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