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 * Return the mutex address when the lock cookie address is provided. 87 * This functionality assumes that struct mtx* have a member named mtx_lock. 88 */ 89 #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock)) 90 91 /* 92 * Internal utility macros. 93 */ 94 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 95 96 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 97 98 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 99 100 static void assert_mtx(const struct lock_object *lock, int what); 101 #ifdef DDB 102 static void db_show_mtx(const struct lock_object *lock); 103 #endif 104 static void lock_mtx(struct lock_object *lock, int how); 105 static void lock_spin(struct lock_object *lock, int how); 106 #ifdef KDTRACE_HOOKS 107 static int owner_mtx(const struct lock_object *lock, 108 struct thread **owner); 109 #endif 110 static int unlock_mtx(struct lock_object *lock); 111 static int unlock_spin(struct lock_object *lock); 112 113 /* 114 * Lock classes for sleep and spin mutexes. 115 */ 116 struct lock_class lock_class_mtx_sleep = { 117 .lc_name = "sleep mutex", 118 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 119 .lc_assert = assert_mtx, 120 #ifdef DDB 121 .lc_ddb_show = db_show_mtx, 122 #endif 123 .lc_lock = lock_mtx, 124 .lc_unlock = unlock_mtx, 125 #ifdef KDTRACE_HOOKS 126 .lc_owner = owner_mtx, 127 #endif 128 }; 129 struct lock_class lock_class_mtx_spin = { 130 .lc_name = "spin mutex", 131 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 132 .lc_assert = assert_mtx, 133 #ifdef DDB 134 .lc_ddb_show = db_show_mtx, 135 #endif 136 .lc_lock = lock_spin, 137 .lc_unlock = unlock_spin, 138 #ifdef KDTRACE_HOOKS 139 .lc_owner = owner_mtx, 140 #endif 141 }; 142 143 /* 144 * System-wide mutexes 145 */ 146 struct mtx blocked_lock; 147 struct mtx Giant; 148 149 void 150 assert_mtx(const struct lock_object *lock, int what) 151 { 152 153 mtx_assert((const struct mtx *)lock, what); 154 } 155 156 void 157 lock_mtx(struct lock_object *lock, int how) 158 { 159 160 mtx_lock((struct mtx *)lock); 161 } 162 163 void 164 lock_spin(struct lock_object *lock, int how) 165 { 166 167 panic("spin locks can only use msleep_spin"); 168 } 169 170 int 171 unlock_mtx(struct lock_object *lock) 172 { 173 struct mtx *m; 174 175 m = (struct mtx *)lock; 176 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 177 mtx_unlock(m); 178 return (0); 179 } 180 181 int 182 unlock_spin(struct lock_object *lock) 183 { 184 185 panic("spin locks can only use msleep_spin"); 186 } 187 188 #ifdef KDTRACE_HOOKS 189 int 190 owner_mtx(const struct lock_object *lock, struct thread **owner) 191 { 192 const struct mtx *m = (const struct mtx *)lock; 193 194 *owner = mtx_owner(m); 195 return (mtx_unowned(m) == 0); 196 } 197 #endif 198 199 /* 200 * Function versions of the inlined __mtx_* macros. These are used by 201 * modules and can also be called from assembly language if needed. 202 */ 203 void 204 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 205 { 206 struct mtx *m; 207 208 if (SCHEDULER_STOPPED()) 209 return; 210 211 m = mtxlock2mtx(c); 212 213 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 214 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d", 215 curthread, m->lock_object.lo_name, file, line)); 216 KASSERT(m->mtx_lock != MTX_DESTROYED, 217 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 218 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 219 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 220 file, line)); 221 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 222 file, line, NULL); 223 224 __mtx_lock(m, curthread, opts, file, line); 225 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 226 line); 227 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 228 curthread->td_locks++; 229 } 230 231 void 232 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 233 { 234 struct mtx *m; 235 236 if (SCHEDULER_STOPPED()) 237 return; 238 239 m = mtxlock2mtx(c); 240 241 KASSERT(m->mtx_lock != MTX_DESTROYED, 242 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 243 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 244 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 245 file, line)); 246 curthread->td_locks--; 247 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 248 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 249 line); 250 mtx_assert(m, MA_OWNED); 251 252 if (m->mtx_recurse == 0) 253 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m); 254 __mtx_unlock(m, curthread, opts, file, line); 255 } 256 257 void 258 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 259 int line) 260 { 261 struct mtx *m; 262 263 if (SCHEDULER_STOPPED()) 264 return; 265 266 m = mtxlock2mtx(c); 267 268 KASSERT(m->mtx_lock != MTX_DESTROYED, 269 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 270 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 271 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 272 m->lock_object.lo_name, file, line)); 273 if (mtx_owned(m)) 274 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 275 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 276 m->lock_object.lo_name, file, line)); 277 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 278 file, line, NULL); 279 __mtx_lock_spin(m, curthread, opts, file, line); 280 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 281 line); 282 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 283 } 284 285 void 286 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 287 int line) 288 { 289 struct mtx *m; 290 291 if (SCHEDULER_STOPPED()) 292 return; 293 294 m = mtxlock2mtx(c); 295 296 KASSERT(m->mtx_lock != MTX_DESTROYED, 297 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 298 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 299 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 300 m->lock_object.lo_name, file, line)); 301 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 302 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 303 line); 304 mtx_assert(m, MA_OWNED); 305 306 __mtx_unlock_spin(m); 307 } 308 309 /* 310 * The important part of mtx_trylock{,_flags}() 311 * Tries to acquire lock `m.' If this function is called on a mutex that 312 * is already owned, it will recursively acquire the lock. 313 */ 314 int 315 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line) 316 { 317 struct mtx *m; 318 #ifdef LOCK_PROFILING 319 uint64_t waittime = 0; 320 int contested = 0; 321 #endif 322 int rval; 323 324 if (SCHEDULER_STOPPED()) 325 return (1); 326 327 m = mtxlock2mtx(c); 328 329 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 330 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", 331 curthread, m->lock_object.lo_name, file, line)); 332 KASSERT(m->mtx_lock != MTX_DESTROYED, 333 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 334 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 335 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 336 file, line)); 337 338 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) { 339 m->mtx_recurse++; 340 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 341 rval = 1; 342 } else 343 rval = _mtx_obtain_lock(m, (uintptr_t)curthread); 344 345 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 346 if (rval) { 347 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 348 file, line); 349 curthread->td_locks++; 350 if (m->mtx_recurse == 0) 351 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, 352 m, contested, waittime, file, line); 353 354 } 355 356 return (rval); 357 } 358 359 /* 360 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 361 * 362 * We call this if the lock is either contested (i.e. we need to go to 363 * sleep waiting for it), or if we need to recurse on it. 364 */ 365 void 366 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts, 367 const char *file, int line) 368 { 369 struct mtx *m; 370 struct turnstile *ts; 371 uintptr_t v; 372 #ifdef ADAPTIVE_MUTEXES 373 volatile struct thread *owner; 374 #endif 375 #ifdef KTR 376 int cont_logged = 0; 377 #endif 378 #ifdef LOCK_PROFILING 379 int contested = 0; 380 uint64_t waittime = 0; 381 #endif 382 #ifdef KDTRACE_HOOKS 383 uint64_t spin_cnt = 0; 384 uint64_t sleep_cnt = 0; 385 int64_t sleep_time = 0; 386 #endif 387 388 if (SCHEDULER_STOPPED()) 389 return; 390 391 m = mtxlock2mtx(c); 392 393 if (mtx_owned(m)) { 394 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 395 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 396 m->lock_object.lo_name, file, line)); 397 m->mtx_recurse++; 398 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 399 if (LOCK_LOG_TEST(&m->lock_object, opts)) 400 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 401 return; 402 } 403 404 #ifdef HWPMC_HOOKS 405 PMC_SOFT_CALL( , , lock, failed); 406 #endif 407 lock_profile_obtain_lock_failed(&m->lock_object, 408 &contested, &waittime); 409 if (LOCK_LOG_TEST(&m->lock_object, opts)) 410 CTR4(KTR_LOCK, 411 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 412 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 413 414 while (!_mtx_obtain_lock(m, tid)) { 415 #ifdef KDTRACE_HOOKS 416 spin_cnt++; 417 #endif 418 #ifdef ADAPTIVE_MUTEXES 419 /* 420 * If the owner is running on another CPU, spin until the 421 * owner stops running or the state of the lock changes. 422 */ 423 v = m->mtx_lock; 424 if (v != MTX_UNOWNED) { 425 owner = (struct thread *)(v & ~MTX_FLAGMASK); 426 if (TD_IS_RUNNING(owner)) { 427 if (LOCK_LOG_TEST(&m->lock_object, 0)) 428 CTR3(KTR_LOCK, 429 "%s: spinning on %p held by %p", 430 __func__, m, owner); 431 while (mtx_owner(m) == owner && 432 TD_IS_RUNNING(owner)) { 433 cpu_spinwait(); 434 #ifdef KDTRACE_HOOKS 435 spin_cnt++; 436 #endif 437 } 438 continue; 439 } 440 } 441 #endif 442 443 ts = turnstile_trywait(&m->lock_object); 444 v = m->mtx_lock; 445 446 /* 447 * Check if the lock has been released while spinning for 448 * the turnstile chain lock. 449 */ 450 if (v == MTX_UNOWNED) { 451 turnstile_cancel(ts); 452 continue; 453 } 454 455 #ifdef ADAPTIVE_MUTEXES 456 /* 457 * The current lock owner might have started executing 458 * on another CPU (or the lock could have changed 459 * owners) while we were waiting on the turnstile 460 * chain lock. If so, drop the turnstile lock and try 461 * again. 462 */ 463 owner = (struct thread *)(v & ~MTX_FLAGMASK); 464 if (TD_IS_RUNNING(owner)) { 465 turnstile_cancel(ts); 466 continue; 467 } 468 #endif 469 470 /* 471 * If the mutex isn't already contested and a failure occurs 472 * setting the contested bit, the mutex was either released 473 * or the state of the MTX_RECURSED bit changed. 474 */ 475 if ((v & MTX_CONTESTED) == 0 && 476 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 477 turnstile_cancel(ts); 478 continue; 479 } 480 481 /* 482 * We definitely must sleep for this lock. 483 */ 484 mtx_assert(m, MA_NOTOWNED); 485 486 #ifdef KTR 487 if (!cont_logged) { 488 CTR6(KTR_CONTENTION, 489 "contention: %p at %s:%d wants %s, taken by %s:%d", 490 (void *)tid, file, line, m->lock_object.lo_name, 491 WITNESS_FILE(&m->lock_object), 492 WITNESS_LINE(&m->lock_object)); 493 cont_logged = 1; 494 } 495 #endif 496 497 /* 498 * Block on the turnstile. 499 */ 500 #ifdef KDTRACE_HOOKS 501 sleep_time -= lockstat_nsecs(); 502 #endif 503 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 504 #ifdef KDTRACE_HOOKS 505 sleep_time += lockstat_nsecs(); 506 sleep_cnt++; 507 #endif 508 } 509 #ifdef KTR 510 if (cont_logged) { 511 CTR4(KTR_CONTENTION, 512 "contention end: %s acquired by %p at %s:%d", 513 m->lock_object.lo_name, (void *)tid, file, line); 514 } 515 #endif 516 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested, 517 waittime, file, line); 518 #ifdef KDTRACE_HOOKS 519 if (sleep_time) 520 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time); 521 522 /* 523 * Only record the loops spinning and not sleeping. 524 */ 525 if (spin_cnt > sleep_cnt) 526 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt)); 527 #endif 528 } 529 530 static void 531 _mtx_lock_spin_failed(struct mtx *m) 532 { 533 struct thread *td; 534 535 td = mtx_owner(m); 536 537 /* If the mutex is unlocked, try again. */ 538 if (td == NULL) 539 return; 540 541 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 542 m, m->lock_object.lo_name, td, td->td_tid); 543 #ifdef WITNESS 544 witness_display_spinlock(&m->lock_object, td, printf); 545 #endif 546 panic("spin lock held too long"); 547 } 548 549 #ifdef SMP 550 /* 551 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock. 552 * 553 * This is only called if we need to actually spin for the lock. Recursion 554 * is handled inline. 555 */ 556 void 557 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts, 558 const char *file, int line) 559 { 560 struct mtx *m; 561 int i = 0; 562 #ifdef LOCK_PROFILING 563 int contested = 0; 564 uint64_t waittime = 0; 565 #endif 566 567 if (SCHEDULER_STOPPED()) 568 return; 569 570 m = mtxlock2mtx(c); 571 572 if (LOCK_LOG_TEST(&m->lock_object, opts)) 573 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 574 575 #ifdef HWPMC_HOOKS 576 PMC_SOFT_CALL( , , lock, failed); 577 #endif 578 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 579 while (!_mtx_obtain_lock(m, tid)) { 580 581 /* Give interrupts a chance while we spin. */ 582 spinlock_exit(); 583 while (m->mtx_lock != MTX_UNOWNED) { 584 if (i++ < 10000000) { 585 cpu_spinwait(); 586 continue; 587 } 588 if (i < 60000000 || kdb_active || panicstr != NULL) 589 DELAY(1); 590 else 591 _mtx_lock_spin_failed(m); 592 cpu_spinwait(); 593 } 594 spinlock_enter(); 595 } 596 597 if (LOCK_LOG_TEST(&m->lock_object, opts)) 598 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 599 600 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m, 601 contested, waittime, (file), (line)); 602 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i); 603 } 604 #endif /* SMP */ 605 606 void 607 thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 608 { 609 struct mtx *m; 610 uintptr_t tid; 611 int i; 612 #ifdef LOCK_PROFILING 613 int contested = 0; 614 uint64_t waittime = 0; 615 #endif 616 #ifdef KDTRACE_HOOKS 617 uint64_t spin_cnt = 0; 618 #endif 619 620 i = 0; 621 tid = (uintptr_t)curthread; 622 623 if (SCHEDULER_STOPPED()) 624 return; 625 626 for (;;) { 627 retry: 628 spinlock_enter(); 629 m = td->td_lock; 630 KASSERT(m->mtx_lock != MTX_DESTROYED, 631 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 632 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 633 ("thread_lock() of sleep mutex %s @ %s:%d", 634 m->lock_object.lo_name, file, line)); 635 if (mtx_owned(m)) 636 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 637 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 638 m->lock_object.lo_name, file, line)); 639 WITNESS_CHECKORDER(&m->lock_object, 640 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 641 while (!_mtx_obtain_lock(m, tid)) { 642 #ifdef KDTRACE_HOOKS 643 spin_cnt++; 644 #endif 645 if (m->mtx_lock == tid) { 646 m->mtx_recurse++; 647 break; 648 } 649 #ifdef HWPMC_HOOKS 650 PMC_SOFT_CALL( , , lock, failed); 651 #endif 652 lock_profile_obtain_lock_failed(&m->lock_object, 653 &contested, &waittime); 654 /* Give interrupts a chance while we spin. */ 655 spinlock_exit(); 656 while (m->mtx_lock != MTX_UNOWNED) { 657 if (i++ < 10000000) 658 cpu_spinwait(); 659 else if (i < 60000000 || 660 kdb_active || panicstr != NULL) 661 DELAY(1); 662 else 663 _mtx_lock_spin_failed(m); 664 cpu_spinwait(); 665 if (m != td->td_lock) 666 goto retry; 667 } 668 spinlock_enter(); 669 } 670 if (m == td->td_lock) 671 break; 672 __mtx_unlock_spin(m); /* does spinlock_exit() */ 673 #ifdef KDTRACE_HOOKS 674 spin_cnt++; 675 #endif 676 } 677 if (m->mtx_recurse == 0) 678 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, 679 m, contested, waittime, (file), (line)); 680 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 681 line); 682 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 683 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt); 684 } 685 686 struct mtx * 687 thread_lock_block(struct thread *td) 688 { 689 struct mtx *lock; 690 691 THREAD_LOCK_ASSERT(td, MA_OWNED); 692 lock = td->td_lock; 693 td->td_lock = &blocked_lock; 694 mtx_unlock_spin(lock); 695 696 return (lock); 697 } 698 699 void 700 thread_lock_unblock(struct thread *td, struct mtx *new) 701 { 702 mtx_assert(new, MA_OWNED); 703 MPASS(td->td_lock == &blocked_lock); 704 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 705 } 706 707 void 708 thread_lock_set(struct thread *td, struct mtx *new) 709 { 710 struct mtx *lock; 711 712 mtx_assert(new, MA_OWNED); 713 THREAD_LOCK_ASSERT(td, MA_OWNED); 714 lock = td->td_lock; 715 td->td_lock = new; 716 mtx_unlock_spin(lock); 717 } 718 719 /* 720 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 721 * 722 * We are only called here if the lock is recursed or contested (i.e. we 723 * need to wake up a blocked thread). 724 */ 725 void 726 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line) 727 { 728 struct mtx *m; 729 struct turnstile *ts; 730 731 if (SCHEDULER_STOPPED()) 732 return; 733 734 m = mtxlock2mtx(c); 735 736 if (mtx_recursed(m)) { 737 if (--(m->mtx_recurse) == 0) 738 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 739 if (LOCK_LOG_TEST(&m->lock_object, opts)) 740 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 741 return; 742 } 743 744 /* 745 * We have to lock the chain before the turnstile so this turnstile 746 * can be removed from the hash list if it is empty. 747 */ 748 turnstile_chain_lock(&m->lock_object); 749 ts = turnstile_lookup(&m->lock_object); 750 if (LOCK_LOG_TEST(&m->lock_object, opts)) 751 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 752 MPASS(ts != NULL); 753 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 754 _mtx_release_lock_quick(m); 755 756 /* 757 * This turnstile is now no longer associated with the mutex. We can 758 * unlock the chain lock so a new turnstile may take it's place. 759 */ 760 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 761 turnstile_chain_unlock(&m->lock_object); 762 } 763 764 /* 765 * All the unlocking of MTX_SPIN locks is done inline. 766 * See the __mtx_unlock_spin() macro for the details. 767 */ 768 769 /* 770 * The backing function for the INVARIANTS-enabled mtx_assert() 771 */ 772 #ifdef INVARIANT_SUPPORT 773 void 774 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line) 775 { 776 const struct mtx *m; 777 778 if (panicstr != NULL || dumping) 779 return; 780 781 m = mtxlock2mtx(c); 782 783 switch (what) { 784 case MA_OWNED: 785 case MA_OWNED | MA_RECURSED: 786 case MA_OWNED | MA_NOTRECURSED: 787 if (!mtx_owned(m)) 788 panic("mutex %s not owned at %s:%d", 789 m->lock_object.lo_name, file, line); 790 if (mtx_recursed(m)) { 791 if ((what & MA_NOTRECURSED) != 0) 792 panic("mutex %s recursed at %s:%d", 793 m->lock_object.lo_name, file, line); 794 } else if ((what & MA_RECURSED) != 0) { 795 panic("mutex %s unrecursed at %s:%d", 796 m->lock_object.lo_name, file, line); 797 } 798 break; 799 case MA_NOTOWNED: 800 if (mtx_owned(m)) 801 panic("mutex %s owned at %s:%d", 802 m->lock_object.lo_name, file, line); 803 break; 804 default: 805 panic("unknown mtx_assert at %s:%d", file, line); 806 } 807 } 808 #endif 809 810 /* 811 * The MUTEX_DEBUG-enabled mtx_validate() 812 * 813 * Most of these checks have been moved off into the LO_INITIALIZED flag 814 * maintained by the witness code. 815 */ 816 #ifdef MUTEX_DEBUG 817 818 void mtx_validate(struct mtx *); 819 820 void 821 mtx_validate(struct mtx *m) 822 { 823 824 /* 825 * XXX: When kernacc() does not require Giant we can reenable this check 826 */ 827 #ifdef notyet 828 /* 829 * Can't call kernacc() from early init386(), especially when 830 * initializing Giant mutex, because some stuff in kernacc() 831 * requires Giant itself. 832 */ 833 if (!cold) 834 if (!kernacc((caddr_t)m, sizeof(m), 835 VM_PROT_READ | VM_PROT_WRITE)) 836 panic("Can't read and write to mutex %p", m); 837 #endif 838 } 839 #endif 840 841 /* 842 * General init routine used by the MTX_SYSINIT() macro. 843 */ 844 void 845 mtx_sysinit(void *arg) 846 { 847 struct mtx_args *margs = arg; 848 849 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL, 850 margs->ma_opts); 851 } 852 853 /* 854 * Mutex initialization routine; initialize lock `m' of type contained in 855 * `opts' with options contained in `opts' and name `name.' The optional 856 * lock type `type' is used as a general lock category name for use with 857 * witness. 858 */ 859 void 860 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts) 861 { 862 struct mtx *m; 863 struct lock_class *class; 864 int flags; 865 866 m = mtxlock2mtx(c); 867 868 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 869 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); 870 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 871 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 872 &m->mtx_lock)); 873 874 #ifdef MUTEX_DEBUG 875 /* Diagnostic and error correction */ 876 mtx_validate(m); 877 #endif 878 879 /* Determine lock class and lock flags. */ 880 if (opts & MTX_SPIN) 881 class = &lock_class_mtx_spin; 882 else 883 class = &lock_class_mtx_sleep; 884 flags = 0; 885 if (opts & MTX_QUIET) 886 flags |= LO_QUIET; 887 if (opts & MTX_RECURSE) 888 flags |= LO_RECURSABLE; 889 if ((opts & MTX_NOWITNESS) == 0) 890 flags |= LO_WITNESS; 891 if (opts & MTX_DUPOK) 892 flags |= LO_DUPOK; 893 if (opts & MTX_NOPROFILE) 894 flags |= LO_NOPROFILE; 895 896 /* Initialize mutex. */ 897 m->mtx_lock = MTX_UNOWNED; 898 m->mtx_recurse = 0; 899 900 lock_init(&m->lock_object, class, name, type, flags); 901 } 902 903 /* 904 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 905 * passed in as a flag here because if the corresponding mtx_init() was 906 * called with MTX_QUIET set, then it will already be set in the mutex's 907 * flags. 908 */ 909 void 910 _mtx_destroy(volatile uintptr_t *c) 911 { 912 struct mtx *m; 913 914 m = mtxlock2mtx(c); 915 916 if (!mtx_owned(m)) 917 MPASS(mtx_unowned(m)); 918 else { 919 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 920 921 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 922 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 923 spinlock_exit(); 924 else 925 curthread->td_locks--; 926 927 lock_profile_release_lock(&m->lock_object); 928 /* Tell witness this isn't locked to make it happy. */ 929 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 930 __LINE__); 931 } 932 933 m->mtx_lock = MTX_DESTROYED; 934 lock_destroy(&m->lock_object); 935 } 936 937 /* 938 * Intialize the mutex code and system mutexes. This is called from the MD 939 * startup code prior to mi_startup(). The per-CPU data space needs to be 940 * setup before this is called. 941 */ 942 void 943 mutex_init(void) 944 { 945 946 /* Setup turnstiles so that sleep mutexes work. */ 947 init_turnstiles(); 948 949 /* 950 * Initialize mutexes. 951 */ 952 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 953 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 954 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 955 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 956 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); 957 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 958 mtx_lock(&Giant); 959 } 960 961 #ifdef DDB 962 void 963 db_show_mtx(const struct lock_object *lock) 964 { 965 struct thread *td; 966 const struct mtx *m; 967 968 m = (const struct mtx *)lock; 969 970 db_printf(" flags: {"); 971 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 972 db_printf("SPIN"); 973 else 974 db_printf("DEF"); 975 if (m->lock_object.lo_flags & LO_RECURSABLE) 976 db_printf(", RECURSE"); 977 if (m->lock_object.lo_flags & LO_DUPOK) 978 db_printf(", DUPOK"); 979 db_printf("}\n"); 980 db_printf(" state: {"); 981 if (mtx_unowned(m)) 982 db_printf("UNOWNED"); 983 else if (mtx_destroyed(m)) 984 db_printf("DESTROYED"); 985 else { 986 db_printf("OWNED"); 987 if (m->mtx_lock & MTX_CONTESTED) 988 db_printf(", CONTESTED"); 989 if (m->mtx_lock & MTX_RECURSED) 990 db_printf(", RECURSED"); 991 } 992 db_printf("}\n"); 993 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 994 td = mtx_owner(m); 995 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 996 td->td_tid, td->td_proc->p_pid, td->td_name); 997 if (mtx_recursed(m)) 998 db_printf(" recursed: %d\n", m->mtx_recurse); 999 } 1000 } 1001 #endif 1002