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_kdtrace.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 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 76 #define ADAPTIVE_MUTEXES 77 #endif 78 79 /* 80 * Internal utility macros. 81 */ 82 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 83 84 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 85 86 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 87 88 static void assert_mtx(struct lock_object *lock, int what); 89 #ifdef DDB 90 static void db_show_mtx(struct lock_object *lock); 91 #endif 92 static void lock_mtx(struct lock_object *lock, int how); 93 static void lock_spin(struct lock_object *lock, int how); 94 #ifdef KDTRACE_HOOKS 95 static int owner_mtx(struct lock_object *lock, struct thread **owner); 96 #endif 97 static int unlock_mtx(struct lock_object *lock); 98 static int unlock_spin(struct lock_object *lock); 99 100 /* 101 * Lock classes for sleep and spin mutexes. 102 */ 103 struct lock_class lock_class_mtx_sleep = { 104 .lc_name = "sleep mutex", 105 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 106 .lc_assert = assert_mtx, 107 #ifdef DDB 108 .lc_ddb_show = db_show_mtx, 109 #endif 110 .lc_lock = lock_mtx, 111 .lc_unlock = unlock_mtx, 112 #ifdef KDTRACE_HOOKS 113 .lc_owner = owner_mtx, 114 #endif 115 }; 116 struct lock_class lock_class_mtx_spin = { 117 .lc_name = "spin mutex", 118 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 119 .lc_assert = assert_mtx, 120 #ifdef DDB 121 .lc_ddb_show = db_show_mtx, 122 #endif 123 .lc_lock = lock_spin, 124 .lc_unlock = unlock_spin, 125 #ifdef KDTRACE_HOOKS 126 .lc_owner = owner_mtx, 127 #endif 128 }; 129 130 /* 131 * System-wide mutexes 132 */ 133 struct mtx blocked_lock; 134 struct mtx Giant; 135 136 void 137 assert_mtx(struct lock_object *lock, int what) 138 { 139 140 mtx_assert((struct mtx *)lock, what); 141 } 142 143 void 144 lock_mtx(struct lock_object *lock, int how) 145 { 146 147 mtx_lock((struct mtx *)lock); 148 } 149 150 void 151 lock_spin(struct lock_object *lock, int how) 152 { 153 154 panic("spin locks can only use msleep_spin"); 155 } 156 157 int 158 unlock_mtx(struct lock_object *lock) 159 { 160 struct mtx *m; 161 162 m = (struct mtx *)lock; 163 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 164 mtx_unlock(m); 165 return (0); 166 } 167 168 int 169 unlock_spin(struct lock_object *lock) 170 { 171 172 panic("spin locks can only use msleep_spin"); 173 } 174 175 #ifdef KDTRACE_HOOKS 176 int 177 owner_mtx(struct lock_object *lock, struct thread **owner) 178 { 179 struct mtx *m = (struct mtx *)lock; 180 181 *owner = mtx_owner(m); 182 return (mtx_unowned(m) == 0); 183 } 184 #endif 185 186 /* 187 * Function versions of the inlined __mtx_* macros. These are used by 188 * modules and can also be called from assembly language if needed. 189 */ 190 void 191 _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 192 { 193 194 MPASS(curthread != NULL); 195 KASSERT(m->mtx_lock != MTX_DESTROYED, 196 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 197 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 198 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 199 file, line)); 200 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 201 file, line, NULL); 202 203 _get_sleep_lock(m, curthread, opts, file, line); 204 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 205 line); 206 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 207 curthread->td_locks++; 208 } 209 210 void 211 _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 212 { 213 MPASS(curthread != NULL); 214 KASSERT(m->mtx_lock != MTX_DESTROYED, 215 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 216 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 217 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 218 file, line)); 219 curthread->td_locks--; 220 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 221 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 222 line); 223 mtx_assert(m, MA_OWNED); 224 225 if (m->mtx_recurse == 0) 226 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m); 227 _rel_sleep_lock(m, curthread, opts, file, line); 228 } 229 230 void 231 _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 232 { 233 234 MPASS(curthread != NULL); 235 KASSERT(m->mtx_lock != MTX_DESTROYED, 236 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 237 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 238 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 239 m->lock_object.lo_name, file, line)); 240 if (mtx_owned(m)) 241 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 242 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 243 m->lock_object.lo_name, file, line)); 244 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 245 file, line, NULL); 246 _get_spin_lock(m, curthread, opts, file, line); 247 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 248 line); 249 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 250 } 251 252 void 253 _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 254 { 255 256 MPASS(curthread != NULL); 257 KASSERT(m->mtx_lock != MTX_DESTROYED, 258 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 259 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 260 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 261 m->lock_object.lo_name, file, line)); 262 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 263 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 264 line); 265 mtx_assert(m, MA_OWNED); 266 267 _rel_spin_lock(m); 268 } 269 270 /* 271 * The important part of mtx_trylock{,_flags}() 272 * Tries to acquire lock `m.' If this function is called on a mutex that 273 * is already owned, it will recursively acquire the lock. 274 */ 275 int 276 _mtx_trylock(struct mtx *m, int opts, const char *file, int line) 277 { 278 #ifdef LOCK_PROFILING 279 uint64_t waittime = 0; 280 int contested = 0; 281 #endif 282 int rval; 283 284 MPASS(curthread != NULL); 285 KASSERT(m->mtx_lock != MTX_DESTROYED, 286 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 287 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 288 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 289 file, line)); 290 291 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 292 m->mtx_recurse++; 293 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 294 rval = 1; 295 } else 296 rval = _obtain_lock(m, (uintptr_t)curthread); 297 298 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 299 if (rval) { 300 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 301 file, line); 302 curthread->td_locks++; 303 if (m->mtx_recurse == 0) 304 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, 305 m, contested, waittime, file, line); 306 307 } 308 309 return (rval); 310 } 311 312 /* 313 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 314 * 315 * We call this if the lock is either contested (i.e. we need to go to 316 * sleep waiting for it), or if we need to recurse on it. 317 */ 318 void 319 _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 320 int line) 321 { 322 struct turnstile *ts; 323 uintptr_t v; 324 #ifdef ADAPTIVE_MUTEXES 325 volatile struct thread *owner; 326 #endif 327 #ifdef KTR 328 int cont_logged = 0; 329 #endif 330 #ifdef LOCK_PROFILING 331 int contested = 0; 332 uint64_t waittime = 0; 333 #endif 334 #ifdef KDTRACE_HOOKS 335 uint64_t spin_cnt = 0; 336 uint64_t sleep_cnt = 0; 337 int64_t sleep_time = 0; 338 #endif 339 340 if (mtx_owned(m)) { 341 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 342 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 343 m->lock_object.lo_name, file, line)); 344 m->mtx_recurse++; 345 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 346 if (LOCK_LOG_TEST(&m->lock_object, opts)) 347 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 348 return; 349 } 350 351 lock_profile_obtain_lock_failed(&m->lock_object, 352 &contested, &waittime); 353 if (LOCK_LOG_TEST(&m->lock_object, opts)) 354 CTR4(KTR_LOCK, 355 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 356 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 357 358 while (!_obtain_lock(m, tid)) { 359 #ifdef KDTRACE_HOOKS 360 spin_cnt++; 361 #endif 362 #ifdef ADAPTIVE_MUTEXES 363 /* 364 * If the owner is running on another CPU, spin until the 365 * owner stops running or the state of the lock changes. 366 */ 367 v = m->mtx_lock; 368 if (v != MTX_UNOWNED) { 369 owner = (struct thread *)(v & ~MTX_FLAGMASK); 370 if (TD_IS_RUNNING(owner)) { 371 if (LOCK_LOG_TEST(&m->lock_object, 0)) 372 CTR3(KTR_LOCK, 373 "%s: spinning on %p held by %p", 374 __func__, m, owner); 375 while (mtx_owner(m) == owner && 376 TD_IS_RUNNING(owner)) { 377 cpu_spinwait(); 378 #ifdef KDTRACE_HOOKS 379 spin_cnt++; 380 #endif 381 } 382 continue; 383 } 384 } 385 #endif 386 387 ts = turnstile_trywait(&m->lock_object); 388 v = m->mtx_lock; 389 390 /* 391 * Check if the lock has been released while spinning for 392 * the turnstile chain lock. 393 */ 394 if (v == MTX_UNOWNED) { 395 turnstile_cancel(ts); 396 continue; 397 } 398 399 #ifdef ADAPTIVE_MUTEXES 400 /* 401 * The current lock owner might have started executing 402 * on another CPU (or the lock could have changed 403 * owners) while we were waiting on the turnstile 404 * chain lock. If so, drop the turnstile lock and try 405 * again. 406 */ 407 owner = (struct thread *)(v & ~MTX_FLAGMASK); 408 if (TD_IS_RUNNING(owner)) { 409 turnstile_cancel(ts); 410 continue; 411 } 412 #endif 413 414 /* 415 * If the mutex isn't already contested and a failure occurs 416 * setting the contested bit, the mutex was either released 417 * or the state of the MTX_RECURSED bit changed. 418 */ 419 if ((v & MTX_CONTESTED) == 0 && 420 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 421 turnstile_cancel(ts); 422 continue; 423 } 424 425 /* 426 * We definitely must sleep for this lock. 427 */ 428 mtx_assert(m, MA_NOTOWNED); 429 430 #ifdef KTR 431 if (!cont_logged) { 432 CTR6(KTR_CONTENTION, 433 "contention: %p at %s:%d wants %s, taken by %s:%d", 434 (void *)tid, file, line, m->lock_object.lo_name, 435 WITNESS_FILE(&m->lock_object), 436 WITNESS_LINE(&m->lock_object)); 437 cont_logged = 1; 438 } 439 #endif 440 441 /* 442 * Block on the turnstile. 443 */ 444 #ifdef KDTRACE_HOOKS 445 sleep_time -= lockstat_nsecs(); 446 #endif 447 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 448 #ifdef KDTRACE_HOOKS 449 sleep_time += lockstat_nsecs(); 450 sleep_cnt++; 451 #endif 452 } 453 #ifdef KTR 454 if (cont_logged) { 455 CTR4(KTR_CONTENTION, 456 "contention end: %s acquired by %p at %s:%d", 457 m->lock_object.lo_name, (void *)tid, file, line); 458 } 459 #endif 460 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested, 461 waittime, file, line); 462 #ifdef KDTRACE_HOOKS 463 if (sleep_time) 464 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time); 465 466 /* 467 * Only record the loops spinning and not sleeping. 468 */ 469 if (spin_cnt > sleep_cnt) 470 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt)); 471 #endif 472 } 473 474 static void 475 _mtx_lock_spin_failed(struct mtx *m) 476 { 477 struct thread *td; 478 479 td = mtx_owner(m); 480 481 /* If the mutex is unlocked, try again. */ 482 if (td == NULL) 483 return; 484 485 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 486 m, m->lock_object.lo_name, td, td->td_tid); 487 #ifdef WITNESS 488 witness_display_spinlock(&m->lock_object, td); 489 #endif 490 panic("spin lock held too long"); 491 } 492 493 #ifdef SMP 494 /* 495 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 496 * 497 * This is only called if we need to actually spin for the lock. Recursion 498 * is handled inline. 499 */ 500 void 501 _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 502 int line) 503 { 504 int i = 0; 505 #ifdef LOCK_PROFILING 506 int contested = 0; 507 uint64_t waittime = 0; 508 #endif 509 510 if (LOCK_LOG_TEST(&m->lock_object, opts)) 511 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 512 513 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 514 while (!_obtain_lock(m, tid)) { 515 516 /* 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 continue; 522 } 523 if (i < 60000000 || kdb_active || panicstr != NULL) 524 DELAY(1); 525 else 526 _mtx_lock_spin_failed(m); 527 cpu_spinwait(); 528 } 529 spinlock_enter(); 530 } 531 532 if (LOCK_LOG_TEST(&m->lock_object, opts)) 533 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 534 535 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m, 536 contested, waittime, (file), (line)); 537 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i); 538 } 539 #endif /* SMP */ 540 541 void 542 _thread_lock_flags(struct thread *td, int opts, const char *file, int line) 543 { 544 struct mtx *m; 545 uintptr_t tid; 546 int i; 547 #ifdef LOCK_PROFILING 548 int contested = 0; 549 uint64_t waittime = 0; 550 #endif 551 #ifdef KDTRACE_HOOKS 552 uint64_t spin_cnt = 0; 553 #endif 554 555 i = 0; 556 tid = (uintptr_t)curthread; 557 for (;;) { 558 retry: 559 spinlock_enter(); 560 m = td->td_lock; 561 KASSERT(m->mtx_lock != MTX_DESTROYED, 562 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 563 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 564 ("thread_lock() of sleep mutex %s @ %s:%d", 565 m->lock_object.lo_name, file, line)); 566 if (mtx_owned(m)) 567 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 568 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 569 m->lock_object.lo_name, file, line)); 570 WITNESS_CHECKORDER(&m->lock_object, 571 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 572 while (!_obtain_lock(m, tid)) { 573 #ifdef KDTRACE_HOOKS 574 spin_cnt++; 575 #endif 576 if (m->mtx_lock == tid) { 577 m->mtx_recurse++; 578 break; 579 } 580 lock_profile_obtain_lock_failed(&m->lock_object, 581 &contested, &waittime); 582 /* Give interrupts a chance while we spin. */ 583 spinlock_exit(); 584 while (m->mtx_lock != MTX_UNOWNED) { 585 if (i++ < 10000000) 586 cpu_spinwait(); 587 else if (i < 60000000 || 588 kdb_active || panicstr != NULL) 589 DELAY(1); 590 else 591 _mtx_lock_spin_failed(m); 592 cpu_spinwait(); 593 if (m != td->td_lock) 594 goto retry; 595 } 596 spinlock_enter(); 597 } 598 if (m == td->td_lock) 599 break; 600 _rel_spin_lock(m); /* does spinlock_exit() */ 601 #ifdef KDTRACE_HOOKS 602 spin_cnt++; 603 #endif 604 } 605 if (m->mtx_recurse == 0) 606 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, 607 m, contested, waittime, (file), (line)); 608 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 609 line); 610 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 611 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt); 612 } 613 614 struct mtx * 615 thread_lock_block(struct thread *td) 616 { 617 struct mtx *lock; 618 619 spinlock_enter(); 620 THREAD_LOCK_ASSERT(td, MA_OWNED); 621 lock = td->td_lock; 622 td->td_lock = &blocked_lock; 623 mtx_unlock_spin(lock); 624 625 return (lock); 626 } 627 628 void 629 thread_lock_unblock(struct thread *td, struct mtx *new) 630 { 631 mtx_assert(new, MA_OWNED); 632 MPASS(td->td_lock == &blocked_lock); 633 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 634 spinlock_exit(); 635 } 636 637 void 638 thread_lock_set(struct thread *td, struct mtx *new) 639 { 640 struct mtx *lock; 641 642 mtx_assert(new, MA_OWNED); 643 THREAD_LOCK_ASSERT(td, MA_OWNED); 644 lock = td->td_lock; 645 td->td_lock = new; 646 mtx_unlock_spin(lock); 647 } 648 649 /* 650 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 651 * 652 * We are only called here if the lock is recursed or contested (i.e. we 653 * need to wake up a blocked thread). 654 */ 655 void 656 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 657 { 658 struct turnstile *ts; 659 660 if (mtx_recursed(m)) { 661 if (--(m->mtx_recurse) == 0) 662 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 663 if (LOCK_LOG_TEST(&m->lock_object, opts)) 664 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 665 return; 666 } 667 668 /* 669 * We have to lock the chain before the turnstile so this turnstile 670 * can be removed from the hash list if it is empty. 671 */ 672 turnstile_chain_lock(&m->lock_object); 673 ts = turnstile_lookup(&m->lock_object); 674 if (LOCK_LOG_TEST(&m->lock_object, opts)) 675 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 676 MPASS(ts != NULL); 677 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 678 _release_lock_quick(m); 679 680 /* 681 * This turnstile is now no longer associated with the mutex. We can 682 * unlock the chain lock so a new turnstile may take it's place. 683 */ 684 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 685 turnstile_chain_unlock(&m->lock_object); 686 } 687 688 /* 689 * All the unlocking of MTX_SPIN locks is done inline. 690 * See the _rel_spin_lock() macro for the details. 691 */ 692 693 /* 694 * The backing function for the INVARIANTS-enabled mtx_assert() 695 */ 696 #ifdef INVARIANT_SUPPORT 697 void 698 _mtx_assert(struct mtx *m, int what, const char *file, int line) 699 { 700 701 if (panicstr != NULL || dumping) 702 return; 703 switch (what) { 704 case MA_OWNED: 705 case MA_OWNED | MA_RECURSED: 706 case MA_OWNED | MA_NOTRECURSED: 707 if (!mtx_owned(m)) 708 panic("mutex %s not owned at %s:%d", 709 m->lock_object.lo_name, file, line); 710 if (mtx_recursed(m)) { 711 if ((what & MA_NOTRECURSED) != 0) 712 panic("mutex %s recursed at %s:%d", 713 m->lock_object.lo_name, file, line); 714 } else if ((what & MA_RECURSED) != 0) { 715 panic("mutex %s unrecursed at %s:%d", 716 m->lock_object.lo_name, file, line); 717 } 718 break; 719 case MA_NOTOWNED: 720 if (mtx_owned(m)) 721 panic("mutex %s owned at %s:%d", 722 m->lock_object.lo_name, file, line); 723 break; 724 default: 725 panic("unknown mtx_assert at %s:%d", file, line); 726 } 727 } 728 #endif 729 730 /* 731 * The MUTEX_DEBUG-enabled mtx_validate() 732 * 733 * Most of these checks have been moved off into the LO_INITIALIZED flag 734 * maintained by the witness code. 735 */ 736 #ifdef MUTEX_DEBUG 737 738 void mtx_validate(struct mtx *); 739 740 void 741 mtx_validate(struct mtx *m) 742 { 743 744 /* 745 * XXX: When kernacc() does not require Giant we can reenable this check 746 */ 747 #ifdef notyet 748 /* 749 * Can't call kernacc() from early init386(), especially when 750 * initializing Giant mutex, because some stuff in kernacc() 751 * requires Giant itself. 752 */ 753 if (!cold) 754 if (!kernacc((caddr_t)m, sizeof(m), 755 VM_PROT_READ | VM_PROT_WRITE)) 756 panic("Can't read and write to mutex %p", m); 757 #endif 758 } 759 #endif 760 761 /* 762 * General init routine used by the MTX_SYSINIT() macro. 763 */ 764 void 765 mtx_sysinit(void *arg) 766 { 767 struct mtx_args *margs = arg; 768 769 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 770 } 771 772 /* 773 * Mutex initialization routine; initialize lock `m' of type contained in 774 * `opts' with options contained in `opts' and name `name.' The optional 775 * lock type `type' is used as a general lock category name for use with 776 * witness. 777 */ 778 void 779 mtx_init(struct mtx *m, const char *name, const char *type, int opts) 780 { 781 struct lock_class *class; 782 int flags; 783 784 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 785 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 786 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 787 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 788 &m->mtx_lock)); 789 790 #ifdef MUTEX_DEBUG 791 /* Diagnostic and error correction */ 792 mtx_validate(m); 793 #endif 794 795 /* Determine lock class and lock flags. */ 796 if (opts & MTX_SPIN) 797 class = &lock_class_mtx_spin; 798 else 799 class = &lock_class_mtx_sleep; 800 flags = 0; 801 if (opts & MTX_QUIET) 802 flags |= LO_QUIET; 803 if (opts & MTX_RECURSE) 804 flags |= LO_RECURSABLE; 805 if ((opts & MTX_NOWITNESS) == 0) 806 flags |= LO_WITNESS; 807 if (opts & MTX_DUPOK) 808 flags |= LO_DUPOK; 809 if (opts & MTX_NOPROFILE) 810 flags |= LO_NOPROFILE; 811 812 /* Initialize mutex. */ 813 m->mtx_lock = MTX_UNOWNED; 814 m->mtx_recurse = 0; 815 816 lock_init(&m->lock_object, class, name, type, flags); 817 } 818 819 /* 820 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 821 * passed in as a flag here because if the corresponding mtx_init() was 822 * called with MTX_QUIET set, then it will already be set in the mutex's 823 * flags. 824 */ 825 void 826 mtx_destroy(struct mtx *m) 827 { 828 829 if (!mtx_owned(m)) 830 MPASS(mtx_unowned(m)); 831 else { 832 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 833 834 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 835 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 836 spinlock_exit(); 837 else 838 curthread->td_locks--; 839 840 lock_profile_release_lock(&m->lock_object); 841 /* Tell witness this isn't locked to make it happy. */ 842 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 843 __LINE__); 844 } 845 846 m->mtx_lock = MTX_DESTROYED; 847 lock_destroy(&m->lock_object); 848 } 849 850 /* 851 * Intialize the mutex code and system mutexes. This is called from the MD 852 * startup code prior to mi_startup(). The per-CPU data space needs to be 853 * setup before this is called. 854 */ 855 void 856 mutex_init(void) 857 { 858 859 /* Setup turnstiles so that sleep mutexes work. */ 860 init_turnstiles(); 861 862 /* 863 * Initialize mutexes. 864 */ 865 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 866 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 867 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 868 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 869 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 870 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 871 mtx_lock(&Giant); 872 } 873 874 #ifdef DDB 875 void 876 db_show_mtx(struct lock_object *lock) 877 { 878 struct thread *td; 879 struct mtx *m; 880 881 m = (struct mtx *)lock; 882 883 db_printf(" flags: {"); 884 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 885 db_printf("SPIN"); 886 else 887 db_printf("DEF"); 888 if (m->lock_object.lo_flags & LO_RECURSABLE) 889 db_printf(", RECURSE"); 890 if (m->lock_object.lo_flags & LO_DUPOK) 891 db_printf(", DUPOK"); 892 db_printf("}\n"); 893 db_printf(" state: {"); 894 if (mtx_unowned(m)) 895 db_printf("UNOWNED"); 896 else if (mtx_destroyed(m)) 897 db_printf("DESTROYED"); 898 else { 899 db_printf("OWNED"); 900 if (m->mtx_lock & MTX_CONTESTED) 901 db_printf(", CONTESTED"); 902 if (m->mtx_lock & MTX_RECURSED) 903 db_printf(", RECURSED"); 904 } 905 db_printf("}\n"); 906 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 907 td = mtx_owner(m); 908 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 909 td->td_tid, td->td_proc->p_pid, td->td_name); 910 if (mtx_recursed(m)) 911 db_printf(" recursed: %d\n", m->mtx_recurse); 912 } 913 } 914 #endif 915