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("$FreeBSD$"); 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 /* 85 * Internal utility macros. 86 */ 87 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 88 89 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 90 91 #ifdef DDB 92 static void db_show_mtx(struct lock_object *lock); 93 #endif 94 95 /* 96 * Lock classes for sleep and spin mutexes. 97 */ 98 struct lock_class lock_class_mtx_sleep = { 99 "sleep mutex", 100 LC_SLEEPLOCK | LC_RECURSABLE, 101 #ifdef DDB 102 db_show_mtx 103 #endif 104 }; 105 struct lock_class lock_class_mtx_spin = { 106 "spin mutex", 107 LC_SPINLOCK | LC_RECURSABLE, 108 #ifdef DDB 109 db_show_mtx 110 #endif 111 }; 112 113 /* 114 * System-wide mutexes 115 */ 116 struct mtx sched_lock; 117 struct mtx Giant; 118 119 #ifdef LOCK_PROFILING 120 static inline void lock_profile_init(void) 121 { 122 int i; 123 /* Initialize the mutex profiling locks */ 124 for (i = 0; i < LPROF_LOCK_SIZE; i++) { 125 mtx_init(&lprof_locks[i], "mprof lock", 126 NULL, MTX_SPIN|MTX_QUIET|MTX_NOPROFILE); 127 } 128 } 129 #else 130 static inline void lock_profile_init(void) {;} 131 #endif 132 133 /* 134 * Function versions of the inlined __mtx_* macros. These are used by 135 * modules and can also be called from assembly language if needed. 136 */ 137 void 138 _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 139 { 140 uint64_t waittime; 141 142 MPASS(curthread != NULL); 143 KASSERT(m->mtx_lock != MTX_DESTROYED, 144 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 145 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_sleep, 146 ("mtx_lock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name, 147 file, line)); 148 WITNESS_CHECKORDER(&m->mtx_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 149 file, line); 150 151 lock_profile_waitstart(&waittime); 152 _get_sleep_lock(m, curthread, opts, file, line); 153 LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file, 154 line); 155 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); 156 curthread->td_locks++; 157 lock_profile_obtain_lock_success(&m->mtx_object, waittime, file, line); 158 } 159 160 void 161 _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 162 { 163 164 MPASS(curthread != NULL); 165 KASSERT(m->mtx_lock != MTX_DESTROYED, 166 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 167 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_sleep, 168 ("mtx_unlock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name, 169 file, line)); 170 curthread->td_locks--; 171 WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); 172 LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file, 173 line); 174 mtx_assert(m, MA_OWNED); 175 176 lock_profile_release_lock(&m->mtx_object); 177 _rel_sleep_lock(m, curthread, opts, file, line); 178 } 179 180 void 181 _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 182 { 183 184 uint64_t waittime; 185 186 MPASS(curthread != NULL); 187 KASSERT(m->mtx_lock != MTX_DESTROYED, 188 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 189 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_spin, 190 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 191 m->mtx_object.lo_name, file, line)); 192 WITNESS_CHECKORDER(&m->mtx_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 193 file, line); 194 lock_profile_waitstart(&waittime); 195 _get_spin_lock(m, curthread, opts, file, line); 196 LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file, 197 line); 198 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); 199 lock_profile_obtain_lock_success(&m->mtx_object, waittime, file, line); 200 } 201 202 void 203 _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 204 { 205 206 MPASS(curthread != NULL); 207 KASSERT(m->mtx_lock != MTX_DESTROYED, 208 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 209 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_spin, 210 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 211 m->mtx_object.lo_name, file, line)); 212 WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); 213 LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file, 214 line); 215 mtx_assert(m, MA_OWNED); 216 lock_profile_release_lock(&m->mtx_object); 217 _rel_spin_lock(m); 218 } 219 220 /* 221 * The important part of mtx_trylock{,_flags}() 222 * Tries to acquire lock `m.' If this function is called on a mutex that 223 * is already owned, it will recursively acquire the lock. 224 */ 225 int 226 _mtx_trylock(struct mtx *m, int opts, const char *file, int line) 227 { 228 int rval; 229 uint64_t waittime = 0; 230 231 MPASS(curthread != NULL); 232 KASSERT(m->mtx_lock != MTX_DESTROYED, 233 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 234 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_sleep, 235 ("mtx_trylock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name, 236 file, line)); 237 238 if (mtx_owned(m) && (m->mtx_object.lo_flags & LO_RECURSABLE) != 0) { 239 m->mtx_recurse++; 240 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 241 rval = 1; 242 } else 243 rval = _obtain_lock(m, (uintptr_t)curthread); 244 245 LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line); 246 if (rval) { 247 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 248 file, line); 249 curthread->td_locks++; 250 lock_profile_obtain_lock_success(&m->mtx_object, waittime, file, line); 251 252 } 253 254 return (rval); 255 } 256 257 /* 258 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 259 * 260 * We call this if the lock is either contested (i.e. we need to go to 261 * sleep waiting for it), or if we need to recurse on it. 262 */ 263 void 264 _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 265 int line) 266 { 267 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 268 volatile struct thread *owner; 269 #endif 270 #ifdef KTR 271 int cont_logged = 0; 272 #endif 273 uintptr_t v; 274 int contested = 0; 275 276 if (mtx_owned(m)) { 277 KASSERT((m->mtx_object.lo_flags & LO_RECURSABLE) != 0, 278 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 279 m->mtx_object.lo_name, file, line)); 280 m->mtx_recurse++; 281 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 282 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 283 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 284 return; 285 } 286 287 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 288 CTR4(KTR_LOCK, 289 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 290 m->mtx_object.lo_name, (void *)m->mtx_lock, file, line); 291 292 while (!_obtain_lock(m, tid)) { 293 lock_profile_obtain_lock_failed(&m->mtx_object, &contested); 294 turnstile_lock(&m->mtx_object); 295 v = m->mtx_lock; 296 297 /* 298 * Check if the lock has been released while spinning for 299 * the turnstile chain lock. 300 */ 301 if (v == MTX_UNOWNED) { 302 turnstile_release(&m->mtx_object); 303 cpu_spinwait(); 304 continue; 305 } 306 307 #ifdef MUTEX_WAKE_ALL 308 MPASS(v != MTX_CONTESTED); 309 #else 310 /* 311 * The mutex was marked contested on release. This means that 312 * there are other threads blocked on it. Grab ownership of 313 * it and propagate its priority to the current thread if 314 * necessary. 315 */ 316 if (v == MTX_CONTESTED) { 317 m->mtx_lock = tid | MTX_CONTESTED; 318 turnstile_claim(&m->mtx_object); 319 break; 320 } 321 #endif 322 323 /* 324 * If the mutex isn't already contested and a failure occurs 325 * setting the contested bit, the mutex was either released 326 * or the state of the MTX_RECURSED bit changed. 327 */ 328 if ((v & MTX_CONTESTED) == 0 && 329 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 330 turnstile_release(&m->mtx_object); 331 cpu_spinwait(); 332 continue; 333 } 334 335 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 336 /* 337 * If the current owner of the lock is executing on another 338 * CPU, spin instead of blocking. 339 */ 340 owner = (struct thread *)(v & ~MTX_FLAGMASK); 341 #ifdef ADAPTIVE_GIANT 342 if (TD_IS_RUNNING(owner)) 343 #else 344 if (m != &Giant && TD_IS_RUNNING(owner)) 345 #endif 346 { 347 turnstile_release(&m->mtx_object); 348 while (mtx_owner(m) == owner && TD_IS_RUNNING(owner)) { 349 cpu_spinwait(); 350 } 351 continue; 352 } 353 #endif /* SMP && !NO_ADAPTIVE_MUTEXES */ 354 355 /* 356 * We definitely must sleep for this lock. 357 */ 358 mtx_assert(m, MA_NOTOWNED); 359 360 #ifdef KTR 361 if (!cont_logged) { 362 CTR6(KTR_CONTENTION, 363 "contention: %p at %s:%d wants %s, taken by %s:%d", 364 (void *)tid, file, line, m->mtx_object.lo_name, 365 WITNESS_FILE(&m->mtx_object), 366 WITNESS_LINE(&m->mtx_object)); 367 cont_logged = 1; 368 } 369 #endif 370 371 /* 372 * Block on the turnstile. 373 */ 374 turnstile_wait(&m->mtx_object, mtx_owner(m), 375 TS_EXCLUSIVE_QUEUE); 376 } 377 #ifdef KTR 378 if (cont_logged) { 379 CTR4(KTR_CONTENTION, 380 "contention end: %s acquired by %p at %s:%d", 381 m->mtx_object.lo_name, (void *)tid, file, line); 382 } 383 #endif 384 #ifdef LOCK_PROFILING 385 m->mtx_object.lo_profile_obj.lpo_contest_holding = 0; 386 if (contested) 387 m->mtx_object.lo_profile_obj.lpo_contest_locking++; 388 #endif 389 return; 390 } 391 392 #ifdef SMP 393 /* 394 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 395 * 396 * This is only called if we need to actually spin for the lock. Recursion 397 * is handled inline. 398 */ 399 void 400 _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 401 int line) 402 { 403 struct thread *td; 404 int contested = 0, i = 0; 405 406 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 407 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 408 409 while (!_obtain_lock(m, tid)) { 410 lock_profile_obtain_lock_failed(&m->mtx_object, &contested); 411 412 /* Give interrupts a chance while we spin. */ 413 spinlock_exit(); 414 while (m->mtx_lock != MTX_UNOWNED) { 415 if (i++ < 10000000) { 416 cpu_spinwait(); 417 continue; 418 } 419 if (i < 60000000 || kdb_active || panicstr != NULL) 420 DELAY(1); 421 else { 422 td = mtx_owner(m); 423 424 /* If the mutex is unlocked, try again. */ 425 if (td == NULL) 426 continue; 427 printf( 428 "spin lock %p (%s) held by %p (tid %d) too long\n", 429 m, m->mtx_object.lo_name, td, td->td_tid); 430 #ifdef WITNESS 431 witness_display_spinlock(&m->mtx_object, td); 432 #endif 433 panic("spin lock held too long"); 434 } 435 cpu_spinwait(); 436 } 437 spinlock_enter(); 438 } 439 440 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 441 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 442 443 return; 444 } 445 #endif /* SMP */ 446 447 /* 448 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 449 * 450 * We are only called here if the lock is recursed or contested (i.e. we 451 * need to wake up a blocked thread). 452 */ 453 void 454 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 455 { 456 struct turnstile *ts; 457 #ifndef PREEMPTION 458 struct thread *td, *td1; 459 #endif 460 461 if (mtx_recursed(m)) { 462 if (--(m->mtx_recurse) == 0) 463 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 464 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 465 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 466 return; 467 } 468 469 turnstile_lock(&m->mtx_object); 470 ts = turnstile_lookup(&m->mtx_object); 471 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 472 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 473 474 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 475 if (ts == NULL) { 476 _release_lock_quick(m); 477 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 478 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m); 479 turnstile_release(&m->mtx_object); 480 return; 481 } 482 #else 483 MPASS(ts != NULL); 484 #endif 485 #ifndef PREEMPTION 486 /* XXX */ 487 td1 = turnstile_head(ts, TS_EXCLUSIVE_QUEUE); 488 #endif 489 #ifdef MUTEX_WAKE_ALL 490 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 491 _release_lock_quick(m); 492 #else 493 if (turnstile_signal(ts, TS_EXCLUSIVE_QUEUE)) { 494 _release_lock_quick(m); 495 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 496 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); 497 } else { 498 m->mtx_lock = MTX_CONTESTED; 499 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 500 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p still contested", 501 m); 502 } 503 #endif 504 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 505 506 #ifndef PREEMPTION 507 /* 508 * XXX: This is just a hack until preemption is done. However, 509 * once preemption is done we need to either wrap the 510 * turnstile_signal() and release of the actual lock in an 511 * extra critical section or change the preemption code to 512 * always just set a flag and never do instant-preempts. 513 */ 514 td = curthread; 515 if (td->td_critnest > 0 || td1->td_priority >= td->td_priority) 516 return; 517 mtx_lock_spin(&sched_lock); 518 if (!TD_IS_RUNNING(td1)) { 519 #ifdef notyet 520 if (td->td_ithd != NULL) { 521 struct ithd *it = td->td_ithd; 522 523 if (it->it_interrupted) { 524 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 525 CTR2(KTR_LOCK, 526 "_mtx_unlock_sleep: %p interrupted %p", 527 it, it->it_interrupted); 528 intr_thd_fixup(it); 529 } 530 } 531 #endif 532 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 533 CTR2(KTR_LOCK, 534 "_mtx_unlock_sleep: %p switching out lock=%p", m, 535 (void *)m->mtx_lock); 536 537 mi_switch(SW_INVOL, NULL); 538 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 539 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p", 540 m, (void *)m->mtx_lock); 541 } 542 mtx_unlock_spin(&sched_lock); 543 #endif 544 545 return; 546 } 547 548 /* 549 * All the unlocking of MTX_SPIN locks is done inline. 550 * See the _rel_spin_lock() macro for the details. 551 */ 552 553 /* 554 * The backing function for the INVARIANTS-enabled mtx_assert() 555 */ 556 #ifdef INVARIANT_SUPPORT 557 void 558 _mtx_assert(struct mtx *m, int what, const char *file, int line) 559 { 560 561 if (panicstr != NULL || dumping) 562 return; 563 switch (what) { 564 case MA_OWNED: 565 case MA_OWNED | MA_RECURSED: 566 case MA_OWNED | MA_NOTRECURSED: 567 if (!mtx_owned(m)) 568 panic("mutex %s not owned at %s:%d", 569 m->mtx_object.lo_name, file, line); 570 if (mtx_recursed(m)) { 571 if ((what & MA_NOTRECURSED) != 0) 572 panic("mutex %s recursed at %s:%d", 573 m->mtx_object.lo_name, file, line); 574 } else if ((what & MA_RECURSED) != 0) { 575 panic("mutex %s unrecursed at %s:%d", 576 m->mtx_object.lo_name, file, line); 577 } 578 break; 579 case MA_NOTOWNED: 580 if (mtx_owned(m)) 581 panic("mutex %s owned at %s:%d", 582 m->mtx_object.lo_name, file, line); 583 break; 584 default: 585 panic("unknown mtx_assert at %s:%d", file, line); 586 } 587 } 588 #endif 589 590 /* 591 * The MUTEX_DEBUG-enabled mtx_validate() 592 * 593 * Most of these checks have been moved off into the LO_INITIALIZED flag 594 * maintained by the witness code. 595 */ 596 #ifdef MUTEX_DEBUG 597 598 void mtx_validate(struct mtx *); 599 600 void 601 mtx_validate(struct mtx *m) 602 { 603 604 /* 605 * XXX: When kernacc() does not require Giant we can reenable this check 606 */ 607 #ifdef notyet 608 /* 609 * Can't call kernacc() from early init386(), especially when 610 * initializing Giant mutex, because some stuff in kernacc() 611 * requires Giant itself. 612 */ 613 if (!cold) 614 if (!kernacc((caddr_t)m, sizeof(m), 615 VM_PROT_READ | VM_PROT_WRITE)) 616 panic("Can't read and write to mutex %p", m); 617 #endif 618 } 619 #endif 620 621 /* 622 * General init routine used by the MTX_SYSINIT() macro. 623 */ 624 void 625 mtx_sysinit(void *arg) 626 { 627 struct mtx_args *margs = arg; 628 629 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 630 } 631 632 /* 633 * Mutex initialization routine; initialize lock `m' of type contained in 634 * `opts' with options contained in `opts' and name `name.' The optional 635 * lock type `type' is used as a general lock category name for use with 636 * witness. 637 */ 638 void 639 mtx_init(struct mtx *m, const char *name, const char *type, int opts) 640 { 641 struct lock_class *class; 642 int flags; 643 644 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 645 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 646 647 #ifdef MUTEX_DEBUG 648 /* Diagnostic and error correction */ 649 mtx_validate(m); 650 #endif 651 652 /* Determine lock class and lock flags. */ 653 if (opts & MTX_SPIN) 654 class = &lock_class_mtx_spin; 655 else 656 class = &lock_class_mtx_sleep; 657 flags = 0; 658 if (opts & MTX_QUIET) 659 flags |= LO_QUIET; 660 if (opts & MTX_RECURSE) 661 flags |= LO_RECURSABLE; 662 if ((opts & MTX_NOWITNESS) == 0) 663 flags |= LO_WITNESS; 664 if (opts & MTX_DUPOK) 665 flags |= LO_DUPOK; 666 if (opts & MTX_NOPROFILE) 667 flags |= LO_NOPROFILE; 668 669 /* Initialize mutex. */ 670 m->mtx_lock = MTX_UNOWNED; 671 m->mtx_recurse = 0; 672 673 lock_profile_object_init(&m->mtx_object, class, name); 674 lock_init(&m->mtx_object, class, name, type, flags); 675 } 676 677 /* 678 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 679 * passed in as a flag here because if the corresponding mtx_init() was 680 * called with MTX_QUIET set, then it will already be set in the mutex's 681 * flags. 682 */ 683 void 684 mtx_destroy(struct mtx *m) 685 { 686 687 if (!mtx_owned(m)) 688 MPASS(mtx_unowned(m)); 689 else { 690 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 691 692 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 693 if (LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_spin) 694 spinlock_exit(); 695 else 696 curthread->td_locks--; 697 698 /* Tell witness this isn't locked to make it happy. */ 699 WITNESS_UNLOCK(&m->mtx_object, LOP_EXCLUSIVE, __FILE__, 700 __LINE__); 701 } 702 703 m->mtx_lock = MTX_DESTROYED; 704 lock_profile_object_destroy(&m->mtx_object); 705 lock_destroy(&m->mtx_object); 706 } 707 708 /* 709 * Intialize the mutex code and system mutexes. This is called from the MD 710 * startup code prior to mi_startup(). The per-CPU data space needs to be 711 * setup before this is called. 712 */ 713 void 714 mutex_init(void) 715 { 716 717 /* Setup turnstiles so that sleep mutexes work. */ 718 init_turnstiles(); 719 720 /* 721 * Initialize mutexes. 722 */ 723 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 724 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 725 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 726 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 727 mtx_lock(&Giant); 728 729 lock_profile_init(); 730 } 731 732 #ifdef DDB 733 void 734 db_show_mtx(struct lock_object *lock) 735 { 736 struct thread *td; 737 struct mtx *m; 738 739 m = (struct mtx *)lock; 740 741 db_printf(" flags: {"); 742 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 743 db_printf("SPIN"); 744 else 745 db_printf("DEF"); 746 if (m->mtx_object.lo_flags & LO_RECURSABLE) 747 db_printf(", RECURSE"); 748 if (m->mtx_object.lo_flags & LO_DUPOK) 749 db_printf(", DUPOK"); 750 db_printf("}\n"); 751 db_printf(" state: {"); 752 if (mtx_unowned(m)) 753 db_printf("UNOWNED"); 754 else { 755 db_printf("OWNED"); 756 if (m->mtx_lock & MTX_CONTESTED) 757 db_printf(", CONTESTED"); 758 if (m->mtx_lock & MTX_RECURSED) 759 db_printf(", RECURSED"); 760 } 761 db_printf("}\n"); 762 if (!mtx_unowned(m)) { 763 td = mtx_owner(m); 764 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 765 td->td_tid, td->td_proc->p_pid, td->td_proc->p_comm); 766 if (mtx_recursed(m)) 767 db_printf(" recursed: %d\n", m->mtx_recurse); 768 } 769 } 770 #endif 771