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 void 285 __mtx_unlock_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; 292 293 m = mtxlock2mtx(c); 294 295 KASSERT(m->mtx_lock != MTX_DESTROYED, 296 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); 297 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 298 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", 299 m->lock_object.lo_name, file, line)); 300 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 301 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, 302 line); 303 mtx_assert(m, MA_OWNED); 304 305 __mtx_unlock_spin(m); 306 } 307 308 /* 309 * The important part of mtx_trylock{,_flags}() 310 * Tries to acquire lock `m.' If this function is called on a mutex that 311 * is already owned, it will recursively acquire the lock. 312 */ 313 int 314 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line) 315 { 316 struct mtx *m; 317 #ifdef LOCK_PROFILING 318 uint64_t waittime = 0; 319 int contested = 0; 320 #endif 321 int rval; 322 323 if (SCHEDULER_STOPPED()) 324 return (1); 325 326 m = mtxlock2mtx(c); 327 328 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 329 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", 330 curthread, m->lock_object.lo_name, file, line)); 331 KASSERT(m->mtx_lock != MTX_DESTROYED, 332 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); 333 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, 334 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, 335 file, line)); 336 337 if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 338 (opts & MTX_RECURSE) != 0)) { 339 m->mtx_recurse++; 340 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 341 rval = 1; 342 } else 343 rval = _mtx_obtain_lock(m, (uintptr_t)curthread); 344 opts &= ~MTX_RECURSE; 345 346 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); 347 if (rval) { 348 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, 349 file, line); 350 TD_LOCKS_INC(curthread); 351 if (m->mtx_recurse == 0) 352 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, 353 m, contested, waittime, file, line); 354 355 } 356 357 return (rval); 358 } 359 360 /* 361 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 362 * 363 * We call this if the lock is either contested (i.e. we need to go to 364 * sleep waiting for it), or if we need to recurse on it. 365 */ 366 void 367 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts, 368 const char *file, int line) 369 { 370 struct mtx *m; 371 struct turnstile *ts; 372 uintptr_t v; 373 #ifdef ADAPTIVE_MUTEXES 374 volatile struct thread *owner; 375 #endif 376 #ifdef KTR 377 int cont_logged = 0; 378 #endif 379 #ifdef LOCK_PROFILING 380 int contested = 0; 381 uint64_t waittime = 0; 382 #endif 383 #ifdef KDTRACE_HOOKS 384 uint64_t spin_cnt = 0; 385 uint64_t sleep_cnt = 0; 386 int64_t sleep_time = 0; 387 int64_t all_time = 0; 388 #endif 389 390 if (SCHEDULER_STOPPED()) 391 return; 392 393 m = mtxlock2mtx(c); 394 395 if (mtx_owned(m)) { 396 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || 397 (opts & MTX_RECURSE) != 0, 398 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", 399 m->lock_object.lo_name, file, line)); 400 opts &= ~MTX_RECURSE; 401 m->mtx_recurse++; 402 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 403 if (LOCK_LOG_TEST(&m->lock_object, opts)) 404 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 405 return; 406 } 407 opts &= ~MTX_RECURSE; 408 409 #ifdef HWPMC_HOOKS 410 PMC_SOFT_CALL( , , lock, failed); 411 #endif 412 lock_profile_obtain_lock_failed(&m->lock_object, 413 &contested, &waittime); 414 if (LOCK_LOG_TEST(&m->lock_object, opts)) 415 CTR4(KTR_LOCK, 416 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 417 m->lock_object.lo_name, (void *)m->mtx_lock, file, line); 418 #ifdef KDTRACE_HOOKS 419 all_time -= lockstat_nsecs(&m->lock_object); 420 #endif 421 422 while (!_mtx_obtain_lock(m, tid)) { 423 #ifdef KDTRACE_HOOKS 424 spin_cnt++; 425 #endif 426 #ifdef ADAPTIVE_MUTEXES 427 /* 428 * If the owner is running on another CPU, spin until the 429 * owner stops running or the state of the lock changes. 430 */ 431 v = m->mtx_lock; 432 if (v != MTX_UNOWNED) { 433 owner = (struct thread *)(v & ~MTX_FLAGMASK); 434 if (TD_IS_RUNNING(owner)) { 435 if (LOCK_LOG_TEST(&m->lock_object, 0)) 436 CTR3(KTR_LOCK, 437 "%s: spinning on %p held by %p", 438 __func__, m, owner); 439 KTR_STATE1(KTR_SCHED, "thread", 440 sched_tdname((struct thread *)tid), 441 "spinning", "lockname:\"%s\"", 442 m->lock_object.lo_name); 443 while (mtx_owner(m) == owner && 444 TD_IS_RUNNING(owner)) { 445 cpu_spinwait(); 446 #ifdef KDTRACE_HOOKS 447 spin_cnt++; 448 #endif 449 } 450 KTR_STATE0(KTR_SCHED, "thread", 451 sched_tdname((struct thread *)tid), 452 "running"); 453 continue; 454 } 455 } 456 #endif 457 458 ts = turnstile_trywait(&m->lock_object); 459 v = m->mtx_lock; 460 461 /* 462 * Check if the lock has been released while spinning for 463 * the turnstile chain lock. 464 */ 465 if (v == MTX_UNOWNED) { 466 turnstile_cancel(ts); 467 continue; 468 } 469 470 #ifdef ADAPTIVE_MUTEXES 471 /* 472 * The current lock owner might have started executing 473 * on another CPU (or the lock could have changed 474 * owners) while we were waiting on the turnstile 475 * chain lock. If so, drop the turnstile lock and try 476 * again. 477 */ 478 owner = (struct thread *)(v & ~MTX_FLAGMASK); 479 if (TD_IS_RUNNING(owner)) { 480 turnstile_cancel(ts); 481 continue; 482 } 483 #endif 484 485 /* 486 * If the mutex isn't already contested and a failure occurs 487 * setting the contested bit, the mutex was either released 488 * or the state of the MTX_RECURSED bit changed. 489 */ 490 if ((v & MTX_CONTESTED) == 0 && 491 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { 492 turnstile_cancel(ts); 493 continue; 494 } 495 496 /* 497 * We definitely must sleep for this lock. 498 */ 499 mtx_assert(m, MA_NOTOWNED); 500 501 #ifdef KTR 502 if (!cont_logged) { 503 CTR6(KTR_CONTENTION, 504 "contention: %p at %s:%d wants %s, taken by %s:%d", 505 (void *)tid, file, line, m->lock_object.lo_name, 506 WITNESS_FILE(&m->lock_object), 507 WITNESS_LINE(&m->lock_object)); 508 cont_logged = 1; 509 } 510 #endif 511 512 /* 513 * Block on the turnstile. 514 */ 515 #ifdef KDTRACE_HOOKS 516 sleep_time -= lockstat_nsecs(&m->lock_object); 517 #endif 518 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); 519 #ifdef KDTRACE_HOOKS 520 sleep_time += lockstat_nsecs(&m->lock_object); 521 sleep_cnt++; 522 #endif 523 } 524 #ifdef KDTRACE_HOOKS 525 all_time += lockstat_nsecs(&m->lock_object); 526 #endif 527 #ifdef KTR 528 if (cont_logged) { 529 CTR4(KTR_CONTENTION, 530 "contention end: %s acquired by %p at %s:%d", 531 m->lock_object.lo_name, (void *)tid, file, line); 532 } 533 #endif 534 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested, 535 waittime, file, line); 536 #ifdef KDTRACE_HOOKS 537 if (sleep_time) 538 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time); 539 540 /* 541 * Only record the loops spinning and not sleeping. 542 */ 543 if (spin_cnt > sleep_cnt) 544 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time); 545 #endif 546 } 547 548 static void 549 _mtx_lock_spin_failed(struct mtx *m) 550 { 551 struct thread *td; 552 553 td = mtx_owner(m); 554 555 /* If the mutex is unlocked, try again. */ 556 if (td == NULL) 557 return; 558 559 printf( "spin lock %p (%s) held by %p (tid %d) too long\n", 560 m, m->lock_object.lo_name, td, td->td_tid); 561 #ifdef WITNESS 562 witness_display_spinlock(&m->lock_object, td, printf); 563 #endif 564 panic("spin lock held too long"); 565 } 566 567 #ifdef SMP 568 /* 569 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock. 570 * 571 * This is only called if we need to actually spin for the lock. Recursion 572 * is handled inline. 573 */ 574 void 575 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts, 576 const char *file, int line) 577 { 578 struct mtx *m; 579 int i = 0; 580 #ifdef LOCK_PROFILING 581 int contested = 0; 582 uint64_t waittime = 0; 583 #endif 584 #ifdef KDTRACE_HOOKS 585 int64_t spin_time = 0; 586 #endif 587 588 if (SCHEDULER_STOPPED()) 589 return; 590 591 m = mtxlock2mtx(c); 592 593 if (LOCK_LOG_TEST(&m->lock_object, opts)) 594 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 595 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 596 "spinning", "lockname:\"%s\"", m->lock_object.lo_name); 597 598 #ifdef HWPMC_HOOKS 599 PMC_SOFT_CALL( , , lock, failed); 600 #endif 601 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); 602 #ifdef KDTRACE_HOOKS 603 spin_time -= lockstat_nsecs(&m->lock_object); 604 #endif 605 while (!_mtx_obtain_lock(m, tid)) { 606 607 /* Give interrupts a chance while we spin. */ 608 spinlock_exit(); 609 while (m->mtx_lock != MTX_UNOWNED) { 610 if (i++ < 10000000) { 611 cpu_spinwait(); 612 continue; 613 } 614 if (i < 60000000 || kdb_active || panicstr != NULL) 615 DELAY(1); 616 else 617 _mtx_lock_spin_failed(m); 618 cpu_spinwait(); 619 } 620 spinlock_enter(); 621 } 622 #ifdef KDTRACE_HOOKS 623 spin_time += lockstat_nsecs(&m->lock_object); 624 #endif 625 626 if (LOCK_LOG_TEST(&m->lock_object, opts)) 627 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 628 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), 629 "running"); 630 631 #ifdef KDTRACE_HOOKS 632 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 633 contested, waittime, file, line); 634 if (spin_time != 0) 635 LOCKSTAT_RECORD1(spin__spin, m, spin_time); 636 #endif 637 } 638 #endif /* SMP */ 639 640 void 641 thread_lock_flags_(struct thread *td, int opts, const char *file, int line) 642 { 643 struct mtx *m; 644 uintptr_t tid; 645 int i; 646 #ifdef LOCK_PROFILING 647 int contested = 0; 648 uint64_t waittime = 0; 649 #endif 650 #ifdef KDTRACE_HOOKS 651 int64_t spin_time = 0; 652 #endif 653 654 i = 0; 655 tid = (uintptr_t)curthread; 656 657 if (SCHEDULER_STOPPED()) 658 return; 659 660 #ifdef KDTRACE_HOOKS 661 spin_time -= lockstat_nsecs(&td->td_lock->lock_object); 662 #endif 663 for (;;) { 664 retry: 665 spinlock_enter(); 666 m = td->td_lock; 667 KASSERT(m->mtx_lock != MTX_DESTROYED, 668 ("thread_lock() of destroyed mutex @ %s:%d", file, line)); 669 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, 670 ("thread_lock() of sleep mutex %s @ %s:%d", 671 m->lock_object.lo_name, file, line)); 672 if (mtx_owned(m)) 673 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, 674 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", 675 m->lock_object.lo_name, file, line)); 676 WITNESS_CHECKORDER(&m->lock_object, 677 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); 678 while (!_mtx_obtain_lock(m, tid)) { 679 if (m->mtx_lock == tid) { 680 m->mtx_recurse++; 681 break; 682 } 683 #ifdef HWPMC_HOOKS 684 PMC_SOFT_CALL( , , lock, failed); 685 #endif 686 lock_profile_obtain_lock_failed(&m->lock_object, 687 &contested, &waittime); 688 /* Give interrupts a chance while we spin. */ 689 spinlock_exit(); 690 while (m->mtx_lock != MTX_UNOWNED) { 691 if (i++ < 10000000) 692 cpu_spinwait(); 693 else if (i < 60000000 || 694 kdb_active || panicstr != NULL) 695 DELAY(1); 696 else 697 _mtx_lock_spin_failed(m); 698 cpu_spinwait(); 699 if (m != td->td_lock) 700 goto retry; 701 } 702 spinlock_enter(); 703 } 704 if (m == td->td_lock) 705 break; 706 __mtx_unlock_spin(m); /* does spinlock_exit() */ 707 } 708 #ifdef KDTRACE_HOOKS 709 spin_time += lockstat_nsecs(&m->lock_object); 710 #endif 711 if (m->mtx_recurse == 0) 712 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, 713 contested, waittime, file, line); 714 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, 715 line); 716 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); 717 LOCKSTAT_RECORD1(thread__spin, m, spin_time); 718 } 719 720 struct mtx * 721 thread_lock_block(struct thread *td) 722 { 723 struct mtx *lock; 724 725 THREAD_LOCK_ASSERT(td, MA_OWNED); 726 lock = td->td_lock; 727 td->td_lock = &blocked_lock; 728 mtx_unlock_spin(lock); 729 730 return (lock); 731 } 732 733 void 734 thread_lock_unblock(struct thread *td, struct mtx *new) 735 { 736 mtx_assert(new, MA_OWNED); 737 MPASS(td->td_lock == &blocked_lock); 738 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); 739 } 740 741 void 742 thread_lock_set(struct thread *td, struct mtx *new) 743 { 744 struct mtx *lock; 745 746 mtx_assert(new, MA_OWNED); 747 THREAD_LOCK_ASSERT(td, MA_OWNED); 748 lock = td->td_lock; 749 td->td_lock = new; 750 mtx_unlock_spin(lock); 751 } 752 753 /* 754 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 755 * 756 * We are only called here if the lock is recursed or contested (i.e. we 757 * need to wake up a blocked thread). 758 */ 759 void 760 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line) 761 { 762 struct mtx *m; 763 struct turnstile *ts; 764 765 if (SCHEDULER_STOPPED()) 766 return; 767 768 m = mtxlock2mtx(c); 769 770 if (mtx_recursed(m)) { 771 if (--(m->mtx_recurse) == 0) 772 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 773 if (LOCK_LOG_TEST(&m->lock_object, opts)) 774 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 775 return; 776 } 777 778 /* 779 * We have to lock the chain before the turnstile so this turnstile 780 * can be removed from the hash list if it is empty. 781 */ 782 turnstile_chain_lock(&m->lock_object); 783 ts = turnstile_lookup(&m->lock_object); 784 if (LOCK_LOG_TEST(&m->lock_object, opts)) 785 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 786 MPASS(ts != NULL); 787 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); 788 _mtx_release_lock_quick(m); 789 790 /* 791 * This turnstile is now no longer associated with the mutex. We can 792 * unlock the chain lock so a new turnstile may take it's place. 793 */ 794 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); 795 turnstile_chain_unlock(&m->lock_object); 796 } 797 798 /* 799 * All the unlocking of MTX_SPIN locks is done inline. 800 * See the __mtx_unlock_spin() macro for the details. 801 */ 802 803 /* 804 * The backing function for the INVARIANTS-enabled mtx_assert() 805 */ 806 #ifdef INVARIANT_SUPPORT 807 void 808 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line) 809 { 810 const struct mtx *m; 811 812 if (panicstr != NULL || dumping) 813 return; 814 815 m = mtxlock2mtx(c); 816 817 switch (what) { 818 case MA_OWNED: 819 case MA_OWNED | MA_RECURSED: 820 case MA_OWNED | MA_NOTRECURSED: 821 if (!mtx_owned(m)) 822 panic("mutex %s not owned at %s:%d", 823 m->lock_object.lo_name, file, line); 824 if (mtx_recursed(m)) { 825 if ((what & MA_NOTRECURSED) != 0) 826 panic("mutex %s recursed at %s:%d", 827 m->lock_object.lo_name, file, line); 828 } else if ((what & MA_RECURSED) != 0) { 829 panic("mutex %s unrecursed at %s:%d", 830 m->lock_object.lo_name, file, line); 831 } 832 break; 833 case MA_NOTOWNED: 834 if (mtx_owned(m)) 835 panic("mutex %s owned at %s:%d", 836 m->lock_object.lo_name, file, line); 837 break; 838 default: 839 panic("unknown mtx_assert at %s:%d", file, line); 840 } 841 } 842 #endif 843 844 /* 845 * The MUTEX_DEBUG-enabled mtx_validate() 846 * 847 * Most of these checks have been moved off into the LO_INITIALIZED flag 848 * maintained by the witness code. 849 */ 850 #ifdef MUTEX_DEBUG 851 852 void mtx_validate(struct mtx *); 853 854 void 855 mtx_validate(struct mtx *m) 856 { 857 858 /* 859 * XXX: When kernacc() does not require Giant we can reenable this check 860 */ 861 #ifdef notyet 862 /* 863 * Can't call kernacc() from early init386(), especially when 864 * initializing Giant mutex, because some stuff in kernacc() 865 * requires Giant itself. 866 */ 867 if (!cold) 868 if (!kernacc((caddr_t)m, sizeof(m), 869 VM_PROT_READ | VM_PROT_WRITE)) 870 panic("Can't read and write to mutex %p", m); 871 #endif 872 } 873 #endif 874 875 /* 876 * General init routine used by the MTX_SYSINIT() macro. 877 */ 878 void 879 mtx_sysinit(void *arg) 880 { 881 struct mtx_args *margs = arg; 882 883 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL, 884 margs->ma_opts); 885 } 886 887 /* 888 * Mutex initialization routine; initialize lock `m' of type contained in 889 * `opts' with options contained in `opts' and name `name.' The optional 890 * lock type `type' is used as a general lock category name for use with 891 * witness. 892 */ 893 void 894 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts) 895 { 896 struct mtx *m; 897 struct lock_class *class; 898 int flags; 899 900 m = mtxlock2mtx(c); 901 902 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | 903 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0); 904 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, 905 ("%s: mtx_lock not aligned for %s: %p", __func__, name, 906 &m->mtx_lock)); 907 908 #ifdef MUTEX_DEBUG 909 /* Diagnostic and error correction */ 910 mtx_validate(m); 911 #endif 912 913 /* Determine lock class and lock flags. */ 914 if (opts & MTX_SPIN) 915 class = &lock_class_mtx_spin; 916 else 917 class = &lock_class_mtx_sleep; 918 flags = 0; 919 if (opts & MTX_QUIET) 920 flags |= LO_QUIET; 921 if (opts & MTX_RECURSE) 922 flags |= LO_RECURSABLE; 923 if ((opts & MTX_NOWITNESS) == 0) 924 flags |= LO_WITNESS; 925 if (opts & MTX_DUPOK) 926 flags |= LO_DUPOK; 927 if (opts & MTX_NOPROFILE) 928 flags |= LO_NOPROFILE; 929 if (opts & MTX_NEW) 930 flags |= LO_NEW; 931 932 /* Initialize mutex. */ 933 lock_init(&m->lock_object, class, name, type, flags); 934 935 m->mtx_lock = MTX_UNOWNED; 936 m->mtx_recurse = 0; 937 } 938 939 /* 940 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be 941 * passed in as a flag here because if the corresponding mtx_init() was 942 * called with MTX_QUIET set, then it will already be set in the mutex's 943 * flags. 944 */ 945 void 946 _mtx_destroy(volatile uintptr_t *c) 947 { 948 struct mtx *m; 949 950 m = mtxlock2mtx(c); 951 952 if (!mtx_owned(m)) 953 MPASS(mtx_unowned(m)); 954 else { 955 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 956 957 /* Perform the non-mtx related part of mtx_unlock_spin(). */ 958 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) 959 spinlock_exit(); 960 else 961 TD_LOCKS_DEC(curthread); 962 963 lock_profile_release_lock(&m->lock_object); 964 /* Tell witness this isn't locked to make it happy. */ 965 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, 966 __LINE__); 967 } 968 969 m->mtx_lock = MTX_DESTROYED; 970 lock_destroy(&m->lock_object); 971 } 972 973 /* 974 * Intialize the mutex code and system mutexes. This is called from the MD 975 * startup code prior to mi_startup(). The per-CPU data space needs to be 976 * setup before this is called. 977 */ 978 void 979 mutex_init(void) 980 { 981 982 /* Setup turnstiles so that sleep mutexes work. */ 983 init_turnstiles(); 984 985 /* 986 * Initialize mutexes. 987 */ 988 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); 989 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); 990 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ 991 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 992 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN); 993 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN); 994 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN); 995 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN); 996 mtx_init(&devmtx, "cdev", NULL, MTX_DEF); 997 mtx_lock(&Giant); 998 } 999 1000 #ifdef DDB 1001 void 1002 db_show_mtx(const struct lock_object *lock) 1003 { 1004 struct thread *td; 1005 const struct mtx *m; 1006 1007 m = (const struct mtx *)lock; 1008 1009 db_printf(" flags: {"); 1010 if (LOCK_CLASS(lock) == &lock_class_mtx_spin) 1011 db_printf("SPIN"); 1012 else 1013 db_printf("DEF"); 1014 if (m->lock_object.lo_flags & LO_RECURSABLE) 1015 db_printf(", RECURSE"); 1016 if (m->lock_object.lo_flags & LO_DUPOK) 1017 db_printf(", DUPOK"); 1018 db_printf("}\n"); 1019 db_printf(" state: {"); 1020 if (mtx_unowned(m)) 1021 db_printf("UNOWNED"); 1022 else if (mtx_destroyed(m)) 1023 db_printf("DESTROYED"); 1024 else { 1025 db_printf("OWNED"); 1026 if (m->mtx_lock & MTX_CONTESTED) 1027 db_printf(", CONTESTED"); 1028 if (m->mtx_lock & MTX_RECURSED) 1029 db_printf(", RECURSED"); 1030 } 1031 db_printf("}\n"); 1032 if (!mtx_unowned(m) && !mtx_destroyed(m)) { 1033 td = mtx_owner(m); 1034 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, 1035 td->td_tid, td->td_proc->p_pid, td->td_name); 1036 if (mtx_recursed(m)) 1037 db_printf(" recursed: %d\n", m->mtx_recurse); 1038 } 1039 } 1040 #endif 1041