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