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 static void assert_mtx(struct lock_object *lock, int what); 88 #ifdef DDB 89 static void db_show_mtx(struct lock_object *lock); 90 #endif 91 static void lock_mtx(struct lock_object *lock, int how); 92 static void lock_spin(struct lock_object *lock, int how); 93 static int unlock_mtx(struct lock_object *lock); 94 static int unlock_spin(struct lock_object *lock); 95 96 /* 97 * Lock classes for sleep and spin mutexes. 98 */ 99 struct 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 }; 109 struct 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 */ 123 struct mtx blocked_lock; 124 struct mtx Giant; 125 126 void 127 assert_mtx(struct lock_object *lock, int what) 128 { 129 130 mtx_assert((struct mtx *)lock, what); 131 } 132 133 void 134 lock_mtx(struct lock_object *lock, int how) 135 { 136 137 mtx_lock((struct mtx *)lock); 138 } 139 140 void 141 lock_spin(struct lock_object *lock, int how) 142 { 143 144 panic("spin locks can only use msleep_spin"); 145 } 146 147 int 148 unlock_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 } 157 158 int 159 unlock_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 */ 169 void 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); 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 } 188 189 void 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 } 208 209 void 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); 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 if (TD_IS_RUNNING(owner)) { 337 if (LOCK_LOG_TEST(&m->lock_object, 0)) 338 CTR3(KTR_LOCK, 339 "%s: spinning on %p held by %p", 340 __func__, m, owner); 341 while (mtx_owner(m) == owner && 342 TD_IS_RUNNING(owner)) 343 cpu_spinwait(); 344 continue; 345 } 346 } 347 #endif 348 349 ts = turnstile_trywait(&m->lock_object); 350 v = m->mtx_lock; 351 352 /* 353 * Check if the lock has been released while spinning for 354 * the turnstile chain lock. 355 */ 356 if (v == MTX_UNOWNED) { 357 turnstile_cancel(ts); 358 cpu_spinwait(); 359 continue; 360 } 361 362 MPASS(v != MTX_CONTESTED); 363 364 #ifdef ADAPTIVE_MUTEXES 365 /* 366 * If the current owner of the lock is executing on another 367 * CPU quit the hard path and try to spin. 368 */ 369 owner = (struct thread *)(v & ~MTX_FLAGMASK); 370 if (TD_IS_RUNNING(owner)) { 371 turnstile_cancel(ts); 372 cpu_spinwait(); 373 continue; 374 } 375 #endif 376 377 /* 378 * If the mutex isn't already contested and a failure occurs 379 * setting the contested bit, the mutex was either released 380 * or the state of the MTX_RECURSED bit changed. 381 */ 382 if ((v & MTX_CONTESTED) == 0 && 383 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 384 turnstile_cancel(ts); 385 cpu_spinwait(); 386 continue; 387 } 388 389 /* 390 * We definitely must sleep for this lock. 391 */ 392 mtx_assert(m, MA_NOTOWNED); 393 394 #ifdef KTR 395 if (!cont_logged) { 396 CTR6(KTR_CONTENTION, 397 "contention: %p at %s:%d wants %s, taken by %s:%d", 398 (void *)tid, file, line, m->lock_object.lo_name, 399 WITNESS_FILE(&m->lock_object), 400 WITNESS_LINE(&m->lock_object)); 401 cont_logged = 1; 402 } 403 #endif 404 405 /* 406 * Block on the turnstile. 407 */ 408 turnstile_wait(ts, mtx_owner(m), 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->lock_object.lo_name, (void *)tid, file, line); 415 } 416 #endif 417 lock_profile_obtain_lock_success(&m->lock_object, contested, 418 waittime, file, line); 419 } 420 421 static void 422 _mtx_lock_spin_failed(struct mtx *m) 423 { 424 struct thread *td; 425 426 td = mtx_owner(m); 427 428 /* If the mutex is unlocked, try again. */ 429 if (td == NULL) 430 return; 431 432 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 433 m, m->lock_object.lo_name, td, td->td_tid); 434 #ifdef WITNESS 435 witness_display_spinlock(&m->lock_object, td); 436 #endif 437 panic("spin lock held too long"); 438 } 439 440 #ifdef SMP 441 /* 442 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 443 * 444 * This is only called if we need to actually spin for the lock. Recursion 445 * is handled inline. 446 */ 447 void 448 _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 449 int line) 450 { 451 int i = 0, contested = 0; 452 uint64_t waittime = 0; 453 454 if (LOCK_LOG_TEST(&m->lock_object, opts)) 455 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 456 457 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 458 while (!_obtain_lock(m, tid)) { 459 460 /* Give interrupts a chance while we spin. */ 461 spinlock_exit(); 462 while (m->mtx_lock != MTX_UNOWNED) { 463 if (i++ < 10000000) { 464 cpu_spinwait(); 465 continue; 466 } 467 if (i < 60000000 || kdb_active || panicstr != NULL) 468 DELAY(1); 469 else 470 _mtx_lock_spin_failed(m); 471 cpu_spinwait(); 472 } 473 spinlock_enter(); 474 } 475 476 if (LOCK_LOG_TEST(&m->lock_object, opts)) 477 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 478 479 lock_profile_obtain_lock_success(&m->lock_object, contested, 480 waittime, (file), (line)); 481 } 482 #endif /* SMP */ 483 484 void 485 _thread_lock_flags(struct thread *td, int opts, const char *file, int line) 486 { 487 struct mtx *m; 488 uintptr_t tid; 489 int i, contested; 490 uint64_t waittime; 491 492 contested = i = 0; 493 waittime = 0; 494 tid = (uintptr_t)curthread; 495 for (;;) { 496 retry: 497 spinlock_enter(); 498 m = td->td_lock; 499 KASSERT(m->mtx_lock != MTX_DESTROYED, 500 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 501 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 502 ("thread_lock() of sleep mutex %s @ %s:%d", 503 m->lock_object.lo_name, file, line)); 504 if (mtx_owned(m)) 505 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 506 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 507 m->lock_object.lo_name, file, line)); 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, 516 &contested, &waittime); 517 /* Give interrupts a chance while we spin. */ 518 spinlock_exit(); 519 while (m->mtx_lock != MTX_UNOWNED) { 520 if (i++ < 10000000) 521 cpu_spinwait(); 522 else if (i < 60000000 || 523 kdb_active || panicstr != NULL) 524 DELAY(1); 525 else 526 _mtx_lock_spin_failed(m); 527 cpu_spinwait(); 528 if (m != td->td_lock) 529 goto retry; 530 } 531 spinlock_enter(); 532 } 533 if (m == td->td_lock) 534 break; 535 _rel_spin_lock(m); /* does spinlock_exit() */ 536 } 537 if (m->mtx_recurse == 0) 538 lock_profile_obtain_lock_success(&m->lock_object, contested, 539 waittime, (file), (line)); 540 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 541 line); 542 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 543 } 544 545 struct mtx * 546 thread_lock_block(struct thread *td) 547 { 548 struct mtx *lock; 549 550 spinlock_enter(); 551 THREAD_LOCK_ASSERT(td, MA_OWNED); 552 lock = td->td_lock; 553 td->td_lock = &blocked_lock; 554 mtx_unlock_spin(lock); 555 556 return (lock); 557 } 558 559 void 560 thread_lock_unblock(struct thread *td, struct mtx *new) 561 { 562 mtx_assert(new, MA_OWNED); 563 MPASS(td->td_lock == &blocked_lock); 564 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 565 spinlock_exit(); 566 } 567 568 void 569 thread_lock_set(struct thread *td, struct mtx *new) 570 { 571 struct mtx *lock; 572 573 mtx_assert(new, MA_OWNED); 574 THREAD_LOCK_ASSERT(td, MA_OWNED); 575 lock = td->td_lock; 576 td->td_lock = new; 577 mtx_unlock_spin(lock); 578 } 579 580 /* 581 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 582 * 583 * We are only called here if the lock is recursed or contested (i.e. we 584 * need to wake up a blocked thread). 585 */ 586 void 587 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 588 { 589 struct turnstile *ts; 590 591 if (mtx_recursed(m)) { 592 if (--(m->mtx_recurse) == 0) 593 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 594 if (LOCK_LOG_TEST(&m->lock_object, opts)) 595 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 596 return; 597 } 598 599 /* 600 * We have to lock the chain before the turnstile so this turnstile 601 * can be removed from the hash list if it is empty. 602 */ 603 turnstile_chain_lock(&m->lock_object); 604 ts = turnstile_lookup(&m->lock_object); 605 if (LOCK_LOG_TEST(&m->lock_object, opts)) 606 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 607 608 MPASS(ts != NULL); 609 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 610 _release_lock_quick(m); 611 /* 612 * This turnstile is now no longer associated with the mutex. We can 613 * unlock the chain lock so a new turnstile may take it's place. 614 */ 615 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 616 turnstile_chain_unlock(&m->lock_object); 617 } 618 619 /* 620 * All the unlocking of MTX_SPIN locks is done inline. 621 * See the _rel_spin_lock() macro for the details. 622 */ 623 624 /* 625 * The backing function for the INVARIANTS-enabled mtx_assert() 626 */ 627 #ifdef INVARIANT_SUPPORT 628 void 629 _mtx_assert(struct mtx *m, int what, const char *file, int line) 630 { 631 632 if (panicstr != NULL || dumping) 633 return; 634 switch (what) { 635 case MA_OWNED: 636 case MA_OWNED | MA_RECURSED: 637 case MA_OWNED | MA_NOTRECURSED: 638 if (!mtx_owned(m)) 639 panic("mutex %s not owned at %s:%d", 640 m->lock_object.lo_name, file, line); 641 if (mtx_recursed(m)) { 642 if ((what & MA_NOTRECURSED) != 0) 643 panic("mutex %s recursed at %s:%d", 644 m->lock_object.lo_name, file, line); 645 } else if ((what & MA_RECURSED) != 0) { 646 panic("mutex %s unrecursed at %s:%d", 647 m->lock_object.lo_name, file, line); 648 } 649 break; 650 case MA_NOTOWNED: 651 if (mtx_owned(m)) 652 panic("mutex %s owned at %s:%d", 653 m->lock_object.lo_name, file, line); 654 break; 655 default: 656 panic("unknown mtx_assert at %s:%d", file, line); 657 } 658 } 659 #endif 660 661 /* 662 * The MUTEX_DEBUG-enabled mtx_validate() 663 * 664 * Most of these checks have been moved off into the LO_INITIALIZED flag 665 * maintained by the witness code. 666 */ 667 #ifdef MUTEX_DEBUG 668 669 void mtx_validate(struct mtx *); 670 671 void 672 mtx_validate(struct mtx *m) 673 { 674 675 /* 676 * XXX: When kernacc() does not require Giant we can reenable this check 677 */ 678 #ifdef notyet 679 /* 680 * Can't call kernacc() from early init386(), especially when 681 * initializing Giant mutex, because some stuff in kernacc() 682 * requires Giant itself. 683 */ 684 if (!cold) 685 if (!kernacc((caddr_t)m, sizeof(m), 686 VM_PROT_READ | VM_PROT_WRITE)) 687 panic("Can't read and write to mutex %p", m); 688 #endif 689 } 690 #endif 691 692 /* 693 * General init routine used by the MTX_SYSINIT() macro. 694 */ 695 void 696 mtx_sysinit(void *arg) 697 { 698 struct mtx_args *margs = arg; 699 700 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 701 } 702 703 /* 704 * Mutex initialization routine; initialize lock `m' of type contained in 705 * `opts' with options contained in `opts' and name `name.' The optional 706 * lock type `type' is used as a general lock category name for use with 707 * witness. 708 */ 709 void 710 mtx_init(struct mtx *m, const char *name, const char *type, int opts) 711 { 712 struct lock_class *class; 713 int flags; 714 715 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 716 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 717 718 #ifdef MUTEX_DEBUG 719 /* Diagnostic and error correction */ 720 mtx_validate(m); 721 #endif 722 723 /* Determine lock class and lock flags. */ 724 if (opts & MTX_SPIN) 725 class = &lock_class_mtx_spin; 726 else 727 class = &lock_class_mtx_sleep; 728 flags = 0; 729 if (opts & MTX_QUIET) 730 flags |= LO_QUIET; 731 if (opts & MTX_RECURSE) 732 flags |= LO_RECURSABLE; 733 if ((opts & MTX_NOWITNESS) == 0) 734 flags |= LO_WITNESS; 735 if (opts & MTX_DUPOK) 736 flags |= LO_DUPOK; 737 if (opts & MTX_NOPROFILE) 738 flags |= LO_NOPROFILE; 739 740 /* Initialize mutex. */ 741 m->mtx_lock = MTX_UNOWNED; 742 m->mtx_recurse = 0; 743 744 lock_init(&m->lock_object, class, name, type, flags); 745 } 746 747 /* 748 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 749 * passed in as a flag here because if the corresponding mtx_init() was 750 * called with MTX_QUIET set, then it will already be set in the mutex's 751 * flags. 752 */ 753 void 754 mtx_destroy(struct mtx *m) 755 { 756 757 if (!mtx_owned(m)) 758 MPASS(mtx_unowned(m)); 759 else { 760 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 761 762 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 763 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 764 spinlock_exit(); 765 else 766 curthread->td_locks--; 767 768 /* Tell witness this isn't locked to make it happy. */ 769 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 770 __LINE__); 771 } 772 773 m->mtx_lock = MTX_DESTROYED; 774 lock_destroy(&m->lock_object); 775 } 776 777 /* 778 * Intialize the mutex code and system mutexes. This is called from the MD 779 * startup code prior to mi_startup(). The per-CPU data space needs to be 780 * setup before this is called. 781 */ 782 void 783 mutex_init(void) 784 { 785 786 /* Setup turnstiles so that sleep mutexes work. */ 787 init_turnstiles(); 788 789 /* 790 * Initialize mutexes. 791 */ 792 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 793 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 794 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 795 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 796 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 797 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 798 mtx_lock(&Giant); 799 } 800 801 #ifdef DDB 802 void 803 db_show_mtx(struct lock_object *lock) 804 { 805 struct thread *td; 806 struct mtx *m; 807 808 m = (struct mtx *)lock; 809 810 db_printf(" flags: {"); 811 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 812 db_printf("SPIN"); 813 else 814 db_printf("DEF"); 815 if (m->lock_object.lo_flags & LO_RECURSABLE) 816 db_printf(", RECURSE"); 817 if (m->lock_object.lo_flags & LO_DUPOK) 818 db_printf(", DUPOK"); 819 db_printf("}\n"); 820 db_printf(" state: {"); 821 if (mtx_unowned(m)) 822 db_printf("UNOWNED"); 823 else if (mtx_destroyed(m)) 824 db_printf("DESTROYED"); 825 else { 826 db_printf("OWNED"); 827 if (m->mtx_lock & MTX_CONTESTED) 828 db_printf(", CONTESTED"); 829 if (m->mtx_lock & MTX_RECURSED) 830 db_printf(", RECURSED"); 831 } 832 db_printf("}\n"); 833 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 834 td = mtx_owner(m); 835 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 836 td->td_tid, td->td_proc->p_pid, td->td_name); 837 if (mtx_recursed(m)) 838 db_printf(" recursed: %d\n", m->mtx_recurse); 839 } 840 } 841 #endif 842