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 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 220 file, line); 221 _get_spin_lock(m, curthread, opts, file, line); 222 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 223 line); 224 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 225 } 226 227 void 228 _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 229 { 230 231 MPASS(curthread != NULL); 232 KASSERT(m->mtx_lock != MTX_DESTROYED, 233 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 234 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 235 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 236 m->lock_object.lo_name, file, line)); 237 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 238 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 239 line); 240 mtx_assert(m, MA_OWNED); 241 242 _rel_spin_lock(m); 243 } 244 245 /* 246 * The important part of mtx_trylock{,_flags}() 247 * Tries to acquire lock `m.' If this function is called on a mutex that 248 * is already owned, it will recursively acquire the lock. 249 */ 250 int 251 _mtx_trylock(struct mtx *m, int opts, const char *file, int line) 252 { 253 int rval, contested = 0; 254 uint64_t waittime = 0; 255 256 MPASS(curthread != NULL); 257 KASSERT(m->mtx_lock != MTX_DESTROYED, 258 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 259 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 260 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 261 file, line)); 262 263 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 264 m->mtx_recurse++; 265 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 266 rval = 1; 267 } else 268 rval = _obtain_lock(m, (uintptr_t)curthread); 269 270 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 271 if (rval) { 272 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 273 file, line); 274 curthread->td_locks++; 275 if (m->mtx_recurse == 0) 276 lock_profile_obtain_lock_success(&m->lock_object, contested, 277 waittime, file, line); 278 279 } 280 281 return (rval); 282 } 283 284 /* 285 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 286 * 287 * We call this if the lock is either contested (i.e. we need to go to 288 * sleep waiting for it), or if we need to recurse on it. 289 */ 290 void 291 _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 292 int line) 293 { 294 struct turnstile *ts; 295 #ifdef ADAPTIVE_MUTEXES 296 volatile struct thread *owner; 297 #endif 298 #ifdef KTR 299 int cont_logged = 0; 300 #endif 301 int contested = 0; 302 uint64_t waittime = 0; 303 uintptr_t v; 304 305 if (mtx_owned(m)) { 306 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 307 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 308 m->lock_object.lo_name, file, line)); 309 m->mtx_recurse++; 310 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 311 if (LOCK_LOG_TEST(&m->lock_object, opts)) 312 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 313 return; 314 } 315 316 lock_profile_obtain_lock_failed(&m->lock_object, 317 &contested, &waittime); 318 if (LOCK_LOG_TEST(&m->lock_object, opts)) 319 CTR4(KTR_LOCK, 320 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 321 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 322 323 while (!_obtain_lock(m, tid)) { 324 #ifdef ADAPTIVE_MUTEXES 325 /* 326 * If the owner is running on another CPU, spin until the 327 * owner stops running or the state of the lock changes. 328 */ 329 v = m->mtx_lock; 330 if (v != MTX_UNOWNED) { 331 owner = (struct thread *)(v & ~MTX_FLAGMASK); 332 if (TD_IS_RUNNING(owner)) { 333 if (LOCK_LOG_TEST(&m->lock_object, 0)) 334 CTR3(KTR_LOCK, 335 "%s: spinning on %p held by %p", 336 __func__, m, owner); 337 while (mtx_owner(m) == owner && 338 TD_IS_RUNNING(owner)) 339 cpu_spinwait(); 340 continue; 341 } 342 } 343 #endif 344 345 ts = turnstile_trywait(&m->lock_object); 346 v = m->mtx_lock; 347 348 /* 349 * Check if the lock has been released while spinning for 350 * the turnstile chain lock. 351 */ 352 if (v == MTX_UNOWNED) { 353 turnstile_cancel(ts); 354 cpu_spinwait(); 355 continue; 356 } 357 358 MPASS(v != MTX_CONTESTED); 359 360 #ifdef ADAPTIVE_MUTEXES 361 /* 362 * If the current owner of the lock is executing on another 363 * CPU quit the hard path and try to spin. 364 */ 365 owner = (struct thread *)(v & ~MTX_FLAGMASK); 366 if (TD_IS_RUNNING(owner)) { 367 turnstile_cancel(ts); 368 cpu_spinwait(); 369 continue; 370 } 371 #endif 372 373 /* 374 * If the mutex isn't already contested and a failure occurs 375 * setting the contested bit, the mutex was either released 376 * or the state of the MTX_RECURSED bit changed. 377 */ 378 if ((v & MTX_CONTESTED) == 0 && 379 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 380 turnstile_cancel(ts); 381 cpu_spinwait(); 382 continue; 383 } 384 385 /* 386 * We definitely must sleep for this lock. 387 */ 388 mtx_assert(m, MA_NOTOWNED); 389 390 #ifdef KTR 391 if (!cont_logged) { 392 CTR6(KTR_CONTENTION, 393 "contention: %p at %s:%d wants %s, taken by %s:%d", 394 (void *)tid, file, line, m->lock_object.lo_name, 395 WITNESS_FILE(&m->lock_object), 396 WITNESS_LINE(&m->lock_object)); 397 cont_logged = 1; 398 } 399 #endif 400 401 /* 402 * Block on the turnstile. 403 */ 404 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 405 } 406 #ifdef KTR 407 if (cont_logged) { 408 CTR4(KTR_CONTENTION, 409 "contention end: %s acquired by %p at %s:%d", 410 m->lock_object.lo_name, (void *)tid, file, line); 411 } 412 #endif 413 lock_profile_obtain_lock_success(&m->lock_object, contested, 414 waittime, file, line); 415 } 416 417 static void 418 _mtx_lock_spin_failed(struct mtx *m) 419 { 420 struct thread *td; 421 422 td = mtx_owner(m); 423 424 /* If the mutex is unlocked, try again. */ 425 if (td == NULL) 426 return; 427 428 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 429 m, m->lock_object.lo_name, td, td->td_tid); 430 #ifdef WITNESS 431 witness_display_spinlock(&m->lock_object, td); 432 #endif 433 panic("spin lock held too long"); 434 } 435 436 #ifdef SMP 437 /* 438 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 439 * 440 * This is only called if we need to actually spin for the lock. Recursion 441 * is handled inline. 442 */ 443 void 444 _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 445 int line) 446 { 447 int i = 0, contested = 0; 448 uint64_t waittime = 0; 449 450 if (LOCK_LOG_TEST(&m->lock_object, opts)) 451 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 452 453 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 454 while (!_obtain_lock(m, tid)) { 455 456 /* Give interrupts a chance while we spin. */ 457 spinlock_exit(); 458 while (m->mtx_lock != MTX_UNOWNED) { 459 if (i++ < 10000000) { 460 cpu_spinwait(); 461 continue; 462 } 463 if (i < 60000000 || kdb_active || panicstr != NULL) 464 DELAY(1); 465 else 466 _mtx_lock_spin_failed(m); 467 cpu_spinwait(); 468 } 469 spinlock_enter(); 470 } 471 472 if (LOCK_LOG_TEST(&m->lock_object, opts)) 473 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 474 475 lock_profile_obtain_lock_success(&m->lock_object, contested, 476 waittime, (file), (line)); 477 } 478 #endif /* SMP */ 479 480 void 481 _thread_lock_flags(struct thread *td, int opts, const char *file, int line) 482 { 483 struct mtx *m; 484 uintptr_t tid; 485 int i, contested; 486 uint64_t waittime; 487 488 489 contested = i = 0; 490 waittime = 0; 491 tid = (uintptr_t)curthread; 492 for (;;) { 493 retry: 494 spinlock_enter(); 495 m = td->td_lock; 496 WITNESS_CHECKORDER(&m->lock_object, 497 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line); 498 while (!_obtain_lock(m, tid)) { 499 if (m->mtx_lock == tid) { 500 m->mtx_recurse++; 501 break; 502 } 503 lock_profile_obtain_lock_failed(&m->lock_object, 504 &contested, &waittime); 505 /* Give interrupts a chance while we spin. */ 506 spinlock_exit(); 507 while (m->mtx_lock != MTX_UNOWNED) { 508 if (i++ < 10000000) 509 cpu_spinwait(); 510 else if (i < 60000000 || 511 kdb_active || panicstr != NULL) 512 DELAY(1); 513 else 514 _mtx_lock_spin_failed(m); 515 cpu_spinwait(); 516 if (m != td->td_lock) 517 goto retry; 518 } 519 spinlock_enter(); 520 } 521 if (m == td->td_lock) 522 break; 523 _rel_spin_lock(m); /* does spinlock_exit() */ 524 } 525 if (m->mtx_recurse == 0) 526 lock_profile_obtain_lock_success(&m->lock_object, contested, 527 waittime, (file), (line)); 528 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 529 } 530 531 struct mtx * 532 thread_lock_block(struct thread *td) 533 { 534 struct mtx *lock; 535 536 spinlock_enter(); 537 THREAD_LOCK_ASSERT(td, MA_OWNED); 538 lock = td->td_lock; 539 td->td_lock = &blocked_lock; 540 mtx_unlock_spin(lock); 541 542 return (lock); 543 } 544 545 void 546 thread_lock_unblock(struct thread *td, struct mtx *new) 547 { 548 mtx_assert(new, MA_OWNED); 549 MPASS(td->td_lock == &blocked_lock); 550 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 551 spinlock_exit(); 552 } 553 554 void 555 thread_lock_set(struct thread *td, struct mtx *new) 556 { 557 struct mtx *lock; 558 559 mtx_assert(new, MA_OWNED); 560 THREAD_LOCK_ASSERT(td, MA_OWNED); 561 lock = td->td_lock; 562 td->td_lock = new; 563 mtx_unlock_spin(lock); 564 } 565 566 /* 567 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 568 * 569 * We are only called here if the lock is recursed or contested (i.e. we 570 * need to wake up a blocked thread). 571 */ 572 void 573 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 574 { 575 struct turnstile *ts; 576 577 if (mtx_recursed(m)) { 578 if (--(m->mtx_recurse) == 0) 579 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 580 if (LOCK_LOG_TEST(&m->lock_object, opts)) 581 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 582 return; 583 } 584 585 /* 586 * We have to lock the chain before the turnstile so this turnstile 587 * can be removed from the hash list if it is empty. 588 */ 589 turnstile_chain_lock(&m->lock_object); 590 ts = turnstile_lookup(&m->lock_object); 591 if (LOCK_LOG_TEST(&m->lock_object, opts)) 592 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 593 594 MPASS(ts != NULL); 595 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 596 _release_lock_quick(m); 597 /* 598 * This turnstile is now no longer associated with the mutex. We can 599 * unlock the chain lock so a new turnstile may take it's place. 600 */ 601 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 602 turnstile_chain_unlock(&m->lock_object); 603 } 604 605 /* 606 * All the unlocking of MTX_SPIN locks is done inline. 607 * See the _rel_spin_lock() macro for the details. 608 */ 609 610 /* 611 * The backing function for the INVARIANTS-enabled mtx_assert() 612 */ 613 #ifdef INVARIANT_SUPPORT 614 void 615 _mtx_assert(struct mtx *m, int what, const char *file, int line) 616 { 617 618 if (panicstr != NULL || dumping) 619 return; 620 switch (what) { 621 case MA_OWNED: 622 case MA_OWNED | MA_RECURSED: 623 case MA_OWNED | MA_NOTRECURSED: 624 if (!mtx_owned(m)) 625 panic("mutex %s not owned at %s:%d", 626 m->lock_object.lo_name, file, line); 627 if (mtx_recursed(m)) { 628 if ((what & MA_NOTRECURSED) != 0) 629 panic("mutex %s recursed at %s:%d", 630 m->lock_object.lo_name, file, line); 631 } else if ((what & MA_RECURSED) != 0) { 632 panic("mutex %s unrecursed at %s:%d", 633 m->lock_object.lo_name, file, line); 634 } 635 break; 636 case MA_NOTOWNED: 637 if (mtx_owned(m)) 638 panic("mutex %s owned at %s:%d", 639 m->lock_object.lo_name, file, line); 640 break; 641 default: 642 panic("unknown mtx_assert at %s:%d", file, line); 643 } 644 } 645 #endif 646 647 /* 648 * The MUTEX_DEBUG-enabled mtx_validate() 649 * 650 * Most of these checks have been moved off into the LO_INITIALIZED flag 651 * maintained by the witness code. 652 */ 653 #ifdef MUTEX_DEBUG 654 655 void mtx_validate(struct mtx *); 656 657 void 658 mtx_validate(struct mtx *m) 659 { 660 661 /* 662 * XXX: When kernacc() does not require Giant we can reenable this check 663 */ 664 #ifdef notyet 665 /* 666 * Can't call kernacc() from early init386(), especially when 667 * initializing Giant mutex, because some stuff in kernacc() 668 * requires Giant itself. 669 */ 670 if (!cold) 671 if (!kernacc((caddr_t)m, sizeof(m), 672 VM_PROT_READ | VM_PROT_WRITE)) 673 panic("Can't read and write to mutex %p", m); 674 #endif 675 } 676 #endif 677 678 /* 679 * General init routine used by the MTX_SYSINIT() macro. 680 */ 681 void 682 mtx_sysinit(void *arg) 683 { 684 struct mtx_args *margs = arg; 685 686 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 687 } 688 689 /* 690 * Mutex initialization routine; initialize lock `m' of type contained in 691 * `opts' with options contained in `opts' and name `name.' The optional 692 * lock type `type' is used as a general lock category name for use with 693 * witness. 694 */ 695 void 696 mtx_init(struct mtx *m, const char *name, const char *type, int opts) 697 { 698 struct lock_class *class; 699 int flags; 700 701 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 702 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 703 704 #ifdef MUTEX_DEBUG 705 /* Diagnostic and error correction */ 706 mtx_validate(m); 707 #endif 708 709 /* Determine lock class and lock flags. */ 710 if (opts & MTX_SPIN) 711 class = &lock_class_mtx_spin; 712 else 713 class = &lock_class_mtx_sleep; 714 flags = 0; 715 if (opts & MTX_QUIET) 716 flags |= LO_QUIET; 717 if (opts & MTX_RECURSE) 718 flags |= LO_RECURSABLE; 719 if ((opts & MTX_NOWITNESS) == 0) 720 flags |= LO_WITNESS; 721 if (opts & MTX_DUPOK) 722 flags |= LO_DUPOK; 723 if (opts & MTX_NOPROFILE) 724 flags |= LO_NOPROFILE; 725 726 /* Initialize mutex. */ 727 m->mtx_lock = MTX_UNOWNED; 728 m->mtx_recurse = 0; 729 730 lock_init(&m->lock_object, class, name, type, flags); 731 } 732 733 /* 734 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 735 * passed in as a flag here because if the corresponding mtx_init() was 736 * called with MTX_QUIET set, then it will already be set in the mutex's 737 * flags. 738 */ 739 void 740 mtx_destroy(struct mtx *m) 741 { 742 743 if (!mtx_owned(m)) 744 MPASS(mtx_unowned(m)); 745 else { 746 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 747 748 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 749 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 750 spinlock_exit(); 751 else 752 curthread->td_locks--; 753 754 /* Tell witness this isn't locked to make it happy. */ 755 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 756 __LINE__); 757 } 758 759 m->mtx_lock = MTX_DESTROYED; 760 lock_destroy(&m->lock_object); 761 } 762 763 /* 764 * Intialize the mutex code and system mutexes. This is called from the MD 765 * startup code prior to mi_startup(). The per-CPU data space needs to be 766 * setup before this is called. 767 */ 768 void 769 mutex_init(void) 770 { 771 772 /* Setup turnstiles so that sleep mutexes work. */ 773 init_turnstiles(); 774 775 /* 776 * Initialize mutexes. 777 */ 778 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 779 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 780 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 781 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 782 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 783 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 784 mtx_lock(&Giant); 785 } 786 787 #ifdef DDB 788 void 789 db_show_mtx(struct lock_object *lock) 790 { 791 struct thread *td; 792 struct mtx *m; 793 794 m = (struct mtx *)lock; 795 796 db_printf(" flags: {"); 797 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 798 db_printf("SPIN"); 799 else 800 db_printf("DEF"); 801 if (m->lock_object.lo_flags & LO_RECURSABLE) 802 db_printf(", RECURSE"); 803 if (m->lock_object.lo_flags & LO_DUPOK) 804 db_printf(", DUPOK"); 805 db_printf("}\n"); 806 db_printf(" state: {"); 807 if (mtx_unowned(m)) 808 db_printf("UNOWNED"); 809 else if (mtx_destroyed(m)) 810 db_printf("DESTROYED"); 811 else { 812 db_printf("OWNED"); 813 if (m->mtx_lock & MTX_CONTESTED) 814 db_printf(", CONTESTED"); 815 if (m->mtx_lock & MTX_RECURSED) 816 db_printf(", RECURSED"); 817 } 818 db_printf("}\n"); 819 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 820 td = mtx_owner(m); 821 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 822 td->td_tid, td->td_proc->p_pid, td->td_name); 823 if (mtx_recursed(m)) 824 db_printf(" recursed: %d\n", m->mtx_recurse); 825 } 826 } 827 #endif 828