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 mtx_delay = { 144 .initial = 1000, 145 .step = 500, 146 .min = 100, 147 .max = 5000, 148 }; 149 150 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_initial, CTLFLAG_RW, &mtx_delay.initial, 151 0, ""); 152 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_step, CTLFLAG_RW, &mtx_delay.step, 153 0, ""); 154 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_min, CTLFLAG_RW, &mtx_delay.min, 155 0, ""); 156 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max, 157 0, ""); 158 159 static void 160 mtx_delay_sysinit(void *dummy) 161 { 162 163 mtx_delay.initial = mp_ncpus * 25; 164 mtx_delay.step = (mp_ncpus * 25) / 2; 165 mtx_delay.min = mp_ncpus * 5; 166 mtx_delay.max = mp_ncpus * 25 * 10; 167 } 168 LOCK_DELAY_SYSINIT(mtx_delay_sysinit); 169 #endif 170 171 static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin, CTLFLAG_RD, NULL, 172 "mtx spin debugging"); 173 174 static struct lock_delay_config mtx_spin_delay = { 175 .initial = 1000, 176 .step = 500, 177 .min = 100, 178 .max = 5000, 179 }; 180 181 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_initial, CTLFLAG_RW, 182 &mtx_spin_delay.initial, 0, ""); 183 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_step, CTLFLAG_RW, &mtx_spin_delay.step, 184 0, ""); 185 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_min, CTLFLAG_RW, &mtx_spin_delay.min, 186 0, ""); 187 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_spin_delay.max, 188 0, ""); 189 190 static void 191 mtx_spin_delay_sysinit(void *dummy) 192 { 193 194 mtx_spin_delay.initial = mp_ncpus * 25; 195 mtx_spin_delay.step = (mp_ncpus * 25) / 2; 196 mtx_spin_delay.min = mp_ncpus * 5; 197 mtx_spin_delay.max = mp_ncpus * 25 * 10; 198 } 199 LOCK_DELAY_SYSINIT(mtx_spin_delay_sysinit); 200 201 /* 202 * System-wide mutexes 203 */ 204 struct mtx blocked_lock; 205 struct mtx Giant; 206 207 void 208 assert_mtx(const struct lock_object *lock, int what) 209 { 210 211 mtx_assert((const struct mtx *)lock, what); 212 } 213 214 void 215 lock_mtx(struct lock_object *lock, uintptr_t how) 216 { 217 218 mtx_lock((struct mtx *)lock); 219 } 220 221 void 222 lock_spin(struct lock_object *lock, uintptr_t how) 223 { 224 225 panic("spin locks can only use msleep_spin"); 226 } 227 228 uintptr_t 229 unlock_mtx(struct lock_object *lock) 230 { 231 struct mtx *m; 232 233 m = (struct mtx *)lock; 234 mtx_assert(m, MA_OWNED | MA_NOTRECURSED); 235 mtx_unlock(m); 236 return (0); 237 } 238 239 uintptr_t 240 unlock_spin(struct lock_object *lock) 241 { 242 243 panic("spin locks can only use msleep_spin"); 244 } 245 246 #ifdef KDTRACE_HOOKS 247 int 248 owner_mtx(const struct lock_object *lock, struct thread **owner) 249 { 250 const struct mtx *m; 251 uintptr_t x; 252 253 m = (const struct mtx *)lock; 254 x = m->mtx_lock; 255 *owner = (struct thread *)(x & ~MTX_FLAGMASK); 256 return (x != MTX_UNOWNED); 257 } 258 #endif 259 260 /* 261 * Function versions of the inlined __mtx_* macros. These are used by 262 * modules and can also be called from assembly language if needed. 263 */ 264 void 265 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 266 { 267 struct mtx *m; 268 269 if (SCHEDULER_STOPPED()) 270 return; 271 272 m = mtxlock2mtx(c); 273 274 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 275 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d", 276 curthread, m->lock_object.lo_name, file, line)); 277 KASSERT(m->mtx_lock != MTX_DESTROYED, 278 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 279 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 280 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 281 file, line)); 282 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) | 283 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 284 285 __mtx_lock(m, curthread, opts, file, line); 286 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 287 line); 288 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE, 289 file, line); 290 TD_LOCKS_INC(curthread); 291 } 292 293 void 294 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line) 295 { 296 struct mtx *m; 297 298 if (SCHEDULER_STOPPED()) 299 return; 300 301 m = mtxlock2mtx(c); 302 303 KASSERT(m->mtx_lock != MTX_DESTROYED, 304 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 305 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 306 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 307 file, line)); 308 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 309 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 310 line); 311 mtx_assert(m, MA_OWNED); 312 313 __mtx_unlock(m, curthread, opts, file, line); 314 TD_LOCKS_DEC(curthread); 315 } 316 317 void 318 __mtx_lock_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; 325 326 m = mtxlock2mtx(c); 327 328 KASSERT(m->mtx_lock != MTX_DESTROYED, 329 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 330 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 331 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 332 m->lock_object.lo_name, file, line)); 333 if (mtx_owned(m)) 334 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 335 (opts & MTX_RECURSE) != 0, 336 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 337 m->lock_object.lo_name, file, line)); 338 opts &= ~MTX_RECURSE; 339 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 340 file, line, NULL); 341 __mtx_lock_spin(m, curthread, opts, file, line); 342 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 343 line); 344 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 345 } 346 347 int 348 __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 349 int line) 350 { 351 struct mtx *m; 352 353 if (SCHEDULER_STOPPED()) 354 return (1); 355 356 m = mtxlock2mtx(c); 357 358 KASSERT(m->mtx_lock != MTX_DESTROYED, 359 ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line)); 360 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 361 ("mtx_trylock_spin() of sleep mutex %s @ %s:%d", 362 m->lock_object.lo_name, file, line)); 363 KASSERT((opts & MTX_RECURSE) == 0, 364 ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n", 365 m->lock_object.lo_name, file, line)); 366 if (__mtx_trylock_spin(m, curthread, opts, file, line)) { 367 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line); 368 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 369 return (1); 370 } 371 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line); 372 return (0); 373 } 374 375 void 376 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 377 int line) 378 { 379 struct mtx *m; 380 381 if (SCHEDULER_STOPPED()) 382 return; 383 384 m = mtxlock2mtx(c); 385 386 KASSERT(m->mtx_lock != MTX_DESTROYED, 387 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 388 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 389 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 390 m->lock_object.lo_name, file, line)); 391 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 392 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 393 line); 394 mtx_assert(m, MA_OWNED); 395 396 __mtx_unlock_spin(m); 397 } 398 399 /* 400 * The important part of mtx_trylock{,_flags}() 401 * Tries to acquire lock `m.' If this function is called on a mutex that 402 * is already owned, it will recursively acquire the lock. 403 */ 404 int 405 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line) 406 { 407 struct mtx *m; 408 #ifdef LOCK_PROFILING 409 uint64_t waittime = 0; 410 int contested = 0; 411 #endif 412 int rval; 413 414 if (SCHEDULER_STOPPED()) 415 return (1); 416 417 m = mtxlock2mtx(c); 418 419 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 420 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", 421 curthread, m->lock_object.lo_name, file, line)); 422 KASSERT(m->mtx_lock != MTX_DESTROYED, 423 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 424 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 425 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 426 file, line)); 427 428 if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 429 (opts & MTX_RECURSE) != 0)) { 430 m->mtx_recurse++; 431 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 432 rval = 1; 433 } else 434 rval = _mtx_obtain_lock(m, (uintptr_t)curthread); 435 opts &= ~MTX_RECURSE; 436 437 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 438 if (rval) { 439 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 440 file, line); 441 TD_LOCKS_INC(curthread); 442 if (m->mtx_recurse == 0) 443 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, 444 m, contested, waittime, file, line); 445 446 } 447 448 return (rval); 449 } 450 451 /* 452 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 453 * 454 * We call this if the lock is either contested (i.e. we need to go to 455 * sleep waiting for it), or if we need to recurse on it. 456 */ 457 void 458 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts, 459 const char *file, int line) 460 { 461 struct mtx *m; 462 struct turnstile *ts; 463 uintptr_t v; 464 #ifdef ADAPTIVE_MUTEXES 465 volatile struct thread *owner; 466 #endif 467 #ifdef KTR 468 int cont_logged = 0; 469 #endif 470 #ifdef LOCK_PROFILING 471 int contested = 0; 472 uint64_t waittime = 0; 473 #endif 474 #if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS) 475 struct lock_delay_arg lda; 476 #endif 477 #ifdef KDTRACE_HOOKS 478 u_int sleep_cnt = 0; 479 int64_t sleep_time = 0; 480 int64_t all_time = 0; 481 #endif 482 483 if (SCHEDULER_STOPPED()) 484 return; 485 486 #if defined(ADAPTIVE_MUTEXES) 487 lock_delay_arg_init(&lda, &mtx_delay); 488 #elif defined(KDTRACE_HOOKS) 489 lock_delay_arg_init(&lda, NULL); 490 #endif 491 m = mtxlock2mtx(c); 492 v = MTX_READ_VALUE(m); 493 494 if (__predict_false(lv_mtx_owner(v) == (struct thread *)tid)) { 495 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 496 (opts & MTX_RECURSE) != 0, 497 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 498 m->lock_object.lo_name, file, line)); 499 opts &= ~MTX_RECURSE; 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 opts &= ~MTX_RECURSE; 507 508 #ifdef HWPMC_HOOKS 509 PMC_SOFT_CALL( , , lock, failed); 510 #endif 511 lock_profile_obtain_lock_failed(&m->lock_object, 512 &contested, &waittime); 513 if (LOCK_LOG_TEST(&m->lock_object, opts)) 514 CTR4(KTR_LOCK, 515 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 516 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 517 #ifdef KDTRACE_HOOKS 518 all_time -= lockstat_nsecs(&m->lock_object); 519 #endif 520 521 for (;;) { 522 if (v == MTX_UNOWNED) { 523 if (_mtx_obtain_lock(m, tid)) 524 break; 525 v = MTX_READ_VALUE(m); 526 continue; 527 } 528 #ifdef KDTRACE_HOOKS 529 lda.spin_cnt++; 530 #endif 531 #ifdef ADAPTIVE_MUTEXES 532 /* 533 * If the owner is running on another CPU, spin until the 534 * owner stops running or the state of the lock changes. 535 */ 536 owner = lv_mtx_owner(v); 537 if (TD_IS_RUNNING(owner)) { 538 if (LOCK_LOG_TEST(&m->lock_object, 0)) 539 CTR3(KTR_LOCK, 540 "%s: spinning on %p held by %p", 541 __func__, m, owner); 542 KTR_STATE1(KTR_SCHED, "thread", 543 sched_tdname((struct thread *)tid), 544 "spinning", "lockname:\"%s\"", 545 m->lock_object.lo_name); 546 do { 547 lock_delay(&lda); 548 v = MTX_READ_VALUE(m); 549 owner = lv_mtx_owner(v); 550 } while (v != MTX_UNOWNED && TD_IS_RUNNING(owner)); 551 KTR_STATE0(KTR_SCHED, "thread", 552 sched_tdname((struct thread *)tid), 553 "running"); 554 continue; 555 } 556 #endif 557 558 ts = turnstile_trywait(&m->lock_object); 559 v = MTX_READ_VALUE(m); 560 561 /* 562 * Check if the lock has been released while spinning for 563 * the turnstile chain lock. 564 */ 565 if (v == MTX_UNOWNED) { 566 turnstile_cancel(ts); 567 continue; 568 } 569 570 #ifdef ADAPTIVE_MUTEXES 571 /* 572 * The current lock owner might have started executing 573 * on another CPU (or the lock could have changed 574 * owners) while we were waiting on the turnstile 575 * chain lock. If so, drop the turnstile lock and try 576 * again. 577 */ 578 owner = lv_mtx_owner(v); 579 if (TD_IS_RUNNING(owner)) { 580 turnstile_cancel(ts); 581 continue; 582 } 583 #endif 584 585 /* 586 * If the mutex isn't already contested and a failure occurs 587 * setting the contested bit, the mutex was either released 588 * or the state of the MTX_RECURSED bit changed. 589 */ 590 if ((v & MTX_CONTESTED) == 0 && 591 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 592 turnstile_cancel(ts); 593 v = MTX_READ_VALUE(m); 594 continue; 595 } 596 597 /* 598 * We definitely must sleep for this lock. 599 */ 600 mtx_assert(m, MA_NOTOWNED); 601 602 #ifdef KTR 603 if (!cont_logged) { 604 CTR6(KTR_CONTENTION, 605 "contention: %p at %s:%d wants %s, taken by %s:%d", 606 (void *)tid, file, line, m->lock_object.lo_name, 607 WITNESS_FILE(&m->lock_object), 608 WITNESS_LINE(&m->lock_object)); 609 cont_logged = 1; 610 } 611 #endif 612 613 /* 614 * Block on the turnstile. 615 */ 616 #ifdef KDTRACE_HOOKS 617 sleep_time -= lockstat_nsecs(&m->lock_object); 618 #endif 619 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 620 #ifdef KDTRACE_HOOKS 621 sleep_time += lockstat_nsecs(&m->lock_object); 622 sleep_cnt++; 623 #endif 624 v = MTX_READ_VALUE(m); 625 } 626 #ifdef KDTRACE_HOOKS 627 all_time += lockstat_nsecs(&m->lock_object); 628 #endif 629 #ifdef KTR 630 if (cont_logged) { 631 CTR4(KTR_CONTENTION, 632 "contention end: %s acquired by %p at %s:%d", 633 m->lock_object.lo_name, (void *)tid, file, line); 634 } 635 #endif 636 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested, 637 waittime, file, line); 638 #ifdef KDTRACE_HOOKS 639 if (sleep_time) 640 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time); 641 642 /* 643 * Only record the loops spinning and not sleeping. 644 */ 645 if (lda.spin_cnt > sleep_cnt) 646 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time); 647 #endif 648 } 649 650 static void 651 _mtx_lock_spin_failed(struct mtx *m) 652 { 653 struct thread *td; 654 655 td = mtx_owner(m); 656 657 /* If the mutex is unlocked, try again. */ 658 if (td == NULL) 659 return; 660 661 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 662 m, m->lock_object.lo_name, td, td->td_tid); 663 #ifdef WITNESS 664 witness_display_spinlock(&m->lock_object, td, printf); 665 #endif 666 panic("spin lock held too long"); 667 } 668 669 #ifdef SMP 670 /* 671 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock. 672 * 673 * This is only called if we need to actually spin for the lock. Recursion 674 * is handled inline. 675 */ 676 void 677 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts, 678 const char *file, int line) 679 { 680 struct mtx *m; 681 struct lock_delay_arg lda; 682 uintptr_t v; 683 #ifdef LOCK_PROFILING 684 int contested = 0; 685 uint64_t waittime = 0; 686 #endif 687 #ifdef KDTRACE_HOOKS 688 int64_t spin_time = 0; 689 #endif 690 691 if (SCHEDULER_STOPPED()) 692 return; 693 694 lock_delay_arg_init(&lda, &mtx_spin_delay); 695 m = mtxlock2mtx(c); 696 697 if (LOCK_LOG_TEST(&m->lock_object, opts)) 698 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 699 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 700 "spinning", "lockname:\"%s\"", m->lock_object.lo_name); 701 702 #ifdef HWPMC_HOOKS 703 PMC_SOFT_CALL( , , lock, failed); 704 #endif 705 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 706 #ifdef KDTRACE_HOOKS 707 spin_time -= lockstat_nsecs(&m->lock_object); 708 #endif 709 v = MTX_READ_VALUE(m); 710 for (;;) { 711 if (v == MTX_UNOWNED) { 712 if (_mtx_obtain_lock(m, tid)) 713 break; 714 v = MTX_READ_VALUE(m); 715 continue; 716 } 717 /* Give interrupts a chance while we spin. */ 718 spinlock_exit(); 719 do { 720 if (lda.spin_cnt < 10000000) { 721 lock_delay(&lda); 722 } else { 723 lda.spin_cnt++; 724 if (lda.spin_cnt < 60000000 || kdb_active || 725 panicstr != NULL) 726 DELAY(1); 727 else 728 _mtx_lock_spin_failed(m); 729 cpu_spinwait(); 730 } 731 v = MTX_READ_VALUE(m); 732 } while (v != MTX_UNOWNED); 733 spinlock_enter(); 734 } 735 #ifdef KDTRACE_HOOKS 736 spin_time += lockstat_nsecs(&m->lock_object); 737 #endif 738 739 if (LOCK_LOG_TEST(&m->lock_object, opts)) 740 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 741 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 742 "running"); 743 744 #ifdef KDTRACE_HOOKS 745 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 746 contested, waittime, file, line); 747 if (spin_time != 0) 748 LOCKSTAT_RECORD1(spin__spin, m, spin_time); 749 #endif 750 } 751 #endif /* SMP */ 752 753 void 754 thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 755 { 756 struct mtx *m; 757 uintptr_t tid, v; 758 struct lock_delay_arg lda; 759 #ifdef LOCK_PROFILING 760 int contested = 0; 761 uint64_t waittime = 0; 762 #endif 763 #ifdef KDTRACE_HOOKS 764 int64_t spin_time = 0; 765 #endif 766 767 tid = (uintptr_t)curthread; 768 769 if (SCHEDULER_STOPPED()) { 770 /* 771 * Ensure that spinlock sections are balanced even when the 772 * scheduler is stopped, since we may otherwise inadvertently 773 * re-enable interrupts while dumping core. 774 */ 775 spinlock_enter(); 776 return; 777 } 778 779 lock_delay_arg_init(&lda, &mtx_spin_delay); 780 781 #ifdef KDTRACE_HOOKS 782 spin_time -= lockstat_nsecs(&td->td_lock->lock_object); 783 #endif 784 for (;;) { 785 retry: 786 spinlock_enter(); 787 m = td->td_lock; 788 KASSERT(m->mtx_lock != MTX_DESTROYED, 789 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 790 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 791 ("thread_lock() of sleep mutex %s @ %s:%d", 792 m->lock_object.lo_name, file, line)); 793 if (mtx_owned(m)) 794 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 795 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 796 m->lock_object.lo_name, file, line)); 797 WITNESS_CHECKORDER(&m->lock_object, 798 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 799 v = MTX_READ_VALUE(m); 800 for (;;) { 801 if (v == MTX_UNOWNED) { 802 if (_mtx_obtain_lock(m, tid)) 803 break; 804 v = MTX_READ_VALUE(m); 805 continue; 806 } 807 if (v == tid) { 808 m->mtx_recurse++; 809 break; 810 } 811 #ifdef HWPMC_HOOKS 812 PMC_SOFT_CALL( , , lock, failed); 813 #endif 814 lock_profile_obtain_lock_failed(&m->lock_object, 815 &contested, &waittime); 816 /* Give interrupts a chance while we spin. */ 817 spinlock_exit(); 818 do { 819 if (lda.spin_cnt < 10000000) { 820 lock_delay(&lda); 821 } else { 822 lda.spin_cnt++; 823 if (lda.spin_cnt < 60000000 || 824 kdb_active || panicstr != NULL) 825 DELAY(1); 826 else 827 _mtx_lock_spin_failed(m); 828 cpu_spinwait(); 829 } 830 if (m != td->td_lock) 831 goto retry; 832 v = MTX_READ_VALUE(m); 833 } while (v != MTX_UNOWNED); 834 spinlock_enter(); 835 } 836 if (m == td->td_lock) 837 break; 838 __mtx_unlock_spin(m); /* does spinlock_exit() */ 839 } 840 #ifdef KDTRACE_HOOKS 841 spin_time += lockstat_nsecs(&m->lock_object); 842 #endif 843 if (m->mtx_recurse == 0) 844 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 845 contested, waittime, file, line); 846 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 847 line); 848 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 849 #ifdef KDTRACE_HOOKS 850 if (spin_time != 0) 851 LOCKSTAT_RECORD1(thread__spin, m, spin_time); 852 #endif 853 } 854 855 struct mtx * 856 thread_lock_block(struct thread *td) 857 { 858 struct mtx *lock; 859 860 THREAD_LOCK_ASSERT(td, MA_OWNED); 861 lock = td->td_lock; 862 td->td_lock = &blocked_lock; 863 mtx_unlock_spin(lock); 864 865 return (lock); 866 } 867 868 void 869 thread_lock_unblock(struct thread *td, struct mtx *new) 870 { 871 mtx_assert(new, MA_OWNED); 872 MPASS(td->td_lock == &blocked_lock); 873 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 874 } 875 876 void 877 thread_lock_set(struct thread *td, struct mtx *new) 878 { 879 struct mtx *lock; 880 881 mtx_assert(new, MA_OWNED); 882 THREAD_LOCK_ASSERT(td, MA_OWNED); 883 lock = td->td_lock; 884 td->td_lock = new; 885 mtx_unlock_spin(lock); 886 } 887 888 /* 889 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 890 * 891 * We are only called here if the lock is recursed or contested (i.e. we 892 * need to wake up a blocked thread). 893 */ 894 void 895 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line) 896 { 897 struct mtx *m; 898 struct turnstile *ts; 899 900 if (SCHEDULER_STOPPED()) 901 return; 902 903 m = mtxlock2mtx(c); 904 905 if (mtx_recursed(m)) { 906 if (--(m->mtx_recurse) == 0) 907 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 908 if (LOCK_LOG_TEST(&m->lock_object, opts)) 909 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 910 return; 911 } 912 913 /* 914 * We have to lock the chain before the turnstile so this turnstile 915 * can be removed from the hash list if it is empty. 916 */ 917 turnstile_chain_lock(&m->lock_object); 918 ts = turnstile_lookup(&m->lock_object); 919 if (LOCK_LOG_TEST(&m->lock_object, opts)) 920 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 921 MPASS(ts != NULL); 922 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 923 _mtx_release_lock_quick(m); 924 925 /* 926 * This turnstile is now no longer associated with the mutex. We can 927 * unlock the chain lock so a new turnstile may take it's place. 928 */ 929 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 930 turnstile_chain_unlock(&m->lock_object); 931 } 932 933 /* 934 * All the unlocking of MTX_SPIN locks is done inline. 935 * See the __mtx_unlock_spin() macro for the details. 936 */ 937 938 /* 939 * The backing function for the INVARIANTS-enabled mtx_assert() 940 */ 941 #ifdef INVARIANT_SUPPORT 942 void 943 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line) 944 { 945 const struct mtx *m; 946 947 if (panicstr != NULL || dumping || SCHEDULER_STOPPED()) 948 return; 949 950 m = mtxlock2mtx(c); 951 952 switch (what) { 953 case MA_OWNED: 954 case MA_OWNED | MA_RECURSED: 955 case MA_OWNED | MA_NOTRECURSED: 956 if (!mtx_owned(m)) 957 panic("mutex %s not owned at %s:%d", 958 m->lock_object.lo_name, file, line); 959 if (mtx_recursed(m)) { 960 if ((what & MA_NOTRECURSED) != 0) 961 panic("mutex %s recursed at %s:%d", 962 m->lock_object.lo_name, file, line); 963 } else if ((what & MA_RECURSED) != 0) { 964 panic("mutex %s unrecursed at %s:%d", 965 m->lock_object.lo_name, file, line); 966 } 967 break; 968 case MA_NOTOWNED: 969 if (mtx_owned(m)) 970 panic("mutex %s owned at %s:%d", 971 m->lock_object.lo_name, file, line); 972 break; 973 default: 974 panic("unknown mtx_assert at %s:%d", file, line); 975 } 976 } 977 #endif 978 979 /* 980 * General init routine used by the MTX_SYSINIT() macro. 981 */ 982 void 983 mtx_sysinit(void *arg) 984 { 985 struct mtx_args *margs = arg; 986 987 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL, 988 margs->ma_opts); 989 } 990 991 /* 992 * Mutex initialization routine; initialize lock `m' of type contained in 993 * `opts' with options contained in `opts' and name `name.' The optional 994 * lock type `type' is used as a general lock category name for use with 995 * witness. 996 */ 997 void 998 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts) 999 { 1000 struct mtx *m; 1001 struct lock_class *class; 1002 int flags; 1003 1004 m = mtxlock2mtx(c); 1005 1006 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 1007 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0); 1008 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 1009 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 1010 &m->mtx_lock)); 1011 1012 /* Determine lock class and lock flags. */ 1013 if (opts & MTX_SPIN) 1014 class = &lock_class_mtx_spin; 1015 else 1016 class = &lock_class_mtx_sleep; 1017 flags = 0; 1018 if (opts & MTX_QUIET) 1019 flags |= LO_QUIET; 1020 if (opts & MTX_RECURSE) 1021 flags |= LO_RECURSABLE; 1022 if ((opts & MTX_NOWITNESS) == 0) 1023 flags |= LO_WITNESS; 1024 if (opts & MTX_DUPOK) 1025 flags |= LO_DUPOK; 1026 if (opts & MTX_NOPROFILE) 1027 flags |= LO_NOPROFILE; 1028 if (opts & MTX_NEW) 1029 flags |= LO_NEW; 1030 1031 /* Initialize mutex. */ 1032 lock_init(&m->lock_object, class, name, type, flags); 1033 1034 m->mtx_lock = MTX_UNOWNED; 1035 m->mtx_recurse = 0; 1036 } 1037 1038 /* 1039 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 1040 * passed in as a flag here because if the corresponding mtx_init() was 1041 * called with MTX_QUIET set, then it will already be set in the mutex's 1042 * flags. 1043 */ 1044 void 1045 _mtx_destroy(volatile uintptr_t *c) 1046 { 1047 struct mtx *m; 1048 1049 m = mtxlock2mtx(c); 1050 1051 if (!mtx_owned(m)) 1052 MPASS(mtx_unowned(m)); 1053 else { 1054 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 1055 1056 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 1057 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 1058 spinlock_exit(); 1059 else 1060 TD_LOCKS_DEC(curthread); 1061 1062 lock_profile_release_lock(&m->lock_object); 1063 /* Tell witness this isn't locked to make it happy. */ 1064 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 1065 __LINE__); 1066 } 1067 1068 m->mtx_lock = MTX_DESTROYED; 1069 lock_destroy(&m->lock_object); 1070 } 1071 1072 /* 1073 * Intialize the mutex code and system mutexes. This is called from the MD 1074 * startup code prior to mi_startup(). The per-CPU data space needs to be 1075 * setup before this is called. 1076 */ 1077 void 1078 mutex_init(void) 1079 { 1080 1081 /* Setup turnstiles so that sleep mutexes work. */ 1082 init_turnstiles(); 1083 1084 /* 1085 * Initialize mutexes. 1086 */ 1087 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 1088 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 1089 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 1090 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 1091 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN); 1092 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN); 1093 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN); 1094 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN); 1095 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 1096 mtx_lock(&Giant); 1097 } 1098 1099 #ifdef DDB 1100 void 1101 db_show_mtx(const struct lock_object *lock) 1102 { 1103 struct thread *td; 1104 const struct mtx *m; 1105 1106 m = (const struct mtx *)lock; 1107 1108 db_printf(" flags: {"); 1109 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 1110 db_printf("SPIN"); 1111 else 1112 db_printf("DEF"); 1113 if (m->lock_object.lo_flags & LO_RECURSABLE) 1114 db_printf(", RECURSE"); 1115 if (m->lock_object.lo_flags & LO_DUPOK) 1116 db_printf(", DUPOK"); 1117 db_printf("}\n"); 1118 db_printf(" state: {"); 1119 if (mtx_unowned(m)) 1120 db_printf("UNOWNED"); 1121 else if (mtx_destroyed(m)) 1122 db_printf("DESTROYED"); 1123 else { 1124 db_printf("OWNED"); 1125 if (m->mtx_lock & MTX_CONTESTED) 1126 db_printf(", CONTESTED"); 1127 if (m->mtx_lock & MTX_RECURSED) 1128 db_printf(", RECURSED"); 1129 } 1130 db_printf("}\n"); 1131 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 1132 td = mtx_owner(m); 1133 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 1134 td->td_tid, td->td_proc->p_pid, td->td_name); 1135 if (mtx_recursed(m)) 1136 db_printf(" recursed: %d\n", m->mtx_recurse); 1137 } 1138 } 1139 #endif 1140