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sys/kern/kern_lock.c
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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_adaptive_lockmgrs.h" 30 #include "opt_ddb.h" 31 #include "opt_kdtrace.h" 32 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD: releng/8.3/sys/kern/kern_lock.c 224704 2011-08-08 08:22:15Z kib $"); 35 36 #include <sys/param.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 CTASSERT(((LK_ADAPTIVE | LK_EXSLPFAIL | LK_NOSHARE) & LO_CLASSFLAGS) == 57 (LK_ADAPTIVE | LK_EXSLPFAIL | LK_NOSHARE)); 58 CTASSERT(LK_UNLOCKED == (LK_UNLOCKED & 59 ~(LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS))); 60 61 #define SQ_EXCLUSIVE_QUEUE 0 62 #define SQ_SHARED_QUEUE 1 63 64 #ifdef ADAPTIVE_LOCKMGRS 65 #define ALK_RETRIES 10 66 #define ALK_LOOPS 10000 67 #endif 68 69 #ifndef INVARIANTS 70 #define _lockmgr_assert(lk, what, file, line) 71 #define TD_LOCKS_INC(td) 72 #define TD_LOCKS_DEC(td) 73 #else 74 #define TD_LOCKS_INC(td) ((td)->td_locks++) 75 #define TD_LOCKS_DEC(td) ((td)->td_locks--) 76 #endif 77 #define TD_SLOCKS_INC(td) ((td)->td_lk_slocks++) 78 #define TD_SLOCKS_DEC(td) ((td)->td_lk_slocks--) 79 80 #ifndef DEBUG_LOCKS 81 #define STACK_PRINT(lk) 82 #define STACK_SAVE(lk) 83 #define STACK_ZERO(lk) 84 #else 85 #define STACK_PRINT(lk) stack_print_ddb(&(lk)->lk_stack) 86 #define STACK_SAVE(lk) stack_save(&(lk)->lk_stack) 87 #define STACK_ZERO(lk) stack_zero(&(lk)->lk_stack) 88 #endif 89 90 #define LOCK_LOG2(lk, string, arg1, arg2) \ 91 if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \ 92 CTR2(KTR_LOCK, (string), (arg1), (arg2)) 93 #define LOCK_LOG3(lk, string, arg1, arg2, arg3) \ 94 if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \ 95 CTR3(KTR_LOCK, (string), (arg1), (arg2), (arg3)) 96 97 #define GIANT_DECLARE \ 98 int _i = 0; \ 99 WITNESS_SAVE_DECL(Giant) 100 #define GIANT_RESTORE() do { \ 101 if (_i > 0) { \ 102 while (_i--) \ 103 mtx_lock(&Giant); \ 104 WITNESS_RESTORE(&Giant.lock_object, Giant); \ 105 } \ 106 } while (0) 107 #define GIANT_SAVE() do { \ 108 if (mtx_owned(&Giant)) { \ 109 WITNESS_SAVE(&Giant.lock_object, Giant); \ 110 while (mtx_owned(&Giant)) { \ 111 _i++; \ 112 mtx_unlock(&Giant); \ 113 } \ 114 } \ 115 } while (0) 116 117 #define LK_CAN_SHARE(x) \ 118 (((x) & LK_SHARE) && (((x) & LK_EXCLUSIVE_WAITERS) == 0 || \ 119 ((x) & LK_EXCLUSIVE_SPINNERS) == 0 || \ 120 curthread->td_lk_slocks || (curthread->td_pflags & TDP_DEADLKTREAT))) 121 #define LK_TRYOP(x) \ 122 ((x) & LK_NOWAIT) 123 124 #define LK_CAN_WITNESS(x) \ 125 (((x) & LK_NOWITNESS) == 0 && !LK_TRYOP(x)) 126 #define LK_TRYWIT(x) \ 127 (LK_TRYOP(x) ? LOP_TRYLOCK : 0) 128 129 #define LK_CAN_ADAPT(lk, f) \ 130 (((lk)->lock_object.lo_flags & LK_ADAPTIVE) != 0 && \ 131 ((f) & LK_SLEEPFAIL) == 0) 132 133 #define lockmgr_disowned(lk) \ 134 (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == LK_KERNPROC) 135 136 #define lockmgr_xlocked(lk) \ 137 (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == (uintptr_t)curthread) 138 139 static void assert_lockmgr(struct lock_object *lock, int how); 140 #ifdef DDB 141 static void db_show_lockmgr(struct lock_object *lock); 142 #endif 143 static void lock_lockmgr(struct lock_object *lock, int how); 144 #ifdef KDTRACE_HOOKS 145 static int owner_lockmgr(struct lock_object *lock, struct thread **owner); 146 #endif 147 static int unlock_lockmgr(struct lock_object *lock); 148 149 struct lock_class lock_class_lockmgr = { 150 .lc_name = "lockmgr", 151 .lc_flags = LC_RECURSABLE | LC_SLEEPABLE | LC_SLEEPLOCK | LC_UPGRADABLE, 152 .lc_assert = assert_lockmgr, 153 #ifdef DDB 154 .lc_ddb_show = db_show_lockmgr, 155 #endif 156 .lc_lock = lock_lockmgr, 157 .lc_unlock = unlock_lockmgr, 158 #ifdef KDTRACE_HOOKS 159 .lc_owner = owner_lockmgr, 160 #endif 161 }; 162 163 static __inline struct thread * 164 lockmgr_xholder(struct lock *lk) 165 { 166 uintptr_t x; 167 168 x = lk->lk_lock; 169 return ((x & LK_SHARE) ? NULL : (struct thread *)LK_HOLDER(x)); 170 } 171 172 /* 173 * It assumes sleepq_lock held and returns with this one unheld. 174 * It also assumes the generic interlock is sane and previously checked. 175 * If LK_INTERLOCK is specified the interlock is not reacquired after the 176 * sleep. 177 */ 178 static __inline int 179 sleeplk(struct lock *lk, u_int flags, struct lock_object *ilk, 180 const char *wmesg, int pri, int timo, int queue) 181 { 182 GIANT_DECLARE; 183 struct lock_class *class; 184 int catch, error; 185 186 class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL; 187 catch = pri & PCATCH; 188 pri &= PRIMASK; 189 error = 0; 190 191 LOCK_LOG3(lk, "%s: %p blocking on the %s sleepqueue", __func__, lk, 192 (queue == SQ_EXCLUSIVE_QUEUE) ? "exclusive" : "shared"); 193 194 if (flags & LK_INTERLOCK) 195 class->lc_unlock(ilk); 196 197 /* 198 * LK_EXSLPFAIL is not invariant during the lock pattern but it is 199 * always protected by the sleepqueue spinlock, thus it is safe to 200 * handle within the lo_flags. 201 */ 202 if (queue == SQ_EXCLUSIVE_QUEUE && (flags & LK_SLEEPFAIL) != 0) 203 lk->lock_object.lo_flags |= LK_EXSLPFAIL; 204 GIANT_SAVE(); 205 sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ? 206 SLEEPQ_INTERRUPTIBLE : 0), queue); 207 if ((flags & LK_TIMELOCK) && timo) 208 sleepq_set_timeout(&lk->lock_object, timo); 209 210 /* 211 * Decisional switch for real sleeping. 212 */ 213 if ((flags & LK_TIMELOCK) && timo && catch) 214 error = sleepq_timedwait_sig(&lk->lock_object, pri); 215 else if ((flags & LK_TIMELOCK) && timo) 216 error = sleepq_timedwait(&lk->lock_object, pri); 217 else if (catch) 218 error = sleepq_wait_sig(&lk->lock_object, pri); 219 else 220 sleepq_wait(&lk->lock_object, pri); 221 GIANT_RESTORE(); 222 if ((flags & LK_SLEEPFAIL) && error == 0) 223 error = ENOLCK; 224 225 return (error); 226 } 227 228 static __inline int 229 wakeupshlk(struct lock *lk, const char *file, int line) 230 { 231 uintptr_t v, x; 232 u_int realexslp; 233 int queue, wakeup_swapper; 234 235 TD_LOCKS_DEC(curthread); 236 TD_SLOCKS_DEC(curthread); 237 WITNESS_UNLOCK(&lk->lock_object, 0, file, line); 238 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, file, line); 239 240 wakeup_swapper = 0; 241 for (;;) { 242 x = lk->lk_lock; 243 244 /* 245 * If there is more than one shared lock held, just drop one 246 * and return. 247 */ 248 if (LK_SHARERS(x) > 1) { 249 if (atomic_cmpset_rel_ptr(&lk->lk_lock, x, 250 x - LK_ONE_SHARER)) 251 break; 252 continue; 253 } 254 255 /* 256 * If there are not waiters on the exclusive queue, drop the 257 * lock quickly. 258 */ 259 if ((x & LK_ALL_WAITERS) == 0) { 260 MPASS((x & ~LK_EXCLUSIVE_SPINNERS) == 261 LK_SHARERS_LOCK(1)); 262 if (atomic_cmpset_rel_ptr(&lk->lk_lock, x, LK_UNLOCKED)) 263 break; 264 continue; 265 } 266 267 /* 268 * We should have a sharer with waiters, so enter the hard 269 * path in order to handle wakeups correctly. 270 */ 271 sleepq_lock(&lk->lock_object); 272 x = lk->lk_lock & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS); 273 v = LK_UNLOCKED; 274 275 /* 276 * If the lock has exclusive waiters, give them preference in 277 * order to avoid deadlock with shared runners up. 278 * If interruptible sleeps left the exclusive queue empty 279 * avoid a starvation for the threads sleeping on the shared 280 * queue by giving them precedence and cleaning up the 281 * exclusive waiters bit anyway. 282 * Please note that the LK_EXSLPFAIL flag may be lying about 283 * the real presence of waiters with the LK_SLEEPFAIL flag on 284 * because they may be used in conjuction with interruptible 285 * sleeps. 286 */ 287 realexslp = sleepq_sleepcnt(&lk->lock_object, 288 SQ_EXCLUSIVE_QUEUE); 289 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) { 290 if ((lk->lock_object.lo_flags & LK_EXSLPFAIL) == 0) { 291 lk->lock_object.lo_flags &= ~LK_EXSLPFAIL; 292 queue = SQ_EXCLUSIVE_QUEUE; 293 v |= (x & LK_SHARED_WAITERS); 294 } else { 295 lk->lock_object.lo_flags &= ~LK_EXSLPFAIL; 296 LOCK_LOG2(lk, 297 "%s: %p has only LK_SLEEPFAIL sleepers", 298 __func__, lk); 299 LOCK_LOG2(lk, 300 "%s: %p waking up threads on the exclusive queue", 301 __func__, lk); 302 wakeup_swapper = 303 sleepq_broadcast(&lk->lock_object, 304 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE); 305 queue = SQ_SHARED_QUEUE; 306 } 307 308 } else { 309 310 /* 311 * Exclusive waiters sleeping with LK_SLEEPFAIL on 312 * and using interruptible sleeps/timeout may have 313 * left spourious LK_EXSLPFAIL flag on, so clean 314 * it up anyway. 315 */ 316 lk->lock_object.lo_flags &= ~LK_EXSLPFAIL; 317 queue = SQ_SHARED_QUEUE; 318 } 319 320 if (!atomic_cmpset_rel_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x, 321 v)) { 322 sleepq_release(&lk->lock_object); 323 continue; 324 } 325 LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue", 326 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" : 327 "exclusive"); 328 wakeup_swapper |= sleepq_broadcast(&lk->lock_object, SLEEPQ_LK, 329 0, queue); 330 sleepq_release(&lk->lock_object); 331 break; 332 } 333 334 lock_profile_release_lock(&lk->lock_object); 335 return (wakeup_swapper); 336 } 337 338 static void 339 assert_lockmgr(struct lock_object *lock, int what) 340 { 341 342 panic("lockmgr locks do not support assertions"); 343 } 344 345 static void 346 lock_lockmgr(struct lock_object *lock, int how) 347 { 348 349 panic("lockmgr locks do not support sleep interlocking"); 350 } 351 352 static int 353 unlock_lockmgr(struct lock_object *lock) 354 { 355 356 panic("lockmgr locks do not support sleep interlocking"); 357 } 358 359 #ifdef KDTRACE_HOOKS 360 static int 361 owner_lockmgr(struct lock_object *lock, struct thread **owner) 362 { 363 364 panic("lockmgr locks do not support owner inquiring"); 365 } 366 #endif 367 368 void 369 lockinit(struct lock *lk, int pri, const char *wmesg, int timo, int flags) 370 { 371 int iflags; 372 373 MPASS((flags & ~LK_INIT_MASK) == 0); 374 ASSERT_ATOMIC_LOAD_PTR(lk->lk_lock, 375 ("%s: lockmgr not aligned for %s: %p", __func__, wmesg, 376 &lk->lk_lock)); 377 378 iflags = LO_SLEEPABLE | LO_UPGRADABLE; 379 if (flags & LK_CANRECURSE) 380 iflags |= LO_RECURSABLE; 381 if ((flags & LK_NODUP) == 0) 382 iflags |= LO_DUPOK; 383 if (flags & LK_NOPROFILE) 384 iflags |= LO_NOPROFILE; 385 if ((flags & LK_NOWITNESS) == 0) 386 iflags |= LO_WITNESS; 387 if (flags & LK_QUIET) 388 iflags |= LO_QUIET; 389 iflags |= flags & (LK_ADAPTIVE | LK_NOSHARE); 390 391 lk->lk_lock = LK_UNLOCKED; 392 lk->lk_recurse = 0; 393 lk->lk_timo = timo; 394 lk->lk_pri = pri; 395 lock_init(&lk->lock_object, &lock_class_lockmgr, wmesg, NULL, iflags); 396 STACK_ZERO(lk); 397 } 398 399 void 400 lockdestroy(struct lock *lk) 401 { 402 403 KASSERT(lk->lk_lock == LK_UNLOCKED, ("lockmgr still held")); 404 KASSERT(lk->lk_recurse == 0, ("lockmgr still recursed")); 405 KASSERT((lk->lock_object.lo_flags & LK_EXSLPFAIL) == 0, 406 ("lockmgr still exclusive waiters")); 407 lock_destroy(&lk->lock_object); 408 } 409 410 int 411 __lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk, 412 const char *wmesg, int pri, int timo, const char *file, int line) 413 { 414 GIANT_DECLARE; 415 struct lock_class *class; 416 const char *iwmesg; 417 uintptr_t tid, v, x; 418 u_int op, realexslp; 419 int error, ipri, itimo, queue, wakeup_swapper; 420 #ifdef LOCK_PROFILING 421 uint64_t waittime = 0; 422 int contested = 0; 423 #endif 424 #ifdef ADAPTIVE_LOCKMGRS 425 volatile struct thread *owner; 426 u_int i, spintries = 0; 427 #endif 428 429 error = 0; 430 tid = (uintptr_t)curthread; 431 op = (flags & LK_TYPE_MASK); 432 iwmesg = (wmesg == LK_WMESG_DEFAULT) ? lk->lock_object.lo_name : wmesg; 433 ipri = (pri == LK_PRIO_DEFAULT) ? lk->lk_pri : pri; 434 itimo = (timo == LK_TIMO_DEFAULT) ? lk->lk_timo : timo; 435 436 MPASS((flags & ~LK_TOTAL_MASK) == 0); 437 KASSERT((op & (op - 1)) == 0, 438 ("%s: Invalid requested operation @ %s:%d", __func__, file, line)); 439 KASSERT((flags & (LK_NOWAIT | LK_SLEEPFAIL)) == 0 || 440 (op != LK_DOWNGRADE && op != LK_RELEASE), 441 ("%s: Invalid flags in regard of the operation desired @ %s:%d", 442 __func__, file, line)); 443 KASSERT((flags & LK_INTERLOCK) == 0 || ilk != NULL, 444 ("%s: LK_INTERLOCK passed without valid interlock @ %s:%d", 445 __func__, file, line)); 446 447 class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL; 448 if (panicstr != NULL) { 449 if (flags & LK_INTERLOCK) 450 class->lc_unlock(ilk); 451 return (0); 452 } 453 454 if (lk->lock_object.lo_flags & LK_NOSHARE) { 455 switch (op) { 456 case LK_SHARED: 457 op = LK_EXCLUSIVE; 458 break; 459 case LK_UPGRADE: 460 case LK_DOWNGRADE: 461 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, 462 file, line); 463 return (0); 464 } 465 } 466 467 wakeup_swapper = 0; 468 switch (op) { 469 case LK_SHARED: 470 if (LK_CAN_WITNESS(flags)) 471 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, 472 file, line, ilk); 473 for (;;) { 474 x = lk->lk_lock; 475 476 /* 477 * If no other thread has an exclusive lock, or 478 * no exclusive waiter is present, bump the count of 479 * sharers. Since we have to preserve the state of 480 * waiters, if we fail to acquire the shared lock 481 * loop back and retry. 482 */ 483 if (LK_CAN_SHARE(x)) { 484 if (atomic_cmpset_acq_ptr(&lk->lk_lock, x, 485 x + LK_ONE_SHARER)) 486 break; 487 continue; 488 } 489 lock_profile_obtain_lock_failed(&lk->lock_object, 490 &contested, &waittime); 491 492 /* 493 * If the lock is already held by curthread in 494 * exclusive way avoid a deadlock. 495 */ 496 if (LK_HOLDER(x) == tid) { 497 LOCK_LOG2(lk, 498 "%s: %p already held in exclusive mode", 499 __func__, lk); 500 error = EDEADLK; 501 break; 502 } 503 504 /* 505 * If the lock is expected to not sleep just give up 506 * and return. 507 */ 508 if (LK_TRYOP(flags)) { 509 LOCK_LOG2(lk, "%s: %p fails the try operation", 510 __func__, lk); 511 error = EBUSY; 512 break; 513 } 514 515 #ifdef ADAPTIVE_LOCKMGRS 516 /* 517 * If the owner is running on another CPU, spin until 518 * the owner stops running or the state of the lock 519 * changes. We need a double-state handle here 520 * because for a failed acquisition the lock can be 521 * either held in exclusive mode or shared mode 522 * (for the writer starvation avoidance technique). 523 */ 524 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && 525 LK_HOLDER(x) != LK_KERNPROC) { 526 owner = (struct thread *)LK_HOLDER(x); 527 if (LOCK_LOG_TEST(&lk->lock_object, 0)) 528 CTR3(KTR_LOCK, 529 "%s: spinning on %p held by %p", 530 __func__, lk, owner); 531 532 /* 533 * If we are holding also an interlock drop it 534 * in order to avoid a deadlock if the lockmgr 535 * owner is adaptively spinning on the 536 * interlock itself. 537 */ 538 if (flags & LK_INTERLOCK) { 539 class->lc_unlock(ilk); 540 flags &= ~LK_INTERLOCK; 541 } 542 GIANT_SAVE(); 543 while (LK_HOLDER(lk->lk_lock) == 544 (uintptr_t)owner && TD_IS_RUNNING(owner)) 545 cpu_spinwait(); 546 GIANT_RESTORE(); 547 continue; 548 } else if (LK_CAN_ADAPT(lk, flags) && 549 (x & LK_SHARE) != 0 && LK_SHARERS(x) && 550 spintries < ALK_RETRIES) { 551 if (flags & LK_INTERLOCK) { 552 class->lc_unlock(ilk); 553 flags &= ~LK_INTERLOCK; 554 } 555 GIANT_SAVE(); 556 spintries++; 557 for (i = 0; i < ALK_LOOPS; i++) { 558 if (LOCK_LOG_TEST(&lk->lock_object, 0)) 559 CTR4(KTR_LOCK, 560 "%s: shared spinning on %p with %u and %u", 561 __func__, lk, spintries, i); 562 x = lk->lk_lock; 563 if ((x & LK_SHARE) == 0 || 564 LK_CAN_SHARE(x) != 0) 565 break; 566 cpu_spinwait(); 567 } 568 GIANT_RESTORE(); 569 if (i != ALK_LOOPS) 570 continue; 571 } 572 #endif 573 574 /* 575 * Acquire the sleepqueue chain lock because we 576 * probabilly will need to manipulate waiters flags. 577 */ 578 sleepq_lock(&lk->lock_object); 579 x = lk->lk_lock; 580 581 /* 582 * if the lock can be acquired in shared mode, try 583 * again. 584 */ 585 if (LK_CAN_SHARE(x)) { 586 sleepq_release(&lk->lock_object); 587 continue; 588 } 589 590 #ifdef ADAPTIVE_LOCKMGRS 591 /* 592 * The current lock owner might have started executing 593 * on another CPU (or the lock could have changed 594 * owner) while we were waiting on the turnstile 595 * chain lock. If so, drop the turnstile lock and try 596 * again. 597 */ 598 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && 599 LK_HOLDER(x) != LK_KERNPROC) { 600 owner = (struct thread *)LK_HOLDER(x); 601 if (TD_IS_RUNNING(owner)) { 602 sleepq_release(&lk->lock_object); 603 continue; 604 } 605 } 606 #endif 607 608 /* 609 * Try to set the LK_SHARED_WAITERS flag. If we fail, 610 * loop back and retry. 611 */ 612 if ((x & LK_SHARED_WAITERS) == 0) { 613 if (!atomic_cmpset_acq_ptr(&lk->lk_lock, x, 614 x | LK_SHARED_WAITERS)) { 615 sleepq_release(&lk->lock_object); 616 continue; 617 } 618 LOCK_LOG2(lk, "%s: %p set shared waiters flag", 619 __func__, lk); 620 } 621 622 /* 623 * As far as we have been unable to acquire the 624 * shared lock and the shared waiters flag is set, 625 * we will sleep. 626 */ 627 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo, 628 SQ_SHARED_QUEUE); 629 flags &= ~LK_INTERLOCK; 630 if (error) { 631 LOCK_LOG3(lk, 632 "%s: interrupted sleep for %p with %d", 633 __func__, lk, error); 634 break; 635 } 636 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue", 637 __func__, lk); 638 } 639 if (error == 0) { 640 lock_profile_obtain_lock_success(&lk->lock_object, 641 contested, waittime, file, line); 642 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, file, 643 line); 644 WITNESS_LOCK(&lk->lock_object, LK_TRYWIT(flags), file, 645 line); 646 TD_LOCKS_INC(curthread); 647 TD_SLOCKS_INC(curthread); 648 STACK_SAVE(lk); 649 } 650 break; 651 case LK_UPGRADE: 652 _lockmgr_assert(lk, KA_SLOCKED, file, line); 653 v = lk->lk_lock; 654 x = v & LK_ALL_WAITERS; 655 v &= LK_EXCLUSIVE_SPINNERS; 656 657 /* 658 * Try to switch from one shared lock to an exclusive one. 659 * We need to preserve waiters flags during the operation. 660 */ 661 if (atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x | v, 662 tid | x)) { 663 LOCK_LOG_LOCK("XUPGRADE", &lk->lock_object, 0, 0, file, 664 line); 665 WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE | 666 LK_TRYWIT(flags), file, line); 667 TD_SLOCKS_DEC(curthread); 668 break; 669 } 670 671 /* 672 * We have been unable to succeed in upgrading, so just 673 * give up the shared lock. 674 */ 675 wakeup_swapper |= wakeupshlk(lk, file, line); 676 677 /* FALLTHROUGH */ 678 case LK_EXCLUSIVE: 679 if (LK_CAN_WITNESS(flags)) 680 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER | 681 LOP_EXCLUSIVE, file, line, ilk); 682 683 /* 684 * If curthread already holds the lock and this one is 685 * allowed to recurse, simply recurse on it. 686 */ 687 if (lockmgr_xlocked(lk)) { 688 if ((flags & LK_CANRECURSE) == 0 && 689 (lk->lock_object.lo_flags & LO_RECURSABLE) == 0) { 690 691 /* 692 * If the lock is expected to not panic just 693 * give up and return. 694 */ 695 if (LK_TRYOP(flags)) { 696 LOCK_LOG2(lk, 697 "%s: %p fails the try operation", 698 __func__, lk); 699 error = EBUSY; 700 break; 701 } 702 if (flags & LK_INTERLOCK) 703 class->lc_unlock(ilk); 704 panic("%s: recursing on non recursive lockmgr %s @ %s:%d\n", 705 __func__, iwmesg, file, line); 706 } 707 lk->lk_recurse++; 708 LOCK_LOG2(lk, "%s: %p recursing", __func__, lk); 709 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0, 710 lk->lk_recurse, file, line); 711 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | 712 LK_TRYWIT(flags), file, line); 713 TD_LOCKS_INC(curthread); 714 break; 715 } 716 717 while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, 718 tid)) { 719 lock_profile_obtain_lock_failed(&lk->lock_object, 720 &contested, &waittime); 721 722 /* 723 * If the lock is expected to not sleep just give up 724 * and return. 725 */ 726 if (LK_TRYOP(flags)) { 727 LOCK_LOG2(lk, "%s: %p fails the try operation", 728 __func__, lk); 729 error = EBUSY; 730 break; 731 } 732 733 #ifdef ADAPTIVE_LOCKMGRS 734 /* 735 * If the owner is running on another CPU, spin until 736 * the owner stops running or the state of the lock 737 * changes. 738 */ 739 x = lk->lk_lock; 740 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && 741 LK_HOLDER(x) != LK_KERNPROC) { 742 owner = (struct thread *)LK_HOLDER(x); 743 if (LOCK_LOG_TEST(&lk->lock_object, 0)) 744 CTR3(KTR_LOCK, 745 "%s: spinning on %p held by %p", 746 __func__, lk, owner); 747 748 /* 749 * If we are holding also an interlock drop it 750 * in order to avoid a deadlock if the lockmgr 751 * owner is adaptively spinning on the 752 * interlock itself. 753 */ 754 if (flags & LK_INTERLOCK) { 755 class->lc_unlock(ilk); 756 flags &= ~LK_INTERLOCK; 757 } 758 GIANT_SAVE(); 759 while (LK_HOLDER(lk->lk_lock) == 760 (uintptr_t)owner && TD_IS_RUNNING(owner)) 761 cpu_spinwait(); 762 GIANT_RESTORE(); 763 continue; 764 } else if (LK_CAN_ADAPT(lk, flags) && 765 (x & LK_SHARE) != 0 && LK_SHARERS(x) && 766 spintries < ALK_RETRIES) { 767 if ((x & LK_EXCLUSIVE_SPINNERS) == 0 && 768 !atomic_cmpset_ptr(&lk->lk_lock, x, 769 x | LK_EXCLUSIVE_SPINNERS)) 770 continue; 771 if (flags & LK_INTERLOCK) { 772 class->lc_unlock(ilk); 773 flags &= ~LK_INTERLOCK; 774 } 775 GIANT_SAVE(); 776 spintries++; 777 for (i = 0; i < ALK_LOOPS; i++) { 778 if (LOCK_LOG_TEST(&lk->lock_object, 0)) 779 CTR4(KTR_LOCK, 780 "%s: shared spinning on %p with %u and %u", 781 __func__, lk, spintries, i); 782 if ((lk->lk_lock & 783 LK_EXCLUSIVE_SPINNERS) == 0) 784 break; 785 cpu_spinwait(); 786 } 787 GIANT_RESTORE(); 788 if (i != ALK_LOOPS) 789 continue; 790 } 791 #endif 792 793 /* 794 * Acquire the sleepqueue chain lock because we 795 * probabilly will need to manipulate waiters flags. 796 */ 797 sleepq_lock(&lk->lock_object); 798 x = lk->lk_lock; 799 800 /* 801 * if the lock has been released while we spun on 802 * the sleepqueue chain lock just try again. 803 */ 804 if (x == LK_UNLOCKED) { 805 sleepq_release(&lk->lock_object); 806 continue; 807 } 808 809 #ifdef ADAPTIVE_LOCKMGRS 810 /* 811 * The current lock owner might have started executing 812 * on another CPU (or the lock could have changed 813 * owner) while we were waiting on the turnstile 814 * chain lock. If so, drop the turnstile lock and try 815 * again. 816 */ 817 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && 818 LK_HOLDER(x) != LK_KERNPROC) { 819 owner = (struct thread *)LK_HOLDER(x); 820 if (TD_IS_RUNNING(owner)) { 821 sleepq_release(&lk->lock_object); 822 continue; 823 } 824 } 825 #endif 826 827 /* 828 * The lock can be in the state where there is a 829 * pending queue of waiters, but still no owner. 830 * This happens when the lock is contested and an 831 * owner is going to claim the lock. 832 * If curthread is the one successfully acquiring it 833 * claim lock ownership and return, preserving waiters 834 * flags. 835 */ 836 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS); 837 if ((x & ~v) == LK_UNLOCKED) { 838 v &= ~LK_EXCLUSIVE_SPINNERS; 839 if (atomic_cmpset_acq_ptr(&lk->lk_lock, x, 840 tid | v)) { 841 sleepq_release(&lk->lock_object); 842 LOCK_LOG2(lk, 843 "%s: %p claimed by a new writer", 844 __func__, lk); 845 break; 846 } 847 sleepq_release(&lk->lock_object); 848 continue; 849 } 850 851 /* 852 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we 853 * fail, loop back and retry. 854 */ 855 if ((x & LK_EXCLUSIVE_WAITERS) == 0) { 856 if (!atomic_cmpset_ptr(&lk->lk_lock, x, 857 x | LK_EXCLUSIVE_WAITERS)) { 858 sleepq_release(&lk->lock_object); 859 continue; 860 } 861 LOCK_LOG2(lk, "%s: %p set excl waiters flag", 862 __func__, lk); 863 } 864 865 /* 866 * As far as we have been unable to acquire the 867 * exclusive lock and the exclusive waiters flag 868 * is set, we will sleep. 869 */ 870 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo, 871 SQ_EXCLUSIVE_QUEUE); 872 flags &= ~LK_INTERLOCK; 873 if (error) { 874 LOCK_LOG3(lk, 875 "%s: interrupted sleep for %p with %d", 876 __func__, lk, error); 877 break; 878 } 879 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue", 880 __func__, lk); 881 } 882 if (error == 0) { 883 lock_profile_obtain_lock_success(&lk->lock_object, 884 contested, waittime, file, line); 885 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0, 886 lk->lk_recurse, file, line); 887 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | 888 LK_TRYWIT(flags), file, line); 889 TD_LOCKS_INC(curthread); 890 STACK_SAVE(lk); 891 } 892 break; 893 case LK_DOWNGRADE: 894 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, file, line); 895 LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line); 896 WITNESS_DOWNGRADE(&lk->lock_object, 0, file, line); 897 TD_SLOCKS_INC(curthread); 898 899 /* 900 * In order to preserve waiters flags, just spin. 901 */ 902 for (;;) { 903 x = lk->lk_lock; 904 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0); 905 x &= LK_ALL_WAITERS; 906 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x, 907 LK_SHARERS_LOCK(1) | x)) 908 break; 909 cpu_spinwait(); 910 } 911 break; 912 case LK_RELEASE: 913 _lockmgr_assert(lk, KA_LOCKED, file, line); 914 x = lk->lk_lock; 915 916 if ((x & LK_SHARE) == 0) { 917 918 /* 919 * As first option, treact the lock as if it has not 920 * any waiter. 921 * Fix-up the tid var if the lock has been disowned. 922 */ 923 if (LK_HOLDER(x) == LK_KERNPROC) 924 tid = LK_KERNPROC; 925 else { 926 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, 927 file, line); 928 TD_LOCKS_DEC(curthread); 929 } 930 LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0, 931 lk->lk_recurse, file, line); 932 933 /* 934 * The lock is held in exclusive mode. 935 * If the lock is recursed also, then unrecurse it. 936 */ 937 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) { 938 LOCK_LOG2(lk, "%s: %p unrecursing", __func__, 939 lk); 940 lk->lk_recurse--; 941 break; 942 } 943 if (tid != LK_KERNPROC) 944 lock_profile_release_lock(&lk->lock_object); 945 946 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid, 947 LK_UNLOCKED)) 948 break; 949 950 sleepq_lock(&lk->lock_object); 951 x = lk->lk_lock; 952 v = LK_UNLOCKED; 953 954 /* 955 * If the lock has exclusive waiters, give them 956 * preference in order to avoid deadlock with 957 * shared runners up. 958 * If interruptible sleeps left the exclusive queue 959 * empty avoid a starvation for the threads sleeping 960 * on the shared queue by giving them precedence 961 * and cleaning up the exclusive waiters bit anyway. 962 * Please note that the LK_EXSLPFAIL flag may be lying 963 * about the real presence of waiters with the 964 * LK_SLEEPFAIL flag on because they may be used in 965 * conjuction with interruptible sleeps. 966 */ 967 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0); 968 realexslp = sleepq_sleepcnt(&lk->lock_object, 969 SQ_EXCLUSIVE_QUEUE); 970 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) { 971 if ((lk->lock_object.lo_flags & 972 LK_EXSLPFAIL) == 0) { 973 lk->lock_object.lo_flags &= 974 ~LK_EXSLPFAIL; 975 queue = SQ_EXCLUSIVE_QUEUE; 976 v |= (x & LK_SHARED_WAITERS); 977 } else { 978 lk->lock_object.lo_flags &= 979 ~LK_EXSLPFAIL; 980 LOCK_LOG2(lk, 981 "%s: %p has only LK_SLEEPFAIL sleepers", 982 __func__, lk); 983 LOCK_LOG2(lk, 984 "%s: %p waking up threads on the exclusive queue", 985 __func__, lk); 986 wakeup_swapper = 987 sleepq_broadcast(&lk->lock_object, 988 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE); 989 queue = SQ_SHARED_QUEUE; 990 } 991 } else { 992 993 /* 994 * Exclusive waiters sleeping with LK_SLEEPFAIL 995 * on and using interruptible sleeps/timeout 996 * may have left spourious LK_EXSLPFAIL flag 997 * on, so clean it up anyway. 998 */ 999 lk->lock_object.lo_flags &= ~LK_EXSLPFAIL; 1000 queue = SQ_SHARED_QUEUE; 1001 } 1002 1003 LOCK_LOG3(lk, 1004 "%s: %p waking up threads on the %s queue", 1005 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" : 1006 "exclusive"); 1007 atomic_store_rel_ptr(&lk->lk_lock, v); 1008 wakeup_swapper |= sleepq_broadcast(&lk->lock_object, 1009 SLEEPQ_LK, 0, queue); 1010 sleepq_release(&lk->lock_object); 1011 break; 1012 } else 1013 wakeup_swapper = wakeupshlk(lk, file, line); 1014 break; 1015 case LK_DRAIN: 1016 if (LK_CAN_WITNESS(flags)) 1017 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER | 1018 LOP_EXCLUSIVE, file, line, ilk); 1019 1020 /* 1021 * Trying to drain a lock we already own will result in a 1022 * deadlock. 1023 */ 1024 if (lockmgr_xlocked(lk)) { 1025 if (flags & LK_INTERLOCK) 1026 class->lc_unlock(ilk); 1027 panic("%s: draining %s with the lock held @ %s:%d\n", 1028 __func__, iwmesg, file, line); 1029 } 1030 1031 while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) { 1032 lock_profile_obtain_lock_failed(&lk->lock_object, 1033 &contested, &waittime); 1034 1035 /* 1036 * If the lock is expected to not sleep just give up 1037 * and return. 1038 */ 1039 if (LK_TRYOP(flags)) { 1040 LOCK_LOG2(lk, "%s: %p fails the try operation", 1041 __func__, lk); 1042 error = EBUSY; 1043 break; 1044 } 1045 1046 /* 1047 * Acquire the sleepqueue chain lock because we 1048 * probabilly will need to manipulate waiters flags. 1049 */ 1050 sleepq_lock(&lk->lock_object); 1051 x = lk->lk_lock; 1052 1053 /* 1054 * if the lock has been released while we spun on 1055 * the sleepqueue chain lock just try again. 1056 */ 1057 if (x == LK_UNLOCKED) { 1058 sleepq_release(&lk->lock_object); 1059 continue; 1060 } 1061 1062 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS); 1063 if ((x & ~v) == LK_UNLOCKED) { 1064 v = (x & ~LK_EXCLUSIVE_SPINNERS); 1065 1066 /* 1067 * If interruptible sleeps left the exclusive 1068 * queue empty avoid a starvation for the 1069 * threads sleeping on the shared queue by 1070 * giving them precedence and cleaning up the 1071 * exclusive waiters bit anyway. 1072 * Please note that the LK_EXSLPFAIL flag may 1073 * be lying about the real presence of waiters 1074 * with the LK_SLEEPFAIL flag on because they 1075 * may be used in conjuction with interruptible 1076 * sleeps. 1077 */ 1078 if (v & LK_EXCLUSIVE_WAITERS) { 1079 queue = SQ_EXCLUSIVE_QUEUE; 1080 v &= ~LK_EXCLUSIVE_WAITERS; 1081 } else { 1082 1083 /* 1084 * Exclusive waiters sleeping with 1085 * LK_SLEEPFAIL on and using 1086 * interruptible sleeps/timeout may 1087 * have left spourious LK_EXSLPFAIL 1088 * flag on, so clean it up anyway. 1089 */ 1090 MPASS(v & LK_SHARED_WAITERS); 1091 lk->lock_object.lo_flags &= 1092 ~LK_EXSLPFAIL; 1093 queue = SQ_SHARED_QUEUE; 1094 v &= ~LK_SHARED_WAITERS; 1095 } 1096 if (queue == SQ_EXCLUSIVE_QUEUE) { 1097 realexslp = 1098 sleepq_sleepcnt(&lk->lock_object, 1099 SQ_EXCLUSIVE_QUEUE); 1100 if ((lk->lock_object.lo_flags & 1101 LK_EXSLPFAIL) == 0) { 1102 lk->lock_object.lo_flags &= 1103 ~LK_EXSLPFAIL; 1104 queue = SQ_SHARED_QUEUE; 1105 v &= ~LK_SHARED_WAITERS; 1106 if (realexslp != 0) { 1107 LOCK_LOG2(lk, 1108 "%s: %p has only LK_SLEEPFAIL sleepers", 1109 __func__, lk); 1110 LOCK_LOG2(lk, 1111 "%s: %p waking up threads on the exclusive queue", 1112 __func__, lk); 1113 wakeup_swapper = 1114 sleepq_broadcast( 1115 &lk->lock_object, 1116 SLEEPQ_LK, 0, 1117 SQ_EXCLUSIVE_QUEUE); 1118 } 1119 } else 1120 lk->lock_object.lo_flags &= 1121 ~LK_EXSLPFAIL; 1122 } 1123 if (!atomic_cmpset_ptr(&lk->lk_lock, x, v)) { 1124 sleepq_release(&lk->lock_object); 1125 continue; 1126 } 1127 LOCK_LOG3(lk, 1128 "%s: %p waking up all threads on the %s queue", 1129 __func__, lk, queue == SQ_SHARED_QUEUE ? 1130 "shared" : "exclusive"); 1131 wakeup_swapper |= sleepq_broadcast( 1132 &lk->lock_object, SLEEPQ_LK, 0, queue); 1133 1134 /* 1135 * If shared waiters have been woken up we need 1136 * to wait for one of them to acquire the lock 1137 * before to set the exclusive waiters in 1138 * order to avoid a deadlock. 1139 */ 1140 if (queue == SQ_SHARED_QUEUE) { 1141 for (v = lk->lk_lock; 1142 (v & LK_SHARE) && !LK_SHARERS(v); 1143 v = lk->lk_lock) 1144 cpu_spinwait(); 1145 } 1146 } 1147 1148 /* 1149 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we 1150 * fail, loop back and retry. 1151 */ 1152 if ((x & LK_EXCLUSIVE_WAITERS) == 0) { 1153 if (!atomic_cmpset_ptr(&lk->lk_lock, x, 1154 x | LK_EXCLUSIVE_WAITERS)) { 1155 sleepq_release(&lk->lock_object); 1156 continue; 1157 } 1158 LOCK_LOG2(lk, "%s: %p set drain waiters flag", 1159 __func__, lk); 1160 } 1161 1162 /* 1163 * As far as we have been unable to acquire the 1164 * exclusive lock and the exclusive waiters flag 1165 * is set, we will sleep. 1166 */ 1167 if (flags & LK_INTERLOCK) { 1168 class->lc_unlock(ilk); 1169 flags &= ~LK_INTERLOCK; 1170 } 1171 GIANT_SAVE(); 1172 sleepq_add(&lk->lock_object, NULL, iwmesg, SLEEPQ_LK, 1173 SQ_EXCLUSIVE_QUEUE); 1174 sleepq_wait(&lk->lock_object, ipri & PRIMASK); 1175 GIANT_RESTORE(); 1176 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue", 1177 __func__, lk); 1178 } 1179 1180 if (error == 0) { 1181 lock_profile_obtain_lock_success(&lk->lock_object, 1182 contested, waittime, file, line); 1183 LOCK_LOG_LOCK("DRAIN", &lk->lock_object, 0, 1184 lk->lk_recurse, file, line); 1185 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | 1186 LK_TRYWIT(flags), file, line); 1187 TD_LOCKS_INC(curthread); 1188 STACK_SAVE(lk); 1189 } 1190 break; 1191 default: 1192 if (flags & LK_INTERLOCK) 1193 class->lc_unlock(ilk); 1194 panic("%s: unknown lockmgr request 0x%x\n", __func__, op); 1195 } 1196 1197 if (flags & LK_INTERLOCK) 1198 class->lc_unlock(ilk); 1199 if (wakeup_swapper) 1200 kick_proc0(); 1201 1202 return (error); 1203 } 1204 1205 void 1206 _lockmgr_disown(struct lock *lk, const char *file, int line) 1207 { 1208 uintptr_t tid, x; 1209 1210 tid = (uintptr_t)curthread; 1211 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, file, line); 1212 1213 /* 1214 * If the owner is already LK_KERNPROC just skip the whole operation. 1215 */ 1216 if (LK_HOLDER(lk->lk_lock) != tid) 1217 return; 1218 lock_profile_release_lock(&lk->lock_object); 1219 LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line); 1220 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line); 1221 TD_LOCKS_DEC(curthread); 1222 STACK_SAVE(lk); 1223 1224 /* 1225 * In order to preserve waiters flags, just spin. 1226 */ 1227 for (;;) { 1228 x = lk->lk_lock; 1229 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0); 1230 x &= LK_ALL_WAITERS; 1231 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x, 1232 LK_KERNPROC | x)) 1233 return; 1234 cpu_spinwait(); 1235 } 1236 } 1237 1238 void 1239 lockmgr_printinfo(struct lock *lk) 1240 { 1241 struct thread *td; 1242 uintptr_t x; 1243 1244 if (lk->lk_lock == LK_UNLOCKED) 1245 printf("lock type %s: UNLOCKED\n", lk->lock_object.lo_name); 1246 else if (lk->lk_lock & LK_SHARE) 1247 printf("lock type %s: SHARED (count %ju)\n", 1248 lk->lock_object.lo_name, 1249 (uintmax_t)LK_SHARERS(lk->lk_lock)); 1250 else { 1251 td = lockmgr_xholder(lk); 1252 printf("lock type %s: EXCL by thread %p (pid %d)\n", 1253 lk->lock_object.lo_name, td, td->td_proc->p_pid); 1254 } 1255 1256 x = lk->lk_lock; 1257 if (x & LK_EXCLUSIVE_WAITERS) 1258 printf(" with exclusive waiters pending\n"); 1259 if (x & LK_SHARED_WAITERS) 1260 printf(" with shared waiters pending\n"); 1261 if (x & LK_EXCLUSIVE_SPINNERS) 1262 printf(" with exclusive spinners pending\n"); 1263 1264 STACK_PRINT(lk); 1265 } 1266 1267 int 1268 lockstatus(struct lock *lk) 1269 { 1270 uintptr_t v, x; 1271 int ret; 1272 1273 ret = LK_SHARED; 1274 x = lk->lk_lock; 1275 v = LK_HOLDER(x); 1276 1277 if ((x & LK_SHARE) == 0) { 1278 if (v == (uintptr_t)curthread || v == LK_KERNPROC) 1279 ret = LK_EXCLUSIVE; 1280 else 1281 ret = LK_EXCLOTHER; 1282 } else if (x == LK_UNLOCKED) 1283 ret = 0; 1284 1285 return (ret); 1286 } 1287 1288 #ifdef INVARIANT_SUPPORT 1289 #ifndef INVARIANTS 1290 #undef _lockmgr_assert 1291 #endif 1292 1293 void 1294 _lockmgr_assert(struct lock *lk, int what, const char *file, int line) 1295 { 1296 int slocked = 0; 1297 1298 if (panicstr != NULL) 1299 return; 1300 switch (what) { 1301 case KA_SLOCKED: 1302 case KA_SLOCKED | KA_NOTRECURSED: 1303 case KA_SLOCKED | KA_RECURSED: 1304 slocked = 1; 1305 case KA_LOCKED: 1306 case KA_LOCKED | KA_NOTRECURSED: 1307 case KA_LOCKED | KA_RECURSED: 1308 #ifdef WITNESS 1309 1310 /* 1311 * We cannot trust WITNESS if the lock is held in exclusive 1312 * mode and a call to lockmgr_disown() happened. 1313 * Workaround this skipping the check if the lock is held in 1314 * exclusive mode even for the KA_LOCKED case. 1315 */ 1316 if (slocked || (lk->lk_lock & LK_SHARE)) { 1317 witness_assert(&lk->lock_object, what, file, line); 1318 break; 1319 } 1320 #endif 1321 if (lk->lk_lock == LK_UNLOCKED || 1322 ((lk->lk_lock & LK_SHARE) == 0 && (slocked || 1323 (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk))))) 1324 panic("Lock %s not %slocked @ %s:%d\n", 1325 lk->lock_object.lo_name, slocked ? "share" : "", 1326 file, line); 1327 1328 if ((lk->lk_lock & LK_SHARE) == 0) { 1329 if (lockmgr_recursed(lk)) { 1330 if (what & KA_NOTRECURSED) 1331 panic("Lock %s recursed @ %s:%d\n", 1332 lk->lock_object.lo_name, file, 1333 line); 1334 } else if (what & KA_RECURSED) 1335 panic("Lock %s not recursed @ %s:%d\n", 1336 lk->lock_object.lo_name, file, line); 1337 } 1338 break; 1339 case KA_XLOCKED: 1340 case KA_XLOCKED | KA_NOTRECURSED: 1341 case KA_XLOCKED | KA_RECURSED: 1342 if (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk)) 1343 panic("Lock %s not exclusively locked @ %s:%d\n", 1344 lk->lock_object.lo_name, file, line); 1345 if (lockmgr_recursed(lk)) { 1346 if (what & KA_NOTRECURSED) 1347 panic("Lock %s recursed @ %s:%d\n", 1348 lk->lock_object.lo_name, file, line); 1349 } else if (what & KA_RECURSED) 1350 panic("Lock %s not recursed @ %s:%d\n", 1351 lk->lock_object.lo_name, file, line); 1352 break; 1353 case KA_UNLOCKED: 1354 if (lockmgr_xlocked(lk) || lockmgr_disowned(lk)) 1355 panic("Lock %s exclusively locked @ %s:%d\n", 1356 lk->lock_object.lo_name, file, line); 1357 break; 1358 default: 1359 panic("Unknown lockmgr assertion: %d @ %s:%d\n", what, file, 1360 line); 1361 } 1362 } 1363 #endif 1364 1365 #ifdef DDB 1366 int 1367 lockmgr_chain(struct thread *td, struct thread **ownerp) 1368 { 1369 struct lock *lk; 1370 1371 lk = td->td_wchan; 1372 1373 if (LOCK_CLASS(&lk->lock_object) != &lock_class_lockmgr) 1374 return (0); 1375 db_printf("blocked on lockmgr %s", lk->lock_object.lo_name); 1376 if (lk->lk_lock & LK_SHARE) 1377 db_printf("SHARED (count %ju)\n", 1378 (uintmax_t)LK_SHARERS(lk->lk_lock)); 1379 else 1380 db_printf("EXCL\n"); 1381 *ownerp = lockmgr_xholder(lk); 1382 1383 return (1); 1384 } 1385 1386 static void 1387 db_show_lockmgr(struct lock_object *lock) 1388 { 1389 struct thread *td; 1390 struct lock *lk; 1391 1392 lk = (struct lock *)lock; 1393 1394 db_printf(" state: "); 1395 if (lk->lk_lock == LK_UNLOCKED) 1396 db_printf("UNLOCKED\n"); 1397 else if (lk->lk_lock & LK_SHARE) 1398 db_printf("SLOCK: %ju\n", (uintmax_t)LK_SHARERS(lk->lk_lock)); 1399 else { 1400 td = lockmgr_xholder(lk); 1401 if (td == (struct thread *)LK_KERNPROC) 1402 db_printf("XLOCK: LK_KERNPROC\n"); 1403 else 1404 db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td, 1405 td->td_tid, td->td_proc->p_pid, 1406 td->td_proc->p_comm); 1407 if (lockmgr_recursed(lk)) 1408 db_printf(" recursed: %d\n", lk->lk_recurse); 1409 } 1410 db_printf(" waiters: "); 1411 switch (lk->lk_lock & LK_ALL_WAITERS) { 1412 case LK_SHARED_WAITERS: 1413 db_printf("shared\n"); 1414 break; 1415 case LK_EXCLUSIVE_WAITERS: 1416 db_printf("exclusive\n"); 1417 break; 1418 case LK_ALL_WAITERS: 1419 db_printf("shared and exclusive\n"); 1420 break; 1421 default: 1422 db_printf("none\n"); 1423 } 1424 db_printf(" spinners: "); 1425 if (lk->lk_lock & LK_EXCLUSIVE_SPINNERS) 1426 db_printf("exclusive\n"); 1427 else 1428 db_printf("none\n"); 1429 } 1430 #endif
Cache object: 3c27ad2cd1c663b87188fe5554e6ddb4
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