1 /*- 2 * Copyright (c) 2008 Attilio Rao <attilio@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice(s), this list of conditions and the following disclaimer as 10 * the first lines of this file unmodified other than the possible 11 * addition of one or more copyright notices. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice(s), this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 19 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 23 * 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 SUCH 26 * DAMAGE. 27 */ 28 29 #include "opt_ddb.h" 30 #include "opt_hwpmc_hooks.h" 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/kdb.h> 37 #include <sys/ktr.h> 38 #include <sys/lock.h> 39 #include <sys/lock_profile.h> 40 #include <sys/lockmgr.h> 41 #include <sys/mutex.h> 42 #include <sys/proc.h> 43 #include <sys/sleepqueue.h> 44 #ifdef DEBUG_LOCKS 45 #include <sys/stack.h> 46 #endif 47 #include <sys/sysctl.h> 48 #include <sys/systm.h> 49 50 #include <machine/cpu.h> 51 52 #ifdef DDB 53 #include <ddb/ddb.h> 54 #endif 55 56 #ifdef HWPMC_HOOKS 57 #include <sys/pmckern.h> 58 PMC_SOFT_DECLARE( , , lock, failed); 59 #endif 60 61 CTASSERT(((LK_ADAPTIVE | LK_NOSHARE) & LO_CLASSFLAGS) == 62 (LK_ADAPTIVE | LK_NOSHARE)); 63 CTASSERT(LK_UNLOCKED == (LK_UNLOCKED & 64 ~(LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS))); 65 66 #define SQ_EXCLUSIVE_QUEUE 0 67 #define SQ_SHARED_QUEUE 1 68 69 #ifndef INVARIANTS 70 #define _lockmgr_assert(lk, what, file, line) 71 #endif 72 73 #define TD_SLOCKS_INC(td) ((td)->td_lk_slocks++) 74 #define TD_SLOCKS_DEC(td) ((td)->td_lk_slocks--) 75 76 #ifndef DEBUG_LOCKS 77 #define STACK_PRINT(lk) 78 #define STACK_SAVE(lk) 79 #define STACK_ZERO(lk) 80 #else 81 #define STACK_PRINT(lk) stack_print_ddb(&(lk)->lk_stack) 82 #define STACK_SAVE(lk) stack_save(&(lk)->lk_stack) 83 #define STACK_ZERO(lk) stack_zero(&(lk)->lk_stack) 84 #endif 85 86 #define LOCK_LOG2(lk, string, arg1, arg2) \ 87 if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \ 88 CTR2(KTR_LOCK, (string), (arg1), (arg2)) 89 #define LOCK_LOG3(lk, string, arg1, arg2, arg3) \ 90 if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \ 91 CTR3(KTR_LOCK, (string), (arg1), (arg2), (arg3)) 92 93 #define GIANT_DECLARE \ 94 int _i = 0; \ 95 WITNESS_SAVE_DECL(Giant) 96 #define GIANT_RESTORE() do { \ 97 if (_i > 0) { \ 98 while (_i--) \ 99 mtx_lock(&Giant); \ 100 WITNESS_RESTORE(&Giant.lock_object, Giant); \ 101 } \ 102 } while (0) 103 #define GIANT_SAVE() do { \ 104 if (mtx_owned(&Giant)) { \ 105 WITNESS_SAVE(&Giant.lock_object, Giant); \ 106 while (mtx_owned(&Giant)) { \ 107 _i++; \ 108 mtx_unlock(&Giant); \ 109 } \ 110 } \ 111 } while (0) 112 113 #define LK_CAN_SHARE(x, flags) \ 114 (((x) & LK_SHARE) && \ 115 (((x) & (LK_EXCLUSIVE_WAITERS | LK_EXCLUSIVE_SPINNERS)) == 0 || \ 116 (curthread->td_lk_slocks != 0 && !(flags & LK_NODDLKTREAT)) || \ 117 (curthread->td_pflags & TDP_DEADLKTREAT))) 118 #define LK_TRYOP(x) \ 119 ((x) & LK_NOWAIT) 120 121 #define LK_CAN_WITNESS(x) \ 122 (((x) & LK_NOWITNESS) == 0 && !LK_TRYOP(x)) 123 #define LK_TRYWIT(x) \ 124 (LK_TRYOP(x) ? LOP_TRYLOCK : 0) 125 126 #define LK_CAN_ADAPT(lk, f) \ 127 (((lk)->lock_object.lo_flags & LK_ADAPTIVE) != 0 && \ 128 ((f) & LK_SLEEPFAIL) == 0) 129 130 #define lockmgr_disowned(lk) \ 131 (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == LK_KERNPROC) 132 133 #define lockmgr_xlocked(lk) \ 134 (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == (uintptr_t)curthread) 135 136 static void assert_lockmgr(const struct lock_object *lock, int how); 137 #ifdef DDB 138 static void db_show_lockmgr(const struct lock_object *lock); 139 #endif 140 static void lock_lockmgr(struct lock_object *lock, uintptr_t how); 141 #ifdef KDTRACE_HOOKS 142 static int owner_lockmgr(const struct lock_object *lock, 143 struct thread **owner); 144 #endif 145 static uintptr_t unlock_lockmgr(struct lock_object *lock); 146 147 struct lock_class lock_class_lockmgr = { 148 .lc_name = "lockmgr", 149 .lc_flags = LC_RECURSABLE | LC_SLEEPABLE | LC_SLEEPLOCK | LC_UPGRADABLE, 150 .lc_assert = assert_lockmgr, 151 #ifdef DDB 152 .lc_ddb_show = db_show_lockmgr, 153 #endif 154 .lc_lock = lock_lockmgr, 155 .lc_unlock = unlock_lockmgr, 156 #ifdef KDTRACE_HOOKS 157 .lc_owner = owner_lockmgr, 158 #endif 159 }; 160 161 static bool __always_inline lockmgr_slock_try(struct lock *lk, uintptr_t *xp, 162 int flags); 163 static bool __always_inline lockmgr_sunlock_try(struct lock *lk, uintptr_t x); 164 165 static void 166 lockmgr_note_shared_acquire(struct lock *lk, int contested, 167 uint64_t waittime, const char *file, int line, int flags) 168 { 169 170 lock_profile_obtain_lock_success(&lk->lock_object, contested, waittime, 171 file, line); 172 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, file, line); 173 WITNESS_LOCK(&lk->lock_object, LK_TRYWIT(flags), file, line); 174 TD_LOCKS_INC(curthread); 175 TD_SLOCKS_INC(curthread); 176 STACK_SAVE(lk); 177 } 178 179 static void 180 lockmgr_note_shared_release(struct lock *lk, const char *file, int line) 181 { 182 183 lock_profile_release_lock(&lk->lock_object); 184 WITNESS_UNLOCK(&lk->lock_object, 0, file, line); 185 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, file, line); 186 TD_LOCKS_DEC(curthread); 187 TD_SLOCKS_DEC(curthread); 188 } 189 190 static void 191 lockmgr_note_exclusive_acquire(struct lock *lk, int contested, 192 uint64_t waittime, const char *file, int line, int flags) 193 { 194 195 lock_profile_obtain_lock_success(&lk->lock_object, contested, waittime, 196 file, line); 197 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0, lk->lk_recurse, file, line); 198 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | LK_TRYWIT(flags), file, 199 line); 200 TD_LOCKS_INC(curthread); 201 STACK_SAVE(lk); 202 } 203 204 static void 205 lockmgr_note_exclusive_release(struct lock *lk, const char *file, int line) 206 { 207 208 lock_profile_release_lock(&lk->lock_object); 209 LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0, lk->lk_recurse, file, 210 line); 211 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line); 212 TD_LOCKS_DEC(curthread); 213 } 214 215 static void 216 lockmgr_note_exclusive_upgrade(struct lock *lk, const char *file, int line, 217 int flags) 218 { 219 220 LOCK_LOG_LOCK("XUPGRADE", &lk->lock_object, 0, 0, file, 221 line); 222 WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE | 223 LK_TRYWIT(flags), file, line); 224 TD_SLOCKS_DEC(curthread); 225 } 226 227 static __inline struct thread * 228 lockmgr_xholder(const struct lock *lk) 229 { 230 uintptr_t x; 231 232 x = lk->lk_lock; 233 return ((x & LK_SHARE) ? NULL : (struct thread *)LK_HOLDER(x)); 234 } 235 236 /* 237 * It assumes sleepq_lock held and returns with this one unheld. 238 * It also assumes the generic interlock is sane and previously checked. 239 * If LK_INTERLOCK is specified the interlock is not reacquired after the 240 * sleep. 241 */ 242 static __inline int 243 sleeplk(struct lock *lk, u_int flags, struct lock_object *ilk, 244 const char *wmesg, int pri, int timo, int queue) 245 { 246 GIANT_DECLARE; 247 struct lock_class *class; 248 int catch, error; 249 250 class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL; 251 catch = pri & PCATCH; 252 pri &= PRIMASK; 253 error = 0; 254 255 LOCK_LOG3(lk, "%s: %p blocking on the %s sleepqueue", __func__, lk, 256 (queue == SQ_EXCLUSIVE_QUEUE) ? "exclusive" : "shared"); 257 258 if (flags & LK_INTERLOCK) 259 class->lc_unlock(ilk); 260 if (queue == SQ_EXCLUSIVE_QUEUE && (flags & LK_SLEEPFAIL) != 0) 261 lk->lk_exslpfail++; 262 GIANT_SAVE(); 263 sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ? 264 SLEEPQ_INTERRUPTIBLE : 0), queue); 265 if ((flags & LK_TIMELOCK) && timo) 266 sleepq_set_timeout(&lk->lock_object, timo); 267 268 /* 269 * Decisional switch for real sleeping. 270 */ 271 if ((flags & LK_TIMELOCK) && timo && catch) 272 error = sleepq_timedwait_sig(&lk->lock_object, pri); 273 else if ((flags & LK_TIMELOCK) && timo) 274 error = sleepq_timedwait(&lk->lock_object, pri); 275 else if (catch) 276 error = sleepq_wait_sig(&lk->lock_object, pri); 277 else 278 sleepq_wait(&lk->lock_object, pri); 279 GIANT_RESTORE(); 280 if ((flags & LK_SLEEPFAIL) && error == 0) 281 error = ENOLCK; 282 283 return (error); 284 } 285 286 static __inline int 287 wakeupshlk(struct lock *lk, const char *file, int line) 288 { 289 uintptr_t v, x; 290 u_int realexslp; 291 int queue, wakeup_swapper; 292 293 wakeup_swapper = 0; 294 for (;;) { 295 x = lk->lk_lock; 296 if (lockmgr_sunlock_try(lk, x)) 297 break; 298 299 /* 300 * We should have a sharer with waiters, so enter the hard 301 * path in order to handle wakeups correctly. 302 */ 303 sleepq_lock(&lk->lock_object); 304 x = lk->lk_lock & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS); 305 v = LK_UNLOCKED; 306 307 /* 308 * If the lock has exclusive waiters, give them preference in 309 * order to avoid deadlock with shared runners up. 310 * If interruptible sleeps left the exclusive queue empty 311 * avoid a starvation for the threads sleeping on the shared 312 * queue by giving them precedence and cleaning up the 313 * exclusive waiters bit anyway. 314 * Please note that lk_exslpfail count may be lying about 315 * the real number of waiters with the LK_SLEEPFAIL flag on 316 * because they may be used in conjunction with interruptible 317 * sleeps so lk_exslpfail might be considered an 'upper limit' 318 * bound, including the edge cases. 319 */ 320 realexslp = sleepq_sleepcnt(&lk->lock_object, 321 SQ_EXCLUSIVE_QUEUE); 322 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) { 323 if (lk->lk_exslpfail < realexslp) { 324 lk->lk_exslpfail = 0; 325 queue = SQ_EXCLUSIVE_QUEUE; 326 v |= (x & LK_SHARED_WAITERS); 327 } else { 328 lk->lk_exslpfail = 0; 329 LOCK_LOG2(lk, 330 "%s: %p has only LK_SLEEPFAIL sleepers", 331 __func__, lk); 332 LOCK_LOG2(lk, 333 "%s: %p waking up threads on the exclusive queue", 334 __func__, lk); 335 wakeup_swapper = 336 sleepq_broadcast(&lk->lock_object, 337 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE); 338 queue = SQ_SHARED_QUEUE; 339 } 340 341 } else { 342 343 /* 344 * Exclusive waiters sleeping with LK_SLEEPFAIL on 345 * and using interruptible sleeps/timeout may have 346 * left spourious lk_exslpfail counts on, so clean 347 * it up anyway. 348 */ 349 lk->lk_exslpfail = 0; 350 queue = SQ_SHARED_QUEUE; 351 } 352 353 if (!atomic_cmpset_rel_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x, 354 v)) { 355 sleepq_release(&lk->lock_object); 356 continue; 357 } 358 LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue", 359 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" : 360 "exclusive"); 361 wakeup_swapper |= sleepq_broadcast(&lk->lock_object, SLEEPQ_LK, 362 0, queue); 363 sleepq_release(&lk->lock_object); 364 break; 365 } 366 367 lockmgr_note_shared_release(lk, file, line); 368 return (wakeup_swapper); 369 } 370 371 static void 372 assert_lockmgr(const struct lock_object *lock, int what) 373 { 374 375 panic("lockmgr locks do not support assertions"); 376 } 377 378 static void 379 lock_lockmgr(struct lock_object *lock, uintptr_t how) 380 { 381 382 panic("lockmgr locks do not support sleep interlocking"); 383 } 384 385 static uintptr_t 386 unlock_lockmgr(struct lock_object *lock) 387 { 388 389 panic("lockmgr locks do not support sleep interlocking"); 390 } 391 392 #ifdef KDTRACE_HOOKS 393 static int 394 owner_lockmgr(const struct lock_object *lock, struct thread **owner) 395 { 396 397 panic("lockmgr locks do not support owner inquiring"); 398 } 399 #endif 400 401 void 402 lockinit(struct lock *lk, int pri, const char *wmesg, int timo, int flags) 403 { 404 int iflags; 405 406 MPASS((flags & ~LK_INIT_MASK) == 0); 407 ASSERT_ATOMIC_LOAD_PTR(lk->lk_lock, 408 ("%s: lockmgr not aligned for %s: %p", __func__, wmesg, 409 &lk->lk_lock)); 410 411 iflags = LO_SLEEPABLE | LO_UPGRADABLE; 412 if (flags & LK_CANRECURSE) 413 iflags |= LO_RECURSABLE; 414 if ((flags & LK_NODUP) == 0) 415 iflags |= LO_DUPOK; 416 if (flags & LK_NOPROFILE) 417 iflags |= LO_NOPROFILE; 418 if ((flags & LK_NOWITNESS) == 0) 419 iflags |= LO_WITNESS; 420 if (flags & LK_QUIET) 421 iflags |= LO_QUIET; 422 if (flags & LK_IS_VNODE) 423 iflags |= LO_IS_VNODE; 424 iflags |= flags & (LK_ADAPTIVE | LK_NOSHARE); 425 426 lock_init(&lk->lock_object, &lock_class_lockmgr, wmesg, NULL, iflags); 427 lk->lk_lock = LK_UNLOCKED; 428 lk->lk_recurse = 0; 429 lk->lk_exslpfail = 0; 430 lk->lk_timo = timo; 431 lk->lk_pri = pri; 432 STACK_ZERO(lk); 433 } 434 435 /* 436 * XXX: Gross hacks to manipulate external lock flags after 437 * initialization. Used for certain vnode and buf locks. 438 */ 439 void 440 lockallowshare(struct lock *lk) 441 { 442 443 lockmgr_assert(lk, KA_XLOCKED); 444 lk->lock_object.lo_flags &= ~LK_NOSHARE; 445 } 446 447 void 448 lockdisableshare(struct lock *lk) 449 { 450 451 lockmgr_assert(lk, KA_XLOCKED); 452 lk->lock_object.lo_flags |= LK_NOSHARE; 453 } 454 455 void 456 lockallowrecurse(struct lock *lk) 457 { 458 459 lockmgr_assert(lk, KA_XLOCKED); 460 lk->lock_object.lo_flags |= LO_RECURSABLE; 461 } 462 463 void 464 lockdisablerecurse(struct lock *lk) 465 { 466 467 lockmgr_assert(lk, KA_XLOCKED); 468 lk->lock_object.lo_flags &= ~LO_RECURSABLE; 469 } 470 471 void 472 lockdestroy(struct lock *lk) 473 { 474 475 KASSERT(lk->lk_lock == LK_UNLOCKED, ("lockmgr still held")); 476 KASSERT(lk->lk_recurse == 0, ("lockmgr still recursed")); 477 KASSERT(lk->lk_exslpfail == 0, ("lockmgr still exclusive waiters")); 478 lock_destroy(&lk->lock_object); 479 } 480 481 static bool __always_inline 482 lockmgr_slock_try(struct lock *lk, uintptr_t *xp, int flags) 483 { 484 485 /* 486 * If no other thread has an exclusive lock, or 487 * no exclusive waiter is present, bump the count of 488 * sharers. Since we have to preserve the state of 489 * waiters, if we fail to acquire the shared lock 490 * loop back and retry. 491 */ 492 *xp = lk->lk_lock; 493 while (LK_CAN_SHARE(*xp, flags)) { 494 if (atomic_fcmpset_acq_ptr(&lk->lk_lock, xp, 495 *xp + LK_ONE_SHARER)) { 496 return (true); 497 } 498 } 499 return (false); 500 } 501 502 static bool __always_inline 503 lockmgr_sunlock_try(struct lock *lk, uintptr_t x) 504 { 505 506 for (;;) { 507 /* 508 * If there is more than one shared lock held, just drop one 509 * and return. 510 */ 511 if (LK_SHARERS(x) > 1) { 512 if (atomic_fcmpset_rel_ptr(&lk->lk_lock, &x, 513 x - LK_ONE_SHARER)) 514 return (true); 515 continue; 516 } 517 518 /* 519 * If there are not waiters on the exclusive queue, drop the 520 * lock quickly. 521 */ 522 if ((x & LK_ALL_WAITERS) == 0) { 523 MPASS((x & ~LK_EXCLUSIVE_SPINNERS) == 524 LK_SHARERS_LOCK(1)); 525 if (atomic_fcmpset_rel_ptr(&lk->lk_lock, &x, 526 LK_UNLOCKED)) 527 return (true); 528 continue; 529 } 530 break; 531 } 532 return (false); 533 } 534 535 int 536 lockmgr_lock_fast_path(struct lock *lk, u_int flags, struct lock_object *ilk, 537 const char *file, int line) 538 { 539 struct lock_class *class; 540 uintptr_t x, v, tid; 541 u_int op; 542 bool locked; 543 544 op = flags & LK_TYPE_MASK; 545 locked = false; 546 switch (op) { 547 case LK_SHARED: 548 if (LK_CAN_WITNESS(flags)) 549 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, 550 file, line, flags & LK_INTERLOCK ? ilk : NULL); 551 if (__predict_false(lk->lock_object.lo_flags & LK_NOSHARE)) 552 break; 553 if (lockmgr_slock_try(lk, &x, flags)) { 554 lockmgr_note_shared_acquire(lk, 0, 0, 555 file, line, flags); 556 locked = true; 557 } 558 break; 559 case LK_EXCLUSIVE: 560 if (LK_CAN_WITNESS(flags)) 561 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER | 562 LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ? 563 ilk : NULL); 564 tid = (uintptr_t)curthread; 565 if (lk->lk_lock == LK_UNLOCKED && 566 atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) { 567 lockmgr_note_exclusive_acquire(lk, 0, 0, file, line, 568 flags); 569 locked = true; 570 } 571 break; 572 case LK_UPGRADE: 573 case LK_TRYUPGRADE: 574 _lockmgr_assert(lk, KA_SLOCKED, file, line); 575 tid = (uintptr_t)curthread; 576 v = lk->lk_lock; 577 x = v & LK_ALL_WAITERS; 578 v &= LK_EXCLUSIVE_SPINNERS; 579 if (atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x | v, 580 tid | x)) { 581 lockmgr_note_exclusive_upgrade(lk, file, line, flags); 582 locked = true; 583 } 584 break; 585 default: 586 break; 587 } 588 if (__predict_true(locked)) { 589 if (__predict_false(flags & LK_INTERLOCK)) { 590 class = LOCK_CLASS(ilk); 591 class->lc_unlock(ilk); 592 } 593 return (0); 594 } else { 595 return (__lockmgr_args(lk, flags, ilk, LK_WMESG_DEFAULT, 596 LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, file, line)); 597 } 598 } 599 600 int 601 lockmgr_unlock_fast_path(struct lock *lk, u_int flags, struct lock_object *ilk) 602 { 603 struct lock_class *class; 604 uintptr_t x, tid; 605 bool unlocked; 606 const char *file; 607 int line; 608 609 file = __FILE__; 610 line = __LINE__; 611 612 _lockmgr_assert(lk, KA_LOCKED, file, line); 613 unlocked = false; 614 x = lk->lk_lock; 615 if (__predict_true(x & LK_SHARE) != 0) { 616 if (lockmgr_sunlock_try(lk, x)) { 617 lockmgr_note_shared_release(lk, file, line); 618 unlocked = true; 619 } 620 } else { 621 tid = (uintptr_t)curthread; 622 if (!lockmgr_recursed(lk) && 623 atomic_cmpset_rel_ptr(&lk->lk_lock, tid, LK_UNLOCKED)) { 624 lockmgr_note_exclusive_release(lk, file, line); 625 unlocked = true; 626 } 627 } 628 if (__predict_true(unlocked)) { 629 if (__predict_false(flags & LK_INTERLOCK)) { 630 class = LOCK_CLASS(ilk); 631 class->lc_unlock(ilk); 632 } 633 return (0); 634 } else { 635 return (__lockmgr_args(lk, flags | LK_RELEASE, ilk, LK_WMESG_DEFAULT, 636 LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, LOCK_FILE, LOCK_LINE)); 637 } 638 } 639 640 int 641 __lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk, 642 const char *wmesg, int pri, int timo, const char *file, int line) 643 { 644 GIANT_DECLARE; 645 struct lock_class *class; 646 const char *iwmesg; 647 uintptr_t tid, v, x; 648 u_int op, realexslp; 649 int error, ipri, itimo, queue, wakeup_swapper; 650 #ifdef LOCK_PROFILING 651 uint64_t waittime = 0; 652 int contested = 0; 653 #endif 654 655 error = 0; 656 tid = (uintptr_t)curthread; 657 op = (flags & LK_TYPE_MASK); 658 iwmesg = (wmesg == LK_WMESG_DEFAULT) ? lk->lock_object.lo_name : wmesg; 659 ipri = (pri == LK_PRIO_DEFAULT) ? lk->lk_pri : pri; 660 itimo = (timo == LK_TIMO_DEFAULT) ? lk->lk_timo : timo; 661 662 MPASS((flags & ~LK_TOTAL_MASK) == 0); 663 KASSERT((op & (op - 1)) == 0, 664 ("%s: Invalid requested operation @ %s:%d", __func__, file, line)); 665 KASSERT((flags & (LK_NOWAIT | LK_SLEEPFAIL)) == 0 || 666 (op != LK_DOWNGRADE && op != LK_RELEASE), 667 ("%s: Invalid flags in regard of the operation desired @ %s:%d", 668 __func__, file, line)); 669 KASSERT((flags & LK_INTERLOCK) == 0 || ilk != NULL, 670 ("%s: LK_INTERLOCK passed without valid interlock @ %s:%d", 671 __func__, file, line)); 672 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 673 ("%s: idle thread %p on lockmgr %s @ %s:%d", __func__, curthread, 674 lk->lock_object.lo_name, file, line)); 675 676 class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL; 677 if (panicstr != NULL) { 678 if (flags & LK_INTERLOCK) 679 class->lc_unlock(ilk); 680 return (0); 681 } 682 683 if (lk->lock_object.lo_flags & LK_NOSHARE) { 684 switch (op) { 685 case LK_SHARED: 686 op = LK_EXCLUSIVE; 687 break; 688 case LK_UPGRADE: 689 case LK_TRYUPGRADE: 690 case LK_DOWNGRADE: 691 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, 692 file, line); 693 if (flags & LK_INTERLOCK) 694 class->lc_unlock(ilk); 695 return (0); 696 } 697 } 698 699 wakeup_swapper = 0; 700 switch (op) { 701 case LK_SHARED: 702 if (LK_CAN_WITNESS(flags)) 703 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, 704 file, line, flags & LK_INTERLOCK ? ilk : NULL); 705 for (;;) { 706 if (lockmgr_slock_try(lk, &x, flags)) 707 break; 708 #ifdef HWPMC_HOOKS 709 PMC_SOFT_CALL( , , lock, failed); 710 #endif 711 lock_profile_obtain_lock_failed(&lk->lock_object, 712 &contested, &waittime); 713 714 /* 715 * If the lock is already held by curthread in 716 * exclusive way avoid a deadlock. 717 */ 718 if (LK_HOLDER(x) == tid) { 719 LOCK_LOG2(lk, 720 "%s: %p already held in exclusive mode", 721 __func__, lk); 722 error = EDEADLK; 723 break; 724 } 725 726 /* 727 * If the lock is expected to not sleep just give up 728 * and return. 729 */ 730 if (LK_TRYOP(flags)) { 731 LOCK_LOG2(lk, "%s: %p fails the try operation", 732 __func__, lk); 733 error = EBUSY; 734 break; 735 } 736 737 /* 738 * Acquire the sleepqueue chain lock because we 739 * probabilly will need to manipulate waiters flags. 740 */ 741 sleepq_lock(&lk->lock_object); 742 x = lk->lk_lock; 743 744 /* 745 * if the lock can be acquired in shared mode, try 746 * again. 747 */ 748 if (LK_CAN_SHARE(x, flags)) { 749 sleepq_release(&lk->lock_object); 750 continue; 751 } 752 753 /* 754 * Try to set the LK_SHARED_WAITERS flag. If we fail, 755 * loop back and retry. 756 */ 757 if ((x & LK_SHARED_WAITERS) == 0) { 758 if (!atomic_cmpset_acq_ptr(&lk->lk_lock, x, 759 x | LK_SHARED_WAITERS)) { 760 sleepq_release(&lk->lock_object); 761 continue; 762 } 763 LOCK_LOG2(lk, "%s: %p set shared waiters flag", 764 __func__, lk); 765 } 766 767 /* 768 * As far as we have been unable to acquire the 769 * shared lock and the shared waiters flag is set, 770 * we will sleep. 771 */ 772 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo, 773 SQ_SHARED_QUEUE); 774 flags &= ~LK_INTERLOCK; 775 if (error) { 776 LOCK_LOG3(lk, 777 "%s: interrupted sleep for %p with %d", 778 __func__, lk, error); 779 break; 780 } 781 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue", 782 __func__, lk); 783 } 784 if (error == 0) { 785 #ifdef LOCK_PROFILING 786 lockmgr_note_shared_acquire(lk, contested, waittime, 787 file, line, flags); 788 #else 789 lockmgr_note_shared_acquire(lk, 0, 0, file, line, 790 flags); 791 #endif 792 } 793 break; 794 case LK_UPGRADE: 795 case LK_TRYUPGRADE: 796 _lockmgr_assert(lk, KA_SLOCKED, file, line); 797 v = lk->lk_lock; 798 x = v & LK_ALL_WAITERS; 799 v &= LK_EXCLUSIVE_SPINNERS; 800 801 /* 802 * Try to switch from one shared lock to an exclusive one. 803 * We need to preserve waiters flags during the operation. 804 */ 805 if (atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x | v, 806 tid | x)) { 807 LOCK_LOG_LOCK("XUPGRADE", &lk->lock_object, 0, 0, file, 808 line); 809 WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE | 810 LK_TRYWIT(flags), file, line); 811 TD_SLOCKS_DEC(curthread); 812 break; 813 } 814 815 /* 816 * In LK_TRYUPGRADE mode, do not drop the lock, 817 * returning EBUSY instead. 818 */ 819 if (op == LK_TRYUPGRADE) { 820 LOCK_LOG2(lk, "%s: %p failed the nowait upgrade", 821 __func__, lk); 822 error = EBUSY; 823 break; 824 } 825 826 /* 827 * We have been unable to succeed in upgrading, so just 828 * give up the shared lock. 829 */ 830 wakeup_swapper |= wakeupshlk(lk, file, line); 831 832 /* FALLTHROUGH */ 833 case LK_EXCLUSIVE: 834 if (LK_CAN_WITNESS(flags)) 835 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER | 836 LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ? 837 ilk : NULL); 838 839 /* 840 * If curthread already holds the lock and this one is 841 * allowed to recurse, simply recurse on it. 842 */ 843 if (lockmgr_xlocked(lk)) { 844 if ((flags & LK_CANRECURSE) == 0 && 845 (lk->lock_object.lo_flags & LO_RECURSABLE) == 0) { 846 847 /* 848 * If the lock is expected to not panic just 849 * give up and return. 850 */ 851 if (LK_TRYOP(flags)) { 852 LOCK_LOG2(lk, 853 "%s: %p fails the try operation", 854 __func__, lk); 855 error = EBUSY; 856 break; 857 } 858 if (flags & LK_INTERLOCK) 859 class->lc_unlock(ilk); 860 panic("%s: recursing on non recursive lockmgr %s @ %s:%d\n", 861 __func__, iwmesg, file, line); 862 } 863 lk->lk_recurse++; 864 LOCK_LOG2(lk, "%s: %p recursing", __func__, lk); 865 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0, 866 lk->lk_recurse, file, line); 867 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | 868 LK_TRYWIT(flags), file, line); 869 TD_LOCKS_INC(curthread); 870 break; 871 } 872 873 for (;;) { 874 if (lk->lk_lock == LK_UNLOCKED && 875 atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) 876 break; 877 #ifdef HWPMC_HOOKS 878 PMC_SOFT_CALL( , , lock, failed); 879 #endif 880 lock_profile_obtain_lock_failed(&lk->lock_object, 881 &contested, &waittime); 882 883 /* 884 * If the lock is expected to not sleep just give up 885 * and return. 886 */ 887 if (LK_TRYOP(flags)) { 888 LOCK_LOG2(lk, "%s: %p fails the try operation", 889 __func__, lk); 890 error = EBUSY; 891 break; 892 } 893 894 /* 895 * Acquire the sleepqueue chain lock because we 896 * probabilly will need to manipulate waiters flags. 897 */ 898 sleepq_lock(&lk->lock_object); 899 x = lk->lk_lock; 900 901 /* 902 * if the lock has been released while we spun on 903 * the sleepqueue chain lock just try again. 904 */ 905 if (x == LK_UNLOCKED) { 906 sleepq_release(&lk->lock_object); 907 continue; 908 } 909 910 /* 911 * The lock can be in the state where there is a 912 * pending queue of waiters, but still no owner. 913 * This happens when the lock is contested and an 914 * owner is going to claim the lock. 915 * If curthread is the one successfully acquiring it 916 * claim lock ownership and return, preserving waiters 917 * flags. 918 */ 919 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS); 920 if ((x & ~v) == LK_UNLOCKED) { 921 v &= ~LK_EXCLUSIVE_SPINNERS; 922 if (atomic_cmpset_acq_ptr(&lk->lk_lock, x, 923 tid | v)) { 924 sleepq_release(&lk->lock_object); 925 LOCK_LOG2(lk, 926 "%s: %p claimed by a new writer", 927 __func__, lk); 928 break; 929 } 930 sleepq_release(&lk->lock_object); 931 continue; 932 } 933 934 /* 935 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we 936 * fail, loop back and retry. 937 */ 938 if ((x & LK_EXCLUSIVE_WAITERS) == 0) { 939 if (!atomic_cmpset_ptr(&lk->lk_lock, x, 940 x | LK_EXCLUSIVE_WAITERS)) { 941 sleepq_release(&lk->lock_object); 942 continue; 943 } 944 LOCK_LOG2(lk, "%s: %p set excl waiters flag", 945 __func__, lk); 946 } 947 948 /* 949 * As far as we have been unable to acquire the 950 * exclusive lock and the exclusive waiters flag 951 * is set, we will sleep. 952 */ 953 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo, 954 SQ_EXCLUSIVE_QUEUE); 955 flags &= ~LK_INTERLOCK; 956 if (error) { 957 LOCK_LOG3(lk, 958 "%s: interrupted sleep for %p with %d", 959 __func__, lk, error); 960 break; 961 } 962 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue", 963 __func__, lk); 964 } 965 if (error == 0) { 966 #ifdef LOCK_PROFILING 967 lockmgr_note_exclusive_acquire(lk, contested, waittime, 968 file, line, flags); 969 #else 970 lockmgr_note_exclusive_acquire(lk, 0, 0, file, line, 971 flags); 972 #endif 973 } 974 break; 975 case LK_DOWNGRADE: 976 _lockmgr_assert(lk, KA_XLOCKED, file, line); 977 LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line); 978 WITNESS_DOWNGRADE(&lk->lock_object, 0, file, line); 979 980 /* 981 * Panic if the lock is recursed. 982 */ 983 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) { 984 if (flags & LK_INTERLOCK) 985 class->lc_unlock(ilk); 986 panic("%s: downgrade a recursed lockmgr %s @ %s:%d\n", 987 __func__, iwmesg, file, line); 988 } 989 TD_SLOCKS_INC(curthread); 990 991 /* 992 * In order to preserve waiters flags, just spin. 993 */ 994 for (;;) { 995 x = lk->lk_lock; 996 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0); 997 x &= LK_ALL_WAITERS; 998 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x, 999 LK_SHARERS_LOCK(1) | x)) 1000 break; 1001 cpu_spinwait(); 1002 } 1003 break; 1004 case LK_RELEASE: 1005 _lockmgr_assert(lk, KA_LOCKED, file, line); 1006 x = lk->lk_lock; 1007 1008 if ((x & LK_SHARE) == 0) { 1009 1010 /* 1011 * As first option, treact the lock as if it has not 1012 * any waiter. 1013 * Fix-up the tid var if the lock has been disowned. 1014 */ 1015 if (LK_HOLDER(x) == LK_KERNPROC) 1016 tid = LK_KERNPROC; 1017 else { 1018 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, 1019 file, line); 1020 TD_LOCKS_DEC(curthread); 1021 } 1022 LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0, 1023 lk->lk_recurse, file, line); 1024 1025 /* 1026 * The lock is held in exclusive mode. 1027 * If the lock is recursed also, then unrecurse it. 1028 */ 1029 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) { 1030 LOCK_LOG2(lk, "%s: %p unrecursing", __func__, 1031 lk); 1032 lk->lk_recurse--; 1033 break; 1034 } 1035 if (tid != LK_KERNPROC) 1036 lock_profile_release_lock(&lk->lock_object); 1037 1038 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid, 1039 LK_UNLOCKED)) 1040 break; 1041 1042 sleepq_lock(&lk->lock_object); 1043 x = lk->lk_lock; 1044 v = LK_UNLOCKED; 1045 1046 /* 1047 * If the lock has exclusive waiters, give them 1048 * preference in order to avoid deadlock with 1049 * shared runners up. 1050 * If interruptible sleeps left the exclusive queue 1051 * empty avoid a starvation for the threads sleeping 1052 * on the shared queue by giving them precedence 1053 * and cleaning up the exclusive waiters bit anyway. 1054 * Please note that lk_exslpfail count may be lying 1055 * about the real number of waiters with the 1056 * LK_SLEEPFAIL flag on because they may be used in 1057 * conjunction with interruptible sleeps so 1058 * lk_exslpfail might be considered an 'upper limit' 1059 * bound, including the edge cases. 1060 */ 1061 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0); 1062 realexslp = sleepq_sleepcnt(&lk->lock_object, 1063 SQ_EXCLUSIVE_QUEUE); 1064 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) { 1065 if (lk->lk_exslpfail < realexslp) { 1066 lk->lk_exslpfail = 0; 1067 queue = SQ_EXCLUSIVE_QUEUE; 1068 v |= (x & LK_SHARED_WAITERS); 1069 } else { 1070 lk->lk_exslpfail = 0; 1071 LOCK_LOG2(lk, 1072 "%s: %p has only LK_SLEEPFAIL sleepers", 1073 __func__, lk); 1074 LOCK_LOG2(lk, 1075 "%s: %p waking up threads on the exclusive queue", 1076 __func__, lk); 1077 wakeup_swapper = 1078 sleepq_broadcast(&lk->lock_object, 1079 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE); 1080 queue = SQ_SHARED_QUEUE; 1081 } 1082 } else { 1083 1084 /* 1085 * Exclusive waiters sleeping with LK_SLEEPFAIL 1086 * on and using interruptible sleeps/timeout 1087 * may have left spourious lk_exslpfail counts 1088 * on, so clean it up anyway. 1089 */ 1090 lk->lk_exslpfail = 0; 1091 queue = SQ_SHARED_QUEUE; 1092 } 1093 1094 LOCK_LOG3(lk, 1095 "%s: %p waking up threads on the %s queue", 1096 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" : 1097 "exclusive"); 1098 atomic_store_rel_ptr(&lk->lk_lock, v); 1099 wakeup_swapper |= sleepq_broadcast(&lk->lock_object, 1100 SLEEPQ_LK, 0, queue); 1101 sleepq_release(&lk->lock_object); 1102 break; 1103 } else 1104 wakeup_swapper = wakeupshlk(lk, file, line); 1105 break; 1106 case LK_DRAIN: 1107 if (LK_CAN_WITNESS(flags)) 1108 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER | 1109 LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ? 1110 ilk : NULL); 1111 1112 /* 1113 * Trying to drain a lock we already own will result in a 1114 * deadlock. 1115 */ 1116 if (lockmgr_xlocked(lk)) { 1117 if (flags & LK_INTERLOCK) 1118 class->lc_unlock(ilk); 1119 panic("%s: draining %s with the lock held @ %s:%d\n", 1120 __func__, iwmesg, file, line); 1121 } 1122 1123 for (;;) { 1124 if (lk->lk_lock == LK_UNLOCKED && 1125 atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) 1126 break; 1127 1128 #ifdef HWPMC_HOOKS 1129 PMC_SOFT_CALL( , , lock, failed); 1130 #endif 1131 lock_profile_obtain_lock_failed(&lk->lock_object, 1132 &contested, &waittime); 1133 1134 /* 1135 * If the lock is expected to not sleep just give up 1136 * and return. 1137 */ 1138 if (LK_TRYOP(flags)) { 1139 LOCK_LOG2(lk, "%s: %p fails the try operation", 1140 __func__, lk); 1141 error = EBUSY; 1142 break; 1143 } 1144 1145 /* 1146 * Acquire the sleepqueue chain lock because we 1147 * probabilly will need to manipulate waiters flags. 1148 */ 1149 sleepq_lock(&lk->lock_object); 1150 x = lk->lk_lock; 1151 1152 /* 1153 * if the lock has been released while we spun on 1154 * the sleepqueue chain lock just try again. 1155 */ 1156 if (x == LK_UNLOCKED) { 1157 sleepq_release(&lk->lock_object); 1158 continue; 1159 } 1160 1161 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS); 1162 if ((x & ~v) == LK_UNLOCKED) { 1163 v = (x & ~LK_EXCLUSIVE_SPINNERS); 1164 1165 /* 1166 * If interruptible sleeps left the exclusive 1167 * queue empty avoid a starvation for the 1168 * threads sleeping on the shared queue by 1169 * giving them precedence and cleaning up the 1170 * exclusive waiters bit anyway. 1171 * Please note that lk_exslpfail count may be 1172 * lying about the real number of waiters with 1173 * the LK_SLEEPFAIL flag on because they may 1174 * be used in conjunction with interruptible 1175 * sleeps so lk_exslpfail might be considered 1176 * an 'upper limit' bound, including the edge 1177 * cases. 1178 */ 1179 if (v & LK_EXCLUSIVE_WAITERS) { 1180 queue = SQ_EXCLUSIVE_QUEUE; 1181 v &= ~LK_EXCLUSIVE_WAITERS; 1182 } else { 1183 1184 /* 1185 * Exclusive waiters sleeping with 1186 * LK_SLEEPFAIL on and using 1187 * interruptible sleeps/timeout may 1188 * have left spourious lk_exslpfail 1189 * counts on, so clean it up anyway. 1190 */ 1191 MPASS(v & LK_SHARED_WAITERS); 1192 lk->lk_exslpfail = 0; 1193 queue = SQ_SHARED_QUEUE; 1194 v &= ~LK_SHARED_WAITERS; 1195 } 1196 if (queue == SQ_EXCLUSIVE_QUEUE) { 1197 realexslp = 1198 sleepq_sleepcnt(&lk->lock_object, 1199 SQ_EXCLUSIVE_QUEUE); 1200 if (lk->lk_exslpfail >= realexslp) { 1201 lk->lk_exslpfail = 0; 1202 queue = SQ_SHARED_QUEUE; 1203 v &= ~LK_SHARED_WAITERS; 1204 if (realexslp != 0) { 1205 LOCK_LOG2(lk, 1206 "%s: %p has only LK_SLEEPFAIL sleepers", 1207 __func__, lk); 1208 LOCK_LOG2(lk, 1209 "%s: %p waking up threads on the exclusive queue", 1210 __func__, lk); 1211 wakeup_swapper = 1212 sleepq_broadcast( 1213 &lk->lock_object, 1214 SLEEPQ_LK, 0, 1215 SQ_EXCLUSIVE_QUEUE); 1216 } 1217 } else 1218 lk->lk_exslpfail = 0; 1219 } 1220 if (!atomic_cmpset_ptr(&lk->lk_lock, x, v)) { 1221 sleepq_release(&lk->lock_object); 1222 continue; 1223 } 1224 LOCK_LOG3(lk, 1225 "%s: %p waking up all threads on the %s queue", 1226 __func__, lk, queue == SQ_SHARED_QUEUE ? 1227 "shared" : "exclusive"); 1228 wakeup_swapper |= sleepq_broadcast( 1229 &lk->lock_object, SLEEPQ_LK, 0, queue); 1230 1231 /* 1232 * If shared waiters have been woken up we need 1233 * to wait for one of them to acquire the lock 1234 * before to set the exclusive waiters in 1235 * order to avoid a deadlock. 1236 */ 1237 if (queue == SQ_SHARED_QUEUE) { 1238 for (v = lk->lk_lock; 1239 (v & LK_SHARE) && !LK_SHARERS(v); 1240 v = lk->lk_lock) 1241 cpu_spinwait(); 1242 } 1243 } 1244 1245 /* 1246 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we 1247 * fail, loop back and retry. 1248 */ 1249 if ((x & LK_EXCLUSIVE_WAITERS) == 0) { 1250 if (!atomic_cmpset_ptr(&lk->lk_lock, x, 1251 x | LK_EXCLUSIVE_WAITERS)) { 1252 sleepq_release(&lk->lock_object); 1253 continue; 1254 } 1255 LOCK_LOG2(lk, "%s: %p set drain waiters flag", 1256 __func__, lk); 1257 } 1258 1259 /* 1260 * As far as we have been unable to acquire the 1261 * exclusive lock and the exclusive waiters flag 1262 * is set, we will sleep. 1263 */ 1264 if (flags & LK_INTERLOCK) { 1265 class->lc_unlock(ilk); 1266 flags &= ~LK_INTERLOCK; 1267 } 1268 GIANT_SAVE(); 1269 sleepq_add(&lk->lock_object, NULL, iwmesg, SLEEPQ_LK, 1270 SQ_EXCLUSIVE_QUEUE); 1271 sleepq_wait(&lk->lock_object, ipri & PRIMASK); 1272 GIANT_RESTORE(); 1273 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue", 1274 __func__, lk); 1275 } 1276 1277 if (error == 0) { 1278 lock_profile_obtain_lock_success(&lk->lock_object, 1279 contested, waittime, file, line); 1280 LOCK_LOG_LOCK("DRAIN", &lk->lock_object, 0, 1281 lk->lk_recurse, file, line); 1282 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | 1283 LK_TRYWIT(flags), file, line); 1284 TD_LOCKS_INC(curthread); 1285 STACK_SAVE(lk); 1286 } 1287 break; 1288 default: 1289 if (flags & LK_INTERLOCK) 1290 class->lc_unlock(ilk); 1291 panic("%s: unknown lockmgr request 0x%x\n", __func__, op); 1292 } 1293 1294 if (flags & LK_INTERLOCK) 1295 class->lc_unlock(ilk); 1296 if (wakeup_swapper) 1297 kick_proc0(); 1298 1299 return (error); 1300 } 1301 1302 void 1303 _lockmgr_disown(struct lock *lk, const char *file, int line) 1304 { 1305 uintptr_t tid, x; 1306 1307 if (SCHEDULER_STOPPED()) 1308 return; 1309 1310 tid = (uintptr_t)curthread; 1311 _lockmgr_assert(lk, KA_XLOCKED, file, line); 1312 1313 /* 1314 * Panic if the lock is recursed. 1315 */ 1316 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) 1317 panic("%s: disown a recursed lockmgr @ %s:%d\n", 1318 __func__, file, line); 1319 1320 /* 1321 * If the owner is already LK_KERNPROC just skip the whole operation. 1322 */ 1323 if (LK_HOLDER(lk->lk_lock) != tid) 1324 return; 1325 lock_profile_release_lock(&lk->lock_object); 1326 LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line); 1327 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line); 1328 TD_LOCKS_DEC(curthread); 1329 STACK_SAVE(lk); 1330 1331 /* 1332 * In order to preserve waiters flags, just spin. 1333 */ 1334 for (;;) { 1335 x = lk->lk_lock; 1336 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0); 1337 x &= LK_ALL_WAITERS; 1338 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x, 1339 LK_KERNPROC | x)) 1340 return; 1341 cpu_spinwait(); 1342 } 1343 } 1344 1345 void 1346 lockmgr_printinfo(const struct lock *lk) 1347 { 1348 struct thread *td; 1349 uintptr_t x; 1350 1351 if (lk->lk_lock == LK_UNLOCKED) 1352 printf("lock type %s: UNLOCKED\n", lk->lock_object.lo_name); 1353 else if (lk->lk_lock & LK_SHARE) 1354 printf("lock type %s: SHARED (count %ju)\n", 1355 lk->lock_object.lo_name, 1356 (uintmax_t)LK_SHARERS(lk->lk_lock)); 1357 else { 1358 td = lockmgr_xholder(lk); 1359 if (td == (struct thread *)LK_KERNPROC) 1360 printf("lock type %s: EXCL by KERNPROC\n", 1361 lk->lock_object.lo_name); 1362 else 1363 printf("lock type %s: EXCL by thread %p " 1364 "(pid %d, %s, tid %d)\n", lk->lock_object.lo_name, 1365 td, td->td_proc->p_pid, td->td_proc->p_comm, 1366 td->td_tid); 1367 } 1368 1369 x = lk->lk_lock; 1370 if (x & LK_EXCLUSIVE_WAITERS) 1371 printf(" with exclusive waiters pending\n"); 1372 if (x & LK_SHARED_WAITERS) 1373 printf(" with shared waiters pending\n"); 1374 if (x & LK_EXCLUSIVE_SPINNERS) 1375 printf(" with exclusive spinners pending\n"); 1376 1377 STACK_PRINT(lk); 1378 } 1379 1380 int 1381 lockstatus(const struct lock *lk) 1382 { 1383 uintptr_t v, x; 1384 int ret; 1385 1386 ret = LK_SHARED; 1387 x = lk->lk_lock; 1388 v = LK_HOLDER(x); 1389 1390 if ((x & LK_SHARE) == 0) { 1391 if (v == (uintptr_t)curthread || v == LK_KERNPROC) 1392 ret = LK_EXCLUSIVE; 1393 else 1394 ret = LK_EXCLOTHER; 1395 } else if (x == LK_UNLOCKED) 1396 ret = 0; 1397 1398 return (ret); 1399 } 1400 1401 #ifdef INVARIANT_SUPPORT 1402 1403 FEATURE(invariant_support, 1404 "Support for modules compiled with INVARIANTS option"); 1405 1406 #ifndef INVARIANTS 1407 #undef _lockmgr_assert 1408 #endif 1409 1410 void 1411 _lockmgr_assert(const struct lock *lk, int what, const char *file, int line) 1412 { 1413 int slocked = 0; 1414 1415 if (panicstr != NULL) 1416 return; 1417 switch (what) { 1418 case KA_SLOCKED: 1419 case KA_SLOCKED | KA_NOTRECURSED: 1420 case KA_SLOCKED | KA_RECURSED: 1421 slocked = 1; 1422 case KA_LOCKED: 1423 case KA_LOCKED | KA_NOTRECURSED: 1424 case KA_LOCKED | KA_RECURSED: 1425 #ifdef WITNESS 1426 1427 /* 1428 * We cannot trust WITNESS if the lock is held in exclusive 1429 * mode and a call to lockmgr_disown() happened. 1430 * Workaround this skipping the check if the lock is held in 1431 * exclusive mode even for the KA_LOCKED case. 1432 */ 1433 if (slocked || (lk->lk_lock & LK_SHARE)) { 1434 witness_assert(&lk->lock_object, what, file, line); 1435 break; 1436 } 1437 #endif 1438 if (lk->lk_lock == LK_UNLOCKED || 1439 ((lk->lk_lock & LK_SHARE) == 0 && (slocked || 1440 (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk))))) 1441 panic("Lock %s not %slocked @ %s:%d\n", 1442 lk->lock_object.lo_name, slocked ? "share" : "", 1443 file, line); 1444 1445 if ((lk->lk_lock & LK_SHARE) == 0) { 1446 if (lockmgr_recursed(lk)) { 1447 if (what & KA_NOTRECURSED) 1448 panic("Lock %s recursed @ %s:%d\n", 1449 lk->lock_object.lo_name, file, 1450 line); 1451 } else if (what & KA_RECURSED) 1452 panic("Lock %s not recursed @ %s:%d\n", 1453 lk->lock_object.lo_name, file, line); 1454 } 1455 break; 1456 case KA_XLOCKED: 1457 case KA_XLOCKED | KA_NOTRECURSED: 1458 case KA_XLOCKED | KA_RECURSED: 1459 if (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk)) 1460 panic("Lock %s not exclusively locked @ %s:%d\n", 1461 lk->lock_object.lo_name, file, line); 1462 if (lockmgr_recursed(lk)) { 1463 if (what & KA_NOTRECURSED) 1464 panic("Lock %s recursed @ %s:%d\n", 1465 lk->lock_object.lo_name, file, line); 1466 } else if (what & KA_RECURSED) 1467 panic("Lock %s not recursed @ %s:%d\n", 1468 lk->lock_object.lo_name, file, line); 1469 break; 1470 case KA_UNLOCKED: 1471 if (lockmgr_xlocked(lk) || lockmgr_disowned(lk)) 1472 panic("Lock %s exclusively locked @ %s:%d\n", 1473 lk->lock_object.lo_name, file, line); 1474 break; 1475 default: 1476 panic("Unknown lockmgr assertion: %d @ %s:%d\n", what, file, 1477 line); 1478 } 1479 } 1480 #endif 1481 1482 #ifdef DDB 1483 int 1484 lockmgr_chain(struct thread *td, struct thread **ownerp) 1485 { 1486 struct lock *lk; 1487 1488 lk = td->td_wchan; 1489 1490 if (LOCK_CLASS(&lk->lock_object) != &lock_class_lockmgr) 1491 return (0); 1492 db_printf("blocked on lockmgr %s", lk->lock_object.lo_name); 1493 if (lk->lk_lock & LK_SHARE) 1494 db_printf("SHARED (count %ju)\n", 1495 (uintmax_t)LK_SHARERS(lk->lk_lock)); 1496 else 1497 db_printf("EXCL\n"); 1498 *ownerp = lockmgr_xholder(lk); 1499 1500 return (1); 1501 } 1502 1503 static void 1504 db_show_lockmgr(const struct lock_object *lock) 1505 { 1506 struct thread *td; 1507 const struct lock *lk; 1508 1509 lk = (const struct lock *)lock; 1510 1511 db_printf(" state: "); 1512 if (lk->lk_lock == LK_UNLOCKED) 1513 db_printf("UNLOCKED\n"); 1514 else if (lk->lk_lock & LK_SHARE) 1515 db_printf("SLOCK: %ju\n", (uintmax_t)LK_SHARERS(lk->lk_lock)); 1516 else { 1517 td = lockmgr_xholder(lk); 1518 if (td == (struct thread *)LK_KERNPROC) 1519 db_printf("XLOCK: LK_KERNPROC\n"); 1520 else 1521 db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td, 1522 td->td_tid, td->td_proc->p_pid, 1523 td->td_proc->p_comm); 1524 if (lockmgr_recursed(lk)) 1525 db_printf(" recursed: %d\n", lk->lk_recurse); 1526 } 1527 db_printf(" waiters: "); 1528 switch (lk->lk_lock & LK_ALL_WAITERS) { 1529 case LK_SHARED_WAITERS: 1530 db_printf("shared\n"); 1531 break; 1532 case LK_EXCLUSIVE_WAITERS: 1533 db_printf("exclusive\n"); 1534 break; 1535 case LK_ALL_WAITERS: 1536 db_printf("shared and exclusive\n"); 1537 break; 1538 default: 1539 db_printf("none\n"); 1540 } 1541 db_printf(" spinners: "); 1542 if (lk->lk_lock & LK_EXCLUSIVE_SPINNERS) 1543 db_printf("exclusive\n"); 1544 else 1545 db_printf("none\n"); 1546 } 1547 #endif 1548