1 /*-
2 * Copyright (c) 2007 Stephan Uphoff <ups@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, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the author nor the names of any co-contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 /*
31 * Machine independent bits of reader/writer lock implementation.
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD: releng/10.3/sys/kern/kern_rmlock.c 288958 2015-10-06 22:28:28Z jhb $");
36
37 #include "opt_ddb.h"
38 #include "opt_kdtrace.h"
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42
43 #include <sys/kernel.h>
44 #include <sys/kdb.h>
45 #include <sys/ktr.h>
46 #include <sys/lock.h>
47 #include <sys/mutex.h>
48 #include <sys/proc.h>
49 #include <sys/rmlock.h>
50 #include <sys/sched.h>
51 #include <sys/smp.h>
52 #include <sys/turnstile.h>
53 #include <sys/lock_profile.h>
54 #include <machine/cpu.h>
55
56 #ifdef DDB
57 #include <ddb/ddb.h>
58 #endif
59
60 /*
61 * A cookie to mark destroyed rmlocks. This is stored in the head of
62 * rm_activeReaders.
63 */
64 #define RM_DESTROYED ((void *)0xdead)
65
66 #define rm_destroyed(rm) \
67 (LIST_FIRST(&(rm)->rm_activeReaders) == RM_DESTROYED)
68
69 #define RMPF_ONQUEUE 1
70 #define RMPF_SIGNAL 2
71
72 #ifndef INVARIANTS
73 #define _rm_assert(c, what, file, line)
74 #endif
75
76 static void assert_rm(const struct lock_object *lock, int what);
77 #ifdef DDB
78 static void db_show_rm(const struct lock_object *lock);
79 #endif
80 static void lock_rm(struct lock_object *lock, uintptr_t how);
81 #ifdef KDTRACE_HOOKS
82 static int owner_rm(const struct lock_object *lock, struct thread **owner);
83 #endif
84 static uintptr_t unlock_rm(struct lock_object *lock);
85
86 struct lock_class lock_class_rm = {
87 .lc_name = "rm",
88 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
89 .lc_assert = assert_rm,
90 #ifdef DDB
91 .lc_ddb_show = db_show_rm,
92 #endif
93 .lc_lock = lock_rm,
94 .lc_unlock = unlock_rm,
95 #ifdef KDTRACE_HOOKS
96 .lc_owner = owner_rm,
97 #endif
98 };
99
100 struct lock_class lock_class_rm_sleepable = {
101 .lc_name = "sleepable rm",
102 .lc_flags = LC_SLEEPLOCK | LC_SLEEPABLE | LC_RECURSABLE,
103 .lc_assert = assert_rm,
104 #ifdef DDB
105 .lc_ddb_show = db_show_rm,
106 #endif
107 .lc_lock = lock_rm,
108 .lc_unlock = unlock_rm,
109 #ifdef KDTRACE_HOOKS
110 .lc_owner = owner_rm,
111 #endif
112 };
113
114 static void
115 assert_rm(const struct lock_object *lock, int what)
116 {
117
118 rm_assert((const struct rmlock *)lock, what);
119 }
120
121 static void
122 lock_rm(struct lock_object *lock, uintptr_t how)
123 {
124 struct rmlock *rm;
125 struct rm_priotracker *tracker;
126
127 rm = (struct rmlock *)lock;
128 if (how == 0)
129 rm_wlock(rm);
130 else {
131 tracker = (struct rm_priotracker *)how;
132 rm_rlock(rm, tracker);
133 }
134 }
135
136 static uintptr_t
137 unlock_rm(struct lock_object *lock)
138 {
139 struct thread *td;
140 struct pcpu *pc;
141 struct rmlock *rm;
142 struct rm_queue *queue;
143 struct rm_priotracker *tracker;
144 uintptr_t how;
145
146 rm = (struct rmlock *)lock;
147 tracker = NULL;
148 how = 0;
149 rm_assert(rm, RA_LOCKED | RA_NOTRECURSED);
150 if (rm_wowned(rm))
151 rm_wunlock(rm);
152 else {
153 /*
154 * Find the right rm_priotracker structure for curthread.
155 * The guarantee about its uniqueness is given by the fact
156 * we already asserted the lock wasn't recursively acquired.
157 */
158 critical_enter();
159 td = curthread;
160 pc = pcpu_find(curcpu);
161 for (queue = pc->pc_rm_queue.rmq_next;
162 queue != &pc->pc_rm_queue; queue = queue->rmq_next) {
163 tracker = (struct rm_priotracker *)queue;
164 if ((tracker->rmp_rmlock == rm) &&
165 (tracker->rmp_thread == td)) {
166 how = (uintptr_t)tracker;
167 break;
168 }
169 }
170 KASSERT(tracker != NULL,
171 ("rm_priotracker is non-NULL when lock held in read mode"));
172 critical_exit();
173 rm_runlock(rm, tracker);
174 }
175 return (how);
176 }
177
178 #ifdef KDTRACE_HOOKS
179 static int
180 owner_rm(const struct lock_object *lock, struct thread **owner)
181 {
182 const struct rmlock *rm;
183 struct lock_class *lc;
184
185 rm = (const struct rmlock *)lock;
186 lc = LOCK_CLASS(&rm->rm_wlock_object);
187 return (lc->lc_owner(&rm->rm_wlock_object, owner));
188 }
189 #endif
190
191 static struct mtx rm_spinlock;
192
193 MTX_SYSINIT(rm_spinlock, &rm_spinlock, "rm_spinlock", MTX_SPIN);
194
195 /*
196 * Add or remove tracker from per-cpu list.
197 *
198 * The per-cpu list can be traversed at any time in forward direction from an
199 * interrupt on the *local* cpu.
200 */
201 static void inline
202 rm_tracker_add(struct pcpu *pc, struct rm_priotracker *tracker)
203 {
204 struct rm_queue *next;
205
206 /* Initialize all tracker pointers */
207 tracker->rmp_cpuQueue.rmq_prev = &pc->pc_rm_queue;
208 next = pc->pc_rm_queue.rmq_next;
209 tracker->rmp_cpuQueue.rmq_next = next;
210
211 /* rmq_prev is not used during froward traversal. */
212 next->rmq_prev = &tracker->rmp_cpuQueue;
213
214 /* Update pointer to first element. */
215 pc->pc_rm_queue.rmq_next = &tracker->rmp_cpuQueue;
216 }
217
218 /*
219 * Return a count of the number of trackers the thread 'td' already
220 * has on this CPU for the lock 'rm'.
221 */
222 static int
223 rm_trackers_present(const struct pcpu *pc, const struct rmlock *rm,
224 const struct thread *td)
225 {
226 struct rm_queue *queue;
227 struct rm_priotracker *tracker;
228 int count;
229
230 count = 0;
231 for (queue = pc->pc_rm_queue.rmq_next; queue != &pc->pc_rm_queue;
232 queue = queue->rmq_next) {
233 tracker = (struct rm_priotracker *)queue;
234 if ((tracker->rmp_rmlock == rm) && (tracker->rmp_thread == td))
235 count++;
236 }
237 return (count);
238 }
239
240 static void inline
241 rm_tracker_remove(struct pcpu *pc, struct rm_priotracker *tracker)
242 {
243 struct rm_queue *next, *prev;
244
245 next = tracker->rmp_cpuQueue.rmq_next;
246 prev = tracker->rmp_cpuQueue.rmq_prev;
247
248 /* Not used during forward traversal. */
249 next->rmq_prev = prev;
250
251 /* Remove from list. */
252 prev->rmq_next = next;
253 }
254
255 static void
256 rm_cleanIPI(void *arg)
257 {
258 struct pcpu *pc;
259 struct rmlock *rm = arg;
260 struct rm_priotracker *tracker;
261 struct rm_queue *queue;
262 pc = pcpu_find(curcpu);
263
264 for (queue = pc->pc_rm_queue.rmq_next; queue != &pc->pc_rm_queue;
265 queue = queue->rmq_next) {
266 tracker = (struct rm_priotracker *)queue;
267 if (tracker->rmp_rmlock == rm && tracker->rmp_flags == 0) {
268 tracker->rmp_flags = RMPF_ONQUEUE;
269 mtx_lock_spin(&rm_spinlock);
270 LIST_INSERT_HEAD(&rm->rm_activeReaders, tracker,
271 rmp_qentry);
272 mtx_unlock_spin(&rm_spinlock);
273 }
274 }
275 }
276
277 void
278 rm_init_flags(struct rmlock *rm, const char *name, int opts)
279 {
280 struct lock_class *lc;
281 int liflags;
282
283 liflags = 0;
284 if (!(opts & RM_NOWITNESS))
285 liflags |= LO_WITNESS;
286 if (opts & RM_RECURSE)
287 liflags |= LO_RECURSABLE;
288 rm->rm_writecpus = all_cpus;
289 LIST_INIT(&rm->rm_activeReaders);
290 if (opts & RM_SLEEPABLE) {
291 liflags |= LO_SLEEPABLE;
292 lc = &lock_class_rm_sleepable;
293 sx_init_flags(&rm->rm_lock_sx, "rmlock_sx", SX_NOWITNESS);
294 } else {
295 lc = &lock_class_rm;
296 mtx_init(&rm->rm_lock_mtx, name, "rmlock_mtx", MTX_NOWITNESS);
297 }
298 lock_init(&rm->lock_object, lc, name, NULL, liflags);
299 }
300
301 void
302 rm_init(struct rmlock *rm, const char *name)
303 {
304
305 rm_init_flags(rm, name, 0);
306 }
307
308 void
309 rm_destroy(struct rmlock *rm)
310 {
311
312 rm_assert(rm, RA_UNLOCKED);
313 LIST_FIRST(&rm->rm_activeReaders) = RM_DESTROYED;
314 if (rm->lock_object.lo_flags & LO_SLEEPABLE)
315 sx_destroy(&rm->rm_lock_sx);
316 else
317 mtx_destroy(&rm->rm_lock_mtx);
318 lock_destroy(&rm->lock_object);
319 }
320
321 int
322 rm_wowned(const struct rmlock *rm)
323 {
324
325 if (rm->lock_object.lo_flags & LO_SLEEPABLE)
326 return (sx_xlocked(&rm->rm_lock_sx));
327 else
328 return (mtx_owned(&rm->rm_lock_mtx));
329 }
330
331 void
332 rm_sysinit(void *arg)
333 {
334 struct rm_args *args = arg;
335
336 rm_init(args->ra_rm, args->ra_desc);
337 }
338
339 void
340 rm_sysinit_flags(void *arg)
341 {
342 struct rm_args_flags *args = arg;
343
344 rm_init_flags(args->ra_rm, args->ra_desc, args->ra_opts);
345 }
346
347 static int
348 _rm_rlock_hard(struct rmlock *rm, struct rm_priotracker *tracker, int trylock)
349 {
350 struct pcpu *pc;
351
352 critical_enter();
353 pc = pcpu_find(curcpu);
354
355 /* Check if we just need to do a proper critical_exit. */
356 if (!CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus)) {
357 critical_exit();
358 return (1);
359 }
360
361 /* Remove our tracker from the per-cpu list. */
362 rm_tracker_remove(pc, tracker);
363
364 /* Check to see if the IPI granted us the lock after all. */
365 if (tracker->rmp_flags) {
366 /* Just add back tracker - we hold the lock. */
367 rm_tracker_add(pc, tracker);
368 critical_exit();
369 return (1);
370 }
371
372 /*
373 * We allow readers to aquire a lock even if a writer is blocked if
374 * the lock is recursive and the reader already holds the lock.
375 */
376 if ((rm->lock_object.lo_flags & LO_RECURSABLE) != 0) {
377 /*
378 * Just grant the lock if this thread already has a tracker
379 * for this lock on the per-cpu queue.
380 */
381 if (rm_trackers_present(pc, rm, curthread) != 0) {
382 mtx_lock_spin(&rm_spinlock);
383 LIST_INSERT_HEAD(&rm->rm_activeReaders, tracker,
384 rmp_qentry);
385 tracker->rmp_flags = RMPF_ONQUEUE;
386 mtx_unlock_spin(&rm_spinlock);
387 rm_tracker_add(pc, tracker);
388 critical_exit();
389 return (1);
390 }
391 }
392
393 sched_unpin();
394 critical_exit();
395
396 if (trylock) {
397 if (rm->lock_object.lo_flags & LO_SLEEPABLE) {
398 if (!sx_try_xlock(&rm->rm_lock_sx))
399 return (0);
400 } else {
401 if (!mtx_trylock(&rm->rm_lock_mtx))
402 return (0);
403 }
404 } else {
405 if (rm->lock_object.lo_flags & LO_SLEEPABLE) {
406 THREAD_SLEEPING_OK();
407 sx_xlock(&rm->rm_lock_sx);
408 THREAD_NO_SLEEPING();
409 } else
410 mtx_lock(&rm->rm_lock_mtx);
411 }
412
413 critical_enter();
414 pc = pcpu_find(curcpu);
415 CPU_CLR(pc->pc_cpuid, &rm->rm_writecpus);
416 rm_tracker_add(pc, tracker);
417 sched_pin();
418 critical_exit();
419
420 if (rm->lock_object.lo_flags & LO_SLEEPABLE)
421 sx_xunlock(&rm->rm_lock_sx);
422 else
423 mtx_unlock(&rm->rm_lock_mtx);
424
425 return (1);
426 }
427
428 int
429 _rm_rlock(struct rmlock *rm, struct rm_priotracker *tracker, int trylock)
430 {
431 struct thread *td = curthread;
432 struct pcpu *pc;
433
434 if (SCHEDULER_STOPPED())
435 return (1);
436
437 tracker->rmp_flags = 0;
438 tracker->rmp_thread = td;
439 tracker->rmp_rmlock = rm;
440
441 if (rm->lock_object.lo_flags & LO_SLEEPABLE)
442 THREAD_NO_SLEEPING();
443
444 td->td_critnest++; /* critical_enter(); */
445
446 __compiler_membar();
447
448 pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */
449
450 rm_tracker_add(pc, tracker);
451
452 sched_pin();
453
454 __compiler_membar();
455
456 td->td_critnest--;
457
458 /*
459 * Fast path to combine two common conditions into a single
460 * conditional jump.
461 */
462 if (0 == (td->td_owepreempt |
463 CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus)))
464 return (1);
465
466 /* We do not have a read token and need to acquire one. */
467 return _rm_rlock_hard(rm, tracker, trylock);
468 }
469
470 static void
471 _rm_unlock_hard(struct thread *td,struct rm_priotracker *tracker)
472 {
473
474 if (td->td_owepreempt) {
475 td->td_critnest++;
476 critical_exit();
477 }
478
479 if (!tracker->rmp_flags)
480 return;
481
482 mtx_lock_spin(&rm_spinlock);
483 LIST_REMOVE(tracker, rmp_qentry);
484
485 if (tracker->rmp_flags & RMPF_SIGNAL) {
486 struct rmlock *rm;
487 struct turnstile *ts;
488
489 rm = tracker->rmp_rmlock;
490
491 turnstile_chain_lock(&rm->lock_object);
492 mtx_unlock_spin(&rm_spinlock);
493
494 ts = turnstile_lookup(&rm->lock_object);
495
496 turnstile_signal(ts, TS_EXCLUSIVE_QUEUE);
497 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
498 turnstile_chain_unlock(&rm->lock_object);
499 } else
500 mtx_unlock_spin(&rm_spinlock);
501 }
502
503 void
504 _rm_runlock(struct rmlock *rm, struct rm_priotracker *tracker)
505 {
506 struct pcpu *pc;
507 struct thread *td = tracker->rmp_thread;
508
509 if (SCHEDULER_STOPPED())
510 return;
511
512 td->td_critnest++; /* critical_enter(); */
513 pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */
514 rm_tracker_remove(pc, tracker);
515 td->td_critnest--;
516 sched_unpin();
517
518 if (rm->lock_object.lo_flags & LO_SLEEPABLE)
519 THREAD_SLEEPING_OK();
520
521 if (0 == (td->td_owepreempt | tracker->rmp_flags))
522 return;
523
524 _rm_unlock_hard(td, tracker);
525 }
526
527 void
528 _rm_wlock(struct rmlock *rm)
529 {
530 struct rm_priotracker *prio;
531 struct turnstile *ts;
532 cpuset_t readcpus;
533
534 if (SCHEDULER_STOPPED())
535 return;
536
537 if (rm->lock_object.lo_flags & LO_SLEEPABLE)
538 sx_xlock(&rm->rm_lock_sx);
539 else
540 mtx_lock(&rm->rm_lock_mtx);
541
542 if (CPU_CMP(&rm->rm_writecpus, &all_cpus)) {
543 /* Get all read tokens back */
544 readcpus = all_cpus;
545 CPU_NAND(&readcpus, &rm->rm_writecpus);
546 rm->rm_writecpus = all_cpus;
547
548 /*
549 * Assumes rm->rm_writecpus update is visible on other CPUs
550 * before rm_cleanIPI is called.
551 */
552 #ifdef SMP
553 smp_rendezvous_cpus(readcpus,
554 smp_no_rendevous_barrier,
555 rm_cleanIPI,
556 smp_no_rendevous_barrier,
557 rm);
558
559 #else
560 rm_cleanIPI(rm);
561 #endif
562
563 mtx_lock_spin(&rm_spinlock);
564 while ((prio = LIST_FIRST(&rm->rm_activeReaders)) != NULL) {
565 ts = turnstile_trywait(&rm->lock_object);
566 prio->rmp_flags = RMPF_ONQUEUE | RMPF_SIGNAL;
567 mtx_unlock_spin(&rm_spinlock);
568 turnstile_wait(ts, prio->rmp_thread,
569 TS_EXCLUSIVE_QUEUE);
570 mtx_lock_spin(&rm_spinlock);
571 }
572 mtx_unlock_spin(&rm_spinlock);
573 }
574 }
575
576 void
577 _rm_wunlock(struct rmlock *rm)
578 {
579
580 if (rm->lock_object.lo_flags & LO_SLEEPABLE)
581 sx_xunlock(&rm->rm_lock_sx);
582 else
583 mtx_unlock(&rm->rm_lock_mtx);
584 }
585
586 #if LOCK_DEBUG > 0
587
588 void
589 _rm_wlock_debug(struct rmlock *rm, const char *file, int line)
590 {
591
592 if (SCHEDULER_STOPPED())
593 return;
594
595 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
596 ("rm_wlock() by idle thread %p on rmlock %s @ %s:%d",
597 curthread, rm->lock_object.lo_name, file, line));
598 KASSERT(!rm_destroyed(rm),
599 ("rm_wlock() of destroyed rmlock @ %s:%d", file, line));
600 _rm_assert(rm, RA_UNLOCKED, file, line);
601
602 WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER | LOP_EXCLUSIVE,
603 file, line, NULL);
604
605 _rm_wlock(rm);
606
607 LOCK_LOG_LOCK("RMWLOCK", &rm->lock_object, 0, 0, file, line);
608
609 WITNESS_LOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line);
610
611 curthread->td_locks++;
612
613 }
614
615 void
616 _rm_wunlock_debug(struct rmlock *rm, const char *file, int line)
617 {
618
619 if (SCHEDULER_STOPPED())
620 return;
621
622 KASSERT(!rm_destroyed(rm),
623 ("rm_wunlock() of destroyed rmlock @ %s:%d", file, line));
624 _rm_assert(rm, RA_WLOCKED, file, line);
625 WITNESS_UNLOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line);
626 LOCK_LOG_LOCK("RMWUNLOCK", &rm->lock_object, 0, 0, file, line);
627 _rm_wunlock(rm);
628 curthread->td_locks--;
629 }
630
631 int
632 _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
633 int trylock, const char *file, int line)
634 {
635
636 if (SCHEDULER_STOPPED())
637 return (1);
638
639 #ifdef INVARIANTS
640 if (!(rm->lock_object.lo_flags & LO_RECURSABLE) && !trylock) {
641 critical_enter();
642 KASSERT(rm_trackers_present(pcpu_find(curcpu), rm,
643 curthread) == 0,
644 ("rm_rlock: recursed on non-recursive rmlock %s @ %s:%d\n",
645 rm->lock_object.lo_name, file, line));
646 critical_exit();
647 }
648 #endif
649 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
650 ("rm_rlock() by idle thread %p on rmlock %s @ %s:%d",
651 curthread, rm->lock_object.lo_name, file, line));
652 KASSERT(!rm_destroyed(rm),
653 ("rm_rlock() of destroyed rmlock @ %s:%d", file, line));
654 if (!trylock) {
655 KASSERT(!rm_wowned(rm),
656 ("rm_rlock: wlock already held for %s @ %s:%d",
657 rm->lock_object.lo_name, file, line));
658 WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER, file, line,
659 NULL);
660 }
661
662 if (_rm_rlock(rm, tracker, trylock)) {
663 if (trylock)
664 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 1, file,
665 line);
666 else
667 LOCK_LOG_LOCK("RMRLOCK", &rm->lock_object, 0, 0, file,
668 line);
669 WITNESS_LOCK(&rm->lock_object, 0, file, line);
670
671 curthread->td_locks++;
672
673 return (1);
674 } else if (trylock)
675 LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 0, file, line);
676
677 return (0);
678 }
679
680 void
681 _rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
682 const char *file, int line)
683 {
684
685 if (SCHEDULER_STOPPED())
686 return;
687
688 KASSERT(!rm_destroyed(rm),
689 ("rm_runlock() of destroyed rmlock @ %s:%d", file, line));
690 _rm_assert(rm, RA_RLOCKED, file, line);
691 WITNESS_UNLOCK(&rm->lock_object, 0, file, line);
692 LOCK_LOG_LOCK("RMRUNLOCK", &rm->lock_object, 0, 0, file, line);
693 _rm_runlock(rm, tracker);
694 curthread->td_locks--;
695 }
696
697 #else
698
699 /*
700 * Just strip out file and line arguments if no lock debugging is enabled in
701 * the kernel - we are called from a kernel module.
702 */
703 void
704 _rm_wlock_debug(struct rmlock *rm, const char *file, int line)
705 {
706
707 _rm_wlock(rm);
708 }
709
710 void
711 _rm_wunlock_debug(struct rmlock *rm, const char *file, int line)
712 {
713
714 _rm_wunlock(rm);
715 }
716
717 int
718 _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
719 int trylock, const char *file, int line)
720 {
721
722 return _rm_rlock(rm, tracker, trylock);
723 }
724
725 void
726 _rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
727 const char *file, int line)
728 {
729
730 _rm_runlock(rm, tracker);
731 }
732
733 #endif
734
735 #ifdef INVARIANT_SUPPORT
736 #ifndef INVARIANTS
737 #undef _rm_assert
738 #endif
739
740 /*
741 * Note that this does not need to use witness_assert() for read lock
742 * assertions since an exact count of read locks held by this thread
743 * is computable.
744 */
745 void
746 _rm_assert(const struct rmlock *rm, int what, const char *file, int line)
747 {
748 int count;
749
750 if (panicstr != NULL)
751 return;
752 switch (what) {
753 case RA_LOCKED:
754 case RA_LOCKED | RA_RECURSED:
755 case RA_LOCKED | RA_NOTRECURSED:
756 case RA_RLOCKED:
757 case RA_RLOCKED | RA_RECURSED:
758 case RA_RLOCKED | RA_NOTRECURSED:
759 /*
760 * Handle the write-locked case. Unlike other
761 * primitives, writers can never recurse.
762 */
763 if (rm_wowned(rm)) {
764 if (what & RA_RLOCKED)
765 panic("Lock %s exclusively locked @ %s:%d\n",
766 rm->lock_object.lo_name, file, line);
767 if (what & RA_RECURSED)
768 panic("Lock %s not recursed @ %s:%d\n",
769 rm->lock_object.lo_name, file, line);
770 break;
771 }
772
773 critical_enter();
774 count = rm_trackers_present(pcpu_find(curcpu), rm, curthread);
775 critical_exit();
776
777 if (count == 0)
778 panic("Lock %s not %slocked @ %s:%d\n",
779 rm->lock_object.lo_name, (what & RA_RLOCKED) ?
780 "read " : "", file, line);
781 if (count > 1) {
782 if (what & RA_NOTRECURSED)
783 panic("Lock %s recursed @ %s:%d\n",
784 rm->lock_object.lo_name, file, line);
785 } else if (what & RA_RECURSED)
786 panic("Lock %s not recursed @ %s:%d\n",
787 rm->lock_object.lo_name, file, line);
788 break;
789 case RA_WLOCKED:
790 if (!rm_wowned(rm))
791 panic("Lock %s not exclusively locked @ %s:%d\n",
792 rm->lock_object.lo_name, file, line);
793 break;
794 case RA_UNLOCKED:
795 if (rm_wowned(rm))
796 panic("Lock %s exclusively locked @ %s:%d\n",
797 rm->lock_object.lo_name, file, line);
798
799 critical_enter();
800 count = rm_trackers_present(pcpu_find(curcpu), rm, curthread);
801 critical_exit();
802
803 if (count != 0)
804 panic("Lock %s read locked @ %s:%d\n",
805 rm->lock_object.lo_name, file, line);
806 break;
807 default:
808 panic("Unknown rm lock assertion: %d @ %s:%d", what, file,
809 line);
810 }
811 }
812 #endif /* INVARIANT_SUPPORT */
813
814 #ifdef DDB
815 static void
816 print_tracker(struct rm_priotracker *tr)
817 {
818 struct thread *td;
819
820 td = tr->rmp_thread;
821 db_printf(" thread %p (tid %d, pid %d, \"%s\") {", td, td->td_tid,
822 td->td_proc->p_pid, td->td_name);
823 if (tr->rmp_flags & RMPF_ONQUEUE) {
824 db_printf("ONQUEUE");
825 if (tr->rmp_flags & RMPF_SIGNAL)
826 db_printf(",SIGNAL");
827 } else
828 db_printf("");
829 db_printf("}\n");
830 }
831
832 static void
833 db_show_rm(const struct lock_object *lock)
834 {
835 struct rm_priotracker *tr;
836 struct rm_queue *queue;
837 const struct rmlock *rm;
838 struct lock_class *lc;
839 struct pcpu *pc;
840
841 rm = (const struct rmlock *)lock;
842 db_printf(" writecpus: ");
843 ddb_display_cpuset(__DEQUALIFY(const cpuset_t *, &rm->rm_writecpus));
844 db_printf("\n");
845 db_printf(" per-CPU readers:\n");
846 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu)
847 for (queue = pc->pc_rm_queue.rmq_next;
848 queue != &pc->pc_rm_queue; queue = queue->rmq_next) {
849 tr = (struct rm_priotracker *)queue;
850 if (tr->rmp_rmlock == rm)
851 print_tracker(tr);
852 }
853 db_printf(" active readers:\n");
854 LIST_FOREACH(tr, &rm->rm_activeReaders, rmp_qentry)
855 print_tracker(tr);
856 lc = LOCK_CLASS(&rm->rm_wlock_object);
857 db_printf("Backing write-lock (%s):\n", lc->lc_name);
858 lc->lc_ddb_show(&rm->rm_wlock_object);
859 }
860 #endif
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