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