Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_mutex.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Berkeley Software Design Inc's name may not be used to endorse or 15 * promote products derived from this software without specific prior 16 * written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 * 30 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 31 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 32 */ 33 34 /* 35 * Machine independent bits of mutex implementation. 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "opt_adaptive_mutexes.h" 42 #include "opt_ddb.h" 43 #include "opt_hwpmc_hooks.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/smp.h> 61 #include <sys/sysctl.h> 62 #include <sys/turnstile.h> 63 #include <sys/vmmeter.h> 64 #include <sys/lock_profile.h> 65 66 #include <machine/atomic.h> 67 #include <machine/bus.h> 68 #include <machine/cpu.h> 69 70 #include <ddb/ddb.h> 71 72 #include <fs/devfs/devfs_int.h> 73 74 #include <vm/vm.h> 75 #include <vm/vm_extern.h> 76 77 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 78 #define ADAPTIVE_MUTEXES 79 #endif 80 81 #ifdef HWPMC_HOOKS 82 #include <sys/pmckern.h> 83 PMC_SOFT_DEFINE( , , lock, failed); 84 #endif 85 86 /* 87 * Return the mutex address when the lock cookie address is provided. 88 * This functionality assumes that struct mtx* have a member named mtx_lock. 89 */ 90 #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock)) 91 92 /* 93 * Internal utility macros. 94 */ 95 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 96 97 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 98 99 static void assert_mtx(const struct lock_object *lock, int what); 100 #ifdef DDB 101 static void db_show_mtx(const struct lock_object *lock); 102 #endif 103 static void lock_mtx(struct lock_object *lock, uintptr_t how); 104 static void lock_spin(struct lock_object *lock, uintptr_t how); 105 #ifdef KDTRACE_HOOKS 106 static int owner_mtx(const struct lock_object *lock, 107 struct thread **owner); 108 #endif 109 static uintptr_t unlock_mtx(struct lock_object *lock); 110 static uintptr_t unlock_spin(struct lock_object *lock); 111 112 /* 113 * Lock classes for sleep and spin mutexes. 114 */ 115 struct lock_class lock_class_mtx_sleep = { 116 .lc_name = "sleep mutex", 117 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 118 .lc_assert = assert_mtx, 119 #ifdef DDB 120 .lc_ddb_show = db_show_mtx, 121 #endif 122 .lc_lock = lock_mtx, 123 .lc_unlock = unlock_mtx, 124 #ifdef KDTRACE_HOOKS 125 .lc_owner = owner_mtx, 126 #endif 127 }; 128 struct lock_class lock_class_mtx_spin = { 129 .lc_name = "spin mutex", 130 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 131 .lc_assert = assert_mtx, 132 #ifdef DDB 133 .lc_ddb_show = db_show_mtx, 134 #endif 135 .lc_lock = lock_spin, 136 .lc_unlock = unlock_spin, 137 #ifdef KDTRACE_HOOKS 138 .lc_owner = owner_mtx, 139 #endif 140 }; 141 142 #ifdef ADAPTIVE_MUTEXES 143 #ifdef MUTEX_CUSTOM_BACKOFF 144 static SYSCTL_NODE(_debug, OID_AUTO, mtx, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 145 "mtx debugging"); 146 147 static struct lock_delay_config __read_frequently mtx_delay; 148 149 SYSCTL_U16(_debug_mtx, OID_AUTO, delay_base, CTLFLAG_RW, &mtx_delay.base, 150 0, ""); 151 SYSCTL_U16(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max, 152 0, ""); 153 154 LOCK_DELAY_SYSINIT_DEFAULT(mtx_delay); 155 #else 156 #define mtx_delay locks_delay 157 #endif 158 #endif 159 160 #ifdef MUTEX_SPIN_CUSTOM_BACKOFF 161 static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin, 162 CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 163 "mtx spin debugging"); 164 165 static struct lock_delay_config __read_frequently mtx_spin_delay; 166 167 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_base, CTLFLAG_RW, 168 &mtx_spin_delay.base, 0, ""); 169 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_max, CTLFLAG_RW, 170 &mtx_spin_delay.max, 0, ""); 171 172 LOCK_DELAY_SYSINIT_DEFAULT(mtx_spin_delay); 173 #else 174 #define mtx_spin_delay locks_delay 175 #endif 176 177 /* 178 * System-wide mutexes 179 */ 180 struct mtx blocked_lock; 181 struct mtx __exclusive_cache_line Giant; 182 183 static void _mtx_lock_indefinite_check(struct mtx *, struct lock_delay_arg *); 184 185 void 186 assert_mtx(const struct lock_object *lock, int what) 187 { 188 189 /* 190 * Treat LA_LOCKED as if LA_XLOCKED was asserted. 191 * 192 * Some callers of lc_assert uses LA_LOCKED to indicate that either 193 * a shared lock or write lock was held, while other callers uses 194 * the more strict LA_XLOCKED (used as MA_OWNED). 195 * 196 * Mutex is the only lock class that can not be shared, as a result, 197 * we can reasonably consider the caller really intends to assert 198 * LA_XLOCKED when they are asserting LA_LOCKED on a mutex object. 199 */ 200 if (what & LA_LOCKED) { 201 what &= ~LA_LOCKED; 202 what |= LA_XLOCKED; 203 } 204 mtx_assert((const struct mtx *)lock, what); 205 } 206 207 void 208 lock_mtx(struct lock_object *lock, uintptr_t how) 209 { 210 211 mtx_lock((struct mtx *)lock); 212 } 213 214 void 215 lock_spin(struct lock_object *lock, uintptr_t how) 216 { 217 218 mtx_lock_spin((struct mtx *)lock); 219 } 220 221 uintptr_t 222 unlock_mtx(struct lock_object *lock) 223 { 224 struct mtx *m; 225 226 m = (struct mtx *)lock; 227 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 228 mtx_unlock(m); 229 return (0); 230 } 231 232 uintptr_t 233 unlock_spin(struct lock_object *lock) 234 { 235 struct mtx *m; 236 237 m = (struct mtx *)lock; 238 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 239 mtx_unlock_spin(m); 240 return (0); 241 } 242 243 #ifdef KDTRACE_HOOKS 244 int 245 owner_mtx(const struct lock_object *lock, struct thread **owner) 246 { 247 const struct mtx *m; 248 uintptr_t x; 249 250 m = (const struct mtx *)lock; 251 x = m->mtx_lock; 252 *owner = (struct thread *)(x & ~MTX_FLAGMASK); 253 return (*owner != NULL); 254 } 255 #endif 256 257 /* 258 * Function versions of the inlined __mtx_* macros. These are used by 259 * modules and can also be called from assembly language if needed. 260 */ 261 void 262 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 263 { 264 struct mtx *m; 265 uintptr_t tid, v; 266 267 m = mtxlock2mtx(c); 268 269 KASSERT(kdb_active != 0 || SCHEDULER_STOPPED() || 270 !TD_IS_IDLETHREAD(curthread), 271 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d", 272 curthread, m->lock_object.lo_name, file, line)); 273 KASSERT(m->mtx_lock != MTX_DESTROYED, 274 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 275 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 276 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 277 file, line)); 278 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) | 279 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 280 281 tid = (uintptr_t)curthread; 282 v = MTX_UNOWNED; 283 if (!_mtx_obtain_lock_fetch(m, &v, tid)) 284 _mtx_lock_sleep(m, v, opts, file, line); 285 else 286 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, 287 m, 0, 0, file, line); 288 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 289 line); 290 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE, 291 file, line); 292 TD_LOCKS_INC(curthread); 293 } 294 295 void 296 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 297 { 298 struct mtx *m; 299 300 m = mtxlock2mtx(c); 301 302 KASSERT(m->mtx_lock != MTX_DESTROYED, 303 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 304 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 305 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 306 file, line)); 307 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 308 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 309 line); 310 mtx_assert(m, MA_OWNED); 311 312 #ifdef LOCK_PROFILING 313 __mtx_unlock_sleep(c, (uintptr_t)curthread, opts, file, line); 314 #else 315 __mtx_unlock(m, curthread, opts, file, line); 316 #endif 317 TD_LOCKS_DEC(curthread); 318 } 319 320 void 321 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 322 int line) 323 { 324 struct mtx *m; 325 #ifdef SMP 326 uintptr_t tid, v; 327 #endif 328 329 m = mtxlock2mtx(c); 330 331 KASSERT(m->mtx_lock != MTX_DESTROYED, 332 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 333 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 334 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 335 m->lock_object.lo_name, file, line)); 336 if (mtx_owned(m)) 337 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 338 (opts & MTX_RECURSE) != 0, 339 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 340 m->lock_object.lo_name, file, line)); 341 opts &= ~MTX_RECURSE; 342 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 343 file, line, NULL); 344 #ifdef SMP 345 spinlock_enter(); 346 tid = (uintptr_t)curthread; 347 v = MTX_UNOWNED; 348 if (!_mtx_obtain_lock_fetch(m, &v, tid)) 349 _mtx_lock_spin(m, v, opts, file, line); 350 else 351 LOCKSTAT_PROFILE_OBTAIN_SPIN_LOCK_SUCCESS(spin__acquire, 352 m, 0, 0, file, line); 353 #else 354 __mtx_lock_spin(m, curthread, opts, file, line); 355 #endif 356 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 357 line); 358 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 359 } 360 361 int 362 __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 363 int line) 364 { 365 struct mtx *m; 366 367 if (SCHEDULER_STOPPED()) 368 return (1); 369 370 m = mtxlock2mtx(c); 371 372 KASSERT(m->mtx_lock != MTX_DESTROYED, 373 ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line)); 374 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 375 ("mtx_trylock_spin() of sleep mutex %s @ %s:%d", 376 m->lock_object.lo_name, file, line)); 377 KASSERT((opts & MTX_RECURSE) == 0, 378 ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n", 379 m->lock_object.lo_name, file, line)); 380 if (__mtx_trylock_spin(m, curthread, opts, file, line)) { 381 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line); 382 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 383 return (1); 384 } 385 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line); 386 return (0); 387 } 388 389 void 390 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 391 int line) 392 { 393 struct mtx *m; 394 395 m = mtxlock2mtx(c); 396 397 KASSERT(m->mtx_lock != MTX_DESTROYED, 398 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 399 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 400 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 401 m->lock_object.lo_name, file, line)); 402 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 403 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 404 line); 405 mtx_assert(m, MA_OWNED); 406 407 __mtx_unlock_spin(m); 408 } 409 410 /* 411 * The important part of mtx_trylock{,_flags}() 412 * Tries to acquire lock `m.' If this function is called on a mutex that 413 * is already owned, it will recursively acquire the lock. 414 */ 415 int 416 _mtx_trylock_flags_int(struct mtx *m, int opts LOCK_FILE_LINE_ARG_DEF) 417 { 418 struct thread *td; 419 uintptr_t tid, v; 420 #ifdef LOCK_PROFILING 421 uint64_t waittime = 0; 422 int contested = 0; 423 #endif 424 int rval; 425 bool recursed; 426 427 td = curthread; 428 tid = (uintptr_t)td; 429 if (SCHEDULER_STOPPED_TD(td)) 430 return (1); 431 432 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(td), 433 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", 434 curthread, m->lock_object.lo_name, file, line)); 435 KASSERT(m->mtx_lock != MTX_DESTROYED, 436 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 437 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 438 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 439 file, line)); 440 441 rval = 1; 442 recursed = false; 443 v = MTX_UNOWNED; 444 for (;;) { 445 if (_mtx_obtain_lock_fetch(m, &v, tid)) 446 break; 447 if (v == MTX_UNOWNED) 448 continue; 449 if (v == tid && 450 ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 451 (opts & MTX_RECURSE) != 0)) { 452 m->mtx_recurse++; 453 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 454 recursed = true; 455 break; 456 } 457 rval = 0; 458 break; 459 } 460 461 opts &= ~MTX_RECURSE; 462 463 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 464 if (rval) { 465 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 466 file, line); 467 TD_LOCKS_INC(curthread); 468 if (!recursed) 469 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, 470 m, contested, waittime, file, line); 471 } 472 473 return (rval); 474 } 475 476 int 477 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line) 478 { 479 struct mtx *m; 480 481 m = mtxlock2mtx(c); 482 return (_mtx_trylock_flags_int(m, opts LOCK_FILE_LINE_ARG)); 483 } 484 485 /* 486 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 487 * 488 * We call this if the lock is either contested (i.e. we need to go to 489 * sleep waiting for it), or if we need to recurse on it. 490 */ 491 #if LOCK_DEBUG > 0 492 void 493 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, int opts, const char *file, 494 int line) 495 #else 496 void 497 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v) 498 #endif 499 { 500 struct thread *td; 501 struct mtx *m; 502 struct turnstile *ts; 503 uintptr_t tid; 504 struct thread *owner; 505 #ifdef LOCK_PROFILING 506 int contested = 0; 507 uint64_t waittime = 0; 508 #endif 509 #if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS) 510 struct lock_delay_arg lda; 511 #endif 512 #ifdef KDTRACE_HOOKS 513 u_int sleep_cnt = 0; 514 int64_t sleep_time = 0; 515 int64_t all_time = 0; 516 #endif 517 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 518 int doing_lockprof = 0; 519 #endif 520 521 td = curthread; 522 tid = (uintptr_t)td; 523 m = mtxlock2mtx(c); 524 525 #ifdef KDTRACE_HOOKS 526 if (LOCKSTAT_PROFILE_ENABLED(adaptive__acquire)) { 527 while (v == MTX_UNOWNED) { 528 if (_mtx_obtain_lock_fetch(m, &v, tid)) 529 goto out_lockstat; 530 } 531 doing_lockprof = 1; 532 all_time -= lockstat_nsecs(&m->lock_object); 533 } 534 #endif 535 #ifdef LOCK_PROFILING 536 doing_lockprof = 1; 537 #endif 538 539 if (SCHEDULER_STOPPED_TD(td)) 540 return; 541 542 if (__predict_false(v == MTX_UNOWNED)) 543 v = MTX_READ_VALUE(m); 544 545 if (__predict_false(lv_mtx_owner(v) == td)) { 546 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 547 (opts & MTX_RECURSE) != 0, 548 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 549 m->lock_object.lo_name, file, line)); 550 #if LOCK_DEBUG > 0 551 opts &= ~MTX_RECURSE; 552 #endif 553 m->mtx_recurse++; 554 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 555 if (LOCK_LOG_TEST(&m->lock_object, opts)) 556 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 557 return; 558 } 559 #if LOCK_DEBUG > 0 560 opts &= ~MTX_RECURSE; 561 #endif 562 563 #if defined(ADAPTIVE_MUTEXES) 564 lock_delay_arg_init(&lda, &mtx_delay); 565 #elif defined(KDTRACE_HOOKS) 566 lock_delay_arg_init_noadapt(&lda); 567 #endif 568 569 #ifdef HWPMC_HOOKS 570 PMC_SOFT_CALL( , , lock, failed); 571 #endif 572 lock_profile_obtain_lock_failed(&m->lock_object, false, 573 &contested, &waittime); 574 if (LOCK_LOG_TEST(&m->lock_object, opts)) 575 CTR4(KTR_LOCK, 576 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 577 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 578 579 for (;;) { 580 if (v == MTX_UNOWNED) { 581 if (_mtx_obtain_lock_fetch(m, &v, tid)) 582 break; 583 continue; 584 } 585 #ifdef KDTRACE_HOOKS 586 lda.spin_cnt++; 587 #endif 588 #ifdef ADAPTIVE_MUTEXES 589 /* 590 * If the owner is running on another CPU, spin until the 591 * owner stops running or the state of the lock changes. 592 */ 593 owner = lv_mtx_owner(v); 594 if (TD_IS_RUNNING(owner)) { 595 if (LOCK_LOG_TEST(&m->lock_object, 0)) 596 CTR3(KTR_LOCK, 597 "%s: spinning on %p held by %p", 598 __func__, m, owner); 599 KTR_STATE1(KTR_SCHED, "thread", 600 sched_tdname((struct thread *)tid), 601 "spinning", "lockname:\"%s\"", 602 m->lock_object.lo_name); 603 do { 604 lock_delay(&lda); 605 v = MTX_READ_VALUE(m); 606 owner = lv_mtx_owner(v); 607 } while (v != MTX_UNOWNED && TD_IS_RUNNING(owner)); 608 KTR_STATE0(KTR_SCHED, "thread", 609 sched_tdname((struct thread *)tid), 610 "running"); 611 continue; 612 } 613 #endif 614 615 ts = turnstile_trywait(&m->lock_object); 616 v = MTX_READ_VALUE(m); 617 retry_turnstile: 618 619 /* 620 * Check if the lock has been released while spinning for 621 * the turnstile chain lock. 622 */ 623 if (v == MTX_UNOWNED) { 624 turnstile_cancel(ts); 625 continue; 626 } 627 628 #ifdef ADAPTIVE_MUTEXES 629 /* 630 * The current lock owner might have started executing 631 * on another CPU (or the lock could have changed 632 * owners) while we were waiting on the turnstile 633 * chain lock. If so, drop the turnstile lock and try 634 * again. 635 */ 636 owner = lv_mtx_owner(v); 637 if (TD_IS_RUNNING(owner)) { 638 turnstile_cancel(ts); 639 continue; 640 } 641 #endif 642 643 /* 644 * If the mutex isn't already contested and a failure occurs 645 * setting the contested bit, the mutex was either released 646 * or the state of the MTX_RECURSED bit changed. 647 */ 648 if ((v & MTX_CONTESTED) == 0 && 649 !atomic_fcmpset_ptr(&m->mtx_lock, &v, v | MTX_CONTESTED)) { 650 goto retry_turnstile; 651 } 652 653 /* 654 * We definitely must sleep for this lock. 655 */ 656 mtx_assert(m, MA_NOTOWNED); 657 658 /* 659 * Block on the turnstile. 660 */ 661 #ifdef KDTRACE_HOOKS 662 sleep_time -= lockstat_nsecs(&m->lock_object); 663 #endif 664 #ifndef ADAPTIVE_MUTEXES 665 owner = mtx_owner(m); 666 #endif 667 MPASS(owner == mtx_owner(m)); 668 turnstile_wait(ts, owner, TS_EXCLUSIVE_QUEUE); 669 #ifdef KDTRACE_HOOKS 670 sleep_time += lockstat_nsecs(&m->lock_object); 671 sleep_cnt++; 672 #endif 673 v = MTX_READ_VALUE(m); 674 } 675 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 676 if (__predict_true(!doing_lockprof)) 677 return; 678 #endif 679 #ifdef KDTRACE_HOOKS 680 all_time += lockstat_nsecs(&m->lock_object); 681 if (sleep_time) 682 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time); 683 684 /* 685 * Only record the loops spinning and not sleeping. 686 */ 687 if (lda.spin_cnt > sleep_cnt) 688 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time); 689 out_lockstat: 690 #endif 691 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested, 692 waittime, file, line); 693 } 694 695 #ifdef SMP 696 /* 697 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock. 698 * 699 * This is only called if we need to actually spin for the lock. Recursion 700 * is handled inline. 701 */ 702 #if LOCK_DEBUG > 0 703 void 704 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v, int opts, 705 const char *file, int line) 706 #else 707 void 708 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v) 709 #endif 710 { 711 struct mtx *m; 712 struct lock_delay_arg lda; 713 uintptr_t tid; 714 #ifdef LOCK_PROFILING 715 int contested = 0; 716 uint64_t waittime = 0; 717 #endif 718 #ifdef KDTRACE_HOOKS 719 int64_t spin_time = 0; 720 #endif 721 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 722 int doing_lockprof = 0; 723 #endif 724 725 tid = (uintptr_t)curthread; 726 m = mtxlock2mtx(c); 727 728 #ifdef KDTRACE_HOOKS 729 if (LOCKSTAT_PROFILE_ENABLED(adaptive__acquire)) { 730 while (v == MTX_UNOWNED) { 731 if (_mtx_obtain_lock_fetch(m, &v, tid)) 732 goto out_lockstat; 733 } 734 doing_lockprof = 1; 735 spin_time -= lockstat_nsecs(&m->lock_object); 736 } 737 #endif 738 #ifdef LOCK_PROFILING 739 doing_lockprof = 1; 740 #endif 741 742 if (__predict_false(v == MTX_UNOWNED)) 743 v = MTX_READ_VALUE(m); 744 745 if (__predict_false(v == tid)) { 746 m->mtx_recurse++; 747 return; 748 } 749 750 if (SCHEDULER_STOPPED()) 751 return; 752 753 if (LOCK_LOG_TEST(&m->lock_object, opts)) 754 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 755 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 756 "spinning", "lockname:\"%s\"", m->lock_object.lo_name); 757 758 lock_delay_arg_init(&lda, &mtx_spin_delay); 759 760 #ifdef HWPMC_HOOKS 761 PMC_SOFT_CALL( , , lock, failed); 762 #endif 763 lock_profile_obtain_lock_failed(&m->lock_object, true, &contested, &waittime); 764 765 for (;;) { 766 if (v == MTX_UNOWNED) { 767 if (_mtx_obtain_lock_fetch(m, &v, tid)) 768 break; 769 continue; 770 } 771 /* Give interrupts a chance while we spin. */ 772 spinlock_exit(); 773 do { 774 if (__predict_true(lda.spin_cnt < 10000000)) { 775 lock_delay(&lda); 776 } else { 777 _mtx_lock_indefinite_check(m, &lda); 778 } 779 v = MTX_READ_VALUE(m); 780 } while (v != MTX_UNOWNED); 781 spinlock_enter(); 782 } 783 784 if (LOCK_LOG_TEST(&m->lock_object, opts)) 785 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 786 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 787 "running"); 788 789 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 790 if (__predict_true(!doing_lockprof)) 791 return; 792 #endif 793 #ifdef KDTRACE_HOOKS 794 spin_time += lockstat_nsecs(&m->lock_object); 795 if (lda.spin_cnt != 0) 796 LOCKSTAT_RECORD1(spin__spin, m, spin_time); 797 out_lockstat: 798 #endif 799 LOCKSTAT_PROFILE_OBTAIN_SPIN_LOCK_SUCCESS(spin__acquire, m, 800 contested, waittime, file, line); 801 } 802 #endif /* SMP */ 803 804 #ifdef INVARIANTS 805 static void 806 thread_lock_validate(struct mtx *m, int opts, const char *file, int line) 807 { 808 809 KASSERT(m->mtx_lock != MTX_DESTROYED, 810 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 811 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 812 ("thread_lock() of sleep mutex %s @ %s:%d", 813 m->lock_object.lo_name, file, line)); 814 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) == 0, 815 ("thread_lock: got a recursive mutex %s @ %s:%d\n", 816 m->lock_object.lo_name, file, line)); 817 WITNESS_CHECKORDER(&m->lock_object, 818 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 819 } 820 #else 821 #define thread_lock_validate(m, opts, file, line) do { } while (0) 822 #endif 823 824 #ifndef LOCK_PROFILING 825 #if LOCK_DEBUG > 0 826 void 827 _thread_lock(struct thread *td, int opts, const char *file, int line) 828 #else 829 void 830 _thread_lock(struct thread *td) 831 #endif 832 { 833 struct mtx *m; 834 uintptr_t tid; 835 836 tid = (uintptr_t)curthread; 837 838 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(spin__acquire))) 839 goto slowpath_noirq; 840 spinlock_enter(); 841 m = td->td_lock; 842 thread_lock_validate(m, 0, file, line); 843 if (__predict_false(m == &blocked_lock)) 844 goto slowpath_unlocked; 845 if (__predict_false(!_mtx_obtain_lock(m, tid))) 846 goto slowpath_unlocked; 847 if (__predict_true(m == td->td_lock)) { 848 WITNESS_LOCK(&m->lock_object, LOP_EXCLUSIVE, file, line); 849 return; 850 } 851 _mtx_release_lock_quick(m); 852 slowpath_unlocked: 853 spinlock_exit(); 854 slowpath_noirq: 855 #if LOCK_DEBUG > 0 856 thread_lock_flags_(td, opts, file, line); 857 #else 858 thread_lock_flags_(td, 0, 0, 0); 859 #endif 860 } 861 #endif 862 863 void 864 thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 865 { 866 struct mtx *m; 867 uintptr_t tid, v; 868 struct lock_delay_arg lda; 869 #ifdef LOCK_PROFILING 870 int contested = 0; 871 uint64_t waittime = 0; 872 #endif 873 #ifdef KDTRACE_HOOKS 874 int64_t spin_time = 0; 875 #endif 876 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 877 int doing_lockprof = 1; 878 #endif 879 880 tid = (uintptr_t)curthread; 881 882 if (SCHEDULER_STOPPED()) { 883 /* 884 * Ensure that spinlock sections are balanced even when the 885 * scheduler is stopped, since we may otherwise inadvertently 886 * re-enable interrupts while dumping core. 887 */ 888 spinlock_enter(); 889 return; 890 } 891 892 lock_delay_arg_init(&lda, &mtx_spin_delay); 893 894 #ifdef HWPMC_HOOKS 895 PMC_SOFT_CALL( , , lock, failed); 896 #endif 897 898 #ifdef LOCK_PROFILING 899 doing_lockprof = 1; 900 #elif defined(KDTRACE_HOOKS) 901 doing_lockprof = lockstat_enabled; 902 #endif 903 #ifdef KDTRACE_HOOKS 904 if (__predict_false(doing_lockprof)) 905 spin_time -= lockstat_nsecs(&td->td_lock->lock_object); 906 #endif 907 spinlock_enter(); 908 909 for (;;) { 910 retry: 911 m = td->td_lock; 912 thread_lock_validate(m, opts, file, line); 913 v = MTX_READ_VALUE(m); 914 for (;;) { 915 if (v == MTX_UNOWNED) { 916 if (_mtx_obtain_lock_fetch(m, &v, tid)) 917 break; 918 continue; 919 } 920 MPASS(v != tid); 921 lock_profile_obtain_lock_failed(&m->lock_object, true, 922 &contested, &waittime); 923 /* Give interrupts a chance while we spin. */ 924 spinlock_exit(); 925 do { 926 if (__predict_true(lda.spin_cnt < 10000000)) { 927 lock_delay(&lda); 928 } else { 929 _mtx_lock_indefinite_check(m, &lda); 930 } 931 if (m != td->td_lock) { 932 spinlock_enter(); 933 goto retry; 934 } 935 v = MTX_READ_VALUE(m); 936 } while (v != MTX_UNOWNED); 937 spinlock_enter(); 938 } 939 if (m == td->td_lock) 940 break; 941 _mtx_release_lock_quick(m); 942 } 943 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 944 line); 945 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 946 947 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 948 if (__predict_true(!doing_lockprof)) 949 return; 950 #endif 951 #ifdef KDTRACE_HOOKS 952 spin_time += lockstat_nsecs(&m->lock_object); 953 #endif 954 LOCKSTAT_PROFILE_OBTAIN_SPIN_LOCK_SUCCESS(spin__acquire, m, contested, 955 waittime, file, line); 956 #ifdef KDTRACE_HOOKS 957 if (lda.spin_cnt != 0) 958 LOCKSTAT_RECORD1(thread__spin, m, spin_time); 959 #endif 960 } 961 962 struct mtx * 963 thread_lock_block(struct thread *td) 964 { 965 struct mtx *lock; 966 967 lock = td->td_lock; 968 mtx_assert(lock, MA_OWNED); 969 td->td_lock = &blocked_lock; 970 971 return (lock); 972 } 973 974 void 975 thread_lock_unblock(struct thread *td, struct mtx *new) 976 { 977 978 mtx_assert(new, MA_OWNED); 979 KASSERT(td->td_lock == &blocked_lock, 980 ("thread %p lock %p not blocked_lock %p", 981 td, td->td_lock, &blocked_lock)); 982 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 983 } 984 985 void 986 thread_lock_block_wait(struct thread *td) 987 { 988 989 while (td->td_lock == &blocked_lock) 990 cpu_spinwait(); 991 992 /* Acquire fence to be certain that all thread state is visible. */ 993 atomic_thread_fence_acq(); 994 } 995 996 void 997 thread_lock_set(struct thread *td, struct mtx *new) 998 { 999 struct mtx *lock; 1000 1001 mtx_assert(new, MA_OWNED); 1002 lock = td->td_lock; 1003 mtx_assert(lock, MA_OWNED); 1004 td->td_lock = new; 1005 mtx_unlock_spin(lock); 1006 } 1007 1008 /* 1009 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 1010 * 1011 * We are only called here if the lock is recursed, contested (i.e. we 1012 * need to wake up a blocked thread) or lockstat probe is active. 1013 */ 1014 #if LOCK_DEBUG > 0 1015 void 1016 __mtx_unlock_sleep(volatile uintptr_t *c, uintptr_t v, int opts, 1017 const char *file, int line) 1018 #else 1019 void 1020 __mtx_unlock_sleep(volatile uintptr_t *c, uintptr_t v) 1021 #endif 1022 { 1023 struct mtx *m; 1024 struct turnstile *ts; 1025 uintptr_t tid; 1026 1027 if (SCHEDULER_STOPPED()) 1028 return; 1029 1030 tid = (uintptr_t)curthread; 1031 m = mtxlock2mtx(c); 1032 1033 if (__predict_false(v == tid)) 1034 v = MTX_READ_VALUE(m); 1035 1036 if (__predict_false(v & MTX_RECURSED)) { 1037 if (--(m->mtx_recurse) == 0) 1038 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 1039 if (LOCK_LOG_TEST(&m->lock_object, opts)) 1040 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 1041 return; 1042 } 1043 1044 LOCKSTAT_PROFILE_RELEASE_LOCK(adaptive__release, m); 1045 if (v == tid && _mtx_release_lock(m, tid)) 1046 return; 1047 1048 /* 1049 * We have to lock the chain before the turnstile so this turnstile 1050 * can be removed from the hash list if it is empty. 1051 */ 1052 turnstile_chain_lock(&m->lock_object); 1053 _mtx_release_lock_quick(m); 1054 ts = turnstile_lookup(&m->lock_object); 1055 MPASS(ts != NULL); 1056 if (LOCK_LOG_TEST(&m->lock_object, opts)) 1057 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 1058 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 1059 1060 /* 1061 * This turnstile is now no longer associated with the mutex. We can 1062 * unlock the chain lock so a new turnstile may take it's place. 1063 */ 1064 turnstile_unpend(ts); 1065 turnstile_chain_unlock(&m->lock_object); 1066 } 1067 1068 /* 1069 * All the unlocking of MTX_SPIN locks is done inline. 1070 * See the __mtx_unlock_spin() macro for the details. 1071 */ 1072 1073 /* 1074 * The backing function for the INVARIANTS-enabled mtx_assert() 1075 */ 1076 #ifdef INVARIANT_SUPPORT 1077 void 1078 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line) 1079 { 1080 const struct mtx *m; 1081 1082 if (KERNEL_PANICKED() || dumping || SCHEDULER_STOPPED()) 1083 return; 1084 1085 m = mtxlock2mtx(c); 1086 1087 switch (what) { 1088 case MA_OWNED: 1089 case MA_OWNED | MA_RECURSED: 1090 case MA_OWNED | MA_NOTRECURSED: 1091 if (!mtx_owned(m)) 1092 panic("mutex %s not owned at %s:%d", 1093 m->lock_object.lo_name, file, line); 1094 if (mtx_recursed(m)) { 1095 if ((what & MA_NOTRECURSED) != 0) 1096 panic("mutex %s recursed at %s:%d", 1097 m->lock_object.lo_name, file, line); 1098 } else if ((what & MA_RECURSED) != 0) { 1099 panic("mutex %s unrecursed at %s:%d", 1100 m->lock_object.lo_name, file, line); 1101 } 1102 break; 1103 case MA_NOTOWNED: 1104 if (mtx_owned(m)) 1105 panic("mutex %s owned at %s:%d", 1106 m->lock_object.lo_name, file, line); 1107 break; 1108 default: 1109 panic("unknown mtx_assert at %s:%d", file, line); 1110 } 1111 } 1112 #endif 1113 1114 /* 1115 * General init routine used by the MTX_SYSINIT() macro. 1116 */ 1117 void 1118 mtx_sysinit(void *arg) 1119 { 1120 struct mtx_args *margs = arg; 1121 1122 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL, 1123 margs->ma_opts); 1124 } 1125 1126 /* 1127 * Mutex initialization routine; initialize lock `m' of type contained in 1128 * `opts' with options contained in `opts' and name `name.' The optional 1129 * lock type `type' is used as a general lock category name for use with 1130 * witness. 1131 */ 1132 void 1133 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts) 1134 { 1135 struct mtx *m; 1136 struct lock_class *class; 1137 int flags; 1138 1139 m = mtxlock2mtx(c); 1140 1141 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 1142 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0); 1143 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 1144 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 1145 &m->mtx_lock)); 1146 1147 /* Determine lock class and lock flags. */ 1148 if (opts & MTX_SPIN) 1149 class = &lock_class_mtx_spin; 1150 else 1151 class = &lock_class_mtx_sleep; 1152 flags = 0; 1153 if (opts & MTX_QUIET) 1154 flags |= LO_QUIET; 1155 if (opts & MTX_RECURSE) 1156 flags |= LO_RECURSABLE; 1157 if ((opts & MTX_NOWITNESS) == 0) 1158 flags |= LO_WITNESS; 1159 if (opts & MTX_DUPOK) 1160 flags |= LO_DUPOK; 1161 if (opts & MTX_NOPROFILE) 1162 flags |= LO_NOPROFILE; 1163 if (opts & MTX_NEW) 1164 flags |= LO_NEW; 1165 1166 /* Initialize mutex. */ 1167 lock_init(&m->lock_object, class, name, type, flags); 1168 1169 m->mtx_lock = MTX_UNOWNED; 1170 m->mtx_recurse = 0; 1171 } 1172 1173 /* 1174 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 1175 * passed in as a flag here because if the corresponding mtx_init() was 1176 * called with MTX_QUIET set, then it will already be set in the mutex's 1177 * flags. 1178 */ 1179 void 1180 _mtx_destroy(volatile uintptr_t *c) 1181 { 1182 struct mtx *m; 1183 1184 m = mtxlock2mtx(c); 1185 1186 if (!mtx_owned(m)) 1187 MPASS(mtx_unowned(m)); 1188 else { 1189 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 1190 1191 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 1192 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) { 1193 lock_profile_release_lock(&m->lock_object, true); 1194 spinlock_exit(); 1195 } else { 1196 TD_LOCKS_DEC(curthread); 1197 lock_profile_release_lock(&m->lock_object, false); 1198 } 1199 1200 /* Tell witness this isn't locked to make it happy. */ 1201 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 1202 __LINE__); 1203 } 1204 1205 m->mtx_lock = MTX_DESTROYED; 1206 lock_destroy(&m->lock_object); 1207 } 1208 1209 /* 1210 * Intialize the mutex code and system mutexes. This is called from the MD 1211 * startup code prior to mi_startup(). The per-CPU data space needs to be 1212 * setup before this is called. 1213 */ 1214 void 1215 mutex_init(void) 1216 { 1217 1218 /* Setup turnstiles so that sleep mutexes work. */ 1219 init_turnstiles(); 1220 1221 /* 1222 * Initialize mutexes. 1223 */ 1224 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 1225 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 1226 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 1227 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 1228 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN); 1229 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN); 1230 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN); 1231 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN); 1232 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 1233 mtx_lock(&Giant); 1234 } 1235 1236 static void __noinline 1237 _mtx_lock_indefinite_check(struct mtx *m, struct lock_delay_arg *ldap) 1238 { 1239 struct thread *td; 1240 1241 ldap->spin_cnt++; 1242 if (ldap->spin_cnt < 60000000 || kdb_active || KERNEL_PANICKED()) 1243 cpu_lock_delay(); 1244 else { 1245 td = mtx_owner(m); 1246 1247 /* If the mutex is unlocked, try again. */ 1248 if (td == NULL) 1249 return; 1250 1251 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 1252 m, m->lock_object.lo_name, td, td->td_tid); 1253 #ifdef WITNESS 1254 witness_display_spinlock(&m->lock_object, td, printf); 1255 #endif 1256 panic("spin lock held too long"); 1257 } 1258 cpu_spinwait(); 1259 } 1260 1261 void 1262 mtx_spin_wait_unlocked(struct mtx *m) 1263 { 1264 struct lock_delay_arg lda; 1265 1266 KASSERT(m->mtx_lock != MTX_DESTROYED, 1267 ("%s() of destroyed mutex %p", __func__, m)); 1268 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 1269 ("%s() of sleep mutex %p (%s)", __func__, m, 1270 m->lock_object.lo_name)); 1271 KASSERT(!mtx_owned(m), ("%s() waiting on myself on lock %p (%s)", __func__, m, 1272 m->lock_object.lo_name)); 1273 1274 lda.spin_cnt = 0; 1275 1276 while (atomic_load_acq_ptr(&m->mtx_lock) != MTX_UNOWNED) { 1277 if (__predict_true(lda.spin_cnt < 10000000)) { 1278 cpu_spinwait(); 1279 lda.spin_cnt++; 1280 } else { 1281 _mtx_lock_indefinite_check(m, &lda); 1282 } 1283 } 1284 } 1285 1286 void 1287 mtx_wait_unlocked(struct mtx *m) 1288 { 1289 struct thread *owner; 1290 uintptr_t v; 1291 1292 KASSERT(m->mtx_lock != MTX_DESTROYED, 1293 ("%s() of destroyed mutex %p", __func__, m)); 1294 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 1295 ("%s() not a sleep mutex %p (%s)", __func__, m, 1296 m->lock_object.lo_name)); 1297 KASSERT(!mtx_owned(m), ("%s() waiting on myself on lock %p (%s)", __func__, m, 1298 m->lock_object.lo_name)); 1299 1300 for (;;) { 1301 v = atomic_load_acq_ptr(&m->mtx_lock); 1302 if (v == MTX_UNOWNED) { 1303 break; 1304 } 1305 owner = lv_mtx_owner(v); 1306 if (!TD_IS_RUNNING(owner)) { 1307 mtx_lock(m); 1308 mtx_unlock(m); 1309 break; 1310 } 1311 cpu_spinwait(); 1312 } 1313 } 1314 1315 #ifdef DDB 1316 void 1317 db_show_mtx(const struct lock_object *lock) 1318 { 1319 struct thread *td; 1320 const struct mtx *m; 1321 1322 m = (const struct mtx *)lock; 1323 1324 db_printf(" flags: {"); 1325 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 1326 db_printf("SPIN"); 1327 else 1328 db_printf("DEF"); 1329 if (m->lock_object.lo_flags & LO_RECURSABLE) 1330 db_printf(", RECURSE"); 1331 if (m->lock_object.lo_flags & LO_DUPOK) 1332 db_printf(", DUPOK"); 1333 db_printf("}\n"); 1334 db_printf(" state: {"); 1335 if (mtx_unowned(m)) 1336 db_printf("UNOWNED"); 1337 else if (mtx_destroyed(m)) 1338 db_printf("DESTROYED"); 1339 else { 1340 db_printf("OWNED"); 1341 if (m->mtx_lock & MTX_CONTESTED) 1342 db_printf(", CONTESTED"); 1343 if (m->mtx_lock & MTX_RECURSED) 1344 db_printf(", RECURSED"); 1345 } 1346 db_printf("}\n"); 1347 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 1348 td = mtx_owner(m); 1349 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 1350 td->td_tid, td->td_proc->p_pid, td->td_name); 1351 if (mtx_recursed(m)) 1352 db_printf(" recursed: %d\n", m->mtx_recurse); 1353 } 1354 } 1355 #endif
Cache object: cb8cb310ef4bc444fe7ea863bcf33aa8
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]