FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_mutex.c
1 /*-
2 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Berkeley Software Design Inc's name may not be used to endorse or
13 * promote products derived from this software without specific prior
14 * written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER 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
26 * SUCH DAMAGE.
27 *
28 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
29 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
30 */
31
32 /*
33 * Machine independent bits of mutex implementation.
34 */
35
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD: src/sys/kern/kern_mutex.c,v 1.205 2008/02/13 23:39:05 jhb Exp $");
38
39 #include "opt_adaptive_mutexes.h"
40 #include "opt_ddb.h"
41 #include "opt_global.h"
42 #include "opt_sched.h"
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/bus.h>
47 #include <sys/conf.h>
48 #include <sys/kdb.h>
49 #include <sys/kernel.h>
50 #include <sys/ktr.h>
51 #include <sys/lock.h>
52 #include <sys/malloc.h>
53 #include <sys/mutex.h>
54 #include <sys/proc.h>
55 #include <sys/resourcevar.h>
56 #include <sys/sched.h>
57 #include <sys/sbuf.h>
58 #include <sys/sysctl.h>
59 #include <sys/turnstile.h>
60 #include <sys/vmmeter.h>
61 #include <sys/lock_profile.h>
62
63 #include <machine/atomic.h>
64 #include <machine/bus.h>
65 #include <machine/cpu.h>
66
67 #include <ddb/ddb.h>
68
69 #include <fs/devfs/devfs_int.h>
70
71 #include <vm/vm.h>
72 #include <vm/vm_extern.h>
73
74 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
75 #define ADAPTIVE_MUTEXES
76 #endif
77
78 /*
79 * Internal utility macros.
80 */
81 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
82
83 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
84
85 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK))
86
87 static void assert_mtx(struct lock_object *lock, int what);
88 #ifdef DDB
89 static void db_show_mtx(struct lock_object *lock);
90 #endif
91 static void lock_mtx(struct lock_object *lock, int how);
92 static void lock_spin(struct lock_object *lock, int how);
93 static int unlock_mtx(struct lock_object *lock);
94 static int unlock_spin(struct lock_object *lock);
95
96 /*
97 * Lock classes for sleep and spin mutexes.
98 */
99 struct lock_class lock_class_mtx_sleep = {
100 .lc_name = "sleep mutex",
101 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
102 .lc_assert = assert_mtx,
103 #ifdef DDB
104 .lc_ddb_show = db_show_mtx,
105 #endif
106 .lc_lock = lock_mtx,
107 .lc_unlock = unlock_mtx,
108 };
109 struct lock_class lock_class_mtx_spin = {
110 .lc_name = "spin mutex",
111 .lc_flags = LC_SPINLOCK | LC_RECURSABLE,
112 .lc_assert = assert_mtx,
113 #ifdef DDB
114 .lc_ddb_show = db_show_mtx,
115 #endif
116 .lc_lock = lock_spin,
117 .lc_unlock = unlock_spin,
118 };
119
120 /*
121 * System-wide mutexes
122 */
123 struct mtx blocked_lock;
124 struct mtx Giant;
125
126 void
127 assert_mtx(struct lock_object *lock, int what)
128 {
129
130 mtx_assert((struct mtx *)lock, what);
131 }
132
133 void
134 lock_mtx(struct lock_object *lock, int how)
135 {
136
137 mtx_lock((struct mtx *)lock);
138 }
139
140 void
141 lock_spin(struct lock_object *lock, int how)
142 {
143
144 panic("spin locks can only use msleep_spin");
145 }
146
147 int
148 unlock_mtx(struct lock_object *lock)
149 {
150 struct mtx *m;
151
152 m = (struct mtx *)lock;
153 mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
154 mtx_unlock(m);
155 return (0);
156 }
157
158 int
159 unlock_spin(struct lock_object *lock)
160 {
161
162 panic("spin locks can only use msleep_spin");
163 }
164
165 /*
166 * Function versions of the inlined __mtx_* macros. These are used by
167 * modules and can also be called from assembly language if needed.
168 */
169 void
170 _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line)
171 {
172
173 MPASS(curthread != NULL);
174 KASSERT(m->mtx_lock != MTX_DESTROYED,
175 ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
176 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
177 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
178 file, line));
179 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
180 file, line);
181
182 _get_sleep_lock(m, curthread, opts, file, line);
183 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
184 line);
185 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
186 curthread->td_locks++;
187 }
188
189 void
190 _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
191 {
192 MPASS(curthread != NULL);
193 KASSERT(m->mtx_lock != MTX_DESTROYED,
194 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
195 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
196 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
197 file, line));
198 curthread->td_locks--;
199 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
200 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
201 line);
202 mtx_assert(m, MA_OWNED);
203
204 if (m->mtx_recurse == 0)
205 lock_profile_release_lock(&m->lock_object);
206 _rel_sleep_lock(m, curthread, opts, file, line);
207 }
208
209 void
210 _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
211 {
212
213 MPASS(curthread != NULL);
214 KASSERT(m->mtx_lock != MTX_DESTROYED,
215 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
216 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
217 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
218 m->lock_object.lo_name, file, line));
219 if (mtx_owned(m))
220 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
221 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
222 m->lock_object.lo_name, file, line));
223 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
224 file, line);
225 _get_spin_lock(m, curthread, opts, file, line);
226 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
227 line);
228 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
229 }
230
231 void
232 _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
233 {
234
235 MPASS(curthread != NULL);
236 KASSERT(m->mtx_lock != MTX_DESTROYED,
237 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
238 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
239 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
240 m->lock_object.lo_name, file, line));
241 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
242 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
243 line);
244 mtx_assert(m, MA_OWNED);
245
246 _rel_spin_lock(m);
247 }
248
249 /*
250 * The important part of mtx_trylock{,_flags}()
251 * Tries to acquire lock `m.' If this function is called on a mutex that
252 * is already owned, it will recursively acquire the lock.
253 */
254 int
255 _mtx_trylock(struct mtx *m, int opts, const char *file, int line)
256 {
257 int rval, contested = 0;
258 uint64_t waittime = 0;
259
260 MPASS(curthread != NULL);
261 KASSERT(m->mtx_lock != MTX_DESTROYED,
262 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
263 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
264 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
265 file, line));
266
267 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) {
268 m->mtx_recurse++;
269 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
270 rval = 1;
271 } else
272 rval = _obtain_lock(m, (uintptr_t)curthread);
273
274 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
275 if (rval) {
276 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
277 file, line);
278 curthread->td_locks++;
279 if (m->mtx_recurse == 0)
280 lock_profile_obtain_lock_success(&m->lock_object, contested,
281 waittime, file, line);
282
283 }
284
285 return (rval);
286 }
287
288 /*
289 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
290 *
291 * We call this if the lock is either contested (i.e. we need to go to
292 * sleep waiting for it), or if we need to recurse on it.
293 */
294 void
295 _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file,
296 int line)
297 {
298 struct turnstile *ts;
299 #ifdef ADAPTIVE_MUTEXES
300 volatile struct thread *owner;
301 #endif
302 #ifdef KTR
303 int cont_logged = 0;
304 #endif
305 int contested = 0;
306 uint64_t waittime = 0;
307 uintptr_t v;
308
309 if (mtx_owned(m)) {
310 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
311 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
312 m->lock_object.lo_name, file, line));
313 m->mtx_recurse++;
314 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
315 if (LOCK_LOG_TEST(&m->lock_object, opts))
316 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
317 return;
318 }
319
320 lock_profile_obtain_lock_failed(&m->lock_object,
321 &contested, &waittime);
322 if (LOCK_LOG_TEST(&m->lock_object, opts))
323 CTR4(KTR_LOCK,
324 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
325 m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
326
327 while (!_obtain_lock(m, tid)) {
328 #ifdef ADAPTIVE_MUTEXES
329 /*
330 * If the owner is running on another CPU, spin until the
331 * owner stops running or the state of the lock changes.
332 */
333 v = m->mtx_lock;
334 if (v != MTX_UNOWNED) {
335 owner = (struct thread *)(v & ~MTX_FLAGMASK);
336 if (TD_IS_RUNNING(owner)) {
337 if (LOCK_LOG_TEST(&m->lock_object, 0))
338 CTR3(KTR_LOCK,
339 "%s: spinning on %p held by %p",
340 __func__, m, owner);
341 while (mtx_owner(m) == owner &&
342 TD_IS_RUNNING(owner))
343 cpu_spinwait();
344 continue;
345 }
346 }
347 #endif
348
349 ts = turnstile_trywait(&m->lock_object);
350 v = m->mtx_lock;
351
352 /*
353 * Check if the lock has been released while spinning for
354 * the turnstile chain lock.
355 */
356 if (v == MTX_UNOWNED) {
357 turnstile_cancel(ts);
358 cpu_spinwait();
359 continue;
360 }
361
362 MPASS(v != MTX_CONTESTED);
363
364 #ifdef ADAPTIVE_MUTEXES
365 /*
366 * If the current owner of the lock is executing on another
367 * CPU quit the hard path and try to spin.
368 */
369 owner = (struct thread *)(v & ~MTX_FLAGMASK);
370 if (TD_IS_RUNNING(owner)) {
371 turnstile_cancel(ts);
372 cpu_spinwait();
373 continue;
374 }
375 #endif
376
377 /*
378 * If the mutex isn't already contested and a failure occurs
379 * setting the contested bit, the mutex was either released
380 * or the state of the MTX_RECURSED bit changed.
381 */
382 if ((v & MTX_CONTESTED) == 0 &&
383 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
384 turnstile_cancel(ts);
385 cpu_spinwait();
386 continue;
387 }
388
389 /*
390 * We definitely must sleep for this lock.
391 */
392 mtx_assert(m, MA_NOTOWNED);
393
394 #ifdef KTR
395 if (!cont_logged) {
396 CTR6(KTR_CONTENTION,
397 "contention: %p at %s:%d wants %s, taken by %s:%d",
398 (void *)tid, file, line, m->lock_object.lo_name,
399 WITNESS_FILE(&m->lock_object),
400 WITNESS_LINE(&m->lock_object));
401 cont_logged = 1;
402 }
403 #endif
404
405 /*
406 * Block on the turnstile.
407 */
408 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
409 }
410 #ifdef KTR
411 if (cont_logged) {
412 CTR4(KTR_CONTENTION,
413 "contention end: %s acquired by %p at %s:%d",
414 m->lock_object.lo_name, (void *)tid, file, line);
415 }
416 #endif
417 lock_profile_obtain_lock_success(&m->lock_object, contested,
418 waittime, file, line);
419 }
420
421 static void
422 _mtx_lock_spin_failed(struct mtx *m)
423 {
424 struct thread *td;
425
426 td = mtx_owner(m);
427
428 /* If the mutex is unlocked, try again. */
429 if (td == NULL)
430 return;
431
432 printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
433 m, m->lock_object.lo_name, td, td->td_tid);
434 #ifdef WITNESS
435 witness_display_spinlock(&m->lock_object, td);
436 #endif
437 panic("spin lock held too long");
438 }
439
440 #ifdef SMP
441 /*
442 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock.
443 *
444 * This is only called if we need to actually spin for the lock. Recursion
445 * is handled inline.
446 */
447 void
448 _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file,
449 int line)
450 {
451 int i = 0, contested = 0;
452 uint64_t waittime = 0;
453
454 if (LOCK_LOG_TEST(&m->lock_object, opts))
455 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
456
457 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
458 while (!_obtain_lock(m, tid)) {
459
460 /* Give interrupts a chance while we spin. */
461 spinlock_exit();
462 while (m->mtx_lock != MTX_UNOWNED) {
463 if (i++ < 10000000) {
464 cpu_spinwait();
465 continue;
466 }
467 if (i < 60000000 || kdb_active || panicstr != NULL)
468 DELAY(1);
469 else
470 _mtx_lock_spin_failed(m);
471 cpu_spinwait();
472 }
473 spinlock_enter();
474 }
475
476 if (LOCK_LOG_TEST(&m->lock_object, opts))
477 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
478
479 lock_profile_obtain_lock_success(&m->lock_object, contested,
480 waittime, (file), (line));
481 }
482 #endif /* SMP */
483
484 void
485 _thread_lock_flags(struct thread *td, int opts, const char *file, int line)
486 {
487 struct mtx *m;
488 uintptr_t tid;
489 int i, contested;
490 uint64_t waittime;
491
492 contested = i = 0;
493 waittime = 0;
494 tid = (uintptr_t)curthread;
495 for (;;) {
496 retry:
497 spinlock_enter();
498 m = td->td_lock;
499 KASSERT(m->mtx_lock != MTX_DESTROYED,
500 ("thread_lock() of destroyed mutex @ %s:%d", file, line));
501 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
502 ("thread_lock() of sleep mutex %s @ %s:%d",
503 m->lock_object.lo_name, file, line));
504 if (mtx_owned(m))
505 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
506 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
507 m->lock_object.lo_name, file, line));
508 WITNESS_CHECKORDER(&m->lock_object,
509 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line);
510 while (!_obtain_lock(m, tid)) {
511 if (m->mtx_lock == tid) {
512 m->mtx_recurse++;
513 break;
514 }
515 lock_profile_obtain_lock_failed(&m->lock_object,
516 &contested, &waittime);
517 /* Give interrupts a chance while we spin. */
518 spinlock_exit();
519 while (m->mtx_lock != MTX_UNOWNED) {
520 if (i++ < 10000000)
521 cpu_spinwait();
522 else if (i < 60000000 ||
523 kdb_active || panicstr != NULL)
524 DELAY(1);
525 else
526 _mtx_lock_spin_failed(m);
527 cpu_spinwait();
528 if (m != td->td_lock)
529 goto retry;
530 }
531 spinlock_enter();
532 }
533 if (m == td->td_lock)
534 break;
535 _rel_spin_lock(m); /* does spinlock_exit() */
536 }
537 if (m->mtx_recurse == 0)
538 lock_profile_obtain_lock_success(&m->lock_object, contested,
539 waittime, (file), (line));
540 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
541 line);
542 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
543 }
544
545 struct mtx *
546 thread_lock_block(struct thread *td)
547 {
548 struct mtx *lock;
549
550 spinlock_enter();
551 THREAD_LOCK_ASSERT(td, MA_OWNED);
552 lock = td->td_lock;
553 td->td_lock = &blocked_lock;
554 mtx_unlock_spin(lock);
555
556 return (lock);
557 }
558
559 void
560 thread_lock_unblock(struct thread *td, struct mtx *new)
561 {
562 mtx_assert(new, MA_OWNED);
563 MPASS(td->td_lock == &blocked_lock);
564 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
565 spinlock_exit();
566 }
567
568 void
569 thread_lock_set(struct thread *td, struct mtx *new)
570 {
571 struct mtx *lock;
572
573 mtx_assert(new, MA_OWNED);
574 THREAD_LOCK_ASSERT(td, MA_OWNED);
575 lock = td->td_lock;
576 td->td_lock = new;
577 mtx_unlock_spin(lock);
578 }
579
580 /*
581 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
582 *
583 * We are only called here if the lock is recursed or contested (i.e. we
584 * need to wake up a blocked thread).
585 */
586 void
587 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line)
588 {
589 struct turnstile *ts;
590
591 if (mtx_recursed(m)) {
592 if (--(m->mtx_recurse) == 0)
593 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
594 if (LOCK_LOG_TEST(&m->lock_object, opts))
595 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
596 return;
597 }
598
599 /*
600 * We have to lock the chain before the turnstile so this turnstile
601 * can be removed from the hash list if it is empty.
602 */
603 turnstile_chain_lock(&m->lock_object);
604 ts = turnstile_lookup(&m->lock_object);
605 if (LOCK_LOG_TEST(&m->lock_object, opts))
606 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
607
608 MPASS(ts != NULL);
609 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
610 _release_lock_quick(m);
611 /*
612 * This turnstile is now no longer associated with the mutex. We can
613 * unlock the chain lock so a new turnstile may take it's place.
614 */
615 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
616 turnstile_chain_unlock(&m->lock_object);
617 }
618
619 /*
620 * All the unlocking of MTX_SPIN locks is done inline.
621 * See the _rel_spin_lock() macro for the details.
622 */
623
624 /*
625 * The backing function for the INVARIANTS-enabled mtx_assert()
626 */
627 #ifdef INVARIANT_SUPPORT
628 void
629 _mtx_assert(struct mtx *m, int what, const char *file, int line)
630 {
631
632 if (panicstr != NULL || dumping)
633 return;
634 switch (what) {
635 case MA_OWNED:
636 case MA_OWNED | MA_RECURSED:
637 case MA_OWNED | MA_NOTRECURSED:
638 if (!mtx_owned(m))
639 panic("mutex %s not owned at %s:%d",
640 m->lock_object.lo_name, file, line);
641 if (mtx_recursed(m)) {
642 if ((what & MA_NOTRECURSED) != 0)
643 panic("mutex %s recursed at %s:%d",
644 m->lock_object.lo_name, file, line);
645 } else if ((what & MA_RECURSED) != 0) {
646 panic("mutex %s unrecursed at %s:%d",
647 m->lock_object.lo_name, file, line);
648 }
649 break;
650 case MA_NOTOWNED:
651 if (mtx_owned(m))
652 panic("mutex %s owned at %s:%d",
653 m->lock_object.lo_name, file, line);
654 break;
655 default:
656 panic("unknown mtx_assert at %s:%d", file, line);
657 }
658 }
659 #endif
660
661 /*
662 * The MUTEX_DEBUG-enabled mtx_validate()
663 *
664 * Most of these checks have been moved off into the LO_INITIALIZED flag
665 * maintained by the witness code.
666 */
667 #ifdef MUTEX_DEBUG
668
669 void mtx_validate(struct mtx *);
670
671 void
672 mtx_validate(struct mtx *m)
673 {
674
675 /*
676 * XXX: When kernacc() does not require Giant we can reenable this check
677 */
678 #ifdef notyet
679 /*
680 * Can't call kernacc() from early init386(), especially when
681 * initializing Giant mutex, because some stuff in kernacc()
682 * requires Giant itself.
683 */
684 if (!cold)
685 if (!kernacc((caddr_t)m, sizeof(m),
686 VM_PROT_READ | VM_PROT_WRITE))
687 panic("Can't read and write to mutex %p", m);
688 #endif
689 }
690 #endif
691
692 /*
693 * General init routine used by the MTX_SYSINIT() macro.
694 */
695 void
696 mtx_sysinit(void *arg)
697 {
698 struct mtx_args *margs = arg;
699
700 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts);
701 }
702
703 /*
704 * Mutex initialization routine; initialize lock `m' of type contained in
705 * `opts' with options contained in `opts' and name `name.' The optional
706 * lock type `type' is used as a general lock category name for use with
707 * witness.
708 */
709 void
710 mtx_init(struct mtx *m, const char *name, const char *type, int opts)
711 {
712 struct lock_class *class;
713 int flags;
714
715 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
716 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0);
717
718 #ifdef MUTEX_DEBUG
719 /* Diagnostic and error correction */
720 mtx_validate(m);
721 #endif
722
723 /* Determine lock class and lock flags. */
724 if (opts & MTX_SPIN)
725 class = &lock_class_mtx_spin;
726 else
727 class = &lock_class_mtx_sleep;
728 flags = 0;
729 if (opts & MTX_QUIET)
730 flags |= LO_QUIET;
731 if (opts & MTX_RECURSE)
732 flags |= LO_RECURSABLE;
733 if ((opts & MTX_NOWITNESS) == 0)
734 flags |= LO_WITNESS;
735 if (opts & MTX_DUPOK)
736 flags |= LO_DUPOK;
737 if (opts & MTX_NOPROFILE)
738 flags |= LO_NOPROFILE;
739
740 /* Initialize mutex. */
741 m->mtx_lock = MTX_UNOWNED;
742 m->mtx_recurse = 0;
743
744 lock_init(&m->lock_object, class, name, type, flags);
745 }
746
747 /*
748 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
749 * passed in as a flag here because if the corresponding mtx_init() was
750 * called with MTX_QUIET set, then it will already be set in the mutex's
751 * flags.
752 */
753 void
754 mtx_destroy(struct mtx *m)
755 {
756
757 if (!mtx_owned(m))
758 MPASS(mtx_unowned(m));
759 else {
760 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
761
762 /* Perform the non-mtx related part of mtx_unlock_spin(). */
763 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
764 spinlock_exit();
765 else
766 curthread->td_locks--;
767
768 /* Tell witness this isn't locked to make it happy. */
769 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
770 __LINE__);
771 }
772
773 m->mtx_lock = MTX_DESTROYED;
774 lock_destroy(&m->lock_object);
775 }
776
777 /*
778 * Intialize the mutex code and system mutexes. This is called from the MD
779 * startup code prior to mi_startup(). The per-CPU data space needs to be
780 * setup before this is called.
781 */
782 void
783 mutex_init(void)
784 {
785
786 /* Setup turnstiles so that sleep mutexes work. */
787 init_turnstiles();
788
789 /*
790 * Initialize mutexes.
791 */
792 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
793 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
794 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
795 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
796 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE);
797 mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
798 mtx_lock(&Giant);
799 }
800
801 #ifdef DDB
802 void
803 db_show_mtx(struct lock_object *lock)
804 {
805 struct thread *td;
806 struct mtx *m;
807
808 m = (struct mtx *)lock;
809
810 db_printf(" flags: {");
811 if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
812 db_printf("SPIN");
813 else
814 db_printf("DEF");
815 if (m->lock_object.lo_flags & LO_RECURSABLE)
816 db_printf(", RECURSE");
817 if (m->lock_object.lo_flags & LO_DUPOK)
818 db_printf(", DUPOK");
819 db_printf("}\n");
820 db_printf(" state: {");
821 if (mtx_unowned(m))
822 db_printf("UNOWNED");
823 else if (mtx_destroyed(m))
824 db_printf("DESTROYED");
825 else {
826 db_printf("OWNED");
827 if (m->mtx_lock & MTX_CONTESTED)
828 db_printf(", CONTESTED");
829 if (m->mtx_lock & MTX_RECURSED)
830 db_printf(", RECURSED");
831 }
832 db_printf("}\n");
833 if (!mtx_unowned(m) && !mtx_destroyed(m)) {
834 td = mtx_owner(m);
835 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
836 td->td_tid, td->td_proc->p_pid, td->td_name);
837 if (mtx_recursed(m))
838 db_printf(" recursed: %d\n", m->mtx_recurse);
839 }
840 }
841 #endif
842
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