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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_hwpmc_hooks.h" 32 #include "opt_kdtrace.h" 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD: releng/10.0/sys/kern/kern_lock.c 255940 2013-09-29 18:02:23Z kib $"); 36 37 #include <sys/param.h> 38 #include <sys/kdb.h> 39 #include <sys/ktr.h> 40 #include <sys/lock.h> 41 #include <sys/lock_profile.h> 42 #include <sys/lockmgr.h> 43 #include <sys/mutex.h> 44 #include <sys/proc.h> 45 #include <sys/sleepqueue.h> 46 #ifdef DEBUG_LOCKS 47 #include <sys/stack.h> 48 #endif 49 #include <sys/sysctl.h> 50 #include <sys/systm.h> 51 52 #include <machine/cpu.h> 53 54 #ifdef DDB 55 #include <ddb/ddb.h> 56 #endif 57 58 #ifdef HWPMC_HOOKS 59 #include <sys/pmckern.h> 60 PMC_SOFT_DECLARE( , , lock, failed); 61 #endif 62 63 CTASSERT(((LK_ADAPTIVE | LK_NOSHARE) & LO_CLASSFLAGS) == 64 (LK_ADAPTIVE | LK_NOSHARE)); 65 CTASSERT(LK_UNLOCKED == (LK_UNLOCKED & 66 ~(LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS))); 67 68 #define SQ_EXCLUSIVE_QUEUE 0 69 #define SQ_SHARED_QUEUE 1 70 71 #ifndef INVARIANTS 72 #define _lockmgr_assert(lk, what, file, line) 73 #define TD_LOCKS_INC(td) 74 #define TD_LOCKS_DEC(td) 75 #else 76 #define TD_LOCKS_INC(td) ((td)->td_locks++) 77 #define TD_LOCKS_DEC(td) ((td)->td_locks--) 78 #endif 79 #define TD_SLOCKS_INC(td) ((td)->td_lk_slocks++) 80 #define TD_SLOCKS_DEC(td) ((td)->td_lk_slocks--) 81 82 #ifndef DEBUG_LOCKS 83 #define STACK_PRINT(lk) 84 #define STACK_SAVE(lk) 85 #define STACK_ZERO(lk) 86 #else 87 #define STACK_PRINT(lk) stack_print_ddb(&(lk)->lk_stack) 88 #define STACK_SAVE(lk) stack_save(&(lk)->lk_stack) 89 #define STACK_ZERO(lk) stack_zero(&(lk)->lk_stack) 90 #endif 91 92 #define LOCK_LOG2(lk, string, arg1, arg2) \ 93 if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \ 94 CTR2(KTR_LOCK, (string), (arg1), (arg2)) 95 #define LOCK_LOG3(lk, string, arg1, arg2, arg3) \ 96 if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \ 97 CTR3(KTR_LOCK, (string), (arg1), (arg2), (arg3)) 98 99 #define GIANT_DECLARE \ 100 int _i = 0; \ 101 WITNESS_SAVE_DECL(Giant) 102 #define GIANT_RESTORE() do { \ 103 if (_i > 0) { \ 104 while (_i--) \ 105 mtx_lock(&Giant); \ 106 WITNESS_RESTORE(&Giant.lock_object, Giant); \ 107 } \ 108 } while (0) 109 #define GIANT_SAVE() do { \ 110 if (mtx_owned(&Giant)) { \ 111 WITNESS_SAVE(&Giant.lock_object, Giant); \ 112 while (mtx_owned(&Giant)) { \ 113 _i++; \ 114 mtx_unlock(&Giant); \ 115 } \ 116 } \ 117 } while (0) 118 119 #define LK_CAN_SHARE(x) \ 120 (((x) & LK_SHARE) && (((x) & LK_EXCLUSIVE_WAITERS) == 0 || \ 121 ((x) & LK_EXCLUSIVE_SPINNERS) == 0 || \ 122 curthread->td_lk_slocks || (curthread->td_pflags & TDP_DEADLKTREAT))) 123 #define LK_TRYOP(x) \ 124 ((x) & LK_NOWAIT) 125 126 #define LK_CAN_WITNESS(x) \ 127 (((x) & LK_NOWITNESS) == 0 && !LK_TRYOP(x)) 128 #define LK_TRYWIT(x) \ 129 (LK_TRYOP(x) ? LOP_TRYLOCK : 0) 130 131 #define LK_CAN_ADAPT(lk, f) \ 132 (((lk)->lock_object.lo_flags & LK_ADAPTIVE) != 0 && \ 133 ((f) & LK_SLEEPFAIL) == 0) 134 135 #define lockmgr_disowned(lk) \ 136 (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == LK_KERNPROC) 137 138 #define lockmgr_xlocked(lk) \ 139 (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == (uintptr_t)curthread) 140 141 static void assert_lockmgr(const struct lock_object *lock, int how); 142 #ifdef DDB 143 static void db_show_lockmgr(const struct lock_object *lock); 144 #endif 145 static void lock_lockmgr(struct lock_object *lock, uintptr_t how); 146 #ifdef KDTRACE_HOOKS 147 static int owner_lockmgr(const struct lock_object *lock, 148 struct thread **owner); 149 #endif 150 static uintptr_t unlock_lockmgr(struct lock_object *lock); 151 152 struct lock_class lock_class_lockmgr = { 153 .lc_name = "lockmgr", 154 .lc_flags = LC_RECURSABLE | LC_SLEEPABLE | LC_SLEEPLOCK | LC_UPGRADABLE, 155 .lc_assert = assert_lockmgr, 156 #ifdef DDB 157 .lc_ddb_show = db_show_lockmgr, 158 #endif 159 .lc_lock = lock_lockmgr, 160 .lc_unlock = unlock_lockmgr, 161 #ifdef KDTRACE_HOOKS 162 .lc_owner = owner_lockmgr, 163 #endif 164 }; 165 166 #ifdef ADAPTIVE_LOCKMGRS 167 static u_int alk_retries = 10; 168 static u_int alk_loops = 10000; 169 static SYSCTL_NODE(_debug, OID_AUTO, lockmgr, CTLFLAG_RD, NULL, 170 "lockmgr debugging"); 171 SYSCTL_UINT(_debug_lockmgr, OID_AUTO, retries, CTLFLAG_RW, &alk_retries, 0, ""); 172 SYSCTL_UINT(_debug_lockmgr, OID_AUTO, loops, CTLFLAG_RW, &alk_loops, 0, ""); 173 #endif 174 175 static __inline struct thread * 176 lockmgr_xholder(const struct lock *lk) 177 { 178 uintptr_t x; 179 180 x = lk->lk_lock; 181 return ((x & LK_SHARE) ? NULL : (struct thread *)LK_HOLDER(x)); 182 } 183 184 /* 185 * It assumes sleepq_lock held and returns with this one unheld. 186 * It also assumes the generic interlock is sane and previously checked. 187 * If LK_INTERLOCK is specified the interlock is not reacquired after the 188 * sleep. 189 */ 190 static __inline int 191 sleeplk(struct lock *lk, u_int flags, struct lock_object *ilk, 192 const char *wmesg, int pri, int timo, int queue) 193 { 194 GIANT_DECLARE; 195 struct lock_class *class; 196 int catch, error; 197 198 class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL; 199 catch = pri & PCATCH; 200 pri &= PRIMASK; 201 error = 0; 202 203 LOCK_LOG3(lk, "%s: %p blocking on the %s sleepqueue", __func__, lk, 204 (queue == SQ_EXCLUSIVE_QUEUE) ? "exclusive" : "shared"); 205 206 if (flags & LK_INTERLOCK) 207 class->lc_unlock(ilk); 208 if (queue == SQ_EXCLUSIVE_QUEUE && (flags & LK_SLEEPFAIL) != 0) 209 lk->lk_exslpfail++; 210 GIANT_SAVE(); 211 sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ? 212 SLEEPQ_INTERRUPTIBLE : 0), queue); 213 if ((flags & LK_TIMELOCK) && timo) 214 sleepq_set_timeout(&lk->lock_object, timo); 215 216 /* 217 * Decisional switch for real sleeping. 218 */ 219 if ((flags & LK_TIMELOCK) && timo && catch) 220 error = sleepq_timedwait_sig(&lk->lock_object, pri); 221 else if ((flags & LK_TIMELOCK) && timo) 222 error = sleepq_timedwait(&lk->lock_object, pri); 223 else if (catch) 224 error = sleepq_wait_sig(&lk->lock_object, pri); 225 else 226 sleepq_wait(&lk->lock_object, pri); 227 GIANT_RESTORE(); 228 if ((flags & LK_SLEEPFAIL) && error == 0) 229 error = ENOLCK; 230 231 return (error); 232 } 233 234 static __inline int 235 wakeupshlk(struct lock *lk, const char *file, int line) 236 { 237 uintptr_t v, x; 238 u_int realexslp; 239 int queue, wakeup_swapper; 240 241 WITNESS_UNLOCK(&lk->lock_object, 0, file, line); 242 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, file, line); 243 244 wakeup_swapper = 0; 245 for (;;) { 246 x = lk->lk_lock; 247 248 /* 249 * If there is more than one shared lock held, just drop one 250 * and return. 251 */ 252 if (LK_SHARERS(x) > 1) { 253 if (atomic_cmpset_rel_ptr(&lk->lk_lock, x, 254 x - LK_ONE_SHARER)) 255 break; 256 continue; 257 } 258 259 /* 260 * If there are not waiters on the exclusive queue, drop the 261 * lock quickly. 262 */ 263 if ((x & LK_ALL_WAITERS) == 0) { 264 MPASS((x & ~LK_EXCLUSIVE_SPINNERS) == 265 LK_SHARERS_LOCK(1)); 266 if (atomic_cmpset_rel_ptr(&lk->lk_lock, x, LK_UNLOCKED)) 267 break; 268 continue; 269 } 270 271 /* 272 * We should have a sharer with waiters, so enter the hard 273 * path in order to handle wakeups correctly. 274 */ 275 sleepq_lock(&lk->lock_object); 276 x = lk->lk_lock & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS); 277 v = LK_UNLOCKED; 278 279 /* 280 * If the lock has exclusive waiters, give them preference in 281 * order to avoid deadlock with shared runners up. 282 * If interruptible sleeps left the exclusive queue empty 283 * avoid a starvation for the threads sleeping on the shared 284 * queue by giving them precedence and cleaning up the 285 * exclusive waiters bit anyway. 286 * Please note that lk_exslpfail count may be lying about 287 * the real number of waiters with the LK_SLEEPFAIL flag on 288 * because they may be used in conjuction with interruptible 289 * sleeps so lk_exslpfail might be considered an 'upper limit' 290 * bound, including the edge cases. 291 */ 292 realexslp = sleepq_sleepcnt(&lk->lock_object, 293 SQ_EXCLUSIVE_QUEUE); 294 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) { 295 if (lk->lk_exslpfail < realexslp) { 296 lk->lk_exslpfail = 0; 297 queue = SQ_EXCLUSIVE_QUEUE; 298 v |= (x & LK_SHARED_WAITERS); 299 } else { 300 lk->lk_exslpfail = 0; 301 LOCK_LOG2(lk, 302 "%s: %p has only LK_SLEEPFAIL sleepers", 303 __func__, lk); 304 LOCK_LOG2(lk, 305 "%s: %p waking up threads on the exclusive queue", 306 __func__, lk); 307 wakeup_swapper = 308 sleepq_broadcast(&lk->lock_object, 309 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE); 310 queue = SQ_SHARED_QUEUE; 311 } 312 313 } else { 314 315 /* 316 * Exclusive waiters sleeping with LK_SLEEPFAIL on 317 * and using interruptible sleeps/timeout may have 318 * left spourious lk_exslpfail counts on, so clean 319 * it up anyway. 320 */ 321 lk->lk_exslpfail = 0; 322 queue = SQ_SHARED_QUEUE; 323 } 324 325 if (!atomic_cmpset_rel_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x, 326 v)) { 327 sleepq_release(&lk->lock_object); 328 continue; 329 } 330 LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue", 331 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" : 332 "exclusive"); 333 wakeup_swapper |= sleepq_broadcast(&lk->lock_object, SLEEPQ_LK, 334 0, queue); 335 sleepq_release(&lk->lock_object); 336 break; 337 } 338 339 lock_profile_release_lock(&lk->lock_object); 340 TD_LOCKS_DEC(curthread); 341 TD_SLOCKS_DEC(curthread); 342 return (wakeup_swapper); 343 } 344 345 static void 346 assert_lockmgr(const struct lock_object *lock, int what) 347 { 348 349 panic("lockmgr locks do not support assertions"); 350 } 351 352 static void 353 lock_lockmgr(struct lock_object *lock, uintptr_t how) 354 { 355 356 panic("lockmgr locks do not support sleep interlocking"); 357 } 358 359 static uintptr_t 360 unlock_lockmgr(struct lock_object *lock) 361 { 362 363 panic("lockmgr locks do not support sleep interlocking"); 364 } 365 366 #ifdef KDTRACE_HOOKS 367 static int 368 owner_lockmgr(const struct lock_object *lock, struct thread **owner) 369 { 370 371 panic("lockmgr locks do not support owner inquiring"); 372 } 373 #endif 374 375 void 376 lockinit(struct lock *lk, int pri, const char *wmesg, int timo, int flags) 377 { 378 int iflags; 379 380 MPASS((flags & ~LK_INIT_MASK) == 0); 381 ASSERT_ATOMIC_LOAD_PTR(lk->lk_lock, 382 ("%s: lockmgr not aligned for %s: %p", __func__, wmesg, 383 &lk->lk_lock)); 384 385 iflags = LO_SLEEPABLE | LO_UPGRADABLE; 386 if (flags & LK_CANRECURSE) 387 iflags |= LO_RECURSABLE; 388 if ((flags & LK_NODUP) == 0) 389 iflags |= LO_DUPOK; 390 if (flags & LK_NOPROFILE) 391 iflags |= LO_NOPROFILE; 392 if ((flags & LK_NOWITNESS) == 0) 393 iflags |= LO_WITNESS; 394 if (flags & LK_QUIET) 395 iflags |= LO_QUIET; 396 if (flags & LK_IS_VNODE) 397 iflags |= LO_IS_VNODE; 398 iflags |= flags & (LK_ADAPTIVE | LK_NOSHARE); 399 400 lock_init(&lk->lock_object, &lock_class_lockmgr, wmesg, NULL, iflags); 401 lk->lk_lock = LK_UNLOCKED; 402 lk->lk_recurse = 0; 403 lk->lk_exslpfail = 0; 404 lk->lk_timo = timo; 405 lk->lk_pri = pri; 406 STACK_ZERO(lk); 407 } 408 409 /* 410 * XXX: Gross hacks to manipulate external lock flags after 411 * initialization. Used for certain vnode and buf locks. 412 */ 413 void 414 lockallowshare(struct lock *lk) 415 { 416 417 lockmgr_assert(lk, KA_XLOCKED); 418 lk->lock_object.lo_flags &= ~LK_NOSHARE; 419 } 420 421 void 422 lockallowrecurse(struct lock *lk) 423 { 424 425 lockmgr_assert(lk, KA_XLOCKED); 426 lk->lock_object.lo_flags |= LO_RECURSABLE; 427 } 428 429 void 430 lockdisablerecurse(struct lock *lk) 431 { 432 433 lockmgr_assert(lk, KA_XLOCKED); 434 lk->lock_object.lo_flags &= ~LO_RECURSABLE; 435 } 436 437 void 438 lockdestroy(struct lock *lk) 439 { 440 441 KASSERT(lk->lk_lock == LK_UNLOCKED, ("lockmgr still held")); 442 KASSERT(lk->lk_recurse == 0, ("lockmgr still recursed")); 443 KASSERT(lk->lk_exslpfail == 0, ("lockmgr still exclusive waiters")); 444 lock_destroy(&lk->lock_object); 445 } 446 447 int 448 __lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk, 449 const char *wmesg, int pri, int timo, const char *file, int line) 450 { 451 GIANT_DECLARE; 452 struct lock_class *class; 453 const char *iwmesg; 454 uintptr_t tid, v, x; 455 u_int op, realexslp; 456 int error, ipri, itimo, queue, wakeup_swapper; 457 #ifdef LOCK_PROFILING 458 uint64_t waittime = 0; 459 int contested = 0; 460 #endif 461 #ifdef ADAPTIVE_LOCKMGRS 462 volatile struct thread *owner; 463 u_int i, spintries = 0; 464 #endif 465 466 error = 0; 467 tid = (uintptr_t)curthread; 468 op = (flags & LK_TYPE_MASK); 469 iwmesg = (wmesg == LK_WMESG_DEFAULT) ? lk->lock_object.lo_name : wmesg; 470 ipri = (pri == LK_PRIO_DEFAULT) ? lk->lk_pri : pri; 471 itimo = (timo == LK_TIMO_DEFAULT) ? lk->lk_timo : timo; 472 473 MPASS((flags & ~LK_TOTAL_MASK) == 0); 474 KASSERT((op & (op - 1)) == 0, 475 ("%s: Invalid requested operation @ %s:%d", __func__, file, line)); 476 KASSERT((flags & (LK_NOWAIT | LK_SLEEPFAIL)) == 0 || 477 (op != LK_DOWNGRADE && op != LK_RELEASE), 478 ("%s: Invalid flags in regard of the operation desired @ %s:%d", 479 __func__, file, line)); 480 KASSERT((flags & LK_INTERLOCK) == 0 || ilk != NULL, 481 ("%s: LK_INTERLOCK passed without valid interlock @ %s:%d", 482 __func__, file, line)); 483 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), 484 ("%s: idle thread %p on lockmgr %s @ %s:%d", __func__, curthread, 485 lk->lock_object.lo_name, file, line)); 486 487 class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL; 488 if (panicstr != NULL) { 489 if (flags & LK_INTERLOCK) 490 class->lc_unlock(ilk); 491 return (0); 492 } 493 494 if (lk->lock_object.lo_flags & LK_NOSHARE) { 495 switch (op) { 496 case LK_SHARED: 497 op = LK_EXCLUSIVE; 498 break; 499 case LK_UPGRADE: 500 case LK_TRYUPGRADE: 501 case LK_DOWNGRADE: 502 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, 503 file, line); 504 if (flags & LK_INTERLOCK) 505 class->lc_unlock(ilk); 506 return (0); 507 } 508 } 509 510 wakeup_swapper = 0; 511 switch (op) { 512 case LK_SHARED: 513 if (LK_CAN_WITNESS(flags)) 514 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, 515 file, line, flags & LK_INTERLOCK ? ilk : NULL); 516 for (;;) { 517 x = lk->lk_lock; 518 519 /* 520 * If no other thread has an exclusive lock, or 521 * no exclusive waiter is present, bump the count of 522 * sharers. Since we have to preserve the state of 523 * waiters, if we fail to acquire the shared lock 524 * loop back and retry. 525 */ 526 if (LK_CAN_SHARE(x)) { 527 if (atomic_cmpset_acq_ptr(&lk->lk_lock, x, 528 x + LK_ONE_SHARER)) 529 break; 530 continue; 531 } 532 #ifdef HWPMC_HOOKS 533 PMC_SOFT_CALL( , , lock, failed); 534 #endif 535 lock_profile_obtain_lock_failed(&lk->lock_object, 536 &contested, &waittime); 537 538 /* 539 * If the lock is already held by curthread in 540 * exclusive way avoid a deadlock. 541 */ 542 if (LK_HOLDER(x) == tid) { 543 LOCK_LOG2(lk, 544 "%s: %p already held in exclusive mode", 545 __func__, lk); 546 error = EDEADLK; 547 break; 548 } 549 550 /* 551 * If the lock is expected to not sleep just give up 552 * and return. 553 */ 554 if (LK_TRYOP(flags)) { 555 LOCK_LOG2(lk, "%s: %p fails the try operation", 556 __func__, lk); 557 error = EBUSY; 558 break; 559 } 560 561 #ifdef ADAPTIVE_LOCKMGRS 562 /* 563 * If the owner is running on another CPU, spin until 564 * the owner stops running or the state of the lock 565 * changes. We need a double-state handle here 566 * because for a failed acquisition the lock can be 567 * either held in exclusive mode or shared mode 568 * (for the writer starvation avoidance technique). 569 */ 570 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && 571 LK_HOLDER(x) != LK_KERNPROC) { 572 owner = (struct thread *)LK_HOLDER(x); 573 if (LOCK_LOG_TEST(&lk->lock_object, 0)) 574 CTR3(KTR_LOCK, 575 "%s: spinning on %p held by %p", 576 __func__, lk, owner); 577 578 /* 579 * If we are holding also an interlock drop it 580 * in order to avoid a deadlock if the lockmgr 581 * owner is adaptively spinning on the 582 * interlock itself. 583 */ 584 if (flags & LK_INTERLOCK) { 585 class->lc_unlock(ilk); 586 flags &= ~LK_INTERLOCK; 587 } 588 GIANT_SAVE(); 589 while (LK_HOLDER(lk->lk_lock) == 590 (uintptr_t)owner && TD_IS_RUNNING(owner)) 591 cpu_spinwait(); 592 GIANT_RESTORE(); 593 continue; 594 } else if (LK_CAN_ADAPT(lk, flags) && 595 (x & LK_SHARE) != 0 && LK_SHARERS(x) && 596 spintries < alk_retries) { 597 if (flags & LK_INTERLOCK) { 598 class->lc_unlock(ilk); 599 flags &= ~LK_INTERLOCK; 600 } 601 GIANT_SAVE(); 602 spintries++; 603 for (i = 0; i < alk_loops; i++) { 604 if (LOCK_LOG_TEST(&lk->lock_object, 0)) 605 CTR4(KTR_LOCK, 606 "%s: shared spinning on %p with %u and %u", 607 __func__, lk, spintries, i); 608 x = lk->lk_lock; 609 if ((x & LK_SHARE) == 0 || 610 LK_CAN_SHARE(x) != 0) 611 break; 612 cpu_spinwait(); 613 } 614 GIANT_RESTORE(); 615 if (i != alk_loops) 616 continue; 617 } 618 #endif 619 620 /* 621 * Acquire the sleepqueue chain lock because we 622 * probabilly will need to manipulate waiters flags. 623 */ 624 sleepq_lock(&lk->lock_object); 625 x = lk->lk_lock; 626 627 /* 628 * if the lock can be acquired in shared mode, try 629 * again. 630 */ 631 if (LK_CAN_SHARE(x)) { 632 sleepq_release(&lk->lock_object); 633 continue; 634 } 635 636 #ifdef ADAPTIVE_LOCKMGRS 637 /* 638 * The current lock owner might have started executing 639 * on another CPU (or the lock could have changed 640 * owner) while we were waiting on the turnstile 641 * chain lock. If so, drop the turnstile lock and try 642 * again. 643 */ 644 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && 645 LK_HOLDER(x) != LK_KERNPROC) { 646 owner = (struct thread *)LK_HOLDER(x); 647 if (TD_IS_RUNNING(owner)) { 648 sleepq_release(&lk->lock_object); 649 continue; 650 } 651 } 652 #endif 653 654 /* 655 * Try to set the LK_SHARED_WAITERS flag. If we fail, 656 * loop back and retry. 657 */ 658 if ((x & LK_SHARED_WAITERS) == 0) { 659 if (!atomic_cmpset_acq_ptr(&lk->lk_lock, x, 660 x | LK_SHARED_WAITERS)) { 661 sleepq_release(&lk->lock_object); 662 continue; 663 } 664 LOCK_LOG2(lk, "%s: %p set shared waiters flag", 665 __func__, lk); 666 } 667 668 /* 669 * As far as we have been unable to acquire the 670 * shared lock and the shared waiters flag is set, 671 * we will sleep. 672 */ 673 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo, 674 SQ_SHARED_QUEUE); 675 flags &= ~LK_INTERLOCK; 676 if (error) { 677 LOCK_LOG3(lk, 678 "%s: interrupted sleep for %p with %d", 679 __func__, lk, error); 680 break; 681 } 682 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue", 683 __func__, lk); 684 } 685 if (error == 0) { 686 lock_profile_obtain_lock_success(&lk->lock_object, 687 contested, waittime, file, line); 688 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, file, 689 line); 690 WITNESS_LOCK(&lk->lock_object, LK_TRYWIT(flags), file, 691 line); 692 TD_LOCKS_INC(curthread); 693 TD_SLOCKS_INC(curthread); 694 STACK_SAVE(lk); 695 } 696 break; 697 case LK_UPGRADE: 698 case LK_TRYUPGRADE: 699 _lockmgr_assert(lk, KA_SLOCKED, file, line); 700 v = lk->lk_lock; 701 x = v & LK_ALL_WAITERS; 702 v &= LK_EXCLUSIVE_SPINNERS; 703 704 /* 705 * Try to switch from one shared lock to an exclusive one. 706 * We need to preserve waiters flags during the operation. 707 */ 708 if (atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x | v, 709 tid | x)) { 710 LOCK_LOG_LOCK("XUPGRADE", &lk->lock_object, 0, 0, file, 711 line); 712 WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE | 713 LK_TRYWIT(flags), file, line); 714 TD_SLOCKS_DEC(curthread); 715 break; 716 } 717 718 /* 719 * In LK_TRYUPGRADE mode, do not drop the lock, 720 * returning EBUSY instead. 721 */ 722 if (op == LK_TRYUPGRADE) { 723 LOCK_LOG2(lk, "%s: %p failed the nowait upgrade", 724 __func__, lk); 725 error = EBUSY; 726 break; 727 } 728 729 /* 730 * We have been unable to succeed in upgrading, so just 731 * give up the shared lock. 732 */ 733 wakeup_swapper |= wakeupshlk(lk, file, line); 734 735 /* FALLTHROUGH */ 736 case LK_EXCLUSIVE: 737 if (LK_CAN_WITNESS(flags)) 738 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER | 739 LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ? 740 ilk : NULL); 741 742 /* 743 * If curthread already holds the lock and this one is 744 * allowed to recurse, simply recurse on it. 745 */ 746 if (lockmgr_xlocked(lk)) { 747 if ((flags & LK_CANRECURSE) == 0 && 748 (lk->lock_object.lo_flags & LO_RECURSABLE) == 0) { 749 750 /* 751 * If the lock is expected to not panic just 752 * give up and return. 753 */ 754 if (LK_TRYOP(flags)) { 755 LOCK_LOG2(lk, 756 "%s: %p fails the try operation", 757 __func__, lk); 758 error = EBUSY; 759 break; 760 } 761 if (flags & LK_INTERLOCK) 762 class->lc_unlock(ilk); 763 panic("%s: recursing on non recursive lockmgr %s @ %s:%d\n", 764 __func__, iwmesg, file, line); 765 } 766 lk->lk_recurse++; 767 LOCK_LOG2(lk, "%s: %p recursing", __func__, lk); 768 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0, 769 lk->lk_recurse, file, line); 770 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | 771 LK_TRYWIT(flags), file, line); 772 TD_LOCKS_INC(curthread); 773 break; 774 } 775 776 while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, 777 tid)) { 778 #ifdef HWPMC_HOOKS 779 PMC_SOFT_CALL( , , lock, failed); 780 #endif 781 lock_profile_obtain_lock_failed(&lk->lock_object, 782 &contested, &waittime); 783 784 /* 785 * If the lock is expected to not sleep just give up 786 * and return. 787 */ 788 if (LK_TRYOP(flags)) { 789 LOCK_LOG2(lk, "%s: %p fails the try operation", 790 __func__, lk); 791 error = EBUSY; 792 break; 793 } 794 795 #ifdef ADAPTIVE_LOCKMGRS 796 /* 797 * If the owner is running on another CPU, spin until 798 * the owner stops running or the state of the lock 799 * changes. 800 */ 801 x = lk->lk_lock; 802 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && 803 LK_HOLDER(x) != LK_KERNPROC) { 804 owner = (struct thread *)LK_HOLDER(x); 805 if (LOCK_LOG_TEST(&lk->lock_object, 0)) 806 CTR3(KTR_LOCK, 807 "%s: spinning on %p held by %p", 808 __func__, lk, owner); 809 810 /* 811 * If we are holding also an interlock drop it 812 * in order to avoid a deadlock if the lockmgr 813 * owner is adaptively spinning on the 814 * interlock itself. 815 */ 816 if (flags & LK_INTERLOCK) { 817 class->lc_unlock(ilk); 818 flags &= ~LK_INTERLOCK; 819 } 820 GIANT_SAVE(); 821 while (LK_HOLDER(lk->lk_lock) == 822 (uintptr_t)owner && TD_IS_RUNNING(owner)) 823 cpu_spinwait(); 824 GIANT_RESTORE(); 825 continue; 826 } else if (LK_CAN_ADAPT(lk, flags) && 827 (x & LK_SHARE) != 0 && LK_SHARERS(x) && 828 spintries < alk_retries) { 829 if ((x & LK_EXCLUSIVE_SPINNERS) == 0 && 830 !atomic_cmpset_ptr(&lk->lk_lock, x, 831 x | LK_EXCLUSIVE_SPINNERS)) 832 continue; 833 if (flags & LK_INTERLOCK) { 834 class->lc_unlock(ilk); 835 flags &= ~LK_INTERLOCK; 836 } 837 GIANT_SAVE(); 838 spintries++; 839 for (i = 0; i < alk_loops; i++) { 840 if (LOCK_LOG_TEST(&lk->lock_object, 0)) 841 CTR4(KTR_LOCK, 842 "%s: shared spinning on %p with %u and %u", 843 __func__, lk, spintries, i); 844 if ((lk->lk_lock & 845 LK_EXCLUSIVE_SPINNERS) == 0) 846 break; 847 cpu_spinwait(); 848 } 849 GIANT_RESTORE(); 850 if (i != alk_loops) 851 continue; 852 } 853 #endif 854 855 /* 856 * Acquire the sleepqueue chain lock because we 857 * probabilly will need to manipulate waiters flags. 858 */ 859 sleepq_lock(&lk->lock_object); 860 x = lk->lk_lock; 861 862 /* 863 * if the lock has been released while we spun on 864 * the sleepqueue chain lock just try again. 865 */ 866 if (x == LK_UNLOCKED) { 867 sleepq_release(&lk->lock_object); 868 continue; 869 } 870 871 #ifdef ADAPTIVE_LOCKMGRS 872 /* 873 * The current lock owner might have started executing 874 * on another CPU (or the lock could have changed 875 * owner) while we were waiting on the turnstile 876 * chain lock. If so, drop the turnstile lock and try 877 * again. 878 */ 879 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 && 880 LK_HOLDER(x) != LK_KERNPROC) { 881 owner = (struct thread *)LK_HOLDER(x); 882 if (TD_IS_RUNNING(owner)) { 883 sleepq_release(&lk->lock_object); 884 continue; 885 } 886 } 887 #endif 888 889 /* 890 * The lock can be in the state where there is a 891 * pending queue of waiters, but still no owner. 892 * This happens when the lock is contested and an 893 * owner is going to claim the lock. 894 * If curthread is the one successfully acquiring it 895 * claim lock ownership and return, preserving waiters 896 * flags. 897 */ 898 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS); 899 if ((x & ~v) == LK_UNLOCKED) { 900 v &= ~LK_EXCLUSIVE_SPINNERS; 901 if (atomic_cmpset_acq_ptr(&lk->lk_lock, x, 902 tid | v)) { 903 sleepq_release(&lk->lock_object); 904 LOCK_LOG2(lk, 905 "%s: %p claimed by a new writer", 906 __func__, lk); 907 break; 908 } 909 sleepq_release(&lk->lock_object); 910 continue; 911 } 912 913 /* 914 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we 915 * fail, loop back and retry. 916 */ 917 if ((x & LK_EXCLUSIVE_WAITERS) == 0) { 918 if (!atomic_cmpset_ptr(&lk->lk_lock, x, 919 x | LK_EXCLUSIVE_WAITERS)) { 920 sleepq_release(&lk->lock_object); 921 continue; 922 } 923 LOCK_LOG2(lk, "%s: %p set excl waiters flag", 924 __func__, lk); 925 } 926 927 /* 928 * As far as we have been unable to acquire the 929 * exclusive lock and the exclusive waiters flag 930 * is set, we will sleep. 931 */ 932 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo, 933 SQ_EXCLUSIVE_QUEUE); 934 flags &= ~LK_INTERLOCK; 935 if (error) { 936 LOCK_LOG3(lk, 937 "%s: interrupted sleep for %p with %d", 938 __func__, lk, error); 939 break; 940 } 941 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue", 942 __func__, lk); 943 } 944 if (error == 0) { 945 lock_profile_obtain_lock_success(&lk->lock_object, 946 contested, waittime, file, line); 947 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0, 948 lk->lk_recurse, file, line); 949 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | 950 LK_TRYWIT(flags), file, line); 951 TD_LOCKS_INC(curthread); 952 STACK_SAVE(lk); 953 } 954 break; 955 case LK_DOWNGRADE: 956 _lockmgr_assert(lk, KA_XLOCKED, file, line); 957 LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line); 958 WITNESS_DOWNGRADE(&lk->lock_object, 0, file, line); 959 960 /* 961 * Panic if the lock is recursed. 962 */ 963 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) { 964 if (flags & LK_INTERLOCK) 965 class->lc_unlock(ilk); 966 panic("%s: downgrade a recursed lockmgr %s @ %s:%d\n", 967 __func__, iwmesg, file, line); 968 } 969 TD_SLOCKS_INC(curthread); 970 971 /* 972 * In order to preserve waiters flags, just spin. 973 */ 974 for (;;) { 975 x = lk->lk_lock; 976 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0); 977 x &= LK_ALL_WAITERS; 978 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x, 979 LK_SHARERS_LOCK(1) | x)) 980 break; 981 cpu_spinwait(); 982 } 983 break; 984 case LK_RELEASE: 985 _lockmgr_assert(lk, KA_LOCKED, file, line); 986 x = lk->lk_lock; 987 988 if ((x & LK_SHARE) == 0) { 989 990 /* 991 * As first option, treact the lock as if it has not 992 * any waiter. 993 * Fix-up the tid var if the lock has been disowned. 994 */ 995 if (LK_HOLDER(x) == LK_KERNPROC) 996 tid = LK_KERNPROC; 997 else { 998 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, 999 file, line); 1000 TD_LOCKS_DEC(curthread); 1001 } 1002 LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0, 1003 lk->lk_recurse, file, line); 1004 1005 /* 1006 * The lock is held in exclusive mode. 1007 * If the lock is recursed also, then unrecurse it. 1008 */ 1009 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) { 1010 LOCK_LOG2(lk, "%s: %p unrecursing", __func__, 1011 lk); 1012 lk->lk_recurse--; 1013 break; 1014 } 1015 if (tid != LK_KERNPROC) 1016 lock_profile_release_lock(&lk->lock_object); 1017 1018 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid, 1019 LK_UNLOCKED)) 1020 break; 1021 1022 sleepq_lock(&lk->lock_object); 1023 x = lk->lk_lock; 1024 v = LK_UNLOCKED; 1025 1026 /* 1027 * If the lock has exclusive waiters, give them 1028 * preference in order to avoid deadlock with 1029 * shared runners up. 1030 * If interruptible sleeps left the exclusive queue 1031 * empty avoid a starvation for the threads sleeping 1032 * on the shared queue by giving them precedence 1033 * and cleaning up the exclusive waiters bit anyway. 1034 * Please note that lk_exslpfail count may be lying 1035 * about the real number of waiters with the 1036 * LK_SLEEPFAIL flag on because they may be used in 1037 * conjuction with interruptible sleeps so 1038 * lk_exslpfail might be considered an 'upper limit' 1039 * bound, including the edge cases. 1040 */ 1041 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0); 1042 realexslp = sleepq_sleepcnt(&lk->lock_object, 1043 SQ_EXCLUSIVE_QUEUE); 1044 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) { 1045 if (lk->lk_exslpfail < realexslp) { 1046 lk->lk_exslpfail = 0; 1047 queue = SQ_EXCLUSIVE_QUEUE; 1048 v |= (x & LK_SHARED_WAITERS); 1049 } else { 1050 lk->lk_exslpfail = 0; 1051 LOCK_LOG2(lk, 1052 "%s: %p has only LK_SLEEPFAIL sleepers", 1053 __func__, lk); 1054 LOCK_LOG2(lk, 1055 "%s: %p waking up threads on the exclusive queue", 1056 __func__, lk); 1057 wakeup_swapper = 1058 sleepq_broadcast(&lk->lock_object, 1059 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE); 1060 queue = SQ_SHARED_QUEUE; 1061 } 1062 } else { 1063 1064 /* 1065 * Exclusive waiters sleeping with LK_SLEEPFAIL 1066 * on and using interruptible sleeps/timeout 1067 * may have left spourious lk_exslpfail counts 1068 * on, so clean it up anyway. 1069 */ 1070 lk->lk_exslpfail = 0; 1071 queue = SQ_SHARED_QUEUE; 1072 } 1073 1074 LOCK_LOG3(lk, 1075 "%s: %p waking up threads on the %s queue", 1076 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" : 1077 "exclusive"); 1078 atomic_store_rel_ptr(&lk->lk_lock, v); 1079 wakeup_swapper |= sleepq_broadcast(&lk->lock_object, 1080 SLEEPQ_LK, 0, queue); 1081 sleepq_release(&lk->lock_object); 1082 break; 1083 } else 1084 wakeup_swapper = wakeupshlk(lk, file, line); 1085 break; 1086 case LK_DRAIN: 1087 if (LK_CAN_WITNESS(flags)) 1088 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER | 1089 LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ? 1090 ilk : NULL); 1091 1092 /* 1093 * Trying to drain a lock we already own will result in a 1094 * deadlock. 1095 */ 1096 if (lockmgr_xlocked(lk)) { 1097 if (flags & LK_INTERLOCK) 1098 class->lc_unlock(ilk); 1099 panic("%s: draining %s with the lock held @ %s:%d\n", 1100 __func__, iwmesg, file, line); 1101 } 1102 1103 while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) { 1104 #ifdef HWPMC_HOOKS 1105 PMC_SOFT_CALL( , , lock, failed); 1106 #endif 1107 lock_profile_obtain_lock_failed(&lk->lock_object, 1108 &contested, &waittime); 1109 1110 /* 1111 * If the lock is expected to not sleep just give up 1112 * and return. 1113 */ 1114 if (LK_TRYOP(flags)) { 1115 LOCK_LOG2(lk, "%s: %p fails the try operation", 1116 __func__, lk); 1117 error = EBUSY; 1118 break; 1119 } 1120 1121 /* 1122 * Acquire the sleepqueue chain lock because we 1123 * probabilly will need to manipulate waiters flags. 1124 */ 1125 sleepq_lock(&lk->lock_object); 1126 x = lk->lk_lock; 1127 1128 /* 1129 * if the lock has been released while we spun on 1130 * the sleepqueue chain lock just try again. 1131 */ 1132 if (x == LK_UNLOCKED) { 1133 sleepq_release(&lk->lock_object); 1134 continue; 1135 } 1136 1137 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS); 1138 if ((x & ~v) == LK_UNLOCKED) { 1139 v = (x & ~LK_EXCLUSIVE_SPINNERS); 1140 1141 /* 1142 * If interruptible sleeps left the exclusive 1143 * queue empty avoid a starvation for the 1144 * threads sleeping on the shared queue by 1145 * giving them precedence and cleaning up the 1146 * exclusive waiters bit anyway. 1147 * Please note that lk_exslpfail count may be 1148 * lying about the real number of waiters with 1149 * the LK_SLEEPFAIL flag on because they may 1150 * be used in conjuction with interruptible 1151 * sleeps so lk_exslpfail might be considered 1152 * an 'upper limit' bound, including the edge 1153 * cases. 1154 */ 1155 if (v & LK_EXCLUSIVE_WAITERS) { 1156 queue = SQ_EXCLUSIVE_QUEUE; 1157 v &= ~LK_EXCLUSIVE_WAITERS; 1158 } else { 1159 1160 /* 1161 * Exclusive waiters sleeping with 1162 * LK_SLEEPFAIL on and using 1163 * interruptible sleeps/timeout may 1164 * have left spourious lk_exslpfail 1165 * counts on, so clean it up anyway. 1166 */ 1167 MPASS(v & LK_SHARED_WAITERS); 1168 lk->lk_exslpfail = 0; 1169 queue = SQ_SHARED_QUEUE; 1170 v &= ~LK_SHARED_WAITERS; 1171 } 1172 if (queue == SQ_EXCLUSIVE_QUEUE) { 1173 realexslp = 1174 sleepq_sleepcnt(&lk->lock_object, 1175 SQ_EXCLUSIVE_QUEUE); 1176 if (lk->lk_exslpfail >= realexslp) { 1177 lk->lk_exslpfail = 0; 1178 queue = SQ_SHARED_QUEUE; 1179 v &= ~LK_SHARED_WAITERS; 1180 if (realexslp != 0) { 1181 LOCK_LOG2(lk, 1182 "%s: %p has only LK_SLEEPFAIL sleepers", 1183 __func__, lk); 1184 LOCK_LOG2(lk, 1185 "%s: %p waking up threads on the exclusive queue", 1186 __func__, lk); 1187 wakeup_swapper = 1188 sleepq_broadcast( 1189 &lk->lock_object, 1190 SLEEPQ_LK, 0, 1191 SQ_EXCLUSIVE_QUEUE); 1192 } 1193 } else 1194 lk->lk_exslpfail = 0; 1195 } 1196 if (!atomic_cmpset_ptr(&lk->lk_lock, x, v)) { 1197 sleepq_release(&lk->lock_object); 1198 continue; 1199 } 1200 LOCK_LOG3(lk, 1201 "%s: %p waking up all threads on the %s queue", 1202 __func__, lk, queue == SQ_SHARED_QUEUE ? 1203 "shared" : "exclusive"); 1204 wakeup_swapper |= sleepq_broadcast( 1205 &lk->lock_object, SLEEPQ_LK, 0, queue); 1206 1207 /* 1208 * If shared waiters have been woken up we need 1209 * to wait for one of them to acquire the lock 1210 * before to set the exclusive waiters in 1211 * order to avoid a deadlock. 1212 */ 1213 if (queue == SQ_SHARED_QUEUE) { 1214 for (v = lk->lk_lock; 1215 (v & LK_SHARE) && !LK_SHARERS(v); 1216 v = lk->lk_lock) 1217 cpu_spinwait(); 1218 } 1219 } 1220 1221 /* 1222 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we 1223 * fail, loop back and retry. 1224 */ 1225 if ((x & LK_EXCLUSIVE_WAITERS) == 0) { 1226 if (!atomic_cmpset_ptr(&lk->lk_lock, x, 1227 x | LK_EXCLUSIVE_WAITERS)) { 1228 sleepq_release(&lk->lock_object); 1229 continue; 1230 } 1231 LOCK_LOG2(lk, "%s: %p set drain waiters flag", 1232 __func__, lk); 1233 } 1234 1235 /* 1236 * As far as we have been unable to acquire the 1237 * exclusive lock and the exclusive waiters flag 1238 * is set, we will sleep. 1239 */ 1240 if (flags & LK_INTERLOCK) { 1241 class->lc_unlock(ilk); 1242 flags &= ~LK_INTERLOCK; 1243 } 1244 GIANT_SAVE(); 1245 sleepq_add(&lk->lock_object, NULL, iwmesg, SLEEPQ_LK, 1246 SQ_EXCLUSIVE_QUEUE); 1247 sleepq_wait(&lk->lock_object, ipri & PRIMASK); 1248 GIANT_RESTORE(); 1249 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue", 1250 __func__, lk); 1251 } 1252 1253 if (error == 0) { 1254 lock_profile_obtain_lock_success(&lk->lock_object, 1255 contested, waittime, file, line); 1256 LOCK_LOG_LOCK("DRAIN", &lk->lock_object, 0, 1257 lk->lk_recurse, file, line); 1258 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | 1259 LK_TRYWIT(flags), file, line); 1260 TD_LOCKS_INC(curthread); 1261 STACK_SAVE(lk); 1262 } 1263 break; 1264 default: 1265 if (flags & LK_INTERLOCK) 1266 class->lc_unlock(ilk); 1267 panic("%s: unknown lockmgr request 0x%x\n", __func__, op); 1268 } 1269 1270 if (flags & LK_INTERLOCK) 1271 class->lc_unlock(ilk); 1272 if (wakeup_swapper) 1273 kick_proc0(); 1274 1275 return (error); 1276 } 1277 1278 void 1279 _lockmgr_disown(struct lock *lk, const char *file, int line) 1280 { 1281 uintptr_t tid, x; 1282 1283 if (SCHEDULER_STOPPED()) 1284 return; 1285 1286 tid = (uintptr_t)curthread; 1287 _lockmgr_assert(lk, KA_XLOCKED, file, line); 1288 1289 /* 1290 * Panic if the lock is recursed. 1291 */ 1292 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) 1293 panic("%s: disown a recursed lockmgr @ %s:%d\n", 1294 __func__, file, line); 1295 1296 /* 1297 * If the owner is already LK_KERNPROC just skip the whole operation. 1298 */ 1299 if (LK_HOLDER(lk->lk_lock) != tid) 1300 return; 1301 lock_profile_release_lock(&lk->lock_object); 1302 LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line); 1303 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line); 1304 TD_LOCKS_DEC(curthread); 1305 STACK_SAVE(lk); 1306 1307 /* 1308 * In order to preserve waiters flags, just spin. 1309 */ 1310 for (;;) { 1311 x = lk->lk_lock; 1312 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0); 1313 x &= LK_ALL_WAITERS; 1314 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x, 1315 LK_KERNPROC | x)) 1316 return; 1317 cpu_spinwait(); 1318 } 1319 } 1320 1321 void 1322 lockmgr_printinfo(const struct lock *lk) 1323 { 1324 struct thread *td; 1325 uintptr_t x; 1326 1327 if (lk->lk_lock == LK_UNLOCKED) 1328 printf("lock type %s: UNLOCKED\n", lk->lock_object.lo_name); 1329 else if (lk->lk_lock & LK_SHARE) 1330 printf("lock type %s: SHARED (count %ju)\n", 1331 lk->lock_object.lo_name, 1332 (uintmax_t)LK_SHARERS(lk->lk_lock)); 1333 else { 1334 td = lockmgr_xholder(lk); 1335 printf("lock type %s: EXCL by thread %p " 1336 "(pid %d, %s, tid %d)\n", lk->lock_object.lo_name, td, 1337 td->td_proc->p_pid, td->td_proc->p_comm, td->td_tid); 1338 } 1339 1340 x = lk->lk_lock; 1341 if (x & LK_EXCLUSIVE_WAITERS) 1342 printf(" with exclusive waiters pending\n"); 1343 if (x & LK_SHARED_WAITERS) 1344 printf(" with shared waiters pending\n"); 1345 if (x & LK_EXCLUSIVE_SPINNERS) 1346 printf(" with exclusive spinners pending\n"); 1347 1348 STACK_PRINT(lk); 1349 } 1350 1351 int 1352 lockstatus(const struct lock *lk) 1353 { 1354 uintptr_t v, x; 1355 int ret; 1356 1357 ret = LK_SHARED; 1358 x = lk->lk_lock; 1359 v = LK_HOLDER(x); 1360 1361 if ((x & LK_SHARE) == 0) { 1362 if (v == (uintptr_t)curthread || v == LK_KERNPROC) 1363 ret = LK_EXCLUSIVE; 1364 else 1365 ret = LK_EXCLOTHER; 1366 } else if (x == LK_UNLOCKED) 1367 ret = 0; 1368 1369 return (ret); 1370 } 1371 1372 #ifdef INVARIANT_SUPPORT 1373 1374 FEATURE(invariant_support, 1375 "Support for modules compiled with INVARIANTS option"); 1376 1377 #ifndef INVARIANTS 1378 #undef _lockmgr_assert 1379 #endif 1380 1381 void 1382 _lockmgr_assert(const struct lock *lk, int what, const char *file, int line) 1383 { 1384 int slocked = 0; 1385 1386 if (panicstr != NULL) 1387 return; 1388 switch (what) { 1389 case KA_SLOCKED: 1390 case KA_SLOCKED | KA_NOTRECURSED: 1391 case KA_SLOCKED | KA_RECURSED: 1392 slocked = 1; 1393 case KA_LOCKED: 1394 case KA_LOCKED | KA_NOTRECURSED: 1395 case KA_LOCKED | KA_RECURSED: 1396 #ifdef WITNESS 1397 1398 /* 1399 * We cannot trust WITNESS if the lock is held in exclusive 1400 * mode and a call to lockmgr_disown() happened. 1401 * Workaround this skipping the check if the lock is held in 1402 * exclusive mode even for the KA_LOCKED case. 1403 */ 1404 if (slocked || (lk->lk_lock & LK_SHARE)) { 1405 witness_assert(&lk->lock_object, what, file, line); 1406 break; 1407 } 1408 #endif 1409 if (lk->lk_lock == LK_UNLOCKED || 1410 ((lk->lk_lock & LK_SHARE) == 0 && (slocked || 1411 (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk))))) 1412 panic("Lock %s not %slocked @ %s:%d\n", 1413 lk->lock_object.lo_name, slocked ? "share" : "", 1414 file, line); 1415 1416 if ((lk->lk_lock & LK_SHARE) == 0) { 1417 if (lockmgr_recursed(lk)) { 1418 if (what & KA_NOTRECURSED) 1419 panic("Lock %s recursed @ %s:%d\n", 1420 lk->lock_object.lo_name, file, 1421 line); 1422 } else if (what & KA_RECURSED) 1423 panic("Lock %s not recursed @ %s:%d\n", 1424 lk->lock_object.lo_name, file, line); 1425 } 1426 break; 1427 case KA_XLOCKED: 1428 case KA_XLOCKED | KA_NOTRECURSED: 1429 case KA_XLOCKED | KA_RECURSED: 1430 if (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk)) 1431 panic("Lock %s not exclusively locked @ %s:%d\n", 1432 lk->lock_object.lo_name, file, line); 1433 if (lockmgr_recursed(lk)) { 1434 if (what & KA_NOTRECURSED) 1435 panic("Lock %s recursed @ %s:%d\n", 1436 lk->lock_object.lo_name, file, line); 1437 } else if (what & KA_RECURSED) 1438 panic("Lock %s not recursed @ %s:%d\n", 1439 lk->lock_object.lo_name, file, line); 1440 break; 1441 case KA_UNLOCKED: 1442 if (lockmgr_xlocked(lk) || lockmgr_disowned(lk)) 1443 panic("Lock %s exclusively locked @ %s:%d\n", 1444 lk->lock_object.lo_name, file, line); 1445 break; 1446 default: 1447 panic("Unknown lockmgr assertion: %d @ %s:%d\n", what, file, 1448 line); 1449 } 1450 } 1451 #endif 1452 1453 #ifdef DDB 1454 int 1455 lockmgr_chain(struct thread *td, struct thread **ownerp) 1456 { 1457 struct lock *lk; 1458 1459 lk = td->td_wchan; 1460 1461 if (LOCK_CLASS(&lk->lock_object) != &lock_class_lockmgr) 1462 return (0); 1463 db_printf("blocked on lockmgr %s", lk->lock_object.lo_name); 1464 if (lk->lk_lock & LK_SHARE) 1465 db_printf("SHARED (count %ju)\n", 1466 (uintmax_t)LK_SHARERS(lk->lk_lock)); 1467 else 1468 db_printf("EXCL\n"); 1469 *ownerp = lockmgr_xholder(lk); 1470 1471 return (1); 1472 } 1473 1474 static void 1475 db_show_lockmgr(const struct lock_object *lock) 1476 { 1477 struct thread *td; 1478 const struct lock *lk; 1479 1480 lk = (const struct lock *)lock; 1481 1482 db_printf(" state: "); 1483 if (lk->lk_lock == LK_UNLOCKED) 1484 db_printf("UNLOCKED\n"); 1485 else if (lk->lk_lock & LK_SHARE) 1486 db_printf("SLOCK: %ju\n", (uintmax_t)LK_SHARERS(lk->lk_lock)); 1487 else { 1488 td = lockmgr_xholder(lk); 1489 if (td == (struct thread *)LK_KERNPROC) 1490 db_printf("XLOCK: LK_KERNPROC\n"); 1491 else 1492 db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td, 1493 td->td_tid, td->td_proc->p_pid, 1494 td->td_proc->p_comm); 1495 if (lockmgr_recursed(lk)) 1496 db_printf(" recursed: %d\n", lk->lk_recurse); 1497 } 1498 db_printf(" waiters: "); 1499 switch (lk->lk_lock & LK_ALL_WAITERS) { 1500 case LK_SHARED_WAITERS: 1501 db_printf("shared\n"); 1502 break; 1503 case LK_EXCLUSIVE_WAITERS: 1504 db_printf("exclusive\n"); 1505 break; 1506 case LK_ALL_WAITERS: 1507 db_printf("shared and exclusive\n"); 1508 break; 1509 default: 1510 db_printf("none\n"); 1511 } 1512 db_printf(" spinners: "); 1513 if (lk->lk_lock & LK_EXCLUSIVE_SPINNERS) 1514 db_printf("exclusive\n"); 1515 else 1516 db_printf("none\n"); 1517 } 1518 #endif
Cache object: ff830886af4ff390430d5002b8d7e91b
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