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