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_hwpmc_hooks.h" 43 #include "opt_kdtrace.h" 44 #include "opt_sched.h" 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/bus.h> 49 #include <sys/conf.h> 50 #include <sys/kdb.h> 51 #include <sys/kernel.h> 52 #include <sys/ktr.h> 53 #include <sys/lock.h> 54 #include <sys/malloc.h> 55 #include <sys/mutex.h> 56 #include <sys/proc.h> 57 #include <sys/resourcevar.h> 58 #include <sys/sched.h> 59 #include <sys/sbuf.h> 60 #include <sys/sysctl.h> 61 #include <sys/turnstile.h> 62 #include <sys/vmmeter.h> 63 #include <sys/lock_profile.h> 64 65 #include <machine/atomic.h> 66 #include <machine/bus.h> 67 #include <machine/cpu.h> 68 69 #include <ddb/ddb.h> 70 71 #include <fs/devfs/devfs_int.h> 72 73 #include <vm/vm.h> 74 #include <vm/vm_extern.h> 75 76 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 77 #define ADAPTIVE_MUTEXES 78 #endif 79 80 #ifdef HWPMC_HOOKS 81 #include <sys/pmckern.h> 82 PMC_SOFT_DEFINE( , , lock, failed); 83 #endif 84 85 /* 86 * Internal utility macros. 87 */ 88 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 89 90 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 91 92 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 93 94 static void assert_mtx(const struct lock_object *lock, int what); 95 #ifdef DDB 96 static void db_show_mtx(const struct lock_object *lock); 97 #endif 98 static void lock_mtx(struct lock_object *lock, int how); 99 static void lock_spin(struct lock_object *lock, int how); 100 #ifdef KDTRACE_HOOKS 101 static int owner_mtx(const struct lock_object *lock, 102 struct thread **owner); 103 #endif 104 static int unlock_mtx(struct lock_object *lock); 105 static int unlock_spin(struct lock_object *lock); 106 107 /* 108 * Lock classes for sleep and spin mutexes. 109 */ 110 struct lock_class lock_class_mtx_sleep = { 111 .lc_name = "sleep mutex", 112 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 113 .lc_assert = assert_mtx, 114 #ifdef DDB 115 .lc_ddb_show = db_show_mtx, 116 #endif 117 .lc_lock = lock_mtx, 118 .lc_unlock = unlock_mtx, 119 #ifdef KDTRACE_HOOKS 120 .lc_owner = owner_mtx, 121 #endif 122 }; 123 struct lock_class lock_class_mtx_spin = { 124 .lc_name = "spin mutex", 125 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 126 .lc_assert = assert_mtx, 127 #ifdef DDB 128 .lc_ddb_show = db_show_mtx, 129 #endif 130 .lc_lock = lock_spin, 131 .lc_unlock = unlock_spin, 132 #ifdef KDTRACE_HOOKS 133 .lc_owner = owner_mtx, 134 #endif 135 }; 136 137 /* 138 * System-wide mutexes 139 */ 140 struct mtx blocked_lock; 141 struct mtx Giant; 142 143 void 144 assert_mtx(const struct lock_object *lock, int what) 145 { 146 147 mtx_assert((const struct mtx *)lock, what); 148 } 149 150 void 151 lock_mtx(struct lock_object *lock, int how) 152 { 153 154 mtx_lock((struct mtx *)lock); 155 } 156 157 void 158 lock_spin(struct lock_object *lock, int how) 159 { 160 161 panic("spin locks can only use msleep_spin"); 162 } 163 164 int 165 unlock_mtx(struct lock_object *lock) 166 { 167 struct mtx *m; 168 169 m = (struct mtx *)lock; 170 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 171 mtx_unlock(m); 172 return (0); 173 } 174 175 int 176 unlock_spin(struct lock_object *lock) 177 { 178 179 panic("spin locks can only use msleep_spin"); 180 } 181 182 #ifdef KDTRACE_HOOKS 183 int 184 owner_mtx(const struct lock_object *lock, struct thread **owner) 185 { 186 const struct mtx *m = (const struct mtx *)lock; 187 188 *owner = mtx_owner(m); 189 return (mtx_unowned(m) == 0); 190 } 191 #endif 192 193 /* 194 * Function versions of the inlined __mtx_* macros. These are used by 195 * modules and can also be called from assembly language if needed. 196 */ 197 void 198 _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 199 { 200 201 if (SCHEDULER_STOPPED()) 202 return; 203 MPASS(curthread != NULL); 204 KASSERT(m->mtx_lock != MTX_DESTROYED, 205 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 206 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 207 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 208 file, line)); 209 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 210 file, line, NULL); 211 212 __mtx_lock(m, curthread, opts, file, line); 213 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 214 line); 215 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 216 curthread->td_locks++; 217 } 218 219 void 220 _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 221 { 222 223 if (SCHEDULER_STOPPED()) 224 return; 225 MPASS(curthread != NULL); 226 KASSERT(m->mtx_lock != MTX_DESTROYED, 227 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 228 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 229 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 230 file, line)); 231 curthread->td_locks--; 232 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 233 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 234 line); 235 mtx_assert(m, MA_OWNED); 236 237 if (m->mtx_recurse == 0) 238 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m); 239 __mtx_unlock(m, curthread, opts, file, line); 240 } 241 242 void 243 _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 244 { 245 246 if (SCHEDULER_STOPPED()) 247 return; 248 MPASS(curthread != NULL); 249 KASSERT(m->mtx_lock != MTX_DESTROYED, 250 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 251 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 252 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 253 m->lock_object.lo_name, file, line)); 254 if (mtx_owned(m)) 255 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 256 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 257 m->lock_object.lo_name, file, line)); 258 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 259 file, line, NULL); 260 __mtx_lock_spin(m, curthread, opts, file, line); 261 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 262 line); 263 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 264 } 265 266 void 267 _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 268 { 269 270 if (SCHEDULER_STOPPED()) 271 return; 272 MPASS(curthread != NULL); 273 KASSERT(m->mtx_lock != MTX_DESTROYED, 274 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 275 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 276 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 277 m->lock_object.lo_name, file, line)); 278 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 279 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 280 line); 281 mtx_assert(m, MA_OWNED); 282 283 __mtx_unlock_spin(m); 284 } 285 286 /* 287 * The important part of mtx_trylock{,_flags}() 288 * Tries to acquire lock `m.' If this function is called on a mutex that 289 * is already owned, it will recursively acquire the lock. 290 */ 291 int 292 mtx_trylock_flags_(struct mtx *m, int opts, const char *file, int line) 293 { 294 #ifdef LOCK_PROFILING 295 uint64_t waittime = 0; 296 int contested = 0; 297 #endif 298 int rval; 299 300 if (SCHEDULER_STOPPED()) 301 return (1); 302 303 MPASS(curthread != NULL); 304 KASSERT(m->mtx_lock != MTX_DESTROYED, 305 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 306 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 307 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 308 file, line)); 309 310 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 311 m->mtx_recurse++; 312 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 313 rval = 1; 314 } else 315 rval = _mtx_obtain_lock(m, (uintptr_t)curthread); 316 317 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 318 if (rval) { 319 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 320 file, line); 321 curthread->td_locks++; 322 if (m->mtx_recurse == 0) 323 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, 324 m, contested, waittime, file, line); 325 326 } 327 328 return (rval); 329 } 330 331 /* 332 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 333 * 334 * We call this if the lock is either contested (i.e. we need to go to 335 * sleep waiting for it), or if we need to recurse on it. 336 */ 337 void 338 _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file, 339 int line) 340 { 341 struct turnstile *ts; 342 uintptr_t v; 343 #ifdef ADAPTIVE_MUTEXES 344 volatile struct thread *owner; 345 #endif 346 #ifdef KTR 347 int cont_logged = 0; 348 #endif 349 #ifdef LOCK_PROFILING 350 int contested = 0; 351 uint64_t waittime = 0; 352 #endif 353 #ifdef KDTRACE_HOOKS 354 uint64_t spin_cnt = 0; 355 uint64_t sleep_cnt = 0; 356 int64_t sleep_time = 0; 357 #endif 358 359 if (SCHEDULER_STOPPED()) 360 return; 361 362 if (mtx_owned(m)) { 363 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 364 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 365 m->lock_object.lo_name, file, line)); 366 m->mtx_recurse++; 367 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 368 if (LOCK_LOG_TEST(&m->lock_object, opts)) 369 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 370 return; 371 } 372 373 #ifdef HWPMC_HOOKS 374 PMC_SOFT_CALL( , , lock, failed); 375 #endif 376 lock_profile_obtain_lock_failed(&m->lock_object, 377 &contested, &waittime); 378 if (LOCK_LOG_TEST(&m->lock_object, opts)) 379 CTR4(KTR_LOCK, 380 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 381 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 382 383 while (!_mtx_obtain_lock(m, tid)) { 384 #ifdef KDTRACE_HOOKS 385 spin_cnt++; 386 #endif 387 #ifdef ADAPTIVE_MUTEXES 388 /* 389 * If the owner is running on another CPU, spin until the 390 * owner stops running or the state of the lock changes. 391 */ 392 v = m->mtx_lock; 393 if (v != MTX_UNOWNED) { 394 owner = (struct thread *)(v & ~MTX_FLAGMASK); 395 if (TD_IS_RUNNING(owner)) { 396 if (LOCK_LOG_TEST(&m->lock_object, 0)) 397 CTR3(KTR_LOCK, 398 "%s: spinning on %p held by %p", 399 __func__, m, owner); 400 while (mtx_owner(m) == owner && 401 TD_IS_RUNNING(owner)) { 402 cpu_spinwait(); 403 #ifdef KDTRACE_HOOKS 404 spin_cnt++; 405 #endif 406 } 407 continue; 408 } 409 } 410 #endif 411 412 ts = turnstile_trywait(&m->lock_object); 413 v = m->mtx_lock; 414 415 /* 416 * Check if the lock has been released while spinning for 417 * the turnstile chain lock. 418 */ 419 if (v == MTX_UNOWNED) { 420 turnstile_cancel(ts); 421 continue; 422 } 423 424 #ifdef ADAPTIVE_MUTEXES 425 /* 426 * The current lock owner might have started executing 427 * on another CPU (or the lock could have changed 428 * owners) while we were waiting on the turnstile 429 * chain lock. If so, drop the turnstile lock and try 430 * again. 431 */ 432 owner = (struct thread *)(v & ~MTX_FLAGMASK); 433 if (TD_IS_RUNNING(owner)) { 434 turnstile_cancel(ts); 435 continue; 436 } 437 #endif 438 439 /* 440 * If the mutex isn't already contested and a failure occurs 441 * setting the contested bit, the mutex was either released 442 * or the state of the MTX_RECURSED bit changed. 443 */ 444 if ((v & MTX_CONTESTED) == 0 && 445 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 446 turnstile_cancel(ts); 447 continue; 448 } 449 450 /* 451 * We definitely must sleep for this lock. 452 */ 453 mtx_assert(m, MA_NOTOWNED); 454 455 #ifdef KTR 456 if (!cont_logged) { 457 CTR6(KTR_CONTENTION, 458 "contention: %p at %s:%d wants %s, taken by %s:%d", 459 (void *)tid, file, line, m->lock_object.lo_name, 460 WITNESS_FILE(&m->lock_object), 461 WITNESS_LINE(&m->lock_object)); 462 cont_logged = 1; 463 } 464 #endif 465 466 /* 467 * Block on the turnstile. 468 */ 469 #ifdef KDTRACE_HOOKS 470 sleep_time -= lockstat_nsecs(); 471 #endif 472 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 473 #ifdef KDTRACE_HOOKS 474 sleep_time += lockstat_nsecs(); 475 sleep_cnt++; 476 #endif 477 } 478 #ifdef KTR 479 if (cont_logged) { 480 CTR4(KTR_CONTENTION, 481 "contention end: %s acquired by %p at %s:%d", 482 m->lock_object.lo_name, (void *)tid, file, line); 483 } 484 #endif 485 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested, 486 waittime, file, line); 487 #ifdef KDTRACE_HOOKS 488 if (sleep_time) 489 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time); 490 491 /* 492 * Only record the loops spinning and not sleeping. 493 */ 494 if (spin_cnt > sleep_cnt) 495 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt)); 496 #endif 497 } 498 499 static void 500 _mtx_lock_spin_failed(struct mtx *m) 501 { 502 struct thread *td; 503 504 td = mtx_owner(m); 505 506 /* If the mutex is unlocked, try again. */ 507 if (td == NULL) 508 return; 509 510 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 511 m, m->lock_object.lo_name, td, td->td_tid); 512 #ifdef WITNESS 513 witness_display_spinlock(&m->lock_object, td, printf); 514 #endif 515 panic("spin lock held too long"); 516 } 517 518 #ifdef SMP 519 /* 520 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 521 * 522 * This is only called if we need to actually spin for the lock. Recursion 523 * is handled inline. 524 */ 525 void 526 _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file, 527 int line) 528 { 529 int i = 0; 530 #ifdef LOCK_PROFILING 531 int contested = 0; 532 uint64_t waittime = 0; 533 #endif 534 535 if (SCHEDULER_STOPPED()) 536 return; 537 538 if (LOCK_LOG_TEST(&m->lock_object, opts)) 539 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 540 541 #ifdef HWPMC_HOOKS 542 PMC_SOFT_CALL( , , lock, failed); 543 #endif 544 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 545 while (!_mtx_obtain_lock(m, tid)) { 546 547 /* Give interrupts a chance while we spin. */ 548 spinlock_exit(); 549 while (m->mtx_lock != MTX_UNOWNED) { 550 if (i++ < 10000000) { 551 cpu_spinwait(); 552 continue; 553 } 554 if (i < 60000000 || kdb_active || panicstr != NULL) 555 DELAY(1); 556 else 557 _mtx_lock_spin_failed(m); 558 cpu_spinwait(); 559 } 560 spinlock_enter(); 561 } 562 563 if (LOCK_LOG_TEST(&m->lock_object, opts)) 564 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 565 566 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m, 567 contested, waittime, (file), (line)); 568 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i); 569 } 570 #endif /* SMP */ 571 572 void 573 thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 574 { 575 struct mtx *m; 576 uintptr_t tid; 577 int i; 578 #ifdef LOCK_PROFILING 579 int contested = 0; 580 uint64_t waittime = 0; 581 #endif 582 #ifdef KDTRACE_HOOKS 583 uint64_t spin_cnt = 0; 584 #endif 585 586 i = 0; 587 tid = (uintptr_t)curthread; 588 589 if (SCHEDULER_STOPPED()) 590 return; 591 592 for (;;) { 593 retry: 594 spinlock_enter(); 595 m = td->td_lock; 596 KASSERT(m->mtx_lock != MTX_DESTROYED, 597 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 598 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 599 ("thread_lock() of sleep mutex %s @ %s:%d", 600 m->lock_object.lo_name, file, line)); 601 if (mtx_owned(m)) 602 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 603 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 604 m->lock_object.lo_name, file, line)); 605 WITNESS_CHECKORDER(&m->lock_object, 606 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 607 while (!_mtx_obtain_lock(m, tid)) { 608 #ifdef KDTRACE_HOOKS 609 spin_cnt++; 610 #endif 611 if (m->mtx_lock == tid) { 612 m->mtx_recurse++; 613 break; 614 } 615 #ifdef HWPMC_HOOKS 616 PMC_SOFT_CALL( , , lock, failed); 617 #endif 618 lock_profile_obtain_lock_failed(&m->lock_object, 619 &contested, &waittime); 620 /* Give interrupts a chance while we spin. */ 621 spinlock_exit(); 622 while (m->mtx_lock != MTX_UNOWNED) { 623 if (i++ < 10000000) 624 cpu_spinwait(); 625 else if (i < 60000000 || 626 kdb_active || panicstr != NULL) 627 DELAY(1); 628 else 629 _mtx_lock_spin_failed(m); 630 cpu_spinwait(); 631 if (m != td->td_lock) 632 goto retry; 633 } 634 spinlock_enter(); 635 } 636 if (m == td->td_lock) 637 break; 638 __mtx_unlock_spin(m); /* does spinlock_exit() */ 639 #ifdef KDTRACE_HOOKS 640 spin_cnt++; 641 #endif 642 } 643 if (m->mtx_recurse == 0) 644 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, 645 m, contested, waittime, (file), (line)); 646 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 647 line); 648 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 649 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt); 650 } 651 652 struct mtx * 653 thread_lock_block(struct thread *td) 654 { 655 struct mtx *lock; 656 657 THREAD_LOCK_ASSERT(td, MA_OWNED); 658 lock = td->td_lock; 659 td->td_lock = &blocked_lock; 660 mtx_unlock_spin(lock); 661 662 return (lock); 663 } 664 665 void 666 thread_lock_unblock(struct thread *td, struct mtx *new) 667 { 668 mtx_assert(new, MA_OWNED); 669 MPASS(td->td_lock == &blocked_lock); 670 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 671 } 672 673 void 674 thread_lock_set(struct thread *td, struct mtx *new) 675 { 676 struct mtx *lock; 677 678 mtx_assert(new, MA_OWNED); 679 THREAD_LOCK_ASSERT(td, MA_OWNED); 680 lock = td->td_lock; 681 td->td_lock = new; 682 mtx_unlock_spin(lock); 683 } 684 685 /* 686 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 687 * 688 * We are only called here if the lock is recursed or contested (i.e. we 689 * need to wake up a blocked thread). 690 */ 691 void 692 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 693 { 694 struct turnstile *ts; 695 696 if (SCHEDULER_STOPPED()) 697 return; 698 699 if (mtx_recursed(m)) { 700 if (--(m->mtx_recurse) == 0) 701 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 702 if (LOCK_LOG_TEST(&m->lock_object, opts)) 703 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 704 return; 705 } 706 707 /* 708 * We have to lock the chain before the turnstile so this turnstile 709 * can be removed from the hash list if it is empty. 710 */ 711 turnstile_chain_lock(&m->lock_object); 712 ts = turnstile_lookup(&m->lock_object); 713 if (LOCK_LOG_TEST(&m->lock_object, opts)) 714 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 715 MPASS(ts != NULL); 716 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 717 _mtx_release_lock_quick(m); 718 719 /* 720 * This turnstile is now no longer associated with the mutex. We can 721 * unlock the chain lock so a new turnstile may take it's place. 722 */ 723 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 724 turnstile_chain_unlock(&m->lock_object); 725 } 726 727 /* 728 * All the unlocking of MTX_SPIN locks is done inline. 729 * See the __mtx_unlock_spin() macro for the details. 730 */ 731 732 /* 733 * The backing function for the INVARIANTS-enabled mtx_assert() 734 */ 735 #ifdef INVARIANT_SUPPORT 736 void 737 _mtx_assert(const struct mtx *m, int what, const char *file, int line) 738 { 739 740 if (panicstr != NULL || dumping) 741 return; 742 switch (what) { 743 case MA_OWNED: 744 case MA_OWNED | MA_RECURSED: 745 case MA_OWNED | MA_NOTRECURSED: 746 if (!mtx_owned(m)) 747 panic("mutex %s not owned at %s:%d", 748 m->lock_object.lo_name, file, line); 749 if (mtx_recursed(m)) { 750 if ((what & MA_NOTRECURSED) != 0) 751 panic("mutex %s recursed at %s:%d", 752 m->lock_object.lo_name, file, line); 753 } else if ((what & MA_RECURSED) != 0) { 754 panic("mutex %s unrecursed at %s:%d", 755 m->lock_object.lo_name, file, line); 756 } 757 break; 758 case MA_NOTOWNED: 759 if (mtx_owned(m)) 760 panic("mutex %s owned at %s:%d", 761 m->lock_object.lo_name, file, line); 762 break; 763 default: 764 panic("unknown mtx_assert at %s:%d", file, line); 765 } 766 } 767 #endif 768 769 /* 770 * The MUTEX_DEBUG-enabled mtx_validate() 771 * 772 * Most of these checks have been moved off into the LO_INITIALIZED flag 773 * maintained by the witness code. 774 */ 775 #ifdef MUTEX_DEBUG 776 777 void mtx_validate(struct mtx *); 778 779 void 780 mtx_validate(struct mtx *m) 781 { 782 783 /* 784 * XXX: When kernacc() does not require Giant we can reenable this check 785 */ 786 #ifdef notyet 787 /* 788 * Can't call kernacc() from early init386(), especially when 789 * initializing Giant mutex, because some stuff in kernacc() 790 * requires Giant itself. 791 */ 792 if (!cold) 793 if (!kernacc((caddr_t)m, sizeof(m), 794 VM_PROT_READ | VM_PROT_WRITE)) 795 panic("Can't read and write to mutex %p", m); 796 #endif 797 } 798 #endif 799 800 /* 801 * General init routine used by the MTX_SYSINIT() macro. 802 */ 803 void 804 mtx_sysinit(void *arg) 805 { 806 struct mtx_args *margs = arg; 807 808 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); 809 } 810 811 /* 812 * Mutex initialization routine; initialize lock `m' of type contained in 813 * `opts' with options contained in `opts' and name `name.' The optional 814 * lock type `type' is used as a general lock category name for use with 815 * witness. 816 */ 817 void 818 mtx_init(struct mtx *m, const char *name, const char *type, int opts) 819 { 820 struct lock_class *class; 821 int flags; 822 823 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 824 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 825 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 826 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 827 &m->mtx_lock)); 828 829 #ifdef MUTEX_DEBUG 830 /* Diagnostic and error correction */ 831 mtx_validate(m); 832 #endif 833 834 /* Determine lock class and lock flags. */ 835 if (opts & MTX_SPIN) 836 class = &lock_class_mtx_spin; 837 else 838 class = &lock_class_mtx_sleep; 839 flags = 0; 840 if (opts & MTX_QUIET) 841 flags |= LO_QUIET; 842 if (opts & MTX_RECURSE) 843 flags |= LO_RECURSABLE; 844 if ((opts & MTX_NOWITNESS) == 0) 845 flags |= LO_WITNESS; 846 if (opts & MTX_DUPOK) 847 flags |= LO_DUPOK; 848 if (opts & MTX_NOPROFILE) 849 flags |= LO_NOPROFILE; 850 851 /* Initialize mutex. */ 852 m->mtx_lock = MTX_UNOWNED; 853 m->mtx_recurse = 0; 854 855 lock_init(&m->lock_object, class, name, type, flags); 856 } 857 858 /* 859 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 860 * passed in as a flag here because if the corresponding mtx_init() was 861 * called with MTX_QUIET set, then it will already be set in the mutex's 862 * flags. 863 */ 864 void 865 mtx_destroy(struct mtx *m) 866 { 867 868 if (!mtx_owned(m)) 869 MPASS(mtx_unowned(m)); 870 else { 871 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 872 873 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 874 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 875 spinlock_exit(); 876 else 877 curthread->td_locks--; 878 879 lock_profile_release_lock(&m->lock_object); 880 /* Tell witness this isn't locked to make it happy. */ 881 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 882 __LINE__); 883 } 884 885 m->mtx_lock = MTX_DESTROYED; 886 lock_destroy(&m->lock_object); 887 } 888 889 /* 890 * Intialize the mutex code and system mutexes. This is called from the MD 891 * startup code prior to mi_startup(). The per-CPU data space needs to be 892 * setup before this is called. 893 */ 894 void 895 mutex_init(void) 896 { 897 898 /* Setup turnstiles so that sleep mutexes work. */ 899 init_turnstiles(); 900 901 /* 902 * Initialize mutexes. 903 */ 904 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 905 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 906 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 907 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 908 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 909 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 910 mtx_lock(&Giant); 911 } 912 913 #ifdef DDB 914 void 915 db_show_mtx(const struct lock_object *lock) 916 { 917 struct thread *td; 918 const struct mtx *m; 919 920 m = (const struct mtx *)lock; 921 922 db_printf(" flags: {"); 923 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 924 db_printf("SPIN"); 925 else 926 db_printf("DEF"); 927 if (m->lock_object.lo_flags & LO_RECURSABLE) 928 db_printf(", RECURSE"); 929 if (m->lock_object.lo_flags & LO_DUPOK) 930 db_printf(", DUPOK"); 931 db_printf("}\n"); 932 db_printf(" state: {"); 933 if (mtx_unowned(m)) 934 db_printf("UNOWNED"); 935 else if (mtx_destroyed(m)) 936 db_printf("DESTROYED"); 937 else { 938 db_printf("OWNED"); 939 if (m->mtx_lock & MTX_CONTESTED) 940 db_printf(", CONTESTED"); 941 if (m->mtx_lock & MTX_RECURSED) 942 db_printf(", RECURSED"); 943 } 944 db_printf("}\n"); 945 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 946 td = mtx_owner(m); 947 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 948 td->td_tid, td->td_proc->p_pid, td->td_name); 949 if (mtx_recursed(m)) 950 db_printf(" recursed: %d\n", m->mtx_recurse); 951 } 952 } 953 #endif 954