FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_lock.c
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/9.0/sys/kern/kern_lock.c 226255 2011-10-11 13:45:04Z attilio $");
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_NOSHARE) & LO_CLASSFLAGS) ==
57 (LK_ADAPTIVE | 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 if (queue == SQ_EXCLUSIVE_QUEUE && (flags & LK_SLEEPFAIL) != 0)
197 lk->lk_exslpfail++;
198 GIANT_SAVE();
199 sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ?
200 SLEEPQ_INTERRUPTIBLE : 0), queue);
201 if ((flags & LK_TIMELOCK) && timo)
202 sleepq_set_timeout(&lk->lock_object, timo);
203
204 /*
205 * Decisional switch for real sleeping.
206 */
207 if ((flags & LK_TIMELOCK) && timo && catch)
208 error = sleepq_timedwait_sig(&lk->lock_object, pri);
209 else if ((flags & LK_TIMELOCK) && timo)
210 error = sleepq_timedwait(&lk->lock_object, pri);
211 else if (catch)
212 error = sleepq_wait_sig(&lk->lock_object, pri);
213 else
214 sleepq_wait(&lk->lock_object, pri);
215 GIANT_RESTORE();
216 if ((flags & LK_SLEEPFAIL) && error == 0)
217 error = ENOLCK;
218
219 return (error);
220 }
221
222 static __inline int
223 wakeupshlk(struct lock *lk, const char *file, int line)
224 {
225 uintptr_t v, x;
226 u_int realexslp;
227 int queue, wakeup_swapper;
228
229 TD_LOCKS_DEC(curthread);
230 TD_SLOCKS_DEC(curthread);
231 WITNESS_UNLOCK(&lk->lock_object, 0, file, line);
232 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, file, line);
233
234 wakeup_swapper = 0;
235 for (;;) {
236 x = lk->lk_lock;
237
238 /*
239 * If there is more than one shared lock held, just drop one
240 * and return.
241 */
242 if (LK_SHARERS(x) > 1) {
243 if (atomic_cmpset_rel_ptr(&lk->lk_lock, x,
244 x - LK_ONE_SHARER))
245 break;
246 continue;
247 }
248
249 /*
250 * If there are not waiters on the exclusive queue, drop the
251 * lock quickly.
252 */
253 if ((x & LK_ALL_WAITERS) == 0) {
254 MPASS((x & ~LK_EXCLUSIVE_SPINNERS) ==
255 LK_SHARERS_LOCK(1));
256 if (atomic_cmpset_rel_ptr(&lk->lk_lock, x, LK_UNLOCKED))
257 break;
258 continue;
259 }
260
261 /*
262 * We should have a sharer with waiters, so enter the hard
263 * path in order to handle wakeups correctly.
264 */
265 sleepq_lock(&lk->lock_object);
266 x = lk->lk_lock & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
267 v = LK_UNLOCKED;
268
269 /*
270 * If the lock has exclusive waiters, give them preference in
271 * order to avoid deadlock with shared runners up.
272 * If interruptible sleeps left the exclusive queue empty
273 * avoid a starvation for the threads sleeping on the shared
274 * queue by giving them precedence and cleaning up the
275 * exclusive waiters bit anyway.
276 * Please note that lk_exslpfail count may be lying about
277 * the real number of waiters with the LK_SLEEPFAIL flag on
278 * because they may be used in conjuction with interruptible
279 * sleeps so lk_exslpfail might be considered an 'upper limit'
280 * bound, including the edge cases.
281 */
282 realexslp = sleepq_sleepcnt(&lk->lock_object,
283 SQ_EXCLUSIVE_QUEUE);
284 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
285 if (lk->lk_exslpfail < realexslp) {
286 lk->lk_exslpfail = 0;
287 queue = SQ_EXCLUSIVE_QUEUE;
288 v |= (x & LK_SHARED_WAITERS);
289 } else {
290 lk->lk_exslpfail = 0;
291 LOCK_LOG2(lk,
292 "%s: %p has only LK_SLEEPFAIL sleepers",
293 __func__, lk);
294 LOCK_LOG2(lk,
295 "%s: %p waking up threads on the exclusive queue",
296 __func__, lk);
297 wakeup_swapper =
298 sleepq_broadcast(&lk->lock_object,
299 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE);
300 queue = SQ_SHARED_QUEUE;
301 }
302
303 } else {
304
305 /*
306 * Exclusive waiters sleeping with LK_SLEEPFAIL on
307 * and using interruptible sleeps/timeout may have
308 * left spourious lk_exslpfail counts on, so clean
309 * it up anyway.
310 */
311 lk->lk_exslpfail = 0;
312 queue = SQ_SHARED_QUEUE;
313 }
314
315 if (!atomic_cmpset_rel_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x,
316 v)) {
317 sleepq_release(&lk->lock_object);
318 continue;
319 }
320 LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue",
321 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
322 "exclusive");
323 wakeup_swapper |= sleepq_broadcast(&lk->lock_object, SLEEPQ_LK,
324 0, queue);
325 sleepq_release(&lk->lock_object);
326 break;
327 }
328
329 lock_profile_release_lock(&lk->lock_object);
330 return (wakeup_swapper);
331 }
332
333 static void
334 assert_lockmgr(struct lock_object *lock, int what)
335 {
336
337 panic("lockmgr locks do not support assertions");
338 }
339
340 static void
341 lock_lockmgr(struct lock_object *lock, int how)
342 {
343
344 panic("lockmgr locks do not support sleep interlocking");
345 }
346
347 static int
348 unlock_lockmgr(struct lock_object *lock)
349 {
350
351 panic("lockmgr locks do not support sleep interlocking");
352 }
353
354 #ifdef KDTRACE_HOOKS
355 static int
356 owner_lockmgr(struct lock_object *lock, struct thread **owner)
357 {
358
359 panic("lockmgr locks do not support owner inquiring");
360 }
361 #endif
362
363 void
364 lockinit(struct lock *lk, int pri, const char *wmesg, int timo, int flags)
365 {
366 int iflags;
367
368 MPASS((flags & ~LK_INIT_MASK) == 0);
369 ASSERT_ATOMIC_LOAD_PTR(lk->lk_lock,
370 ("%s: lockmgr not aligned for %s: %p", __func__, wmesg,
371 &lk->lk_lock));
372
373 iflags = LO_SLEEPABLE | LO_UPGRADABLE;
374 if (flags & LK_CANRECURSE)
375 iflags |= LO_RECURSABLE;
376 if ((flags & LK_NODUP) == 0)
377 iflags |= LO_DUPOK;
378 if (flags & LK_NOPROFILE)
379 iflags |= LO_NOPROFILE;
380 if ((flags & LK_NOWITNESS) == 0)
381 iflags |= LO_WITNESS;
382 if (flags & LK_QUIET)
383 iflags |= LO_QUIET;
384 iflags |= flags & (LK_ADAPTIVE | LK_NOSHARE);
385
386 lk->lk_lock = LK_UNLOCKED;
387 lk->lk_recurse = 0;
388 lk->lk_exslpfail = 0;
389 lk->lk_timo = timo;
390 lk->lk_pri = pri;
391 lock_init(&lk->lock_object, &lock_class_lockmgr, wmesg, NULL, iflags);
392 STACK_ZERO(lk);
393 }
394
395 /*
396 * XXX: Gross hacks to manipulate external lock flags after
397 * initialization. Used for certain vnode and buf locks.
398 */
399 void
400 lockallowshare(struct lock *lk)
401 {
402
403 lockmgr_assert(lk, KA_XLOCKED);
404 lk->lock_object.lo_flags &= ~LK_NOSHARE;
405 }
406
407 void
408 lockallowrecurse(struct lock *lk)
409 {
410
411 lockmgr_assert(lk, KA_XLOCKED);
412 lk->lock_object.lo_flags |= LO_RECURSABLE;
413 }
414
415 void
416 lockdisablerecurse(struct lock *lk)
417 {
418
419 lockmgr_assert(lk, KA_XLOCKED);
420 lk->lock_object.lo_flags &= ~LO_RECURSABLE;
421 }
422
423 void
424 lockdestroy(struct lock *lk)
425 {
426
427 KASSERT(lk->lk_lock == LK_UNLOCKED, ("lockmgr still held"));
428 KASSERT(lk->lk_recurse == 0, ("lockmgr still recursed"));
429 KASSERT(lk->lk_exslpfail == 0, ("lockmgr still exclusive waiters"));
430 lock_destroy(&lk->lock_object);
431 }
432
433 int
434 __lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk,
435 const char *wmesg, int pri, int timo, const char *file, int line)
436 {
437 GIANT_DECLARE;
438 struct lock_class *class;
439 const char *iwmesg;
440 uintptr_t tid, v, x;
441 u_int op, realexslp;
442 int error, ipri, itimo, queue, wakeup_swapper;
443 #ifdef LOCK_PROFILING
444 uint64_t waittime = 0;
445 int contested = 0;
446 #endif
447 #ifdef ADAPTIVE_LOCKMGRS
448 volatile struct thread *owner;
449 u_int i, spintries = 0;
450 #endif
451
452 error = 0;
453 tid = (uintptr_t)curthread;
454 op = (flags & LK_TYPE_MASK);
455 iwmesg = (wmesg == LK_WMESG_DEFAULT) ? lk->lock_object.lo_name : wmesg;
456 ipri = (pri == LK_PRIO_DEFAULT) ? lk->lk_pri : pri;
457 itimo = (timo == LK_TIMO_DEFAULT) ? lk->lk_timo : timo;
458
459 MPASS((flags & ~LK_TOTAL_MASK) == 0);
460 KASSERT((op & (op - 1)) == 0,
461 ("%s: Invalid requested operation @ %s:%d", __func__, file, line));
462 KASSERT((flags & (LK_NOWAIT | LK_SLEEPFAIL)) == 0 ||
463 (op != LK_DOWNGRADE && op != LK_RELEASE),
464 ("%s: Invalid flags in regard of the operation desired @ %s:%d",
465 __func__, file, line));
466 KASSERT((flags & LK_INTERLOCK) == 0 || ilk != NULL,
467 ("%s: LK_INTERLOCK passed without valid interlock @ %s:%d",
468 __func__, file, line));
469
470 class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL;
471 if (panicstr != NULL) {
472 if (flags & LK_INTERLOCK)
473 class->lc_unlock(ilk);
474 return (0);
475 }
476
477 if (lk->lock_object.lo_flags & LK_NOSHARE) {
478 switch (op) {
479 case LK_SHARED:
480 op = LK_EXCLUSIVE;
481 break;
482 case LK_UPGRADE:
483 case LK_DOWNGRADE:
484 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED,
485 file, line);
486 return (0);
487 }
488 }
489
490 wakeup_swapper = 0;
491 switch (op) {
492 case LK_SHARED:
493 if (LK_CAN_WITNESS(flags))
494 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
495 file, line, ilk);
496 for (;;) {
497 x = lk->lk_lock;
498
499 /*
500 * If no other thread has an exclusive lock, or
501 * no exclusive waiter is present, bump the count of
502 * sharers. Since we have to preserve the state of
503 * waiters, if we fail to acquire the shared lock
504 * loop back and retry.
505 */
506 if (LK_CAN_SHARE(x)) {
507 if (atomic_cmpset_acq_ptr(&lk->lk_lock, x,
508 x + LK_ONE_SHARER))
509 break;
510 continue;
511 }
512 lock_profile_obtain_lock_failed(&lk->lock_object,
513 &contested, &waittime);
514
515 /*
516 * If the lock is already held by curthread in
517 * exclusive way avoid a deadlock.
518 */
519 if (LK_HOLDER(x) == tid) {
520 LOCK_LOG2(lk,
521 "%s: %p already held in exclusive mode",
522 __func__, lk);
523 error = EDEADLK;
524 break;
525 }
526
527 /*
528 * If the lock is expected to not sleep just give up
529 * and return.
530 */
531 if (LK_TRYOP(flags)) {
532 LOCK_LOG2(lk, "%s: %p fails the try operation",
533 __func__, lk);
534 error = EBUSY;
535 break;
536 }
537
538 #ifdef ADAPTIVE_LOCKMGRS
539 /*
540 * If the owner is running on another CPU, spin until
541 * the owner stops running or the state of the lock
542 * changes. We need a double-state handle here
543 * because for a failed acquisition the lock can be
544 * either held in exclusive mode or shared mode
545 * (for the writer starvation avoidance technique).
546 */
547 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
548 LK_HOLDER(x) != LK_KERNPROC) {
549 owner = (struct thread *)LK_HOLDER(x);
550 if (LOCK_LOG_TEST(&lk->lock_object, 0))
551 CTR3(KTR_LOCK,
552 "%s: spinning on %p held by %p",
553 __func__, lk, owner);
554
555 /*
556 * If we are holding also an interlock drop it
557 * in order to avoid a deadlock if the lockmgr
558 * owner is adaptively spinning on the
559 * interlock itself.
560 */
561 if (flags & LK_INTERLOCK) {
562 class->lc_unlock(ilk);
563 flags &= ~LK_INTERLOCK;
564 }
565 GIANT_SAVE();
566 while (LK_HOLDER(lk->lk_lock) ==
567 (uintptr_t)owner && TD_IS_RUNNING(owner))
568 cpu_spinwait();
569 GIANT_RESTORE();
570 continue;
571 } else if (LK_CAN_ADAPT(lk, flags) &&
572 (x & LK_SHARE) != 0 && LK_SHARERS(x) &&
573 spintries < ALK_RETRIES) {
574 if (flags & LK_INTERLOCK) {
575 class->lc_unlock(ilk);
576 flags &= ~LK_INTERLOCK;
577 }
578 GIANT_SAVE();
579 spintries++;
580 for (i = 0; i < ALK_LOOPS; i++) {
581 if (LOCK_LOG_TEST(&lk->lock_object, 0))
582 CTR4(KTR_LOCK,
583 "%s: shared spinning on %p with %u and %u",
584 __func__, lk, spintries, i);
585 x = lk->lk_lock;
586 if ((x & LK_SHARE) == 0 ||
587 LK_CAN_SHARE(x) != 0)
588 break;
589 cpu_spinwait();
590 }
591 GIANT_RESTORE();
592 if (i != ALK_LOOPS)
593 continue;
594 }
595 #endif
596
597 /*
598 * Acquire the sleepqueue chain lock because we
599 * probabilly will need to manipulate waiters flags.
600 */
601 sleepq_lock(&lk->lock_object);
602 x = lk->lk_lock;
603
604 /*
605 * if the lock can be acquired in shared mode, try
606 * again.
607 */
608 if (LK_CAN_SHARE(x)) {
609 sleepq_release(&lk->lock_object);
610 continue;
611 }
612
613 #ifdef ADAPTIVE_LOCKMGRS
614 /*
615 * The current lock owner might have started executing
616 * on another CPU (or the lock could have changed
617 * owner) while we were waiting on the turnstile
618 * chain lock. If so, drop the turnstile lock and try
619 * again.
620 */
621 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
622 LK_HOLDER(x) != LK_KERNPROC) {
623 owner = (struct thread *)LK_HOLDER(x);
624 if (TD_IS_RUNNING(owner)) {
625 sleepq_release(&lk->lock_object);
626 continue;
627 }
628 }
629 #endif
630
631 /*
632 * Try to set the LK_SHARED_WAITERS flag. If we fail,
633 * loop back and retry.
634 */
635 if ((x & LK_SHARED_WAITERS) == 0) {
636 if (!atomic_cmpset_acq_ptr(&lk->lk_lock, x,
637 x | LK_SHARED_WAITERS)) {
638 sleepq_release(&lk->lock_object);
639 continue;
640 }
641 LOCK_LOG2(lk, "%s: %p set shared waiters flag",
642 __func__, lk);
643 }
644
645 /*
646 * As far as we have been unable to acquire the
647 * shared lock and the shared waiters flag is set,
648 * we will sleep.
649 */
650 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
651 SQ_SHARED_QUEUE);
652 flags &= ~LK_INTERLOCK;
653 if (error) {
654 LOCK_LOG3(lk,
655 "%s: interrupted sleep for %p with %d",
656 __func__, lk, error);
657 break;
658 }
659 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
660 __func__, lk);
661 }
662 if (error == 0) {
663 lock_profile_obtain_lock_success(&lk->lock_object,
664 contested, waittime, file, line);
665 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, file,
666 line);
667 WITNESS_LOCK(&lk->lock_object, LK_TRYWIT(flags), file,
668 line);
669 TD_LOCKS_INC(curthread);
670 TD_SLOCKS_INC(curthread);
671 STACK_SAVE(lk);
672 }
673 break;
674 case LK_UPGRADE:
675 _lockmgr_assert(lk, KA_SLOCKED, file, line);
676 v = lk->lk_lock;
677 x = v & LK_ALL_WAITERS;
678 v &= LK_EXCLUSIVE_SPINNERS;
679
680 /*
681 * Try to switch from one shared lock to an exclusive one.
682 * We need to preserve waiters flags during the operation.
683 */
684 if (atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x | v,
685 tid | x)) {
686 LOCK_LOG_LOCK("XUPGRADE", &lk->lock_object, 0, 0, file,
687 line);
688 WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE |
689 LK_TRYWIT(flags), file, line);
690 TD_SLOCKS_DEC(curthread);
691 break;
692 }
693
694 /*
695 * We have been unable to succeed in upgrading, so just
696 * give up the shared lock.
697 */
698 wakeup_swapper |= wakeupshlk(lk, file, line);
699
700 /* FALLTHROUGH */
701 case LK_EXCLUSIVE:
702 if (LK_CAN_WITNESS(flags))
703 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
704 LOP_EXCLUSIVE, file, line, ilk);
705
706 /*
707 * If curthread already holds the lock and this one is
708 * allowed to recurse, simply recurse on it.
709 */
710 if (lockmgr_xlocked(lk)) {
711 if ((flags & LK_CANRECURSE) == 0 &&
712 (lk->lock_object.lo_flags & LO_RECURSABLE) == 0) {
713
714 /*
715 * If the lock is expected to not panic just
716 * give up and return.
717 */
718 if (LK_TRYOP(flags)) {
719 LOCK_LOG2(lk,
720 "%s: %p fails the try operation",
721 __func__, lk);
722 error = EBUSY;
723 break;
724 }
725 if (flags & LK_INTERLOCK)
726 class->lc_unlock(ilk);
727 panic("%s: recursing on non recursive lockmgr %s @ %s:%d\n",
728 __func__, iwmesg, file, line);
729 }
730 lk->lk_recurse++;
731 LOCK_LOG2(lk, "%s: %p recursing", __func__, lk);
732 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0,
733 lk->lk_recurse, file, line);
734 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
735 LK_TRYWIT(flags), file, line);
736 TD_LOCKS_INC(curthread);
737 break;
738 }
739
740 while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED,
741 tid)) {
742 lock_profile_obtain_lock_failed(&lk->lock_object,
743 &contested, &waittime);
744
745 /*
746 * If the lock is expected to not sleep just give up
747 * and return.
748 */
749 if (LK_TRYOP(flags)) {
750 LOCK_LOG2(lk, "%s: %p fails the try operation",
751 __func__, lk);
752 error = EBUSY;
753 break;
754 }
755
756 #ifdef ADAPTIVE_LOCKMGRS
757 /*
758 * If the owner is running on another CPU, spin until
759 * the owner stops running or the state of the lock
760 * changes.
761 */
762 x = lk->lk_lock;
763 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
764 LK_HOLDER(x) != LK_KERNPROC) {
765 owner = (struct thread *)LK_HOLDER(x);
766 if (LOCK_LOG_TEST(&lk->lock_object, 0))
767 CTR3(KTR_LOCK,
768 "%s: spinning on %p held by %p",
769 __func__, lk, owner);
770
771 /*
772 * If we are holding also an interlock drop it
773 * in order to avoid a deadlock if the lockmgr
774 * owner is adaptively spinning on the
775 * interlock itself.
776 */
777 if (flags & LK_INTERLOCK) {
778 class->lc_unlock(ilk);
779 flags &= ~LK_INTERLOCK;
780 }
781 GIANT_SAVE();
782 while (LK_HOLDER(lk->lk_lock) ==
783 (uintptr_t)owner && TD_IS_RUNNING(owner))
784 cpu_spinwait();
785 GIANT_RESTORE();
786 continue;
787 } else if (LK_CAN_ADAPT(lk, flags) &&
788 (x & LK_SHARE) != 0 && LK_SHARERS(x) &&
789 spintries < ALK_RETRIES) {
790 if ((x & LK_EXCLUSIVE_SPINNERS) == 0 &&
791 !atomic_cmpset_ptr(&lk->lk_lock, x,
792 x | LK_EXCLUSIVE_SPINNERS))
793 continue;
794 if (flags & LK_INTERLOCK) {
795 class->lc_unlock(ilk);
796 flags &= ~LK_INTERLOCK;
797 }
798 GIANT_SAVE();
799 spintries++;
800 for (i = 0; i < ALK_LOOPS; i++) {
801 if (LOCK_LOG_TEST(&lk->lock_object, 0))
802 CTR4(KTR_LOCK,
803 "%s: shared spinning on %p with %u and %u",
804 __func__, lk, spintries, i);
805 if ((lk->lk_lock &
806 LK_EXCLUSIVE_SPINNERS) == 0)
807 break;
808 cpu_spinwait();
809 }
810 GIANT_RESTORE();
811 if (i != ALK_LOOPS)
812 continue;
813 }
814 #endif
815
816 /*
817 * Acquire the sleepqueue chain lock because we
818 * probabilly will need to manipulate waiters flags.
819 */
820 sleepq_lock(&lk->lock_object);
821 x = lk->lk_lock;
822
823 /*
824 * if the lock has been released while we spun on
825 * the sleepqueue chain lock just try again.
826 */
827 if (x == LK_UNLOCKED) {
828 sleepq_release(&lk->lock_object);
829 continue;
830 }
831
832 #ifdef ADAPTIVE_LOCKMGRS
833 /*
834 * The current lock owner might have started executing
835 * on another CPU (or the lock could have changed
836 * owner) while we were waiting on the turnstile
837 * chain lock. If so, drop the turnstile lock and try
838 * again.
839 */
840 if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
841 LK_HOLDER(x) != LK_KERNPROC) {
842 owner = (struct thread *)LK_HOLDER(x);
843 if (TD_IS_RUNNING(owner)) {
844 sleepq_release(&lk->lock_object);
845 continue;
846 }
847 }
848 #endif
849
850 /*
851 * The lock can be in the state where there is a
852 * pending queue of waiters, but still no owner.
853 * This happens when the lock is contested and an
854 * owner is going to claim the lock.
855 * If curthread is the one successfully acquiring it
856 * claim lock ownership and return, preserving waiters
857 * flags.
858 */
859 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
860 if ((x & ~v) == LK_UNLOCKED) {
861 v &= ~LK_EXCLUSIVE_SPINNERS;
862 if (atomic_cmpset_acq_ptr(&lk->lk_lock, x,
863 tid | v)) {
864 sleepq_release(&lk->lock_object);
865 LOCK_LOG2(lk,
866 "%s: %p claimed by a new writer",
867 __func__, lk);
868 break;
869 }
870 sleepq_release(&lk->lock_object);
871 continue;
872 }
873
874 /*
875 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we
876 * fail, loop back and retry.
877 */
878 if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
879 if (!atomic_cmpset_ptr(&lk->lk_lock, x,
880 x | LK_EXCLUSIVE_WAITERS)) {
881 sleepq_release(&lk->lock_object);
882 continue;
883 }
884 LOCK_LOG2(lk, "%s: %p set excl waiters flag",
885 __func__, lk);
886 }
887
888 /*
889 * As far as we have been unable to acquire the
890 * exclusive lock and the exclusive waiters flag
891 * is set, we will sleep.
892 */
893 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
894 SQ_EXCLUSIVE_QUEUE);
895 flags &= ~LK_INTERLOCK;
896 if (error) {
897 LOCK_LOG3(lk,
898 "%s: interrupted sleep for %p with %d",
899 __func__, lk, error);
900 break;
901 }
902 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
903 __func__, lk);
904 }
905 if (error == 0) {
906 lock_profile_obtain_lock_success(&lk->lock_object,
907 contested, waittime, file, line);
908 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0,
909 lk->lk_recurse, file, line);
910 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
911 LK_TRYWIT(flags), file, line);
912 TD_LOCKS_INC(curthread);
913 STACK_SAVE(lk);
914 }
915 break;
916 case LK_DOWNGRADE:
917 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, file, line);
918 LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line);
919 WITNESS_DOWNGRADE(&lk->lock_object, 0, file, line);
920 TD_SLOCKS_INC(curthread);
921
922 /*
923 * In order to preserve waiters flags, just spin.
924 */
925 for (;;) {
926 x = lk->lk_lock;
927 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
928 x &= LK_ALL_WAITERS;
929 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
930 LK_SHARERS_LOCK(1) | x))
931 break;
932 cpu_spinwait();
933 }
934 break;
935 case LK_RELEASE:
936 _lockmgr_assert(lk, KA_LOCKED, file, line);
937 x = lk->lk_lock;
938
939 if ((x & LK_SHARE) == 0) {
940
941 /*
942 * As first option, treact the lock as if it has not
943 * any waiter.
944 * Fix-up the tid var if the lock has been disowned.
945 */
946 if (LK_HOLDER(x) == LK_KERNPROC)
947 tid = LK_KERNPROC;
948 else {
949 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE,
950 file, line);
951 TD_LOCKS_DEC(curthread);
952 }
953 LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0,
954 lk->lk_recurse, file, line);
955
956 /*
957 * The lock is held in exclusive mode.
958 * If the lock is recursed also, then unrecurse it.
959 */
960 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) {
961 LOCK_LOG2(lk, "%s: %p unrecursing", __func__,
962 lk);
963 lk->lk_recurse--;
964 break;
965 }
966 if (tid != LK_KERNPROC)
967 lock_profile_release_lock(&lk->lock_object);
968
969 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid,
970 LK_UNLOCKED))
971 break;
972
973 sleepq_lock(&lk->lock_object);
974 x = lk->lk_lock;
975 v = LK_UNLOCKED;
976
977 /*
978 * If the lock has exclusive waiters, give them
979 * preference in order to avoid deadlock with
980 * shared runners up.
981 * If interruptible sleeps left the exclusive queue
982 * empty avoid a starvation for the threads sleeping
983 * on the shared queue by giving them precedence
984 * and cleaning up the exclusive waiters bit anyway.
985 * Please note that lk_exslpfail count may be lying
986 * about the real number of waiters with the
987 * LK_SLEEPFAIL flag on because they may be used in
988 * conjuction with interruptible sleeps so
989 * lk_exslpfail might be considered an 'upper limit'
990 * bound, including the edge cases.
991 */
992 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
993 realexslp = sleepq_sleepcnt(&lk->lock_object,
994 SQ_EXCLUSIVE_QUEUE);
995 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
996 if (lk->lk_exslpfail < realexslp) {
997 lk->lk_exslpfail = 0;
998 queue = SQ_EXCLUSIVE_QUEUE;
999 v |= (x & LK_SHARED_WAITERS);
1000 } else {
1001 lk->lk_exslpfail = 0;
1002 LOCK_LOG2(lk,
1003 "%s: %p has only LK_SLEEPFAIL sleepers",
1004 __func__, lk);
1005 LOCK_LOG2(lk,
1006 "%s: %p waking up threads on the exclusive queue",
1007 __func__, lk);
1008 wakeup_swapper =
1009 sleepq_broadcast(&lk->lock_object,
1010 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE);
1011 queue = SQ_SHARED_QUEUE;
1012 }
1013 } else {
1014
1015 /*
1016 * Exclusive waiters sleeping with LK_SLEEPFAIL
1017 * on and using interruptible sleeps/timeout
1018 * may have left spourious lk_exslpfail counts
1019 * on, so clean it up anyway.
1020 */
1021 lk->lk_exslpfail = 0;
1022 queue = SQ_SHARED_QUEUE;
1023 }
1024
1025 LOCK_LOG3(lk,
1026 "%s: %p waking up threads on the %s queue",
1027 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
1028 "exclusive");
1029 atomic_store_rel_ptr(&lk->lk_lock, v);
1030 wakeup_swapper |= sleepq_broadcast(&lk->lock_object,
1031 SLEEPQ_LK, 0, queue);
1032 sleepq_release(&lk->lock_object);
1033 break;
1034 } else
1035 wakeup_swapper = wakeupshlk(lk, file, line);
1036 break;
1037 case LK_DRAIN:
1038 if (LK_CAN_WITNESS(flags))
1039 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
1040 LOP_EXCLUSIVE, file, line, ilk);
1041
1042 /*
1043 * Trying to drain a lock we already own will result in a
1044 * deadlock.
1045 */
1046 if (lockmgr_xlocked(lk)) {
1047 if (flags & LK_INTERLOCK)
1048 class->lc_unlock(ilk);
1049 panic("%s: draining %s with the lock held @ %s:%d\n",
1050 __func__, iwmesg, file, line);
1051 }
1052
1053 while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) {
1054 lock_profile_obtain_lock_failed(&lk->lock_object,
1055 &contested, &waittime);
1056
1057 /*
1058 * If the lock is expected to not sleep just give up
1059 * and return.
1060 */
1061 if (LK_TRYOP(flags)) {
1062 LOCK_LOG2(lk, "%s: %p fails the try operation",
1063 __func__, lk);
1064 error = EBUSY;
1065 break;
1066 }
1067
1068 /*
1069 * Acquire the sleepqueue chain lock because we
1070 * probabilly will need to manipulate waiters flags.
1071 */
1072 sleepq_lock(&lk->lock_object);
1073 x = lk->lk_lock;
1074
1075 /*
1076 * if the lock has been released while we spun on
1077 * the sleepqueue chain lock just try again.
1078 */
1079 if (x == LK_UNLOCKED) {
1080 sleepq_release(&lk->lock_object);
1081 continue;
1082 }
1083
1084 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
1085 if ((x & ~v) == LK_UNLOCKED) {
1086 v = (x & ~LK_EXCLUSIVE_SPINNERS);
1087
1088 /*
1089 * If interruptible sleeps left the exclusive
1090 * queue empty avoid a starvation for the
1091 * threads sleeping on the shared queue by
1092 * giving them precedence and cleaning up the
1093 * exclusive waiters bit anyway.
1094 * Please note that lk_exslpfail count may be
1095 * lying about the real number of waiters with
1096 * the LK_SLEEPFAIL flag on because they may
1097 * be used in conjuction with interruptible
1098 * sleeps so lk_exslpfail might be considered
1099 * an 'upper limit' bound, including the edge
1100 * cases.
1101 */
1102 if (v & LK_EXCLUSIVE_WAITERS) {
1103 queue = SQ_EXCLUSIVE_QUEUE;
1104 v &= ~LK_EXCLUSIVE_WAITERS;
1105 } else {
1106
1107 /*
1108 * Exclusive waiters sleeping with
1109 * LK_SLEEPFAIL on and using
1110 * interruptible sleeps/timeout may
1111 * have left spourious lk_exslpfail
1112 * counts on, so clean it up anyway.
1113 */
1114 MPASS(v & LK_SHARED_WAITERS);
1115 lk->lk_exslpfail = 0;
1116 queue = SQ_SHARED_QUEUE;
1117 v &= ~LK_SHARED_WAITERS;
1118 }
1119 if (queue == SQ_EXCLUSIVE_QUEUE) {
1120 realexslp =
1121 sleepq_sleepcnt(&lk->lock_object,
1122 SQ_EXCLUSIVE_QUEUE);
1123 if (lk->lk_exslpfail >= realexslp) {
1124 lk->lk_exslpfail = 0;
1125 queue = SQ_SHARED_QUEUE;
1126 v &= ~LK_SHARED_WAITERS;
1127 if (realexslp != 0) {
1128 LOCK_LOG2(lk,
1129 "%s: %p has only LK_SLEEPFAIL sleepers",
1130 __func__, lk);
1131 LOCK_LOG2(lk,
1132 "%s: %p waking up threads on the exclusive queue",
1133 __func__, lk);
1134 wakeup_swapper =
1135 sleepq_broadcast(
1136 &lk->lock_object,
1137 SLEEPQ_LK, 0,
1138 SQ_EXCLUSIVE_QUEUE);
1139 }
1140 } else
1141 lk->lk_exslpfail = 0;
1142 }
1143 if (!atomic_cmpset_ptr(&lk->lk_lock, x, v)) {
1144 sleepq_release(&lk->lock_object);
1145 continue;
1146 }
1147 LOCK_LOG3(lk,
1148 "%s: %p waking up all threads on the %s queue",
1149 __func__, lk, queue == SQ_SHARED_QUEUE ?
1150 "shared" : "exclusive");
1151 wakeup_swapper |= sleepq_broadcast(
1152 &lk->lock_object, SLEEPQ_LK, 0, queue);
1153
1154 /*
1155 * If shared waiters have been woken up we need
1156 * to wait for one of them to acquire the lock
1157 * before to set the exclusive waiters in
1158 * order to avoid a deadlock.
1159 */
1160 if (queue == SQ_SHARED_QUEUE) {
1161 for (v = lk->lk_lock;
1162 (v & LK_SHARE) && !LK_SHARERS(v);
1163 v = lk->lk_lock)
1164 cpu_spinwait();
1165 }
1166 }
1167
1168 /*
1169 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we
1170 * fail, loop back and retry.
1171 */
1172 if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
1173 if (!atomic_cmpset_ptr(&lk->lk_lock, x,
1174 x | LK_EXCLUSIVE_WAITERS)) {
1175 sleepq_release(&lk->lock_object);
1176 continue;
1177 }
1178 LOCK_LOG2(lk, "%s: %p set drain waiters flag",
1179 __func__, lk);
1180 }
1181
1182 /*
1183 * As far as we have been unable to acquire the
1184 * exclusive lock and the exclusive waiters flag
1185 * is set, we will sleep.
1186 */
1187 if (flags & LK_INTERLOCK) {
1188 class->lc_unlock(ilk);
1189 flags &= ~LK_INTERLOCK;
1190 }
1191 GIANT_SAVE();
1192 sleepq_add(&lk->lock_object, NULL, iwmesg, SLEEPQ_LK,
1193 SQ_EXCLUSIVE_QUEUE);
1194 sleepq_wait(&lk->lock_object, ipri & PRIMASK);
1195 GIANT_RESTORE();
1196 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
1197 __func__, lk);
1198 }
1199
1200 if (error == 0) {
1201 lock_profile_obtain_lock_success(&lk->lock_object,
1202 contested, waittime, file, line);
1203 LOCK_LOG_LOCK("DRAIN", &lk->lock_object, 0,
1204 lk->lk_recurse, file, line);
1205 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
1206 LK_TRYWIT(flags), file, line);
1207 TD_LOCKS_INC(curthread);
1208 STACK_SAVE(lk);
1209 }
1210 break;
1211 default:
1212 if (flags & LK_INTERLOCK)
1213 class->lc_unlock(ilk);
1214 panic("%s: unknown lockmgr request 0x%x\n", __func__, op);
1215 }
1216
1217 if (flags & LK_INTERLOCK)
1218 class->lc_unlock(ilk);
1219 if (wakeup_swapper)
1220 kick_proc0();
1221
1222 return (error);
1223 }
1224
1225 void
1226 _lockmgr_disown(struct lock *lk, const char *file, int line)
1227 {
1228 uintptr_t tid, x;
1229
1230 tid = (uintptr_t)curthread;
1231 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, file, line);
1232
1233 /*
1234 * If the owner is already LK_KERNPROC just skip the whole operation.
1235 */
1236 if (LK_HOLDER(lk->lk_lock) != tid)
1237 return;
1238 lock_profile_release_lock(&lk->lock_object);
1239 LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line);
1240 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
1241 TD_LOCKS_DEC(curthread);
1242 STACK_SAVE(lk);
1243
1244 /*
1245 * In order to preserve waiters flags, just spin.
1246 */
1247 for (;;) {
1248 x = lk->lk_lock;
1249 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
1250 x &= LK_ALL_WAITERS;
1251 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
1252 LK_KERNPROC | x))
1253 return;
1254 cpu_spinwait();
1255 }
1256 }
1257
1258 void
1259 lockmgr_printinfo(struct lock *lk)
1260 {
1261 struct thread *td;
1262 uintptr_t x;
1263
1264 if (lk->lk_lock == LK_UNLOCKED)
1265 printf("lock type %s: UNLOCKED\n", lk->lock_object.lo_name);
1266 else if (lk->lk_lock & LK_SHARE)
1267 printf("lock type %s: SHARED (count %ju)\n",
1268 lk->lock_object.lo_name,
1269 (uintmax_t)LK_SHARERS(lk->lk_lock));
1270 else {
1271 td = lockmgr_xholder(lk);
1272 printf("lock type %s: EXCL by thread %p (pid %d)\n",
1273 lk->lock_object.lo_name, td, td->td_proc->p_pid);
1274 }
1275
1276 x = lk->lk_lock;
1277 if (x & LK_EXCLUSIVE_WAITERS)
1278 printf(" with exclusive waiters pending\n");
1279 if (x & LK_SHARED_WAITERS)
1280 printf(" with shared waiters pending\n");
1281 if (x & LK_EXCLUSIVE_SPINNERS)
1282 printf(" with exclusive spinners pending\n");
1283
1284 STACK_PRINT(lk);
1285 }
1286
1287 int
1288 lockstatus(struct lock *lk)
1289 {
1290 uintptr_t v, x;
1291 int ret;
1292
1293 ret = LK_SHARED;
1294 x = lk->lk_lock;
1295 v = LK_HOLDER(x);
1296
1297 if ((x & LK_SHARE) == 0) {
1298 if (v == (uintptr_t)curthread || v == LK_KERNPROC)
1299 ret = LK_EXCLUSIVE;
1300 else
1301 ret = LK_EXCLOTHER;
1302 } else if (x == LK_UNLOCKED)
1303 ret = 0;
1304
1305 return (ret);
1306 }
1307
1308 #ifdef INVARIANT_SUPPORT
1309
1310 FEATURE(invariant_support,
1311 "Support for modules compiled with INVARIANTS option");
1312
1313 #ifndef INVARIANTS
1314 #undef _lockmgr_assert
1315 #endif
1316
1317 void
1318 _lockmgr_assert(struct lock *lk, int what, const char *file, int line)
1319 {
1320 int slocked = 0;
1321
1322 if (panicstr != NULL)
1323 return;
1324 switch (what) {
1325 case KA_SLOCKED:
1326 case KA_SLOCKED | KA_NOTRECURSED:
1327 case KA_SLOCKED | KA_RECURSED:
1328 slocked = 1;
1329 case KA_LOCKED:
1330 case KA_LOCKED | KA_NOTRECURSED:
1331 case KA_LOCKED | KA_RECURSED:
1332 #ifdef WITNESS
1333
1334 /*
1335 * We cannot trust WITNESS if the lock is held in exclusive
1336 * mode and a call to lockmgr_disown() happened.
1337 * Workaround this skipping the check if the lock is held in
1338 * exclusive mode even for the KA_LOCKED case.
1339 */
1340 if (slocked || (lk->lk_lock & LK_SHARE)) {
1341 witness_assert(&lk->lock_object, what, file, line);
1342 break;
1343 }
1344 #endif
1345 if (lk->lk_lock == LK_UNLOCKED ||
1346 ((lk->lk_lock & LK_SHARE) == 0 && (slocked ||
1347 (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk)))))
1348 panic("Lock %s not %slocked @ %s:%d\n",
1349 lk->lock_object.lo_name, slocked ? "share" : "",
1350 file, line);
1351
1352 if ((lk->lk_lock & LK_SHARE) == 0) {
1353 if (lockmgr_recursed(lk)) {
1354 if (what & KA_NOTRECURSED)
1355 panic("Lock %s recursed @ %s:%d\n",
1356 lk->lock_object.lo_name, file,
1357 line);
1358 } else if (what & KA_RECURSED)
1359 panic("Lock %s not recursed @ %s:%d\n",
1360 lk->lock_object.lo_name, file, line);
1361 }
1362 break;
1363 case KA_XLOCKED:
1364 case KA_XLOCKED | KA_NOTRECURSED:
1365 case KA_XLOCKED | KA_RECURSED:
1366 if (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk))
1367 panic("Lock %s not exclusively locked @ %s:%d\n",
1368 lk->lock_object.lo_name, file, line);
1369 if (lockmgr_recursed(lk)) {
1370 if (what & KA_NOTRECURSED)
1371 panic("Lock %s recursed @ %s:%d\n",
1372 lk->lock_object.lo_name, file, line);
1373 } else if (what & KA_RECURSED)
1374 panic("Lock %s not recursed @ %s:%d\n",
1375 lk->lock_object.lo_name, file, line);
1376 break;
1377 case KA_UNLOCKED:
1378 if (lockmgr_xlocked(lk) || lockmgr_disowned(lk))
1379 panic("Lock %s exclusively locked @ %s:%d\n",
1380 lk->lock_object.lo_name, file, line);
1381 break;
1382 default:
1383 panic("Unknown lockmgr assertion: %d @ %s:%d\n", what, file,
1384 line);
1385 }
1386 }
1387 #endif
1388
1389 #ifdef DDB
1390 int
1391 lockmgr_chain(struct thread *td, struct thread **ownerp)
1392 {
1393 struct lock *lk;
1394
1395 lk = td->td_wchan;
1396
1397 if (LOCK_CLASS(&lk->lock_object) != &lock_class_lockmgr)
1398 return (0);
1399 db_printf("blocked on lockmgr %s", lk->lock_object.lo_name);
1400 if (lk->lk_lock & LK_SHARE)
1401 db_printf("SHARED (count %ju)\n",
1402 (uintmax_t)LK_SHARERS(lk->lk_lock));
1403 else
1404 db_printf("EXCL\n");
1405 *ownerp = lockmgr_xholder(lk);
1406
1407 return (1);
1408 }
1409
1410 static void
1411 db_show_lockmgr(struct lock_object *lock)
1412 {
1413 struct thread *td;
1414 struct lock *lk;
1415
1416 lk = (struct lock *)lock;
1417
1418 db_printf(" state: ");
1419 if (lk->lk_lock == LK_UNLOCKED)
1420 db_printf("UNLOCKED\n");
1421 else if (lk->lk_lock & LK_SHARE)
1422 db_printf("SLOCK: %ju\n", (uintmax_t)LK_SHARERS(lk->lk_lock));
1423 else {
1424 td = lockmgr_xholder(lk);
1425 if (td == (struct thread *)LK_KERNPROC)
1426 db_printf("XLOCK: LK_KERNPROC\n");
1427 else
1428 db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td,
1429 td->td_tid, td->td_proc->p_pid,
1430 td->td_proc->p_comm);
1431 if (lockmgr_recursed(lk))
1432 db_printf(" recursed: %d\n", lk->lk_recurse);
1433 }
1434 db_printf(" waiters: ");
1435 switch (lk->lk_lock & LK_ALL_WAITERS) {
1436 case LK_SHARED_WAITERS:
1437 db_printf("shared\n");
1438 break;
1439 case LK_EXCLUSIVE_WAITERS:
1440 db_printf("exclusive\n");
1441 break;
1442 case LK_ALL_WAITERS:
1443 db_printf("shared and exclusive\n");
1444 break;
1445 default:
1446 db_printf("none\n");
1447 }
1448 db_printf(" spinners: ");
1449 if (lk->lk_lock & LK_EXCLUSIVE_SPINNERS)
1450 db_printf("exclusive\n");
1451 else
1452 db_printf("none\n");
1453 }
1454 #endif
Cache object: 22856697f16365ffe4c5ab0c9f83ff7f
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