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 static void lock_mtx(struct lock_object *lock, int how); 95 static void lock_spin(struct lock_object *lock, int how); 96 static int unlock_mtx(struct lock_object *lock); 97 static int unlock_spin(struct lock_object *lock); 98 99 /* 100 * Lock classes for sleep and spin mutexes. 101 */ 102 struct lock_class lock_class_mtx_sleep = { 103 .lc_name = "sleep mutex", 104 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 105 #ifdef DDB 106 .lc_ddb_show = db_show_mtx, 107 #endif 108 .lc_lock = lock_mtx, 109 .lc_unlock = unlock_mtx, 110 }; 111 struct lock_class lock_class_mtx_spin = { 112 .lc_name = "spin mutex", 113 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 114 #ifdef DDB 115 .lc_ddb_show = db_show_mtx, 116 #endif 117 .lc_lock = lock_spin, 118 .lc_unlock = unlock_spin, 119 }; 120 121 /* 122 * System-wide mutexes 123 */ 124 struct mtx sched_lock; 125 struct mtx Giant; 126 127 #ifdef LOCK_PROFILING 128 static inline void lock_profile_init(void) 129 { 130 int i; 131 /* Initialize the mutex profiling locks */ 132 for (i = 0; i < LPROF_LOCK_SIZE; i++) { 133 mtx_init(&lprof_locks[i], "mprof lock", 134 NULL, MTX_SPIN|MTX_QUIET|MTX_NOPROFILE); 135 } 136 } 137 #else 138 static inline void lock_profile_init(void) {;} 139 #endif 140 141 void 142 lock_mtx(struct lock_object *lock, int how) 143 { 144 145 mtx_lock((struct mtx *)lock); 146 } 147 148 void 149 lock_spin(struct lock_object *lock, int how) 150 { 151 152 panic("spin locks can only use msleep_spin"); 153 } 154 155 int 156 unlock_mtx(struct lock_object *lock) 157 { 158 struct mtx *m; 159 160 m = (struct mtx *)lock; 161 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 162 mtx_unlock(m); 163 return (0); 164 } 165 166 int 167 unlock_spin(struct lock_object *lock) 168 { 169 170 panic("spin locks can only use msleep_spin"); 171 } 172 173 /* 174 * Function versions of the inlined __mtx_* macros. These are used by 175 * modules and can also be called from assembly language if needed. 176 */ 177 void 178 _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 179 { 180 181 MPASS(curthread != NULL); 182 KASSERT(m->mtx_lock != MTX_DESTROYED, 183 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 184 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_sleep, 185 ("mtx_lock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name, 186 file, line)); 187 WITNESS_CHECKORDER(&m->mtx_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 188 file, line); 189 190 _get_sleep_lock(m, curthread, opts, file, line); 191 LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file, 192 line); 193 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); 194 curthread->td_locks++; 195 } 196 197 void 198 _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 199 { 200 MPASS(curthread != NULL); 201 KASSERT(m->mtx_lock != MTX_DESTROYED, 202 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 203 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_sleep, 204 ("mtx_unlock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name, 205 file, line)); 206 curthread->td_locks--; 207 WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); 208 LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file, 209 line); 210 mtx_assert(m, MA_OWNED); 211 212 lock_profile_release_lock(&m->mtx_object); 213 _rel_sleep_lock(m, curthread, opts, file, line); 214 } 215 216 void 217 _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 218 { 219 220 MPASS(curthread != NULL); 221 KASSERT(m->mtx_lock != MTX_DESTROYED, 222 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 223 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_spin, 224 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 225 m->mtx_object.lo_name, file, line)); 226 WITNESS_CHECKORDER(&m->mtx_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 227 file, line); 228 _get_spin_lock(m, curthread, opts, file, line); 229 LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file, 230 line); 231 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); 232 } 233 234 void 235 _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 236 { 237 238 MPASS(curthread != NULL); 239 KASSERT(m->mtx_lock != MTX_DESTROYED, 240 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 241 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_spin, 242 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 243 m->mtx_object.lo_name, file, line)); 244 WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); 245 LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file, 246 line); 247 mtx_assert(m, MA_OWNED); 248 249 lock_profile_release_lock(&m->mtx_object); 250 _rel_spin_lock(m); 251 } 252 253 /* 254 * The important part of mtx_trylock{,_flags}() 255 * Tries to acquire lock `m.' If this function is called on a mutex that 256 * is already owned, it will recursively acquire the lock. 257 */ 258 int 259 _mtx_trylock(struct mtx *m, int opts, const char *file, int line) 260 { 261 int rval, contested = 0; 262 uint64_t waittime = 0; 263 264 MPASS(curthread != NULL); 265 KASSERT(m->mtx_lock != MTX_DESTROYED, 266 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 267 KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_sleep, 268 ("mtx_trylock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name, 269 file, line)); 270 271 if (mtx_owned(m) && (m->mtx_object.lo_flags & LO_RECURSABLE) != 0) { 272 m->mtx_recurse++; 273 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 274 rval = 1; 275 } else 276 rval = _obtain_lock(m, (uintptr_t)curthread); 277 278 LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line); 279 if (rval) { 280 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 281 file, line); 282 curthread->td_locks++; 283 if (m->mtx_recurse == 0) 284 lock_profile_obtain_lock_success(&m->mtx_object, contested, 285 waittime, file, line); 286 287 } 288 289 return (rval); 290 } 291 292 /* 293 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 294 * 295 * We call this if the lock is either contested (i.e. we need to go to 296 * sleep waiting for it), or if we need to recurse on it. 297 */ 298 void 299 _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 300 int line) 301 { 302 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 303 volatile struct thread *owner; 304 #endif 305 #ifdef KTR 306 int cont_logged = 0; 307 #endif 308 uintptr_t v; 309 310 if (mtx_owned(m)) { 311 KASSERT((m->mtx_object.lo_flags & LO_RECURSABLE) != 0, 312 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 313 m->mtx_object.lo_name, file, line)); 314 m->mtx_recurse++; 315 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 316 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 317 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 318 return; 319 } 320 321 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 322 CTR4(KTR_LOCK, 323 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 324 m->mtx_object.lo_name, (void *)m->mtx_lock, file, line); 325 326 while (!_obtain_lock(m, tid)) { 327 turnstile_lock(&m->mtx_object); 328 v = m->mtx_lock; 329 330 /* 331 * Check if the lock has been released while spinning for 332 * the turnstile chain lock. 333 */ 334 if (v == MTX_UNOWNED) { 335 turnstile_release(&m->mtx_object); 336 cpu_spinwait(); 337 continue; 338 } 339 340 #ifdef MUTEX_WAKE_ALL 341 MPASS(v != MTX_CONTESTED); 342 #else 343 /* 344 * The mutex was marked contested on release. This means that 345 * there are other threads blocked on it. Grab ownership of 346 * it and propagate its priority to the current thread if 347 * necessary. 348 */ 349 if (v == MTX_CONTESTED) { 350 m->mtx_lock = tid | MTX_CONTESTED; 351 turnstile_claim(&m->mtx_object); 352 break; 353 } 354 #endif 355 356 /* 357 * If the mutex isn't already contested and a failure occurs 358 * setting the contested bit, the mutex was either released 359 * or the state of the MTX_RECURSED bit changed. 360 */ 361 if ((v & MTX_CONTESTED) == 0 && 362 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 363 turnstile_release(&m->mtx_object); 364 cpu_spinwait(); 365 continue; 366 } 367 368 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 369 /* 370 * If the current owner of the lock is executing on another 371 * CPU, spin instead of blocking. 372 */ 373 owner = (struct thread *)(v & ~MTX_FLAGMASK); 374 #ifdef ADAPTIVE_GIANT 375 if (TD_IS_RUNNING(owner)) 376 #else 377 if (m != &Giant && TD_IS_RUNNING(owner)) 378 #endif 379 { 380 turnstile_release(&m->mtx_object); 381 while (mtx_owner(m) == owner && TD_IS_RUNNING(owner)) { 382 cpu_spinwait(); 383 } 384 continue; 385 } 386 #endif /* SMP && !NO_ADAPTIVE_MUTEXES */ 387 388 /* 389 * We definitely must sleep for this lock. 390 */ 391 mtx_assert(m, MA_NOTOWNED); 392 393 #ifdef KTR 394 if (!cont_logged) { 395 CTR6(KTR_CONTENTION, 396 "contention: %p at %s:%d wants %s, taken by %s:%d", 397 (void *)tid, file, line, m->mtx_object.lo_name, 398 WITNESS_FILE(&m->mtx_object), 399 WITNESS_LINE(&m->mtx_object)); 400 cont_logged = 1; 401 } 402 #endif 403 404 /* 405 * Block on the turnstile. 406 */ 407 turnstile_wait(&m->mtx_object, mtx_owner(m), 408 TS_EXCLUSIVE_QUEUE); 409 } 410 #ifdef KTR 411 if (cont_logged) { 412 CTR4(KTR_CONTENTION, 413 "contention end: %s acquired by %p at %s:%d", 414 m->mtx_object.lo_name, (void *)tid, file, line); 415 } 416 #endif 417 return; 418 } 419 420 #ifdef SMP 421 /* 422 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 423 * 424 * This is only called if we need to actually spin for the lock. Recursion 425 * is handled inline. 426 */ 427 void 428 _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 429 int line) 430 { 431 int i = 0; 432 struct thread *td; 433 434 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 435 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 436 437 while (!_obtain_lock(m, tid)) { 438 439 /* Give interrupts a chance while we spin. */ 440 spinlock_exit(); 441 while (m->mtx_lock != MTX_UNOWNED) { 442 if (i++ < 10000000) { 443 cpu_spinwait(); 444 continue; 445 } 446 if (i < 60000000 || kdb_active || panicstr != NULL) 447 DELAY(1); 448 else { 449 td = mtx_owner(m); 450 451 /* If the mutex is unlocked, try again. */ 452 if (td == NULL) 453 continue; 454 printf( 455 "spin lock %p (%s) held by %p (tid %d) too long\n", 456 m, m->mtx_object.lo_name, td, td->td_tid); 457 #ifdef WITNESS 458 witness_display_spinlock(&m->mtx_object, td); 459 #endif 460 panic("spin lock held too long"); 461 } 462 cpu_spinwait(); 463 } 464 spinlock_enter(); 465 } 466 467 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 468 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 469 470 return; 471 } 472 #endif /* SMP */ 473 474 /* 475 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 476 * 477 * We are only called here if the lock is recursed or contested (i.e. we 478 * need to wake up a blocked thread). 479 */ 480 void 481 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 482 { 483 struct turnstile *ts; 484 #ifndef PREEMPTION 485 struct thread *td, *td1; 486 #endif 487 488 if (mtx_recursed(m)) { 489 if (--(m->mtx_recurse) == 0) 490 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 491 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 492 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 493 return; 494 } 495 496 turnstile_lock(&m->mtx_object); 497 ts = turnstile_lookup(&m->mtx_object); 498 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 499 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 500 501 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 502 if (ts == NULL) { 503 _release_lock_quick(m); 504 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 505 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m); 506 turnstile_release(&m->mtx_object); 507 return; 508 } 509 #else 510 MPASS(ts != NULL); 511 #endif 512 #ifndef PREEMPTION 513 /* XXX */ 514 td1 = turnstile_head(ts, TS_EXCLUSIVE_QUEUE); 515 #endif 516 #ifdef MUTEX_WAKE_ALL 517 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 518 _release_lock_quick(m); 519 #else 520 if (turnstile_signal(ts, TS_EXCLUSIVE_QUEUE)) { 521 _release_lock_quick(m); 522 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 523 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); 524 } else { 525 m->mtx_lock = MTX_CONTESTED; 526 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 527 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p still contested", 528 m); 529 } 530 #endif 531 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 532 533 #ifndef PREEMPTION 534 /* 535 * XXX: This is just a hack until preemption is done. However, 536 * once preemption is done we need to either wrap the 537 * turnstile_signal() and release of the actual lock in an 538 * extra critical section or change the preemption code to 539 * always just set a flag and never do instant-preempts. 540 */ 541 td = curthread; 542 if (td->td_critnest > 0 || td1->td_priority >= td->td_priority) 543 return; 544 mtx_lock_spin(&sched_lock); 545 if (!TD_IS_RUNNING(td1)) { 546 #ifdef notyet 547 if (td->td_ithd != NULL) { 548 struct ithd *it = td->td_ithd; 549 550 if (it->it_interrupted) { 551 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 552 CTR2(KTR_LOCK, 553 "_mtx_unlock_sleep: %p interrupted %p", 554 it, it->it_interrupted); 555 intr_thd_fixup(it); 556 } 557 } 558 #endif 559 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 560 CTR2(KTR_LOCK, 561 "_mtx_unlock_sleep: %p switching out lock=%p", m, 562 (void *)m->mtx_lock); 563 564 mi_switch(SW_INVOL, NULL); 565 if (LOCK_LOG_TEST(&m->mtx_object, opts)) 566 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p", 567 m, (void *)m->mtx_lock); 568 } 569 mtx_unlock_spin(&sched_lock); 570 #endif 571 572 return; 573 } 574 575 /* 576 * All the unlocking of MTX_SPIN locks is done inline. 577 * See the _rel_spin_lock() macro for the details. 578 */ 579 580 /* 581 * The backing function for the INVARIANTS-enabled mtx_assert() 582 */ 583 #ifdef INVARIANT_SUPPORT 584 void 585 _mtx_assert(struct mtx *m, int what, const char *file, int line) 586 { 587 588 if (panicstr != NULL || dumping) 589 return; 590 switch (what) { 591 case MA_OWNED: 592 case MA_OWNED | MA_RECURSED: 593 case MA_OWNED | MA_NOTRECURSED: 594 if (!mtx_owned(m)) 595 panic("mutex %s not owned at %s:%d", 596 m->mtx_object.lo_name, file, line); 597 if (mtx_recursed(m)) { 598 if ((what & MA_NOTRECURSED) != 0) 599 panic("mutex %s recursed at %s:%d", 600 m->mtx_object.lo_name, file, line); 601 } else if ((what & MA_RECURSED) != 0) { 602 panic("mutex %s unrecursed at %s:%d", 603 m->mtx_object.lo_name, file, line); 604 } 605 break; 606 case MA_NOTOWNED: 607 if (mtx_owned(m)) 608 panic("mutex %s owned at %s:%d", 609 m->mtx_object.lo_name, file, line); 610 break; 611 default: 612 panic("unknown mtx_assert at %s:%d", file, line); 613 } 614 } 615 #endif 616 617 /* 618 * The MUTEX_DEBUG-enabled mtx_validate() 619 * 620 * Most of these checks have been moved off into the LO_INITIALIZED flag 621 * maintained by the witness code. 622 */ 623 #ifdef MUTEX_DEBUG 624 625 void mtx_validate(struct mtx *); 626 627 void 628 mtx_validate(struct mtx *m) 629 { 630 631 /* 632 * XXX: When kernacc() does not require Giant we can reenable this check 633 */ 634 #ifdef notyet 635 /* 636 * Can't call kernacc() from early init386(), especially when 637 * initializing Giant mutex, because some stuff in kernacc() 638 * requires Giant itself. 639 */ 640 if (!cold) 641 if (!kernacc((caddr_t)m, sizeof(m), 642 VM_PROT_READ | VM_PROT_WRITE)) 643 panic("Can't read and write to mutex %p", m); 644 #endif 645 } 646 #endif 647 648 /* 649 * General init routine used by the MTX_SYSINIT() macro. 650 */ 651 void 652 mtx_sysinit(void *arg) 653 { 654 struct mtx_args *margs = arg; 655 656 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 657 } 658 659 /* 660 * Mutex initialization routine; initialize lock `m' of type contained in 661 * `opts' with options contained in `opts' and name `name.' The optional 662 * lock type `type' is used as a general lock category name for use with 663 * witness. 664 */ 665 void 666 mtx_init(struct mtx *m, const char *name, const char *type, int opts) 667 { 668 struct lock_class *class; 669 int flags; 670 671 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 672 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 673 674 #ifdef MUTEX_DEBUG 675 /* Diagnostic and error correction */ 676 mtx_validate(m); 677 #endif 678 679 /* Determine lock class and lock flags. */ 680 if (opts & MTX_SPIN) 681 class = &lock_class_mtx_spin; 682 else 683 class = &lock_class_mtx_sleep; 684 flags = 0; 685 if (opts & MTX_QUIET) 686 flags |= LO_QUIET; 687 if (opts & MTX_RECURSE) 688 flags |= LO_RECURSABLE; 689 if ((opts & MTX_NOWITNESS) == 0) 690 flags |= LO_WITNESS; 691 if (opts & MTX_DUPOK) 692 flags |= LO_DUPOK; 693 if (opts & MTX_NOPROFILE) 694 flags |= LO_NOPROFILE; 695 696 /* Initialize mutex. */ 697 m->mtx_lock = MTX_UNOWNED; 698 m->mtx_recurse = 0; 699 700 lock_profile_object_init(&m->mtx_object, class, name); 701 lock_init(&m->mtx_object, class, name, type, flags); 702 } 703 704 /* 705 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 706 * passed in as a flag here because if the corresponding mtx_init() was 707 * called with MTX_QUIET set, then it will already be set in the mutex's 708 * flags. 709 */ 710 void 711 mtx_destroy(struct mtx *m) 712 { 713 714 if (!mtx_owned(m)) 715 MPASS(mtx_unowned(m)); 716 else { 717 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 718 719 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 720 if (LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_spin) 721 spinlock_exit(); 722 else 723 curthread->td_locks--; 724 725 /* Tell witness this isn't locked to make it happy. */ 726 WITNESS_UNLOCK(&m->mtx_object, LOP_EXCLUSIVE, __FILE__, 727 __LINE__); 728 } 729 730 m->mtx_lock = MTX_DESTROYED; 731 lock_profile_object_destroy(&m->mtx_object); 732 lock_destroy(&m->mtx_object); 733 } 734 735 /* 736 * Intialize the mutex code and system mutexes. This is called from the MD 737 * startup code prior to mi_startup(). The per-CPU data space needs to be 738 * setup before this is called. 739 */ 740 void 741 mutex_init(void) 742 { 743 744 /* Setup turnstiles so that sleep mutexes work. */ 745 init_turnstiles(); 746 747 /* 748 * Initialize mutexes. 749 */ 750 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 751 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 752 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 753 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 754 mtx_lock(&Giant); 755 756 lock_profile_init(); 757 } 758 759 #ifdef DDB 760 void 761 db_show_mtx(struct lock_object *lock) 762 { 763 struct thread *td; 764 struct mtx *m; 765 766 m = (struct mtx *)lock; 767 768 db_printf(" flags: {"); 769 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 770 db_printf("SPIN"); 771 else 772 db_printf("DEF"); 773 if (m->mtx_object.lo_flags & LO_RECURSABLE) 774 db_printf(", RECURSE"); 775 if (m->mtx_object.lo_flags & LO_DUPOK) 776 db_printf(", DUPOK"); 777 db_printf("}\n"); 778 db_printf(" state: {"); 779 if (mtx_unowned(m)) 780 db_printf("UNOWNED"); 781 else { 782 db_printf("OWNED"); 783 if (m->mtx_lock & MTX_CONTESTED) 784 db_printf(", CONTESTED"); 785 if (m->mtx_lock & MTX_RECURSED) 786 db_printf(", RECURSED"); 787 } 788 db_printf("}\n"); 789 if (!mtx_unowned(m)) { 790 td = mtx_owner(m); 791 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 792 td->td_tid, td->td_proc->p_pid, td->td_proc->p_comm); 793 if (mtx_recursed(m)) 794 db_printf(" recursed: %d\n", m->mtx_recurse); 795 } 796 } 797 #endif 798