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 if (SCHEDULER_STOPPED()) 235 return; 236 237 m = mtxlock2mtx(c); 238 239 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 240 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d", 241 curthread, m->lock_object.lo_name, file, line)); 242 KASSERT(m->mtx_lock != MTX_DESTROYED, 243 ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); 244 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 245 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 246 file, line)); 247 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) | 248 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 249 250 tid = (uintptr_t)curthread; 251 v = MTX_UNOWNED; 252 if (!_mtx_obtain_lock_fetch(m, &v, tid)) 253 _mtx_lock_sleep(m, v, tid, opts, file, line); 254 else 255 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, 256 m, 0, 0, file, line); 257 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 258 line); 259 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE, 260 file, line); 261 TD_LOCKS_INC(curthread); 262 } 263 264 void 265 __mtx_unlock_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(m->mtx_lock != MTX_DESTROYED, 275 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); 276 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 277 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 278 file, line)); 279 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 280 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 281 line); 282 mtx_assert(m, MA_OWNED); 283 284 __mtx_unlock_sleep(c, opts, file, line); 285 TD_LOCKS_DEC(curthread); 286 } 287 288 void 289 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 290 int line) 291 { 292 struct mtx *m; 293 294 if (SCHEDULER_STOPPED()) 295 return; 296 297 m = mtxlock2mtx(c); 298 299 KASSERT(m->mtx_lock != MTX_DESTROYED, 300 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); 301 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 302 ("mtx_lock_spin() of sleep mutex %s @ %s:%d", 303 m->lock_object.lo_name, file, line)); 304 if (mtx_owned(m)) 305 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 306 (opts & MTX_RECURSE) != 0, 307 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", 308 m->lock_object.lo_name, file, line)); 309 opts &= ~MTX_RECURSE; 310 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, 311 file, line, NULL); 312 __mtx_lock_spin(m, curthread, opts, file, line); 313 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 314 line); 315 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 316 } 317 318 int 319 __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 320 int line) 321 { 322 struct mtx *m; 323 324 if (SCHEDULER_STOPPED()) 325 return (1); 326 327 m = mtxlock2mtx(c); 328 329 KASSERT(m->mtx_lock != MTX_DESTROYED, 330 ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line)); 331 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 332 ("mtx_trylock_spin() of sleep mutex %s @ %s:%d", 333 m->lock_object.lo_name, file, line)); 334 KASSERT((opts & MTX_RECURSE) == 0, 335 ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n", 336 m->lock_object.lo_name, file, line)); 337 if (__mtx_trylock_spin(m, curthread, opts, file, line)) { 338 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line); 339 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 340 return (1); 341 } 342 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line); 343 return (0); 344 } 345 346 void 347 __mtx_unlock_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; 354 355 m = mtxlock2mtx(c); 356 357 KASSERT(m->mtx_lock != MTX_DESTROYED, 358 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 359 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 360 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 361 m->lock_object.lo_name, file, line)); 362 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 363 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 364 line); 365 mtx_assert(m, MA_OWNED); 366 367 __mtx_unlock_spin(m); 368 } 369 370 /* 371 * The important part of mtx_trylock{,_flags}() 372 * Tries to acquire lock `m.' If this function is called on a mutex that 373 * is already owned, it will recursively acquire the lock. 374 */ 375 int 376 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line) 377 { 378 struct mtx *m; 379 #ifdef LOCK_PROFILING 380 uint64_t waittime = 0; 381 int contested = 0; 382 #endif 383 int rval; 384 385 if (SCHEDULER_STOPPED()) 386 return (1); 387 388 m = mtxlock2mtx(c); 389 390 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 391 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", 392 curthread, m->lock_object.lo_name, file, line)); 393 KASSERT(m->mtx_lock != MTX_DESTROYED, 394 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 395 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 396 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 397 file, line)); 398 399 if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 400 (opts & MTX_RECURSE) != 0)) { 401 m->mtx_recurse++; 402 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 403 rval = 1; 404 } else 405 rval = _mtx_obtain_lock(m, (uintptr_t)curthread); 406 opts &= ~MTX_RECURSE; 407 408 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 409 if (rval) { 410 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 411 file, line); 412 TD_LOCKS_INC(curthread); 413 if (m->mtx_recurse == 0) 414 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, 415 m, contested, waittime, file, line); 416 417 } 418 419 return (rval); 420 } 421 422 /* 423 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 424 * 425 * We call this if the lock is either contested (i.e. we need to go to 426 * sleep waiting for it), or if we need to recurse on it. 427 */ 428 void 429 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, int opts, 430 const char *file, int line) 431 { 432 struct mtx *m; 433 struct turnstile *ts; 434 #ifdef ADAPTIVE_MUTEXES 435 volatile struct thread *owner; 436 #endif 437 #ifdef KTR 438 int cont_logged = 0; 439 #endif 440 #ifdef LOCK_PROFILING 441 int contested = 0; 442 uint64_t waittime = 0; 443 #endif 444 #if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS) 445 struct lock_delay_arg lda; 446 #endif 447 #ifdef KDTRACE_HOOKS 448 u_int sleep_cnt = 0; 449 int64_t sleep_time = 0; 450 int64_t all_time = 0; 451 #endif 452 453 if (SCHEDULER_STOPPED()) 454 return; 455 456 #if defined(ADAPTIVE_MUTEXES) 457 lock_delay_arg_init(&lda, &mtx_delay); 458 #elif defined(KDTRACE_HOOKS) 459 lock_delay_arg_init(&lda, NULL); 460 #endif 461 m = mtxlock2mtx(c); 462 if (__predict_false(v == MTX_UNOWNED)) 463 v = MTX_READ_VALUE(m); 464 465 if (__predict_false(lv_mtx_owner(v) == (struct thread *)tid)) { 466 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 467 (opts & MTX_RECURSE) != 0, 468 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 469 m->lock_object.lo_name, file, line)); 470 opts &= ~MTX_RECURSE; 471 m->mtx_recurse++; 472 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 473 if (LOCK_LOG_TEST(&m->lock_object, opts)) 474 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 475 return; 476 } 477 opts &= ~MTX_RECURSE; 478 479 #ifdef HWPMC_HOOKS 480 PMC_SOFT_CALL( , , lock, failed); 481 #endif 482 lock_profile_obtain_lock_failed(&m->lock_object, 483 &contested, &waittime); 484 if (LOCK_LOG_TEST(&m->lock_object, opts)) 485 CTR4(KTR_LOCK, 486 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 487 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 488 #ifdef KDTRACE_HOOKS 489 all_time -= lockstat_nsecs(&m->lock_object); 490 #endif 491 492 for (;;) { 493 if (v == MTX_UNOWNED) { 494 if (_mtx_obtain_lock_fetch(m, &v, tid)) 495 break; 496 continue; 497 } 498 #ifdef KDTRACE_HOOKS 499 lda.spin_cnt++; 500 #endif 501 #ifdef ADAPTIVE_MUTEXES 502 /* 503 * If the owner is running on another CPU, spin until the 504 * owner stops running or the state of the lock changes. 505 */ 506 owner = lv_mtx_owner(v); 507 if (TD_IS_RUNNING(owner)) { 508 if (LOCK_LOG_TEST(&m->lock_object, 0)) 509 CTR3(KTR_LOCK, 510 "%s: spinning on %p held by %p", 511 __func__, m, owner); 512 KTR_STATE1(KTR_SCHED, "thread", 513 sched_tdname((struct thread *)tid), 514 "spinning", "lockname:\"%s\"", 515 m->lock_object.lo_name); 516 do { 517 lock_delay(&lda); 518 v = MTX_READ_VALUE(m); 519 owner = lv_mtx_owner(v); 520 } while (v != MTX_UNOWNED && TD_IS_RUNNING(owner)); 521 KTR_STATE0(KTR_SCHED, "thread", 522 sched_tdname((struct thread *)tid), 523 "running"); 524 continue; 525 } 526 #endif 527 528 ts = turnstile_trywait(&m->lock_object); 529 v = MTX_READ_VALUE(m); 530 531 /* 532 * Check if the lock has been released while spinning for 533 * the turnstile chain lock. 534 */ 535 if (v == MTX_UNOWNED) { 536 turnstile_cancel(ts); 537 continue; 538 } 539 540 #ifdef ADAPTIVE_MUTEXES 541 /* 542 * The current lock owner might have started executing 543 * on another CPU (or the lock could have changed 544 * owners) while we were waiting on the turnstile 545 * chain lock. If so, drop the turnstile lock and try 546 * again. 547 */ 548 owner = lv_mtx_owner(v); 549 if (TD_IS_RUNNING(owner)) { 550 turnstile_cancel(ts); 551 continue; 552 } 553 #endif 554 555 /* 556 * If the mutex isn't already contested and a failure occurs 557 * setting the contested bit, the mutex was either released 558 * or the state of the MTX_RECURSED bit changed. 559 */ 560 if ((v & MTX_CONTESTED) == 0 && 561 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 562 turnstile_cancel(ts); 563 v = MTX_READ_VALUE(m); 564 continue; 565 } 566 567 /* 568 * We definitely must sleep for this lock. 569 */ 570 mtx_assert(m, MA_NOTOWNED); 571 572 #ifdef KTR 573 if (!cont_logged) { 574 CTR6(KTR_CONTENTION, 575 "contention: %p at %s:%d wants %s, taken by %s:%d", 576 (void *)tid, file, line, m->lock_object.lo_name, 577 WITNESS_FILE(&m->lock_object), 578 WITNESS_LINE(&m->lock_object)); 579 cont_logged = 1; 580 } 581 #endif 582 583 /* 584 * Block on the turnstile. 585 */ 586 #ifdef KDTRACE_HOOKS 587 sleep_time -= lockstat_nsecs(&m->lock_object); 588 #endif 589 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 590 #ifdef KDTRACE_HOOKS 591 sleep_time += lockstat_nsecs(&m->lock_object); 592 sleep_cnt++; 593 #endif 594 v = MTX_READ_VALUE(m); 595 } 596 #ifdef KDTRACE_HOOKS 597 all_time += lockstat_nsecs(&m->lock_object); 598 #endif 599 #ifdef KTR 600 if (cont_logged) { 601 CTR4(KTR_CONTENTION, 602 "contention end: %s acquired by %p at %s:%d", 603 m->lock_object.lo_name, (void *)tid, file, line); 604 } 605 #endif 606 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested, 607 waittime, file, line); 608 #ifdef KDTRACE_HOOKS 609 if (sleep_time) 610 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time); 611 612 /* 613 * Only record the loops spinning and not sleeping. 614 */ 615 if (lda.spin_cnt > sleep_cnt) 616 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time); 617 #endif 618 } 619 620 static void 621 _mtx_lock_spin_failed(struct mtx *m) 622 { 623 struct thread *td; 624 625 td = mtx_owner(m); 626 627 /* If the mutex is unlocked, try again. */ 628 if (td == NULL) 629 return; 630 631 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 632 m, m->lock_object.lo_name, td, td->td_tid); 633 #ifdef WITNESS 634 witness_display_spinlock(&m->lock_object, td, printf); 635 #endif 636 panic("spin lock held too long"); 637 } 638 639 #ifdef SMP 640 /* 641 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock. 642 * 643 * This is only called if we need to actually spin for the lock. Recursion 644 * is handled inline. 645 */ 646 void 647 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, 648 int opts, const char *file, int line) 649 { 650 struct mtx *m; 651 struct lock_delay_arg lda; 652 #ifdef LOCK_PROFILING 653 int contested = 0; 654 uint64_t waittime = 0; 655 #endif 656 #ifdef KDTRACE_HOOKS 657 int64_t spin_time = 0; 658 #endif 659 660 if (SCHEDULER_STOPPED()) 661 return; 662 663 lock_delay_arg_init(&lda, &mtx_spin_delay); 664 m = mtxlock2mtx(c); 665 666 if (LOCK_LOG_TEST(&m->lock_object, opts)) 667 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 668 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 669 "spinning", "lockname:\"%s\"", m->lock_object.lo_name); 670 671 #ifdef HWPMC_HOOKS 672 PMC_SOFT_CALL( , , lock, failed); 673 #endif 674 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 675 #ifdef KDTRACE_HOOKS 676 spin_time -= lockstat_nsecs(&m->lock_object); 677 #endif 678 for (;;) { 679 if (v == MTX_UNOWNED) { 680 if (_mtx_obtain_lock_fetch(m, &v, tid)) 681 break; 682 continue; 683 } 684 /* Give interrupts a chance while we spin. */ 685 spinlock_exit(); 686 do { 687 if (lda.spin_cnt < 10000000) { 688 lock_delay(&lda); 689 } else { 690 lda.spin_cnt++; 691 if (lda.spin_cnt < 60000000 || kdb_active || 692 panicstr != NULL) 693 DELAY(1); 694 else 695 _mtx_lock_spin_failed(m); 696 cpu_spinwait(); 697 } 698 v = MTX_READ_VALUE(m); 699 } while (v != MTX_UNOWNED); 700 spinlock_enter(); 701 } 702 #ifdef KDTRACE_HOOKS 703 spin_time += lockstat_nsecs(&m->lock_object); 704 #endif 705 706 if (LOCK_LOG_TEST(&m->lock_object, opts)) 707 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 708 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 709 "running"); 710 711 #ifdef KDTRACE_HOOKS 712 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 713 contested, waittime, file, line); 714 if (spin_time != 0) 715 LOCKSTAT_RECORD1(spin__spin, m, spin_time); 716 #endif 717 } 718 #endif /* SMP */ 719 720 void 721 thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 722 { 723 struct mtx *m; 724 uintptr_t tid, v; 725 struct lock_delay_arg lda; 726 #ifdef LOCK_PROFILING 727 int contested = 0; 728 uint64_t waittime = 0; 729 #endif 730 #ifdef KDTRACE_HOOKS 731 int64_t spin_time = 0; 732 #endif 733 734 tid = (uintptr_t)curthread; 735 736 if (SCHEDULER_STOPPED()) { 737 /* 738 * Ensure that spinlock sections are balanced even when the 739 * scheduler is stopped, since we may otherwise inadvertently 740 * re-enable interrupts while dumping core. 741 */ 742 spinlock_enter(); 743 return; 744 } 745 746 lock_delay_arg_init(&lda, &mtx_spin_delay); 747 748 #ifdef KDTRACE_HOOKS 749 spin_time -= lockstat_nsecs(&td->td_lock->lock_object); 750 #endif 751 for (;;) { 752 retry: 753 v = MTX_UNOWNED; 754 spinlock_enter(); 755 m = td->td_lock; 756 KASSERT(m->mtx_lock != MTX_DESTROYED, 757 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 758 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 759 ("thread_lock() of sleep mutex %s @ %s:%d", 760 m->lock_object.lo_name, file, line)); 761 if (mtx_owned(m)) 762 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 763 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 764 m->lock_object.lo_name, file, line)); 765 WITNESS_CHECKORDER(&m->lock_object, 766 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 767 for (;;) { 768 if (_mtx_obtain_lock_fetch(m, &v, tid)) 769 break; 770 if (v == MTX_UNOWNED) 771 continue; 772 if (v == tid) { 773 m->mtx_recurse++; 774 break; 775 } 776 #ifdef HWPMC_HOOKS 777 PMC_SOFT_CALL( , , lock, failed); 778 #endif 779 lock_profile_obtain_lock_failed(&m->lock_object, 780 &contested, &waittime); 781 /* Give interrupts a chance while we spin. */ 782 spinlock_exit(); 783 do { 784 if (lda.spin_cnt < 10000000) { 785 lock_delay(&lda); 786 } else { 787 lda.spin_cnt++; 788 if (lda.spin_cnt < 60000000 || 789 kdb_active || panicstr != NULL) 790 DELAY(1); 791 else 792 _mtx_lock_spin_failed(m); 793 cpu_spinwait(); 794 } 795 if (m != td->td_lock) 796 goto retry; 797 v = MTX_READ_VALUE(m); 798 } while (v != MTX_UNOWNED); 799 spinlock_enter(); 800 } 801 if (m == td->td_lock) 802 break; 803 __mtx_unlock_spin(m); /* does spinlock_exit() */ 804 } 805 #ifdef KDTRACE_HOOKS 806 spin_time += lockstat_nsecs(&m->lock_object); 807 #endif 808 if (m->mtx_recurse == 0) 809 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 810 contested, waittime, file, line); 811 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 812 line); 813 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 814 #ifdef KDTRACE_HOOKS 815 if (spin_time != 0) 816 LOCKSTAT_RECORD1(thread__spin, m, spin_time); 817 #endif 818 } 819 820 struct mtx * 821 thread_lock_block(struct thread *td) 822 { 823 struct mtx *lock; 824 825 THREAD_LOCK_ASSERT(td, MA_OWNED); 826 lock = td->td_lock; 827 td->td_lock = &blocked_lock; 828 mtx_unlock_spin(lock); 829 830 return (lock); 831 } 832 833 void 834 thread_lock_unblock(struct thread *td, struct mtx *new) 835 { 836 mtx_assert(new, MA_OWNED); 837 MPASS(td->td_lock == &blocked_lock); 838 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 839 } 840 841 void 842 thread_lock_set(struct thread *td, struct mtx *new) 843 { 844 struct mtx *lock; 845 846 mtx_assert(new, MA_OWNED); 847 THREAD_LOCK_ASSERT(td, MA_OWNED); 848 lock = td->td_lock; 849 td->td_lock = new; 850 mtx_unlock_spin(lock); 851 } 852 853 /* 854 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 855 * 856 * We are only called here if the lock is recursed, contested (i.e. we 857 * need to wake up a blocked thread) or lockstat probe is active. 858 */ 859 void 860 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line) 861 { 862 struct mtx *m; 863 struct turnstile *ts; 864 uintptr_t tid, v; 865 866 if (SCHEDULER_STOPPED()) 867 return; 868 869 tid = (uintptr_t)curthread; 870 m = mtxlock2mtx(c); 871 v = MTX_READ_VALUE(m); 872 873 if (v & MTX_RECURSED) { 874 if (--(m->mtx_recurse) == 0) 875 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 876 if (LOCK_LOG_TEST(&m->lock_object, opts)) 877 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 878 return; 879 } 880 881 LOCKSTAT_PROFILE_RELEASE_LOCK(adaptive__release, m); 882 if (v == tid && _mtx_release_lock(m, tid)) 883 return; 884 885 /* 886 * We have to lock the chain before the turnstile so this turnstile 887 * can be removed from the hash list if it is empty. 888 */ 889 turnstile_chain_lock(&m->lock_object); 890 ts = turnstile_lookup(&m->lock_object); 891 if (LOCK_LOG_TEST(&m->lock_object, opts)) 892 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 893 MPASS(ts != NULL); 894 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 895 _mtx_release_lock_quick(m); 896 897 /* 898 * This turnstile is now no longer associated with the mutex. We can 899 * unlock the chain lock so a new turnstile may take it's place. 900 */ 901 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 902 turnstile_chain_unlock(&m->lock_object); 903 } 904 905 /* 906 * All the unlocking of MTX_SPIN locks is done inline. 907 * See the __mtx_unlock_spin() macro for the details. 908 */ 909 910 /* 911 * The backing function for the INVARIANTS-enabled mtx_assert() 912 */ 913 #ifdef INVARIANT_SUPPORT 914 void 915 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line) 916 { 917 const struct mtx *m; 918 919 if (panicstr != NULL || dumping || SCHEDULER_STOPPED()) 920 return; 921 922 m = mtxlock2mtx(c); 923 924 switch (what) { 925 case MA_OWNED: 926 case MA_OWNED | MA_RECURSED: 927 case MA_OWNED | MA_NOTRECURSED: 928 if (!mtx_owned(m)) 929 panic("mutex %s not owned at %s:%d", 930 m->lock_object.lo_name, file, line); 931 if (mtx_recursed(m)) { 932 if ((what & MA_NOTRECURSED) != 0) 933 panic("mutex %s recursed at %s:%d", 934 m->lock_object.lo_name, file, line); 935 } else if ((what & MA_RECURSED) != 0) { 936 panic("mutex %s unrecursed at %s:%d", 937 m->lock_object.lo_name, file, line); 938 } 939 break; 940 case MA_NOTOWNED: 941 if (mtx_owned(m)) 942 panic("mutex %s owned at %s:%d", 943 m->lock_object.lo_name, file, line); 944 break; 945 default: 946 panic("unknown mtx_assert at %s:%d", file, line); 947 } 948 } 949 #endif 950 951 /* 952 * General init routine used by the MTX_SYSINIT() macro. 953 */ 954 void 955 mtx_sysinit(void *arg) 956 { 957 struct mtx_args *margs = arg; 958 959 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL, 960 margs->ma_opts); 961 } 962 963 /* 964 * Mutex initialization routine; initialize lock `m' of type contained in 965 * `opts' with options contained in `opts' and name `name.' The optional 966 * lock type `type' is used as a general lock category name for use with 967 * witness. 968 */ 969 void 970 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts) 971 { 972 struct mtx *m; 973 struct lock_class *class; 974 int flags; 975 976 m = mtxlock2mtx(c); 977 978 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 979 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0); 980 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 981 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 982 &m->mtx_lock)); 983 984 /* Determine lock class and lock flags. */ 985 if (opts & MTX_SPIN) 986 class = &lock_class_mtx_spin; 987 else 988 class = &lock_class_mtx_sleep; 989 flags = 0; 990 if (opts & MTX_QUIET) 991 flags |= LO_QUIET; 992 if (opts & MTX_RECURSE) 993 flags |= LO_RECURSABLE; 994 if ((opts & MTX_NOWITNESS) == 0) 995 flags |= LO_WITNESS; 996 if (opts & MTX_DUPOK) 997 flags |= LO_DUPOK; 998 if (opts & MTX_NOPROFILE) 999 flags |= LO_NOPROFILE; 1000 if (opts & MTX_NEW) 1001 flags |= LO_NEW; 1002 1003 /* Initialize mutex. */ 1004 lock_init(&m->lock_object, class, name, type, flags); 1005 1006 m->mtx_lock = MTX_UNOWNED; 1007 m->mtx_recurse = 0; 1008 } 1009 1010 /* 1011 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 1012 * passed in as a flag here because if the corresponding mtx_init() was 1013 * called with MTX_QUIET set, then it will already be set in the mutex's 1014 * flags. 1015 */ 1016 void 1017 _mtx_destroy(volatile uintptr_t *c) 1018 { 1019 struct mtx *m; 1020 1021 m = mtxlock2mtx(c); 1022 1023 if (!mtx_owned(m)) 1024 MPASS(mtx_unowned(m)); 1025 else { 1026 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 1027 1028 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 1029 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 1030 spinlock_exit(); 1031 else 1032 TD_LOCKS_DEC(curthread); 1033 1034 lock_profile_release_lock(&m->lock_object); 1035 /* Tell witness this isn't locked to make it happy. */ 1036 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 1037 __LINE__); 1038 } 1039 1040 m->mtx_lock = MTX_DESTROYED; 1041 lock_destroy(&m->lock_object); 1042 } 1043 1044 /* 1045 * Intialize the mutex code and system mutexes. This is called from the MD 1046 * startup code prior to mi_startup(). The per-CPU data space needs to be 1047 * setup before this is called. 1048 */ 1049 void 1050 mutex_init(void) 1051 { 1052 1053 /* Setup turnstiles so that sleep mutexes work. */ 1054 init_turnstiles(); 1055 1056 /* 1057 * Initialize mutexes. 1058 */ 1059 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 1060 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 1061 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 1062 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 1063 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN); 1064 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN); 1065 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN); 1066 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN); 1067 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 1068 mtx_lock(&Giant); 1069 } 1070 1071 #ifdef DDB 1072 void 1073 db_show_mtx(const struct lock_object *lock) 1074 { 1075 struct thread *td; 1076 const struct mtx *m; 1077 1078 m = (const struct mtx *)lock; 1079 1080 db_printf(" flags: {"); 1081 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 1082 db_printf("SPIN"); 1083 else 1084 db_printf("DEF"); 1085 if (m->lock_object.lo_flags & LO_RECURSABLE) 1086 db_printf(", RECURSE"); 1087 if (m->lock_object.lo_flags & LO_DUPOK) 1088 db_printf(", DUPOK"); 1089 db_printf("}\n"); 1090 db_printf(" state: {"); 1091 if (mtx_unowned(m)) 1092 db_printf("UNOWNED"); 1093 else if (mtx_destroyed(m)) 1094 db_printf("DESTROYED"); 1095 else { 1096 db_printf("OWNED"); 1097 if (m->mtx_lock & MTX_CONTESTED) 1098 db_printf(", CONTESTED"); 1099 if (m->mtx_lock & MTX_RECURSED) 1100 db_printf(", RECURSED"); 1101 } 1102 db_printf("}\n"); 1103 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 1104 td = mtx_owner(m); 1105 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 1106 td->td_tid, td->td_proc->p_pid, td->td_name); 1107 if (mtx_recursed(m)) 1108 db_printf(" recursed: %d\n", m->mtx_recurse); 1109 } 1110 } 1111 #endif 1112