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_hwpmc_hooks.h" 42 #include "opt_sched.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/bus.h> 47 #include <sys/conf.h> 48 #include <sys/kdb.h> 49 #include <sys/kernel.h> 50 #include <sys/ktr.h> 51 #include <sys/lock.h> 52 #include <sys/malloc.h> 53 #include <sys/mutex.h> 54 #include <sys/proc.h> 55 #include <sys/resourcevar.h> 56 #include <sys/sched.h> 57 #include <sys/sbuf.h> 58 #include <sys/smp.h> 59 #include <sys/sysctl.h> 60 #include <sys/turnstile.h> 61 #include <sys/vmmeter.h> 62 #include <sys/lock_profile.h> 63 64 #include <machine/atomic.h> 65 #include <machine/bus.h> 66 #include <machine/cpu.h> 67 68 #include <ddb/ddb.h> 69 70 #include <fs/devfs/devfs_int.h> 71 72 #include <vm/vm.h> 73 #include <vm/vm_extern.h> 74 75 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) 76 #define ADAPTIVE_MUTEXES 77 #endif 78 79 #ifdef HWPMC_HOOKS 80 #include <sys/pmckern.h> 81 PMC_SOFT_DEFINE( , , lock, failed); 82 #endif 83 84 /* 85 * Return the mutex address when the lock cookie address is provided. 86 * This functionality assumes that struct mtx* have a member named mtx_lock. 87 */ 88 #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock)) 89 90 /* 91 * Internal utility macros. 92 */ 93 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 94 95 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) 96 97 static void assert_mtx(const struct lock_object *lock, int what); 98 #ifdef DDB 99 static void db_show_mtx(const struct lock_object *lock); 100 #endif 101 static void lock_mtx(struct lock_object *lock, uintptr_t how); 102 static void lock_spin(struct lock_object *lock, uintptr_t how); 103 #ifdef KDTRACE_HOOKS 104 static int owner_mtx(const struct lock_object *lock, 105 struct thread **owner); 106 #endif 107 static uintptr_t unlock_mtx(struct lock_object *lock); 108 static uintptr_t unlock_spin(struct lock_object *lock); 109 110 /* 111 * Lock classes for sleep and spin mutexes. 112 */ 113 struct lock_class lock_class_mtx_sleep = { 114 .lc_name = "sleep mutex", 115 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, 116 .lc_assert = assert_mtx, 117 #ifdef DDB 118 .lc_ddb_show = db_show_mtx, 119 #endif 120 .lc_lock = lock_mtx, 121 .lc_unlock = unlock_mtx, 122 #ifdef KDTRACE_HOOKS 123 .lc_owner = owner_mtx, 124 #endif 125 }; 126 struct lock_class lock_class_mtx_spin = { 127 .lc_name = "spin mutex", 128 .lc_flags = LC_SPINLOCK | LC_RECURSABLE, 129 .lc_assert = assert_mtx, 130 #ifdef DDB 131 .lc_ddb_show = db_show_mtx, 132 #endif 133 .lc_lock = lock_spin, 134 .lc_unlock = unlock_spin, 135 #ifdef KDTRACE_HOOKS 136 .lc_owner = owner_mtx, 137 #endif 138 }; 139 140 #ifdef ADAPTIVE_MUTEXES 141 static SYSCTL_NODE(_debug, OID_AUTO, mtx, CTLFLAG_RD, NULL, "mtx debugging"); 142 143 static struct lock_delay_config __read_frequently mtx_delay; 144 145 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_base, CTLFLAG_RW, &mtx_delay.base, 146 0, ""); 147 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max, 148 0, ""); 149 150 LOCK_DELAY_SYSINIT_DEFAULT(mtx_delay); 151 #endif 152 153 static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin, CTLFLAG_RD, NULL, 154 "mtx spin debugging"); 155 156 static struct lock_delay_config __read_frequently mtx_spin_delay; 157 158 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_base, CTLFLAG_RW, 159 &mtx_spin_delay.base, 0, ""); 160 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_max, CTLFLAG_RW, 161 &mtx_spin_delay.max, 0, ""); 162 163 LOCK_DELAY_SYSINIT_DEFAULT(mtx_spin_delay); 164 165 /* 166 * System-wide mutexes 167 */ 168 struct mtx blocked_lock; 169 struct mtx __exclusive_cache_line Giant; 170 171 void 172 assert_mtx(const struct lock_object *lock, int what) 173 { 174 175 mtx_assert((const struct mtx *)lock, what); 176 } 177 178 void 179 lock_mtx(struct lock_object *lock, uintptr_t how) 180 { 181 182 mtx_lock((struct mtx *)lock); 183 } 184 185 void 186 lock_spin(struct lock_object *lock, uintptr_t how) 187 { 188 189 panic("spin locks can only use msleep_spin"); 190 } 191 192 uintptr_t 193 unlock_mtx(struct lock_object *lock) 194 { 195 struct mtx *m; 196 197 m = (struct mtx *)lock; 198 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 199 mtx_unlock(m); 200 return (0); 201 } 202 203 uintptr_t 204 unlock_spin(struct lock_object *lock) 205 { 206 207 panic("spin locks can only use msleep_spin"); 208 } 209 210 #ifdef KDTRACE_HOOKS 211 int 212 owner_mtx(const struct lock_object *lock, struct thread **owner) 213 { 214 const struct mtx *m; 215 uintptr_t x; 216 217 m = (const struct mtx *)lock; 218 x = m->mtx_lock; 219 *owner = (struct thread *)(x & ~MTX_FLAGMASK); 220 return (x != MTX_UNOWNED); 221 } 222 #endif 223 224 /* 225 * Function versions of the inlined __mtx_* macros. These are used by 226 * modules and can also be called from assembly language if needed. 227 */ 228 void 229 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 230 { 231 struct mtx *m; 232 uintptr_t tid, v; 233 234 m = mtxlock2mtx(c); 235 236 KASSERT(kdb_active != 0 || SCHEDULER_STOPPED() || 237 !TD_IS_IDLETHREAD(curthread), 238 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d", 239 curthread, m->lock_object.lo_name, file, line)); 240 KASSERT(m->mtx_lock != MTX_DESTROYED, 241 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 242 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 243 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 244 file, line)); 245 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) | 246 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 247 248 tid = (uintptr_t)curthread; 249 v = MTX_UNOWNED; 250 if (!_mtx_obtain_lock_fetch(m, &v, tid)) 251 _mtx_lock_sleep(m, v, opts, file, line); 252 else 253 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, 254 m, 0, 0, file, line); 255 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 256 line); 257 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE, 258 file, line); 259 TD_LOCKS_INC(curthread); 260 } 261 262 void 263 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 264 { 265 struct mtx *m; 266 267 m = mtxlock2mtx(c); 268 269 KASSERT(m->mtx_lock != MTX_DESTROYED, 270 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 271 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 272 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 273 file, line)); 274 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 275 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 276 line); 277 mtx_assert(m, MA_OWNED); 278 279 #ifdef LOCK_PROFILING 280 __mtx_unlock_sleep(c, opts, file, line); 281 #else 282 __mtx_unlock(m, curthread, opts, file, line); 283 #endif 284 TD_LOCKS_DEC(curthread); 285 } 286 287 void 288 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 289 int line) 290 { 291 struct mtx *m; 292 293 if (SCHEDULER_STOPPED()) 294 return; 295 296 m = mtxlock2mtx(c); 297 298 KASSERT(m->mtx_lock != MTX_DESTROYED, 299 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 300 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 301 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 302 m->lock_object.lo_name, file, line)); 303 if (mtx_owned(m)) 304 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 305 (opts & MTX_RECURSE) != 0, 306 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 307 m->lock_object.lo_name, file, line)); 308 opts &= ~MTX_RECURSE; 309 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 310 file, line, NULL); 311 __mtx_lock_spin(m, curthread, opts, file, line); 312 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 313 line); 314 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 315 } 316 317 int 318 __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 319 int line) 320 { 321 struct mtx *m; 322 323 if (SCHEDULER_STOPPED()) 324 return (1); 325 326 m = mtxlock2mtx(c); 327 328 KASSERT(m->mtx_lock != MTX_DESTROYED, 329 ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line)); 330 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 331 ("mtx_trylock_spin() of sleep mutex %s @ %s:%d", 332 m->lock_object.lo_name, file, line)); 333 KASSERT((opts & MTX_RECURSE) == 0, 334 ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n", 335 m->lock_object.lo_name, file, line)); 336 if (__mtx_trylock_spin(m, curthread, opts, file, line)) { 337 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line); 338 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 339 return (1); 340 } 341 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line); 342 return (0); 343 } 344 345 void 346 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 347 int line) 348 { 349 struct mtx *m; 350 351 if (SCHEDULER_STOPPED()) 352 return; 353 354 m = mtxlock2mtx(c); 355 356 KASSERT(m->mtx_lock != MTX_DESTROYED, 357 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 358 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 359 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 360 m->lock_object.lo_name, file, line)); 361 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 362 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 363 line); 364 mtx_assert(m, MA_OWNED); 365 366 __mtx_unlock_spin(m); 367 } 368 369 /* 370 * The important part of mtx_trylock{,_flags}() 371 * Tries to acquire lock `m.' If this function is called on a mutex that 372 * is already owned, it will recursively acquire the lock. 373 */ 374 int 375 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line) 376 { 377 struct mtx *m; 378 struct thread *td; 379 uintptr_t tid, v; 380 #ifdef LOCK_PROFILING 381 uint64_t waittime = 0; 382 int contested = 0; 383 #endif 384 int rval; 385 bool recursed; 386 387 td = curthread; 388 tid = (uintptr_t)td; 389 if (SCHEDULER_STOPPED_TD(td)) 390 return (1); 391 392 m = mtxlock2mtx(c); 393 394 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(td), 395 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", 396 curthread, m->lock_object.lo_name, file, line)); 397 KASSERT(m->mtx_lock != MTX_DESTROYED, 398 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 399 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 400 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 401 file, line)); 402 403 rval = 1; 404 recursed = false; 405 v = MTX_UNOWNED; 406 for (;;) { 407 if (_mtx_obtain_lock_fetch(m, &v, tid)) 408 break; 409 if (v == MTX_UNOWNED) 410 continue; 411 if (v == tid && 412 ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 413 (opts & MTX_RECURSE) != 0)) { 414 m->mtx_recurse++; 415 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 416 recursed = true; 417 break; 418 } 419 rval = 0; 420 break; 421 } 422 423 opts &= ~MTX_RECURSE; 424 425 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 426 if (rval) { 427 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 428 file, line); 429 TD_LOCKS_INC(curthread); 430 if (!recursed) 431 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, 432 m, contested, waittime, file, line); 433 } 434 435 return (rval); 436 } 437 438 /* 439 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 440 * 441 * We call this if the lock is either contested (i.e. we need to go to 442 * sleep waiting for it), or if we need to recurse on it. 443 */ 444 #if LOCK_DEBUG > 0 445 void 446 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, int opts, const char *file, 447 int line) 448 #else 449 void 450 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v) 451 #endif 452 { 453 struct thread *td; 454 struct mtx *m; 455 struct turnstile *ts; 456 uintptr_t tid; 457 #ifdef ADAPTIVE_MUTEXES 458 volatile struct thread *owner; 459 #endif 460 #ifdef KTR 461 int cont_logged = 0; 462 #endif 463 #ifdef LOCK_PROFILING 464 int contested = 0; 465 uint64_t waittime = 0; 466 #endif 467 #if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS) 468 struct lock_delay_arg lda; 469 #endif 470 #ifdef KDTRACE_HOOKS 471 u_int sleep_cnt = 0; 472 int64_t sleep_time = 0; 473 int64_t all_time = 0; 474 #endif 475 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 476 int doing_lockprof; 477 #endif 478 td = curthread; 479 tid = (uintptr_t)td; 480 if (SCHEDULER_STOPPED_TD(td)) 481 return; 482 483 #if defined(ADAPTIVE_MUTEXES) 484 lock_delay_arg_init(&lda, &mtx_delay); 485 #elif defined(KDTRACE_HOOKS) 486 lock_delay_arg_init(&lda, NULL); 487 #endif 488 m = mtxlock2mtx(c); 489 if (__predict_false(v == MTX_UNOWNED)) 490 v = MTX_READ_VALUE(m); 491 492 if (__predict_false(lv_mtx_owner(v) == td)) { 493 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 494 (opts & MTX_RECURSE) != 0, 495 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 496 m->lock_object.lo_name, file, line)); 497 #if LOCK_DEBUG > 0 498 opts &= ~MTX_RECURSE; 499 #endif 500 m->mtx_recurse++; 501 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 502 if (LOCK_LOG_TEST(&m->lock_object, opts)) 503 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 504 return; 505 } 506 #if LOCK_DEBUG > 0 507 opts &= ~MTX_RECURSE; 508 #endif 509 510 #ifdef HWPMC_HOOKS 511 PMC_SOFT_CALL( , , lock, failed); 512 #endif 513 lock_profile_obtain_lock_failed(&m->lock_object, 514 &contested, &waittime); 515 if (LOCK_LOG_TEST(&m->lock_object, opts)) 516 CTR4(KTR_LOCK, 517 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 518 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 519 #ifdef LOCK_PROFILING 520 doing_lockprof = 1; 521 #elif defined(KDTRACE_HOOKS) 522 doing_lockprof = lockstat_enabled; 523 if (__predict_false(doing_lockprof)) 524 all_time -= lockstat_nsecs(&m->lock_object); 525 #endif 526 527 for (;;) { 528 if (v == MTX_UNOWNED) { 529 if (_mtx_obtain_lock_fetch(m, &v, tid)) 530 break; 531 continue; 532 } 533 #ifdef KDTRACE_HOOKS 534 lda.spin_cnt++; 535 #endif 536 #ifdef ADAPTIVE_MUTEXES 537 /* 538 * If the owner is running on another CPU, spin until the 539 * owner stops running or the state of the lock changes. 540 */ 541 owner = lv_mtx_owner(v); 542 if (TD_IS_RUNNING(owner)) { 543 if (LOCK_LOG_TEST(&m->lock_object, 0)) 544 CTR3(KTR_LOCK, 545 "%s: spinning on %p held by %p", 546 __func__, m, owner); 547 KTR_STATE1(KTR_SCHED, "thread", 548 sched_tdname((struct thread *)tid), 549 "spinning", "lockname:\"%s\"", 550 m->lock_object.lo_name); 551 do { 552 lock_delay(&lda); 553 v = MTX_READ_VALUE(m); 554 owner = lv_mtx_owner(v); 555 } while (v != MTX_UNOWNED && TD_IS_RUNNING(owner)); 556 KTR_STATE0(KTR_SCHED, "thread", 557 sched_tdname((struct thread *)tid), 558 "running"); 559 continue; 560 } 561 #endif 562 563 ts = turnstile_trywait(&m->lock_object); 564 v = MTX_READ_VALUE(m); 565 566 /* 567 * Check if the lock has been released while spinning for 568 * the turnstile chain lock. 569 */ 570 if (v == MTX_UNOWNED) { 571 turnstile_cancel(ts); 572 continue; 573 } 574 575 #ifdef ADAPTIVE_MUTEXES 576 /* 577 * The current lock owner might have started executing 578 * on another CPU (or the lock could have changed 579 * owners) while we were waiting on the turnstile 580 * chain lock. If so, drop the turnstile lock and try 581 * again. 582 */ 583 owner = lv_mtx_owner(v); 584 if (TD_IS_RUNNING(owner)) { 585 turnstile_cancel(ts); 586 continue; 587 } 588 #endif 589 590 /* 591 * If the mutex isn't already contested and a failure occurs 592 * setting the contested bit, the mutex was either released 593 * or the state of the MTX_RECURSED bit changed. 594 */ 595 if ((v & MTX_CONTESTED) == 0 && 596 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 597 turnstile_cancel(ts); 598 v = MTX_READ_VALUE(m); 599 continue; 600 } 601 602 /* 603 * We definitely must sleep for this lock. 604 */ 605 mtx_assert(m, MA_NOTOWNED); 606 607 #ifdef KTR 608 if (!cont_logged) { 609 CTR6(KTR_CONTENTION, 610 "contention: %p at %s:%d wants %s, taken by %s:%d", 611 (void *)tid, file, line, m->lock_object.lo_name, 612 WITNESS_FILE(&m->lock_object), 613 WITNESS_LINE(&m->lock_object)); 614 cont_logged = 1; 615 } 616 #endif 617 618 /* 619 * Block on the turnstile. 620 */ 621 #ifdef KDTRACE_HOOKS 622 sleep_time -= lockstat_nsecs(&m->lock_object); 623 #endif 624 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 625 #ifdef KDTRACE_HOOKS 626 sleep_time += lockstat_nsecs(&m->lock_object); 627 sleep_cnt++; 628 #endif 629 v = MTX_READ_VALUE(m); 630 } 631 #ifdef KTR 632 if (cont_logged) { 633 CTR4(KTR_CONTENTION, 634 "contention end: %s acquired by %p at %s:%d", 635 m->lock_object.lo_name, (void *)tid, file, line); 636 } 637 #endif 638 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 639 if (__predict_true(!doing_lockprof)) 640 return; 641 #endif 642 #ifdef KDTRACE_HOOKS 643 all_time += lockstat_nsecs(&m->lock_object); 644 #endif 645 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested, 646 waittime, file, line); 647 #ifdef KDTRACE_HOOKS 648 if (sleep_time) 649 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time); 650 651 /* 652 * Only record the loops spinning and not sleeping. 653 */ 654 if (lda.spin_cnt > sleep_cnt) 655 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time); 656 #endif 657 } 658 659 static void 660 _mtx_lock_spin_failed(struct mtx *m) 661 { 662 struct thread *td; 663 664 td = mtx_owner(m); 665 666 /* If the mutex is unlocked, try again. */ 667 if (td == NULL) 668 return; 669 670 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 671 m, m->lock_object.lo_name, td, td->td_tid); 672 #ifdef WITNESS 673 witness_display_spinlock(&m->lock_object, td, printf); 674 #endif 675 panic("spin lock held too long"); 676 } 677 678 #ifdef SMP 679 /* 680 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock. 681 * 682 * This is only called if we need to actually spin for the lock. Recursion 683 * is handled inline. 684 */ 685 void 686 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, 687 int opts, const char *file, int line) 688 { 689 struct mtx *m; 690 struct lock_delay_arg lda; 691 #ifdef LOCK_PROFILING 692 int contested = 0; 693 uint64_t waittime = 0; 694 #endif 695 #ifdef KDTRACE_HOOKS 696 int64_t spin_time = 0; 697 #endif 698 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 699 int doing_lockprof; 700 #endif 701 702 if (SCHEDULER_STOPPED()) 703 return; 704 705 lock_delay_arg_init(&lda, &mtx_spin_delay); 706 m = mtxlock2mtx(c); 707 708 if (__predict_false(v == MTX_UNOWNED)) 709 v = MTX_READ_VALUE(m); 710 711 if (__predict_false(v == tid)) { 712 m->mtx_recurse++; 713 return; 714 } 715 716 if (LOCK_LOG_TEST(&m->lock_object, opts)) 717 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 718 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 719 "spinning", "lockname:\"%s\"", m->lock_object.lo_name); 720 721 #ifdef HWPMC_HOOKS 722 PMC_SOFT_CALL( , , lock, failed); 723 #endif 724 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 725 #ifdef LOCK_PROFILING 726 doing_lockprof = 1; 727 #elif defined(KDTRACE_HOOKS) 728 doing_lockprof = lockstat_enabled; 729 if (__predict_false(doing_lockprof)) 730 spin_time -= lockstat_nsecs(&m->lock_object); 731 #endif 732 for (;;) { 733 if (v == MTX_UNOWNED) { 734 if (_mtx_obtain_lock_fetch(m, &v, tid)) 735 break; 736 continue; 737 } 738 /* Give interrupts a chance while we spin. */ 739 spinlock_exit(); 740 do { 741 if (lda.spin_cnt < 10000000) { 742 lock_delay(&lda); 743 } else { 744 lda.spin_cnt++; 745 if (lda.spin_cnt < 60000000 || kdb_active || 746 panicstr != NULL) 747 DELAY(1); 748 else 749 _mtx_lock_spin_failed(m); 750 cpu_spinwait(); 751 } 752 v = MTX_READ_VALUE(m); 753 } while (v != MTX_UNOWNED); 754 spinlock_enter(); 755 } 756 757 if (LOCK_LOG_TEST(&m->lock_object, opts)) 758 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 759 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 760 "running"); 761 762 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 763 if (__predict_true(!doing_lockprof)) 764 return; 765 #endif 766 #ifdef KDTRACE_HOOKS 767 spin_time += lockstat_nsecs(&m->lock_object); 768 #endif 769 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 770 contested, waittime, file, line); 771 #ifdef KDTRACE_HOOKS 772 if (lda.spin_cnt != 0) 773 LOCKSTAT_RECORD1(spin__spin, m, spin_time); 774 #endif 775 } 776 #endif /* SMP */ 777 778 void 779 thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 780 { 781 struct mtx *m; 782 uintptr_t tid, v; 783 struct lock_delay_arg lda; 784 #ifdef LOCK_PROFILING 785 int contested = 0; 786 uint64_t waittime = 0; 787 #endif 788 #ifdef KDTRACE_HOOKS 789 int64_t spin_time = 0; 790 #endif 791 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 792 int doing_lockprof = 1; 793 #endif 794 795 tid = (uintptr_t)curthread; 796 797 if (SCHEDULER_STOPPED()) { 798 /* 799 * Ensure that spinlock sections are balanced even when the 800 * scheduler is stopped, since we may otherwise inadvertently 801 * re-enable interrupts while dumping core. 802 */ 803 spinlock_enter(); 804 return; 805 } 806 807 lock_delay_arg_init(&lda, &mtx_spin_delay); 808 809 #ifdef LOCK_PROFILING 810 doing_lockprof = 1; 811 #elif defined(KDTRACE_HOOKS) 812 doing_lockprof = lockstat_enabled; 813 if (__predict_false(doing_lockprof)) 814 spin_time -= lockstat_nsecs(&td->td_lock->lock_object); 815 #endif 816 for (;;) { 817 retry: 818 v = MTX_UNOWNED; 819 spinlock_enter(); 820 m = td->td_lock; 821 KASSERT(m->mtx_lock != MTX_DESTROYED, 822 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 823 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 824 ("thread_lock() of sleep mutex %s @ %s:%d", 825 m->lock_object.lo_name, file, line)); 826 if (mtx_owned(m)) 827 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 828 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 829 m->lock_object.lo_name, file, line)); 830 WITNESS_CHECKORDER(&m->lock_object, 831 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 832 for (;;) { 833 if (_mtx_obtain_lock_fetch(m, &v, tid)) 834 break; 835 if (v == MTX_UNOWNED) 836 continue; 837 if (v == tid) { 838 m->mtx_recurse++; 839 break; 840 } 841 #ifdef HWPMC_HOOKS 842 PMC_SOFT_CALL( , , lock, failed); 843 #endif 844 lock_profile_obtain_lock_failed(&m->lock_object, 845 &contested, &waittime); 846 /* Give interrupts a chance while we spin. */ 847 spinlock_exit(); 848 do { 849 if (lda.spin_cnt < 10000000) { 850 lock_delay(&lda); 851 } else { 852 lda.spin_cnt++; 853 if (lda.spin_cnt < 60000000 || 854 kdb_active || panicstr != NULL) 855 DELAY(1); 856 else 857 _mtx_lock_spin_failed(m); 858 cpu_spinwait(); 859 } 860 if (m != td->td_lock) 861 goto retry; 862 v = MTX_READ_VALUE(m); 863 } while (v != MTX_UNOWNED); 864 spinlock_enter(); 865 } 866 if (m == td->td_lock) 867 break; 868 __mtx_unlock_spin(m); /* does spinlock_exit() */ 869 } 870 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 871 line); 872 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 873 874 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING) 875 if (__predict_true(!doing_lockprof)) 876 return; 877 #endif 878 #ifdef KDTRACE_HOOKS 879 spin_time += lockstat_nsecs(&m->lock_object); 880 #endif 881 if (m->mtx_recurse == 0) 882 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 883 contested, waittime, file, line); 884 #ifdef KDTRACE_HOOKS 885 if (lda.spin_cnt != 0) 886 LOCKSTAT_RECORD1(thread__spin, m, spin_time); 887 #endif 888 } 889 890 struct mtx * 891 thread_lock_block(struct thread *td) 892 { 893 struct mtx *lock; 894 895 THREAD_LOCK_ASSERT(td, MA_OWNED); 896 lock = td->td_lock; 897 td->td_lock = &blocked_lock; 898 mtx_unlock_spin(lock); 899 900 return (lock); 901 } 902 903 void 904 thread_lock_unblock(struct thread *td, struct mtx *new) 905 { 906 mtx_assert(new, MA_OWNED); 907 MPASS(td->td_lock == &blocked_lock); 908 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 909 } 910 911 void 912 thread_lock_set(struct thread *td, struct mtx *new) 913 { 914 struct mtx *lock; 915 916 mtx_assert(new, MA_OWNED); 917 THREAD_LOCK_ASSERT(td, MA_OWNED); 918 lock = td->td_lock; 919 td->td_lock = new; 920 mtx_unlock_spin(lock); 921 } 922 923 /* 924 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 925 * 926 * We are only called here if the lock is recursed, contested (i.e. we 927 * need to wake up a blocked thread) or lockstat probe is active. 928 */ 929 #if LOCK_DEBUG > 0 930 void 931 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line) 932 #else 933 void 934 __mtx_unlock_sleep(volatile uintptr_t *c) 935 #endif 936 { 937 struct mtx *m; 938 struct turnstile *ts; 939 uintptr_t tid, v; 940 941 if (SCHEDULER_STOPPED()) 942 return; 943 944 tid = (uintptr_t)curthread; 945 m = mtxlock2mtx(c); 946 v = MTX_READ_VALUE(m); 947 948 if (v & MTX_RECURSED) { 949 if (--(m->mtx_recurse) == 0) 950 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 951 if (LOCK_LOG_TEST(&m->lock_object, opts)) 952 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 953 return; 954 } 955 956 LOCKSTAT_PROFILE_RELEASE_LOCK(adaptive__release, m); 957 if (v == tid && _mtx_release_lock(m, tid)) 958 return; 959 960 /* 961 * We have to lock the chain before the turnstile so this turnstile 962 * can be removed from the hash list if it is empty. 963 */ 964 turnstile_chain_lock(&m->lock_object); 965 ts = turnstile_lookup(&m->lock_object); 966 if (LOCK_LOG_TEST(&m->lock_object, opts)) 967 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 968 MPASS(ts != NULL); 969 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 970 _mtx_release_lock_quick(m); 971 972 /* 973 * This turnstile is now no longer associated with the mutex. We can 974 * unlock the chain lock so a new turnstile may take it's place. 975 */ 976 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 977 turnstile_chain_unlock(&m->lock_object); 978 } 979 980 /* 981 * All the unlocking of MTX_SPIN locks is done inline. 982 * See the __mtx_unlock_spin() macro for the details. 983 */ 984 985 /* 986 * The backing function for the INVARIANTS-enabled mtx_assert() 987 */ 988 #ifdef INVARIANT_SUPPORT 989 void 990 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line) 991 { 992 const struct mtx *m; 993 994 if (panicstr != NULL || dumping || SCHEDULER_STOPPED()) 995 return; 996 997 m = mtxlock2mtx(c); 998 999 switch (what) { 1000 case MA_OWNED: 1001 case MA_OWNED | MA_RECURSED: 1002 case MA_OWNED | MA_NOTRECURSED: 1003 if (!mtx_owned(m)) 1004 panic("mutex %s not owned at %s:%d", 1005 m->lock_object.lo_name, file, line); 1006 if (mtx_recursed(m)) { 1007 if ((what & MA_NOTRECURSED) != 0) 1008 panic("mutex %s recursed at %s:%d", 1009 m->lock_object.lo_name, file, line); 1010 } else if ((what & MA_RECURSED) != 0) { 1011 panic("mutex %s unrecursed at %s:%d", 1012 m->lock_object.lo_name, file, line); 1013 } 1014 break; 1015 case MA_NOTOWNED: 1016 if (mtx_owned(m)) 1017 panic("mutex %s owned at %s:%d", 1018 m->lock_object.lo_name, file, line); 1019 break; 1020 default: 1021 panic("unknown mtx_assert at %s:%d", file, line); 1022 } 1023 } 1024 #endif 1025 1026 /* 1027 * General init routine used by the MTX_SYSINIT() macro. 1028 */ 1029 void 1030 mtx_sysinit(void *arg) 1031 { 1032 struct mtx_args *margs = arg; 1033 1034 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL, 1035 margs->ma_opts); 1036 } 1037 1038 /* 1039 * Mutex initialization routine; initialize lock `m' of type contained in 1040 * `opts' with options contained in `opts' and name `name.' The optional 1041 * lock type `type' is used as a general lock category name for use with 1042 * witness. 1043 */ 1044 void 1045 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts) 1046 { 1047 struct mtx *m; 1048 struct lock_class *class; 1049 int flags; 1050 1051 m = mtxlock2mtx(c); 1052 1053 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 1054 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0); 1055 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 1056 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 1057 &m->mtx_lock)); 1058 1059 /* Determine lock class and lock flags. */ 1060 if (opts & MTX_SPIN) 1061 class = &lock_class_mtx_spin; 1062 else 1063 class = &lock_class_mtx_sleep; 1064 flags = 0; 1065 if (opts & MTX_QUIET) 1066 flags |= LO_QUIET; 1067 if (opts & MTX_RECURSE) 1068 flags |= LO_RECURSABLE; 1069 if ((opts & MTX_NOWITNESS) == 0) 1070 flags |= LO_WITNESS; 1071 if (opts & MTX_DUPOK) 1072 flags |= LO_DUPOK; 1073 if (opts & MTX_NOPROFILE) 1074 flags |= LO_NOPROFILE; 1075 if (opts & MTX_NEW) 1076 flags |= LO_NEW; 1077 1078 /* Initialize mutex. */ 1079 lock_init(&m->lock_object, class, name, type, flags); 1080 1081 m->mtx_lock = MTX_UNOWNED; 1082 m->mtx_recurse = 0; 1083 } 1084 1085 /* 1086 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 1087 * passed in as a flag here because if the corresponding mtx_init() was 1088 * called with MTX_QUIET set, then it will already be set in the mutex's 1089 * flags. 1090 */ 1091 void 1092 _mtx_destroy(volatile uintptr_t *c) 1093 { 1094 struct mtx *m; 1095 1096 m = mtxlock2mtx(c); 1097 1098 if (!mtx_owned(m)) 1099 MPASS(mtx_unowned(m)); 1100 else { 1101 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 1102 1103 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 1104 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 1105 spinlock_exit(); 1106 else 1107 TD_LOCKS_DEC(curthread); 1108 1109 lock_profile_release_lock(&m->lock_object); 1110 /* Tell witness this isn't locked to make it happy. */ 1111 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 1112 __LINE__); 1113 } 1114 1115 m->mtx_lock = MTX_DESTROYED; 1116 lock_destroy(&m->lock_object); 1117 } 1118 1119 /* 1120 * Intialize the mutex code and system mutexes. This is called from the MD 1121 * startup code prior to mi_startup(). The per-CPU data space needs to be 1122 * setup before this is called. 1123 */ 1124 void 1125 mutex_init(void) 1126 { 1127 1128 /* Setup turnstiles so that sleep mutexes work. */ 1129 init_turnstiles(); 1130 1131 /* 1132 * Initialize mutexes. 1133 */ 1134 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 1135 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 1136 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 1137 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 1138 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN); 1139 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN); 1140 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN); 1141 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN); 1142 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 1143 mtx_lock(&Giant); 1144 } 1145 1146 #ifdef DDB 1147 void 1148 db_show_mtx(const struct lock_object *lock) 1149 { 1150 struct thread *td; 1151 const struct mtx *m; 1152 1153 m = (const struct mtx *)lock; 1154 1155 db_printf(" flags: {"); 1156 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 1157 db_printf("SPIN"); 1158 else 1159 db_printf("DEF"); 1160 if (m->lock_object.lo_flags & LO_RECURSABLE) 1161 db_printf(", RECURSE"); 1162 if (m->lock_object.lo_flags & LO_DUPOK) 1163 db_printf(", DUPOK"); 1164 db_printf("}\n"); 1165 db_printf(" state: {"); 1166 if (mtx_unowned(m)) 1167 db_printf("UNOWNED"); 1168 else if (mtx_destroyed(m)) 1169 db_printf("DESTROYED"); 1170 else { 1171 db_printf("OWNED"); 1172 if (m->mtx_lock & MTX_CONTESTED) 1173 db_printf(", CONTESTED"); 1174 if (m->mtx_lock & MTX_RECURSED) 1175 db_printf(", RECURSED"); 1176 } 1177 db_printf("}\n"); 1178 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 1179 td = mtx_owner(m); 1180 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 1181 td->td_tid, td->td_proc->p_pid, td->td_name); 1182 if (mtx_recursed(m)) 1183 db_printf(" recursed: %d\n", m->mtx_recurse); 1184 } 1185 } 1186 #endif 1187