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 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) 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 static SYSCTL_NODE(_debug, OID_AUTO, mtx, CTLFLAG_RD, NULL, "mtx debugging"); 144 145 static struct lock_delay_config mtx_delay = { 146 .initial = 1000, 147 .step = 500, 148 .min = 100, 149 .max = 5000, 150 }; 151 152 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_initial, CTLFLAG_RW, &mtx_delay.initial, 153 0, ""); 154 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_step, CTLFLAG_RW, &mtx_delay.step, 155 0, ""); 156 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_min, CTLFLAG_RW, &mtx_delay.min, 157 0, ""); 158 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max, 159 0, ""); 160 161 static void 162 mtx_delay_sysinit(void *dummy) 163 { 164 165 mtx_delay.initial = mp_ncpus * 25; 166 mtx_delay.step = (mp_ncpus * 25) / 2; 167 mtx_delay.min = mp_ncpus * 5; 168 mtx_delay.max = mp_ncpus * 25 * 10; 169 } 170 LOCK_DELAY_SYSINIT(mtx_delay_sysinit); 171 #endif 172 173 static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin, CTLFLAG_RD, NULL, 174 "mtx spin debugging"); 175 176 static struct lock_delay_config mtx_spin_delay = { 177 .initial = 1000, 178 .step = 500, 179 .min = 100, 180 .max = 5000, 181 }; 182 183 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_initial, CTLFLAG_RW, 184 &mtx_spin_delay.initial, 0, ""); 185 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_step, CTLFLAG_RW, &mtx_spin_delay.step, 186 0, ""); 187 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_min, CTLFLAG_RW, &mtx_spin_delay.min, 188 0, ""); 189 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_spin_delay.max, 190 0, ""); 191 192 static void 193 mtx_spin_delay_sysinit(void *dummy) 194 { 195 196 mtx_spin_delay.initial = mp_ncpus * 25; 197 mtx_spin_delay.step = (mp_ncpus * 25) / 2; 198 mtx_spin_delay.min = mp_ncpus * 5; 199 mtx_spin_delay.max = mp_ncpus * 25 * 10; 200 } 201 LOCK_DELAY_SYSINIT(mtx_spin_delay_sysinit); 202 203 /* 204 * System-wide mutexes 205 */ 206 struct mtx blocked_lock; 207 struct mtx Giant; 208 209 void 210 assert_mtx(const struct lock_object *lock, int what) 211 { 212 213 mtx_assert((const struct mtx *)lock, what); 214 } 215 216 void 217 lock_mtx(struct lock_object *lock, uintptr_t how) 218 { 219 220 mtx_lock((struct mtx *)lock); 221 } 222 223 void 224 lock_spin(struct lock_object *lock, uintptr_t how) 225 { 226 227 panic("spin locks can only use msleep_spin"); 228 } 229 230 uintptr_t 231 unlock_mtx(struct lock_object *lock) 232 { 233 struct mtx *m; 234 235 m = (struct mtx *)lock; 236 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 237 mtx_unlock(m); 238 return (0); 239 } 240 241 uintptr_t 242 unlock_spin(struct lock_object *lock) 243 { 244 245 panic("spin locks can only use msleep_spin"); 246 } 247 248 #ifdef KDTRACE_HOOKS 249 int 250 owner_mtx(const struct lock_object *lock, struct thread **owner) 251 { 252 const struct mtx *m = (const struct mtx *)lock; 253 254 *owner = mtx_owner(m); 255 return (mtx_unowned(m) == 0); 256 } 257 #endif 258 259 /* 260 * Function versions of the inlined __mtx_* macros. These are used by 261 * modules and can also be called from assembly language if needed. 262 */ 263 void 264 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 265 { 266 struct mtx *m; 267 268 if (SCHEDULER_STOPPED()) 269 return; 270 271 m = mtxlock2mtx(c); 272 273 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 274 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d", 275 curthread, m->lock_object.lo_name, file, line)); 276 KASSERT(m->mtx_lock != MTX_DESTROYED, 277 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 278 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 279 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 280 file, line)); 281 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) | 282 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 283 284 __mtx_lock(m, curthread, opts, file, line); 285 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 286 line); 287 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE, 288 file, line); 289 TD_LOCKS_INC(curthread); 290 } 291 292 void 293 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 294 { 295 struct mtx *m; 296 297 if (SCHEDULER_STOPPED()) 298 return; 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 __mtx_unlock(m, curthread, opts, file, line); 313 TD_LOCKS_DEC(curthread); 314 } 315 316 void 317 __mtx_lock_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; 324 325 m = mtxlock2mtx(c); 326 327 KASSERT(m->mtx_lock != MTX_DESTROYED, 328 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 329 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 330 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 331 m->lock_object.lo_name, file, line)); 332 if (mtx_owned(m)) 333 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 334 (opts & MTX_RECURSE) != 0, 335 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 336 m->lock_object.lo_name, file, line)); 337 opts &= ~MTX_RECURSE; 338 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 339 file, line, NULL); 340 __mtx_lock_spin(m, curthread, opts, file, line); 341 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 342 line); 343 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 344 } 345 346 int 347 __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 348 int line) 349 { 350 struct mtx *m; 351 352 if (SCHEDULER_STOPPED()) 353 return (1); 354 355 m = mtxlock2mtx(c); 356 357 KASSERT(m->mtx_lock != MTX_DESTROYED, 358 ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line)); 359 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 360 ("mtx_trylock_spin() of sleep mutex %s @ %s:%d", 361 m->lock_object.lo_name, file, line)); 362 KASSERT((opts & MTX_RECURSE) == 0, 363 ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n", 364 m->lock_object.lo_name, file, line)); 365 if (__mtx_trylock_spin(m, curthread, opts, file, line)) { 366 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line); 367 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 368 return (1); 369 } 370 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line); 371 return (0); 372 } 373 374 void 375 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 376 int line) 377 { 378 struct mtx *m; 379 380 if (SCHEDULER_STOPPED()) 381 return; 382 383 m = mtxlock2mtx(c); 384 385 KASSERT(m->mtx_lock != MTX_DESTROYED, 386 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 387 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 388 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 389 m->lock_object.lo_name, file, line)); 390 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 391 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 392 line); 393 mtx_assert(m, MA_OWNED); 394 395 __mtx_unlock_spin(m); 396 } 397 398 /* 399 * The important part of mtx_trylock{,_flags}() 400 * Tries to acquire lock `m.' If this function is called on a mutex that 401 * is already owned, it will recursively acquire the lock. 402 */ 403 int 404 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line) 405 { 406 struct mtx *m; 407 #ifdef LOCK_PROFILING 408 uint64_t waittime = 0; 409 int contested = 0; 410 #endif 411 int rval; 412 413 if (SCHEDULER_STOPPED()) 414 return (1); 415 416 m = mtxlock2mtx(c); 417 418 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 419 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", 420 curthread, m->lock_object.lo_name, file, line)); 421 KASSERT(m->mtx_lock != MTX_DESTROYED, 422 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 423 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 424 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 425 file, line)); 426 427 if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 428 (opts & MTX_RECURSE) != 0)) { 429 m->mtx_recurse++; 430 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 431 rval = 1; 432 } else 433 rval = _mtx_obtain_lock(m, (uintptr_t)curthread); 434 opts &= ~MTX_RECURSE; 435 436 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 437 if (rval) { 438 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 439 file, line); 440 TD_LOCKS_INC(curthread); 441 if (m->mtx_recurse == 0) 442 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, 443 m, contested, waittime, file, line); 444 445 } 446 447 return (rval); 448 } 449 450 /* 451 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 452 * 453 * We call this if the lock is either contested (i.e. we need to go to 454 * sleep waiting for it), or if we need to recurse on it. 455 */ 456 void 457 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts, 458 const char *file, int line) 459 { 460 struct mtx *m; 461 struct turnstile *ts; 462 uintptr_t v; 463 #ifdef ADAPTIVE_MUTEXES 464 volatile struct thread *owner; 465 #endif 466 #ifdef KTR 467 int cont_logged = 0; 468 #endif 469 #ifdef LOCK_PROFILING 470 int contested = 0; 471 uint64_t waittime = 0; 472 #endif 473 #if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS) 474 struct lock_delay_arg lda; 475 #endif 476 #ifdef KDTRACE_HOOKS 477 u_int sleep_cnt = 0; 478 int64_t sleep_time = 0; 479 int64_t all_time = 0; 480 #endif 481 482 if (SCHEDULER_STOPPED()) 483 return; 484 485 #if defined(ADAPTIVE_MUTEXES) 486 lock_delay_arg_init(&lda, &mtx_delay); 487 #elif defined(KDTRACE_HOOKS) 488 lock_delay_arg_init(&lda, NULL); 489 #endif 490 m = mtxlock2mtx(c); 491 492 if (mtx_owned(m)) { 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 opts &= ~MTX_RECURSE; 498 m->mtx_recurse++; 499 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 500 if (LOCK_LOG_TEST(&m->lock_object, opts)) 501 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 502 return; 503 } 504 opts &= ~MTX_RECURSE; 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 KDTRACE_HOOKS 516 all_time -= lockstat_nsecs(&m->lock_object); 517 #endif 518 519 for (;;) { 520 if (m->mtx_lock == MTX_UNOWNED && _mtx_obtain_lock(m, tid)) 521 break; 522 #ifdef KDTRACE_HOOKS 523 lda.spin_cnt++; 524 #endif 525 #ifdef ADAPTIVE_MUTEXES 526 /* 527 * If the owner is running on another CPU, spin until the 528 * owner stops running or the state of the lock changes. 529 */ 530 v = m->mtx_lock; 531 if (v != MTX_UNOWNED) { 532 owner = (struct thread *)(v & ~MTX_FLAGMASK); 533 if (TD_IS_RUNNING(owner)) { 534 if (LOCK_LOG_TEST(&m->lock_object, 0)) 535 CTR3(KTR_LOCK, 536 "%s: spinning on %p held by %p", 537 __func__, m, owner); 538 KTR_STATE1(KTR_SCHED, "thread", 539 sched_tdname((struct thread *)tid), 540 "spinning", "lockname:\"%s\"", 541 m->lock_object.lo_name); 542 while (mtx_owner(m) == owner && 543 TD_IS_RUNNING(owner)) 544 lock_delay(&lda); 545 KTR_STATE0(KTR_SCHED, "thread", 546 sched_tdname((struct thread *)tid), 547 "running"); 548 continue; 549 } 550 } 551 #endif 552 553 ts = turnstile_trywait(&m->lock_object); 554 v = m->mtx_lock; 555 556 /* 557 * Check if the lock has been released while spinning for 558 * the turnstile chain lock. 559 */ 560 if (v == MTX_UNOWNED) { 561 turnstile_cancel(ts); 562 continue; 563 } 564 565 #ifdef ADAPTIVE_MUTEXES 566 /* 567 * The current lock owner might have started executing 568 * on another CPU (or the lock could have changed 569 * owners) while we were waiting on the turnstile 570 * chain lock. If so, drop the turnstile lock and try 571 * again. 572 */ 573 owner = (struct thread *)(v & ~MTX_FLAGMASK); 574 if (TD_IS_RUNNING(owner)) { 575 turnstile_cancel(ts); 576 continue; 577 } 578 #endif 579 580 /* 581 * If the mutex isn't already contested and a failure occurs 582 * setting the contested bit, the mutex was either released 583 * or the state of the MTX_RECURSED bit changed. 584 */ 585 if ((v & MTX_CONTESTED) == 0 && 586 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 587 turnstile_cancel(ts); 588 continue; 589 } 590 591 /* 592 * We definitely must sleep for this lock. 593 */ 594 mtx_assert(m, MA_NOTOWNED); 595 596 #ifdef KTR 597 if (!cont_logged) { 598 CTR6(KTR_CONTENTION, 599 "contention: %p at %s:%d wants %s, taken by %s:%d", 600 (void *)tid, file, line, m->lock_object.lo_name, 601 WITNESS_FILE(&m->lock_object), 602 WITNESS_LINE(&m->lock_object)); 603 cont_logged = 1; 604 } 605 #endif 606 607 /* 608 * Block on the turnstile. 609 */ 610 #ifdef KDTRACE_HOOKS 611 sleep_time -= lockstat_nsecs(&m->lock_object); 612 #endif 613 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 614 #ifdef KDTRACE_HOOKS 615 sleep_time += lockstat_nsecs(&m->lock_object); 616 sleep_cnt++; 617 #endif 618 } 619 #ifdef KDTRACE_HOOKS 620 all_time += lockstat_nsecs(&m->lock_object); 621 #endif 622 #ifdef KTR 623 if (cont_logged) { 624 CTR4(KTR_CONTENTION, 625 "contention end: %s acquired by %p at %s:%d", 626 m->lock_object.lo_name, (void *)tid, file, line); 627 } 628 #endif 629 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested, 630 waittime, file, line); 631 #ifdef KDTRACE_HOOKS 632 if (sleep_time) 633 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time); 634 635 /* 636 * Only record the loops spinning and not sleeping. 637 */ 638 if (lda.spin_cnt > sleep_cnt) 639 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time); 640 #endif 641 } 642 643 static void 644 _mtx_lock_spin_failed(struct mtx *m) 645 { 646 struct thread *td; 647 648 td = mtx_owner(m); 649 650 /* If the mutex is unlocked, try again. */ 651 if (td == NULL) 652 return; 653 654 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 655 m, m->lock_object.lo_name, td, td->td_tid); 656 #ifdef WITNESS 657 witness_display_spinlock(&m->lock_object, td, printf); 658 #endif 659 panic("spin lock held too long"); 660 } 661 662 #ifdef SMP 663 /* 664 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock. 665 * 666 * This is only called if we need to actually spin for the lock. Recursion 667 * is handled inline. 668 */ 669 void 670 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts, 671 const char *file, int line) 672 { 673 struct mtx *m; 674 struct lock_delay_arg lda; 675 #ifdef LOCK_PROFILING 676 int contested = 0; 677 uint64_t waittime = 0; 678 #endif 679 #ifdef KDTRACE_HOOKS 680 int64_t spin_time = 0; 681 #endif 682 683 if (SCHEDULER_STOPPED()) 684 return; 685 686 lock_delay_arg_init(&lda, &mtx_spin_delay); 687 m = mtxlock2mtx(c); 688 689 if (LOCK_LOG_TEST(&m->lock_object, opts)) 690 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 691 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 692 "spinning", "lockname:\"%s\"", m->lock_object.lo_name); 693 694 #ifdef HWPMC_HOOKS 695 PMC_SOFT_CALL( , , lock, failed); 696 #endif 697 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 698 #ifdef KDTRACE_HOOKS 699 spin_time -= lockstat_nsecs(&m->lock_object); 700 #endif 701 for (;;) { 702 if (m->mtx_lock == MTX_UNOWNED && _mtx_obtain_lock(m, tid)) 703 break; 704 /* Give interrupts a chance while we spin. */ 705 spinlock_exit(); 706 while (m->mtx_lock != MTX_UNOWNED) { 707 if (lda.spin_cnt < 10000000) { 708 lock_delay(&lda); 709 continue; 710 } 711 lda.spin_cnt++; 712 if (lda.spin_cnt < 60000000 || kdb_active || 713 panicstr != NULL) 714 DELAY(1); 715 else 716 _mtx_lock_spin_failed(m); 717 cpu_spinwait(); 718 } 719 spinlock_enter(); 720 } 721 #ifdef KDTRACE_HOOKS 722 spin_time += lockstat_nsecs(&m->lock_object); 723 #endif 724 725 if (LOCK_LOG_TEST(&m->lock_object, opts)) 726 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 727 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 728 "running"); 729 730 #ifdef KDTRACE_HOOKS 731 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 732 contested, waittime, file, line); 733 if (spin_time != 0) 734 LOCKSTAT_RECORD1(spin__spin, m, spin_time); 735 #endif 736 } 737 #endif /* SMP */ 738 739 void 740 thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 741 { 742 struct mtx *m; 743 uintptr_t tid; 744 struct lock_delay_arg lda; 745 #ifdef LOCK_PROFILING 746 int contested = 0; 747 uint64_t waittime = 0; 748 #endif 749 #ifdef KDTRACE_HOOKS 750 int64_t spin_time = 0; 751 #endif 752 753 tid = (uintptr_t)curthread; 754 755 if (SCHEDULER_STOPPED()) { 756 /* 757 * Ensure that spinlock sections are balanced even when the 758 * scheduler is stopped, since we may otherwise inadvertently 759 * re-enable interrupts while dumping core. 760 */ 761 spinlock_enter(); 762 return; 763 } 764 765 lock_delay_arg_init(&lda, &mtx_spin_delay); 766 767 #ifdef KDTRACE_HOOKS 768 spin_time -= lockstat_nsecs(&td->td_lock->lock_object); 769 #endif 770 for (;;) { 771 retry: 772 spinlock_enter(); 773 m = td->td_lock; 774 KASSERT(m->mtx_lock != MTX_DESTROYED, 775 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 776 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 777 ("thread_lock() of sleep mutex %s @ %s:%d", 778 m->lock_object.lo_name, file, line)); 779 if (mtx_owned(m)) 780 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 781 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 782 m->lock_object.lo_name, file, line)); 783 WITNESS_CHECKORDER(&m->lock_object, 784 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 785 for (;;) { 786 if (m->mtx_lock == MTX_UNOWNED && _mtx_obtain_lock(m, tid)) 787 break; 788 if (m->mtx_lock == tid) { 789 m->mtx_recurse++; 790 break; 791 } 792 #ifdef HWPMC_HOOKS 793 PMC_SOFT_CALL( , , lock, failed); 794 #endif 795 lock_profile_obtain_lock_failed(&m->lock_object, 796 &contested, &waittime); 797 /* Give interrupts a chance while we spin. */ 798 spinlock_exit(); 799 while (m->mtx_lock != MTX_UNOWNED) { 800 if (lda.spin_cnt < 10000000) { 801 lock_delay(&lda); 802 } else { 803 lda.spin_cnt++; 804 if (lda.spin_cnt < 60000000 || 805 kdb_active || panicstr != NULL) 806 DELAY(1); 807 else 808 _mtx_lock_spin_failed(m); 809 cpu_spinwait(); 810 } 811 if (m != td->td_lock) 812 goto retry; 813 } 814 spinlock_enter(); 815 } 816 if (m == td->td_lock) 817 break; 818 __mtx_unlock_spin(m); /* does spinlock_exit() */ 819 } 820 #ifdef KDTRACE_HOOKS 821 spin_time += lockstat_nsecs(&m->lock_object); 822 #endif 823 if (m->mtx_recurse == 0) 824 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 825 contested, waittime, file, line); 826 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 827 line); 828 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 829 #ifdef KDTRACE_HOOKS 830 if (spin_time != 0) 831 LOCKSTAT_RECORD1(thread__spin, m, spin_time); 832 #endif 833 } 834 835 struct mtx * 836 thread_lock_block(struct thread *td) 837 { 838 struct mtx *lock; 839 840 THREAD_LOCK_ASSERT(td, MA_OWNED); 841 lock = td->td_lock; 842 td->td_lock = &blocked_lock; 843 mtx_unlock_spin(lock); 844 845 return (lock); 846 } 847 848 void 849 thread_lock_unblock(struct thread *td, struct mtx *new) 850 { 851 mtx_assert(new, MA_OWNED); 852 MPASS(td->td_lock == &blocked_lock); 853 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 854 } 855 856 void 857 thread_lock_set(struct thread *td, struct mtx *new) 858 { 859 struct mtx *lock; 860 861 mtx_assert(new, MA_OWNED); 862 THREAD_LOCK_ASSERT(td, MA_OWNED); 863 lock = td->td_lock; 864 td->td_lock = new; 865 mtx_unlock_spin(lock); 866 } 867 868 /* 869 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 870 * 871 * We are only called here if the lock is recursed or contested (i.e. we 872 * need to wake up a blocked thread). 873 */ 874 void 875 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line) 876 { 877 struct mtx *m; 878 struct turnstile *ts; 879 880 if (SCHEDULER_STOPPED()) 881 return; 882 883 m = mtxlock2mtx(c); 884 885 if (mtx_recursed(m)) { 886 if (--(m->mtx_recurse) == 0) 887 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 888 if (LOCK_LOG_TEST(&m->lock_object, opts)) 889 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 890 return; 891 } 892 893 /* 894 * We have to lock the chain before the turnstile so this turnstile 895 * can be removed from the hash list if it is empty. 896 */ 897 turnstile_chain_lock(&m->lock_object); 898 ts = turnstile_lookup(&m->lock_object); 899 if (LOCK_LOG_TEST(&m->lock_object, opts)) 900 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 901 MPASS(ts != NULL); 902 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 903 _mtx_release_lock_quick(m); 904 905 /* 906 * This turnstile is now no longer associated with the mutex. We can 907 * unlock the chain lock so a new turnstile may take it's place. 908 */ 909 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 910 turnstile_chain_unlock(&m->lock_object); 911 } 912 913 /* 914 * All the unlocking of MTX_SPIN locks is done inline. 915 * See the __mtx_unlock_spin() macro for the details. 916 */ 917 918 /* 919 * The backing function for the INVARIANTS-enabled mtx_assert() 920 */ 921 #ifdef INVARIANT_SUPPORT 922 void 923 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line) 924 { 925 const struct mtx *m; 926 927 if (panicstr != NULL || dumping || SCHEDULER_STOPPED()) 928 return; 929 930 m = mtxlock2mtx(c); 931 932 switch (what) { 933 case MA_OWNED: 934 case MA_OWNED | MA_RECURSED: 935 case MA_OWNED | MA_NOTRECURSED: 936 if (!mtx_owned(m)) 937 panic("mutex %s not owned at %s:%d", 938 m->lock_object.lo_name, file, line); 939 if (mtx_recursed(m)) { 940 if ((what & MA_NOTRECURSED) != 0) 941 panic("mutex %s recursed at %s:%d", 942 m->lock_object.lo_name, file, line); 943 } else if ((what & MA_RECURSED) != 0) { 944 panic("mutex %s unrecursed at %s:%d", 945 m->lock_object.lo_name, file, line); 946 } 947 break; 948 case MA_NOTOWNED: 949 if (mtx_owned(m)) 950 panic("mutex %s owned at %s:%d", 951 m->lock_object.lo_name, file, line); 952 break; 953 default: 954 panic("unknown mtx_assert at %s:%d", file, line); 955 } 956 } 957 #endif 958 959 /* 960 * General init routine used by the MTX_SYSINIT() macro. 961 */ 962 void 963 mtx_sysinit(void *arg) 964 { 965 struct mtx_args *margs = arg; 966 967 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL, 968 margs->ma_opts); 969 } 970 971 /* 972 * Mutex initialization routine; initialize lock `m' of type contained in 973 * `opts' with options contained in `opts' and name `name.' The optional 974 * lock type `type' is used as a general lock category name for use with 975 * witness. 976 */ 977 void 978 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts) 979 { 980 struct mtx *m; 981 struct lock_class *class; 982 int flags; 983 984 m = mtxlock2mtx(c); 985 986 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 987 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0); 988 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 989 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 990 &m->mtx_lock)); 991 992 /* Determine lock class and lock flags. */ 993 if (opts & MTX_SPIN) 994 class = &lock_class_mtx_spin; 995 else 996 class = &lock_class_mtx_sleep; 997 flags = 0; 998 if (opts & MTX_QUIET) 999 flags |= LO_QUIET; 1000 if (opts & MTX_RECURSE) 1001 flags |= LO_RECURSABLE; 1002 if ((opts & MTX_NOWITNESS) == 0) 1003 flags |= LO_WITNESS; 1004 if (opts & MTX_DUPOK) 1005 flags |= LO_DUPOK; 1006 if (opts & MTX_NOPROFILE) 1007 flags |= LO_NOPROFILE; 1008 if (opts & MTX_NEW) 1009 flags |= LO_NEW; 1010 1011 /* Initialize mutex. */ 1012 lock_init(&m->lock_object, class, name, type, flags); 1013 1014 m->mtx_lock = MTX_UNOWNED; 1015 m->mtx_recurse = 0; 1016 } 1017 1018 /* 1019 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 1020 * passed in as a flag here because if the corresponding mtx_init() was 1021 * called with MTX_QUIET set, then it will already be set in the mutex's 1022 * flags. 1023 */ 1024 void 1025 _mtx_destroy(volatile uintptr_t *c) 1026 { 1027 struct mtx *m; 1028 1029 m = mtxlock2mtx(c); 1030 1031 if (!mtx_owned(m)) 1032 MPASS(mtx_unowned(m)); 1033 else { 1034 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 1035 1036 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 1037 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 1038 spinlock_exit(); 1039 else 1040 TD_LOCKS_DEC(curthread); 1041 1042 lock_profile_release_lock(&m->lock_object); 1043 /* Tell witness this isn't locked to make it happy. */ 1044 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 1045 __LINE__); 1046 } 1047 1048 m->mtx_lock = MTX_DESTROYED; 1049 lock_destroy(&m->lock_object); 1050 } 1051 1052 /* 1053 * Intialize the mutex code and system mutexes. This is called from the MD 1054 * startup code prior to mi_startup(). The per-CPU data space needs to be 1055 * setup before this is called. 1056 */ 1057 void 1058 mutex_init(void) 1059 { 1060 1061 /* Setup turnstiles so that sleep mutexes work. */ 1062 init_turnstiles(); 1063 1064 /* 1065 * Initialize mutexes. 1066 */ 1067 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 1068 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 1069 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 1070 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 1071 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN); 1072 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN); 1073 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN); 1074 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN); 1075 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 1076 mtx_lock(&Giant); 1077 } 1078 1079 #ifdef DDB 1080 void 1081 db_show_mtx(const struct lock_object *lock) 1082 { 1083 struct thread *td; 1084 const struct mtx *m; 1085 1086 m = (const struct mtx *)lock; 1087 1088 db_printf(" flags: {"); 1089 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 1090 db_printf("SPIN"); 1091 else 1092 db_printf("DEF"); 1093 if (m->lock_object.lo_flags & LO_RECURSABLE) 1094 db_printf(", RECURSE"); 1095 if (m->lock_object.lo_flags & LO_DUPOK) 1096 db_printf(", DUPOK"); 1097 db_printf("}\n"); 1098 db_printf(" state: {"); 1099 if (mtx_unowned(m)) 1100 db_printf("UNOWNED"); 1101 else if (mtx_destroyed(m)) 1102 db_printf("DESTROYED"); 1103 else { 1104 db_printf("OWNED"); 1105 if (m->mtx_lock & MTX_CONTESTED) 1106 db_printf(", CONTESTED"); 1107 if (m->mtx_lock & MTX_RECURSED) 1108 db_printf(", RECURSED"); 1109 } 1110 db_printf("}\n"); 1111 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 1112 td = mtx_owner(m); 1113 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 1114 td->td_tid, td->td_proc->p_pid, td->td_name); 1115 if (mtx_recursed(m)) 1116 db_printf(" recursed: %d\n", m->mtx_recurse); 1117 } 1118 } 1119 #endif 1120