() 251 * Tries to acquire lock `m.' If this function is called on a mutex that 252 * is already owned, it will recursively acquire the lock. 253 */ 254int 255_mtx_trylock(struct mtx *m, int opts, const char *file, int line) 256{ 257#ifdef LOCK_PROFILING 258 uint64_t waittime = 0; 259 int contested = 0; 260#endif 261 int rval; 262 263 MPASS(curthread != NULL); 264 KASSERT(m->mtx_lock != MTX_DESTROYED, 265 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 266 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 267 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 268 file, line)); 269 270 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 271 m->mtx_recurse++; 272 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 273 rval = 1; 274 } else 275 rval = _obtain_lock(m, (uintptr_t)curthread); 276 277 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 278 if (rval) { 279 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 280 file, line); 281 curthread->td_locks++; 282 if (m->mtx_recurse == 0) 283 lock_profile_obtain_lock_success(&m->lock_object, contested, 284 waittime, file, line); 285 286 } 287 288 return (rval); 289} 290 291/* 292 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 293 * 294 * We call this if the lock is either contested (i.e. we need to go to 295 * sleep waiting for it), or if we need to recurse on it. 296 */ 297void 298_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 299 int line) 300{ 301 struct turnstile *ts; 302 uintptr_t v; 303#ifdef ADAPTIVE_MUTEXES 304 volatile struct thread *owner; 305#endif 306#ifdef KTR 307 int cont_logged = 0; 308#endif 309#ifdef LOCK_PROFILING 310 int contested = 0; 311 uint64_t waittime = 0; 312#endif 313 314 if (mtx_owned(m)) { 315 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 316 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 317 m->lock_object.lo_name, file, line)); 318 m->mtx_recurse++; 319 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 320 if (LOCK_LOG_TEST(&m->lock_object, opts)) 321 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 322 return; 323 } 324 325 lock_profile_obtain_lock_failed(&m->lock_object, 326 &contested, &waittime); 327 if (LOCK_LOG_TEST(&m->lock_object, opts)) 328 CTR4(KTR_LOCK, 329 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 330 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 331 332 while (!_obtain_lock(m, tid)) { 333#ifdef ADAPTIVE_MUTEXES 334 /* 335 * If the owner is running on another CPU, spin until the 336 * owner stops running or the state of the lock changes. 337 */ 338 v = m->mtx_lock; 339 if (v != MTX_UNOWNED) { 340 owner = (struct thread *)(v & ~MTX_FLAGMASK); 341 if (TD_IS_RUNNING(owner)) { 342 if (LOCK_LOG_TEST(&m->lock_object, 0)) 343 CTR3(KTR_LOCK, 344 "%s: spinning on %p held by %p", 345 __func__, m, owner); 346 while (mtx_owner(m) == owner && 347 TD_IS_RUNNING(owner)) 348 cpu_spinwait(); 349 continue; 350 } 351 } 352#endif 353 354 ts = turnstile_trywait(&m->lock_object); 355 v = m->mtx_lock; 356 357 /* 358 * Check if the lock has been released while spinning for 359 * the turnstile chain lock. 360 */ 361 if (v == MTX_UNOWNED) { 362 turnstile_cancel(ts); 363 cpu_spinwait(); 364 continue; 365 } 366 367#ifdef ADAPTIVE_MUTEXES 368 /* 369 * If the current owner of the lock is executing on another 370 * CPU quit the hard path and try to spin. 371 */ 372 owner = (struct thread *)(v & ~MTX_FLAGMASK); 373 if (TD_IS_RUNNING(owner)) { 374 turnstile_cancel(ts); 375 cpu_spinwait(); 376 continue; 377 } 378#endif 379 380 /* 381 * If the mutex isn't already contested and a failure occurs 382 * setting the contested bit, the mutex was either released 383 * or the state of the MTX_RECURSED bit changed. 384 */ 385 if ((v & MTX_CONTESTED) == 0 && 386 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 387 turnstile_cancel(ts); 388 cpu_spinwait(); 389 continue; 390 } 391 392 /* 393 * We definitely must sleep for this lock. 394 */ 395 mtx_assert(m, MA_NOTOWNED); 396 397#ifdef KTR 398 if (!cont_logged) { 399 CTR6(KTR_CONTENTION, 400 "contention: %p at %s:%d wants %s, taken by %s:%d", 401 (void *)tid, file, line, m->lock_object.lo_name, 402 WITNESS_FILE(&m->lock_object), 403 WITNESS_LINE(&m->lock_object)); 404 cont_logged = 1; 405 } 406#endif 407 408 /* 409 * Block on the turnstile. 410 */ 411 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 412 } 413#ifdef KTR 414 if (cont_logged) { 415 CTR4(KTR_CONTENTION, 416 "contention end: %s acquired by %p at %s:%d", 417 m->lock_object.lo_name, (void *)tid, file, line); 418 } 419#endif 420 lock_profile_obtain_lock_success(&m->lock_object, contested, 421 waittime, file, line); 422} 423 424static void 425_mtx_lock_spin_failed(struct mtx *m) 426{ 427 struct thread *td; 428 429 td = mtx_owner(m); 430 431 /* If the mutex is unlocked, try again. */ 432 if (td == NULL) 433 return; 434 435 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 436 m, m->lock_object.lo_name, td, td->td_tid); 437#ifdef WITNESS 438 witness_display_spinlock(&m->lock_object, td); 439#endif 440 panic("spin lock held too long"); 441} 442 443#ifdef SMP 444/* 445 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 446 * 447 * This is only called if we need to actually spin for the lock. Recursion 448 * is handled inline. 449 */ 450void 451_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 452 int line) 453{ 454 int i = 0; 455#ifdef LOCK_PROFILING 456 int contested = 0; 457 uint64_t waittime = 0; 458#endif 459 460 if (LOCK_LOG_TEST(&m->lock_object, opts)) 461 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 462 463 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 464 while (!_obtain_lock(m, tid)) { 465 466 /* Give interrupts a chance while we spin. */ 467 spinlock_exit(); 468 while (m->mtx_lock != MTX_UNOWNED) { 469 if (i++ < 10000000) { 470 cpu_spinwait(); 471 continue; 472 } 473 if (i < 60000000 || kdb_active || panicstr != NULL) 474 DELAY(1); 475 else 476 _mtx_lock_spin_failed(m); 477 cpu_spinwait(); 478 } 479 spinlock_enter(); 480 } 481 482 if (LOCK_LOG_TEST(&m->lock_object, opts)) 483 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 484 485 lock_profile_obtain_lock_success(&m->lock_object, contested, 486 waittime, (file), (line)); 487} 488#endif /* SMP */ 489 490void 491_thread_lock_flags(struct thread *td, int opts, const char *file, int line) 492{ 493 struct mtx *m; 494 uintptr_t tid; 495 int i; 496#ifdef LOCK_PROFILING 497 int contested = 0; 498 uint64_t waittime = 0; 499#endif 500 501 i = 0; 502 tid = (uintptr_t)curthread; 503 for (;;) { 504retry: 505 spinlock_enter(); 506 m = td->td_lock; 507 KASSERT(m->mtx_lock != MTX_DESTROYED, 508 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 509 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 510 ("thread_lock() of sleep mutex %s @ %s:%d", 511 m->lock_object.lo_name, file, line)); 512 if (mtx_owned(m)) 513 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 514 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 515 m->lock_object.lo_name, file, line)); 516 WITNESS_CHECKORDER(&m->lock_object, 517 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 518 while (!_obtain_lock(m, tid)) { 519 if (m->mtx_lock == tid) { 520 m->mtx_recurse++; 521 break; 522 } 523 lock_profile_obtain_lock_failed(&m->lock_object, 524 &contested, &waittime); 525 /* Give interrupts a chance while we spin. */ 526 spinlock_exit(); 527 while (m->mtx_lock != MTX_UNOWNED) { 528 if (i++ < 10000000) 529 cpu_spinwait(); 530 else if (i < 60000000 || 531 kdb_active || panicstr != NULL) 532 DELAY(1); 533 else 534 _mtx_lock_spin_failed(m); 535 cpu_spinwait(); 536 if (m != td->td_lock) 537 goto retry; 538 } 539 spinlock_enter(); 540 } 541 if (m == td->td_lock) 542 break; 543 _rel_spin_lock(m); /* does spinlock_exit() */ 544 } 545 if (m->mtx_recurse == 0) 546 lock_profile_obtain_lock_success(&m->lock_object, contested, 547 waittime, (file), (line)); 548 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 549 line); 550 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 551} 552 553struct mtx * 554thread_lock_block(struct thread *td) 555{ 556 struct mtx *lock; 557 558 spinlock_enter(); 559 THREAD_LOCK_ASSERT(td, MA_OWNED); 560 lock = td->td_lock; 561 td->td_lock = &blocked_lock; 562 mtx_unlock_spin(lock); 563 564 return (lock); 565} 566 567void 568thread_lock_unblock(struct thread *td, struct mtx *new) 569{ 570 mtx_assert(new, MA_OWNED); 571 MPASS(td->td_lock == &blocked_lock); 572 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 573 spinlock_exit(); 574} 575 576void 577thread_lock_set(struct thread *td, struct mtx *new) 578{ 579 struct mtx *lock; 580 581 mtx_assert(new, MA_OWNED); 582 THREAD_LOCK_ASSERT(td, MA_OWNED); 583 lock = td->td_lock; 584 td->td_lock = new; 585 mtx_unlock_spin(lock); 586} 587 588/* 589 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 590 * 591 * We are only called here if the lock is recursed or contested (i.e. we 592 * need to wake up a blocked thread). 593 */ 594void 595_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 596{ 597 struct turnstile *ts; 598 599 if (mtx_recursed(m)) { 600 if (--(m->mtx_recurse) == 0) 601 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 602 if (LOCK_LOG_TEST(&m->lock_object, opts)) 603 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 604 return; 605 } 606 607 /* 608 * We have to lock the chain before the turnstile so this turnstile 609 * can be removed from the hash list if it is empty. 610 */ 611 turnstile_chain_lock(&m->lock_object); 612 ts = turnstile_lookup(&m->lock_object); 613 if (LOCK_LOG_TEST(&m->lock_object, opts)) 614 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 615 MPASS(ts != NULL); 616 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 617 _release_lock_quick(m); 618 619 /* 620 * This turnstile is now no longer associated with the mutex. We can 621 * unlock the chain lock so a new turnstile may take it's place. 622 */ 623 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 624 turnstile_chain_unlock(&m->lock_object); 625} 626 627/* 628 * All the unlocking of MTX_SPIN locks is done inline. 629 * See the _rel_spin_lock() macro for the details. 630 */ 631 632/* 633 * The backing function for the INVARIANTS-enabled mtx_assert() 634 */ 635#ifdef INVARIANT_SUPPORT 636void 637_mtx_assert(struct mtx *m, int what, const char *file, int line) 638{ 639 640 if (panicstr != NULL || dumping) 641 return; 642 switch (what) { 643 case MA_OWNED: 644 case MA_OWNED | MA_RECURSED: 645 case MA_OWNED | MA_NOTRECURSED: 646 if (!mtx_owned(m)) 647 panic("mutex %s not owned at %s:%d", 648 m->lock_object.lo_name, file, line); 649 if (mtx_recursed(m)) { 650 if ((what & MA_NOTRECURSED) != 0) 651 panic("mutex %s recursed at %s:%d", 652 m->lock_object.lo_name, file, line); 653 } else if ((what & MA_RECURSED) != 0) { 654 panic("mutex %s unrecursed at %s:%d", 655 m->lock_object.lo_name, file, line); 656 } 657 break; 658 case MA_NOTOWNED: 659 if (mtx_owned(m)) 660 panic("mutex %s owned at %s:%d", 661 m->lock_object.lo_name, file, line); 662 break; 663 default: 664 panic("unknown mtx_assert at %s:%d", file, line); 665 } 666} 667#endif 668 669/* 670 * The MUTEX_DEBUG-enabled mtx_validate() 671 * 672 * Most of these checks have been moved off into the LO_INITIALIZED flag 673 * maintained by the witness code. 674 */ 675#ifdef MUTEX_DEBUG 676 677void mtx_validate(struct mtx *); 678 679void 680mtx_validate(struct mtx *m) 681{ 682 683/* 684 * XXX: When kernacc() does not require Giant we can reenable this check 685 */ 686#ifdef notyet 687 /* 688 * Can't call kernacc() from early init386(), especially when 689 * initializing Giant mutex, because some stuff in kernacc() 690 * requires Giant itself. 691 */ 692 if (!cold) 693 if (!kernacc((caddr_t)m, sizeof(m), 694 VM_PROT_READ | VM_PROT_WRITE)) 695 panic("Can't read and write to mutex %p", m); 696#endif 697} 698#endif 699 700/* 701 * General init routine used by the MTX_SYSINIT() macro. 702 */ 703void 704mtx_sysinit(void *arg) 705{ 706 struct mtx_args *margs = arg; 707 708 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 709} 710 711/* 712 * Mutex initialization routine; initialize lock `m' of type contained in 713 * `opts' with options contained in `opts' and name `name.' The optional 714 * lock type `type' is used as a general lock category name for use with 715 * witness. 716 */ 717void 718mtx_init(struct mtx *m, const char *name, const char *type, int opts) 719{ 720 struct lock_class *class; 721 int flags; 722 723 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 724 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 725 726#ifdef MUTEX_DEBUG 727 /* Diagnostic and error correction */ 728 mtx_validate(m); 729#endif 730 731 /* Determine lock class and lock flags. */ 732 if (opts & MTX_SPIN) 733 class = &lock_class_mtx_spin; 734 else 735 class = &lock_class_mtx_sleep; 736 flags = 0; 737 if (opts & MTX_QUIET) 738 flags |= LO_QUIET; 739 if (opts & MTX_RECURSE) 740 flags |= LO_RECURSABLE; 741 if ((opts & MTX_NOWITNESS) == 0) 742 flags |= LO_WITNESS; 743 if (opts & MTX_DUPOK) 744 flags |= LO_DUPOK; 745 if (opts & MTX_NOPROFILE) 746 flags |= LO_NOPROFILE; 747 748 /* Initialize mutex. */ 749 m->mtx_lock = MTX_UNOWNED; 750 m->mtx_recurse = 0; 751 752 lock_init(&m->lock_object, class, name, type, flags); 753} 754 755/* 756 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 757 * passed in as a flag here because if the corresponding mtx_init() was 758 * called with MTX_QUIET set, then it will already be set in the mutex's 759 * flags. 760 */ 761void 762mtx_destroy(struct mtx *m) 763{ 764 765 if (!mtx_owned(m)) 766 MPASS(mtx_unowned(m)); 767 else { 768 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 769 770 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 771 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 772 spinlock_exit(); 773 else 774 curthread->td_locks--; 775 776 lock_profile_release_lock(&m->lock_object); 777 /* Tell witness this isn't locked to make it happy. */ 778 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 779 __LINE__); 780 } 781 782 m->mtx_lock = MTX_DESTROYED; 783 lock_destroy(&m->lock_object); 784} 785 786/* 787 * Intialize the mutex code and system mutexes. This is called from the MD 788 * startup code prior to mi_startup(). The per-CPU data space needs to be 789 * setup before this is called. 790 */ 791void 792mutex_init(void) 793{ 794 795 /* Setup turnstiles so that sleep mutexes work. */ 796 init_turnstiles(); 797 798 /* 799 * Initialize mutexes. 800 */ 801 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 802 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 803 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 804 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 805 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 806 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 807 mtx_lock(&Giant); 808} 809 810#ifdef DDB 811void 812db_show_mtx(struct lock_object *lock) 813{ 814 struct thread *td; 815 struct mtx *m; 816 817 m = (struct mtx *)lock; 818 819 db_printf(" flags: {"); 820 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 821 db_printf("SPIN"); 822 else 823 db_printf("DEF"); 824 if (m->lock_object.lo_flags & LO_RECURSABLE) 825 db_printf(", RECURSE"); 826 if (m->lock_object.lo_flags & LO_DUPOK) 827 db_printf(", DUPOK"); 828 db_printf("}\n"); 829 db_printf(" state: {"); 830 if (mtx_unowned(m)) 831 db_printf("UNOWNED"); 832 else if (mtx_destroyed(m)) 833 db_printf("DESTROYED"); 834 else { 835 db_printf("OWNED"); 836 if (m->mtx_lock & MTX_CONTESTED) 837 db_printf(", CONTESTED"); 838 if (m->mtx_lock & MTX_RECURSED) 839 db_printf(", RECURSED"); 840 } 841 db_printf("}\n"); 842 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 843 td = mtx_owner(m); 844 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 845 td->td_tid, td->td_proc->p_pid, td->td_name); 846 if (mtx_recursed(m)) 847 db_printf(" recursed: %d\n", m->mtx_recurse); 848 } 849} 850#endif 851