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("$FreeBSD$");
38
39 #include "opt_adaptive_mutexes.h"
40 #include "opt_ddb.h"
41 #include "opt_hwpmc_hooks.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/smp.h>
59 #include <sys/sysctl.h>
60 #include <sys/turnstile.h>
61 #include <sys/vmmeter.h>
62 #include <sys/lock_profile.h>
63
64 #include <machine/atomic.h>
65 #include <machine/bus.h>
66 #include <machine/cpu.h>
67
68 #include <ddb/ddb.h>
69
70 #include <fs/devfs/devfs_int.h>
71
72 #include <vm/vm.h>
73 #include <vm/vm_extern.h>
74
75 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
76 #define ADAPTIVE_MUTEXES
77 #endif
78
79 #ifdef HWPMC_HOOKS
80 #include <sys/pmckern.h>
81 PMC_SOFT_DEFINE( , , lock, failed);
82 #endif
83
84 /*
85 * Return the mutex address when the lock cookie address is provided.
86 * This functionality assumes that struct mtx* have a member named mtx_lock.
87 */
88 #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock))
89
90 /*
91 * Internal utility macros.
92 */
93 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
94
95 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
96
97 static void assert_mtx(const struct lock_object *lock, int what);
98 #ifdef DDB
99 static void db_show_mtx(const struct lock_object *lock);
100 #endif
101 static void lock_mtx(struct lock_object *lock, uintptr_t how);
102 static void lock_spin(struct lock_object *lock, uintptr_t how);
103 #ifdef KDTRACE_HOOKS
104 static int owner_mtx(const struct lock_object *lock,
105 struct thread **owner);
106 #endif
107 static uintptr_t unlock_mtx(struct lock_object *lock);
108 static uintptr_t unlock_spin(struct lock_object *lock);
109
110 /*
111 * Lock classes for sleep and spin mutexes.
112 */
113 struct lock_class lock_class_mtx_sleep = {
114 .lc_name = "sleep mutex",
115 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
116 .lc_assert = assert_mtx,
117 #ifdef DDB
118 .lc_ddb_show = db_show_mtx,
119 #endif
120 .lc_lock = lock_mtx,
121 .lc_unlock = unlock_mtx,
122 #ifdef KDTRACE_HOOKS
123 .lc_owner = owner_mtx,
124 #endif
125 };
126 struct lock_class lock_class_mtx_spin = {
127 .lc_name = "spin mutex",
128 .lc_flags = LC_SPINLOCK | LC_RECURSABLE,
129 .lc_assert = assert_mtx,
130 #ifdef DDB
131 .lc_ddb_show = db_show_mtx,
132 #endif
133 .lc_lock = lock_spin,
134 .lc_unlock = unlock_spin,
135 #ifdef KDTRACE_HOOKS
136 .lc_owner = owner_mtx,
137 #endif
138 };
139
140 #ifdef ADAPTIVE_MUTEXES
141 static SYSCTL_NODE(_debug, OID_AUTO, mtx, CTLFLAG_RD, NULL, "mtx debugging");
142
143 static struct lock_delay_config __read_frequently mtx_delay;
144
145 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_base, CTLFLAG_RW, &mtx_delay.base,
146 0, "");
147 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max,
148 0, "");
149
150 LOCK_DELAY_SYSINIT_DEFAULT(mtx_delay);
151 #endif
152
153 static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin, CTLFLAG_RD, NULL,
154 "mtx spin debugging");
155
156 static struct lock_delay_config __read_frequently mtx_spin_delay;
157
158 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_base, CTLFLAG_RW,
159 &mtx_spin_delay.base, 0, "");
160 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_max, CTLFLAG_RW,
161 &mtx_spin_delay.max, 0, "");
162
163 LOCK_DELAY_SYSINIT_DEFAULT(mtx_spin_delay);
164
165 /*
166 * System-wide mutexes
167 */
168 struct mtx blocked_lock;
169 struct mtx Giant;
170
171 static void _mtx_lock_indefinite_check(struct mtx *, struct lock_delay_arg *);
172
173 void
assert_mtx(const struct lock_object * lock,int what)174 assert_mtx(const struct lock_object *lock, int what)
175 {
176
177 mtx_assert((const struct mtx *)lock, what);
178 }
179
180 void
lock_mtx(struct lock_object * lock,uintptr_t how)181 lock_mtx(struct lock_object *lock, uintptr_t how)
182 {
183
184 mtx_lock((struct mtx *)lock);
185 }
186
187 void
lock_spin(struct lock_object * lock,uintptr_t how)188 lock_spin(struct lock_object *lock, uintptr_t how)
189 {
190
191 panic("spin locks can only use msleep_spin");
192 }
193
194 uintptr_t
unlock_mtx(struct lock_object * lock)195 unlock_mtx(struct lock_object *lock)
196 {
197 struct mtx *m;
198
199 m = (struct mtx *)lock;
200 mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
201 mtx_unlock(m);
202 return (0);
203 }
204
205 uintptr_t
unlock_spin(struct lock_object * lock)206 unlock_spin(struct lock_object *lock)
207 {
208
209 panic("spin locks can only use msleep_spin");
210 }
211
212 #ifdef KDTRACE_HOOKS
213 int
owner_mtx(const struct lock_object * lock,struct thread ** owner)214 owner_mtx(const struct lock_object *lock, struct thread **owner)
215 {
216 const struct mtx *m;
217 uintptr_t x;
218
219 m = (const struct mtx *)lock;
220 x = m->mtx_lock;
221 *owner = (struct thread *)(x & ~MTX_FLAGMASK);
222 return (*owner != NULL);
223 }
224 #endif
225
226 /*
227 * Function versions of the inlined __mtx_* macros. These are used by
228 * modules and can also be called from assembly language if needed.
229 */
230 void
__mtx_lock_flags(volatile uintptr_t * c,int opts,const char * file,int line)231 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
232 {
233 struct mtx *m;
234 uintptr_t tid, v;
235
236 m = mtxlock2mtx(c);
237
238 KASSERT(kdb_active != 0 || SCHEDULER_STOPPED() ||
239 !TD_IS_IDLETHREAD(curthread),
240 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d",
241 curthread, m->lock_object.lo_name, file, line));
242 KASSERT(m->mtx_lock != MTX_DESTROYED,
243 ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
244 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
245 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
246 file, line));
247 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
248 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
249
250 tid = (uintptr_t)curthread;
251 v = MTX_UNOWNED;
252 if (!_mtx_obtain_lock_fetch(m, &v, tid))
253 _mtx_lock_sleep(m, v, opts, file, line);
254 else
255 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
256 m, 0, 0, file, line);
257 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
258 line);
259 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
260 file, line);
261 TD_LOCKS_INC(curthread);
262 }
263
264 void
__mtx_unlock_flags(volatile uintptr_t * c,int opts,const char * file,int line)265 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
266 {
267 struct mtx *m;
268
269 m = mtxlock2mtx(c);
270
271 KASSERT(m->mtx_lock != MTX_DESTROYED,
272 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
273 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
274 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
275 file, line));
276 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
277 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
278 line);
279 mtx_assert(m, MA_OWNED);
280
281 #ifdef LOCK_PROFILING
282 __mtx_unlock_sleep(c, (uintptr_t)curthread, opts, file, line);
283 #else
284 __mtx_unlock(m, curthread, opts, file, line);
285 #endif
286 TD_LOCKS_DEC(curthread);
287 }
288
289 void
__mtx_lock_spin_flags(volatile uintptr_t * c,int opts,const char * file,int line)290 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
291 int line)
292 {
293 struct mtx *m;
294 #ifdef SMP
295 uintptr_t tid, v;
296 #endif
297
298 m = mtxlock2mtx(c);
299
300 KASSERT(m->mtx_lock != MTX_DESTROYED,
301 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
302 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
303 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
304 m->lock_object.lo_name, file, line));
305 if (mtx_owned(m))
306 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
307 (opts & MTX_RECURSE) != 0,
308 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
309 m->lock_object.lo_name, file, line));
310 opts &= ~MTX_RECURSE;
311 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
312 file, line, NULL);
313 #ifdef SMP
314 spinlock_enter();
315 tid = (uintptr_t)curthread;
316 v = MTX_UNOWNED;
317 if (!_mtx_obtain_lock_fetch(m, &v, tid))
318 _mtx_lock_spin(m, v, opts, file, line);
319 else
320 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire,
321 m, 0, 0, file, line);
322 #else
323 __mtx_lock_spin(m, curthread, opts, file, line);
324 #endif
325 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
326 line);
327 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
328 }
329
330 int
__mtx_trylock_spin_flags(volatile uintptr_t * c,int opts,const char * file,int line)331 __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
332 int line)
333 {
334 struct mtx *m;
335
336 if (SCHEDULER_STOPPED())
337 return (1);
338
339 m = mtxlock2mtx(c);
340
341 KASSERT(m->mtx_lock != MTX_DESTROYED,
342 ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line));
343 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
344 ("mtx_trylock_spin() of sleep mutex %s @ %s:%d",
345 m->lock_object.lo_name, file, line));
346 KASSERT((opts & MTX_RECURSE) == 0,
347 ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n",
348 m->lock_object.lo_name, file, line));
349 if (__mtx_trylock_spin(m, curthread, opts, file, line)) {
350 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line);
351 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
352 return (1);
353 }
354 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line);
355 return (0);
356 }
357
358 void
__mtx_unlock_spin_flags(volatile uintptr_t * c,int opts,const char * file,int line)359 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
360 int line)
361 {
362 struct mtx *m;
363
364 m = mtxlock2mtx(c);
365
366 KASSERT(m->mtx_lock != MTX_DESTROYED,
367 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
368 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
369 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
370 m->lock_object.lo_name, file, line));
371 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
372 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
373 line);
374 mtx_assert(m, MA_OWNED);
375
376 __mtx_unlock_spin(m);
377 }
378
379 /*
380 * The important part of mtx_trylock{,_flags}()
381 * Tries to acquire lock `m.' If this function is called on a mutex that
382 * is already owned, it will recursively acquire the lock.
383 */
384 int
_mtx_trylock_flags_int(struct mtx * m,int opts LOCK_FILE_LINE_ARG_DEF)385 _mtx_trylock_flags_int(struct mtx *m, int opts LOCK_FILE_LINE_ARG_DEF)
386 {
387 struct thread *td;
388 uintptr_t tid, v;
389 #ifdef LOCK_PROFILING
390 uint64_t waittime = 0;
391 int contested = 0;
392 #endif
393 int rval;
394 bool recursed;
395
396 td = curthread;
397 tid = (uintptr_t)td;
398 if (SCHEDULER_STOPPED_TD(td))
399 return (1);
400
401 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(td),
402 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
403 curthread, m->lock_object.lo_name, file, line));
404 KASSERT(m->mtx_lock != MTX_DESTROYED,
405 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
406 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
407 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
408 file, line));
409
410 rval = 1;
411 recursed = false;
412 v = MTX_UNOWNED;
413 for (;;) {
414 if (_mtx_obtain_lock_fetch(m, &v, tid))
415 break;
416 if (v == MTX_UNOWNED)
417 continue;
418 if (v == tid &&
419 ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
420 (opts & MTX_RECURSE) != 0)) {
421 m->mtx_recurse++;
422 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
423 recursed = true;
424 break;
425 }
426 rval = 0;
427 break;
428 }
429
430 opts &= ~MTX_RECURSE;
431
432 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
433 if (rval) {
434 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
435 file, line);
436 TD_LOCKS_INC(curthread);
437 if (!recursed)
438 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
439 m, contested, waittime, file, line);
440 }
441
442 return (rval);
443 }
444
445 int
_mtx_trylock_flags_(volatile uintptr_t * c,int opts,const char * file,int line)446 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
447 {
448 struct mtx *m;
449
450 m = mtxlock2mtx(c);
451 return (_mtx_trylock_flags_int(m, opts LOCK_FILE_LINE_ARG));
452 }
453
454 /*
455 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
456 *
457 * We call this if the lock is either contested (i.e. we need to go to
458 * sleep waiting for it), or if we need to recurse on it.
459 */
460 #if LOCK_DEBUG > 0
461 void
__mtx_lock_sleep(volatile uintptr_t * c,uintptr_t v,int opts,const char * file,int line)462 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, int opts, const char *file,
463 int line)
464 #else
465 void
466 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v)
467 #endif
468 {
469 struct thread *td;
470 struct mtx *m;
471 struct turnstile *ts;
472 uintptr_t tid;
473 struct thread *owner;
474 #ifdef LOCK_PROFILING
475 int contested = 0;
476 uint64_t waittime = 0;
477 #endif
478 #if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS)
479 struct lock_delay_arg lda;
480 #endif
481 #ifdef KDTRACE_HOOKS
482 u_int sleep_cnt = 0;
483 int64_t sleep_time = 0;
484 int64_t all_time = 0;
485 #endif
486 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
487 int doing_lockprof;
488 #endif
489
490 td = curthread;
491 tid = (uintptr_t)td;
492 m = mtxlock2mtx(c);
493
494 #ifdef KDTRACE_HOOKS
495 if (LOCKSTAT_PROFILE_ENABLED(adaptive__acquire)) {
496 while (v == MTX_UNOWNED) {
497 if (_mtx_obtain_lock_fetch(m, &v, tid))
498 goto out_lockstat;
499 }
500 doing_lockprof = 1;
501 all_time -= lockstat_nsecs(&m->lock_object);
502 }
503 #endif
504 #ifdef LOCK_PROFILING
505 doing_lockprof = 1;
506 #endif
507
508 if (SCHEDULER_STOPPED_TD(td))
509 return;
510
511 #if defined(ADAPTIVE_MUTEXES)
512 lock_delay_arg_init(&lda, &mtx_delay);
513 #elif defined(KDTRACE_HOOKS)
514 lock_delay_arg_init(&lda, NULL);
515 #endif
516
517 if (__predict_false(v == MTX_UNOWNED))
518 v = MTX_READ_VALUE(m);
519
520 if (__predict_false(lv_mtx_owner(v) == td)) {
521 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
522 (opts & MTX_RECURSE) != 0,
523 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
524 m->lock_object.lo_name, file, line));
525 #if LOCK_DEBUG > 0
526 opts &= ~MTX_RECURSE;
527 #endif
528 m->mtx_recurse++;
529 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
530 if (LOCK_LOG_TEST(&m->lock_object, opts))
531 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
532 return;
533 }
534 #if LOCK_DEBUG > 0
535 opts &= ~MTX_RECURSE;
536 #endif
537
538 #ifdef HWPMC_HOOKS
539 PMC_SOFT_CALL( , , lock, failed);
540 #endif
541 lock_profile_obtain_lock_failed(&m->lock_object,
542 &contested, &waittime);
543 if (LOCK_LOG_TEST(&m->lock_object, opts))
544 CTR4(KTR_LOCK,
545 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
546 m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
547
548 for (;;) {
549 if (v == MTX_UNOWNED) {
550 if (_mtx_obtain_lock_fetch(m, &v, tid))
551 break;
552 continue;
553 }
554 #ifdef KDTRACE_HOOKS
555 lda.spin_cnt++;
556 #endif
557 #ifdef ADAPTIVE_MUTEXES
558 /*
559 * If the owner is running on another CPU, spin until the
560 * owner stops running or the state of the lock changes.
561 */
562 owner = lv_mtx_owner(v);
563 if (TD_IS_RUNNING(owner)) {
564 if (LOCK_LOG_TEST(&m->lock_object, 0))
565 CTR3(KTR_LOCK,
566 "%s: spinning on %p held by %p",
567 __func__, m, owner);
568 KTR_STATE1(KTR_SCHED, "thread",
569 sched_tdname((struct thread *)tid),
570 "spinning", "lockname:\"%s\"",
571 m->lock_object.lo_name);
572 do {
573 lock_delay(&lda);
574 v = MTX_READ_VALUE(m);
575 owner = lv_mtx_owner(v);
576 } while (v != MTX_UNOWNED && TD_IS_RUNNING(owner));
577 KTR_STATE0(KTR_SCHED, "thread",
578 sched_tdname((struct thread *)tid),
579 "running");
580 continue;
581 }
582 #endif
583
584 ts = turnstile_trywait(&m->lock_object);
585 v = MTX_READ_VALUE(m);
586 retry_turnstile:
587
588 /*
589 * Check if the lock has been released while spinning for
590 * the turnstile chain lock.
591 */
592 if (v == MTX_UNOWNED) {
593 turnstile_cancel(ts);
594 continue;
595 }
596
597 #ifdef ADAPTIVE_MUTEXES
598 /*
599 * The current lock owner might have started executing
600 * on another CPU (or the lock could have changed
601 * owners) while we were waiting on the turnstile
602 * chain lock. If so, drop the turnstile lock and try
603 * again.
604 */
605 owner = lv_mtx_owner(v);
606 if (TD_IS_RUNNING(owner)) {
607 turnstile_cancel(ts);
608 continue;
609 }
610 #endif
611
612 /*
613 * If the mutex isn't already contested and a failure occurs
614 * setting the contested bit, the mutex was either released
615 * or the state of the MTX_RECURSED bit changed.
616 */
617 if ((v & MTX_CONTESTED) == 0 &&
618 !atomic_fcmpset_ptr(&m->mtx_lock, &v, v | MTX_CONTESTED)) {
619 goto retry_turnstile;
620 }
621
622 /*
623 * We definitely must sleep for this lock.
624 */
625 mtx_assert(m, MA_NOTOWNED);
626
627 /*
628 * Block on the turnstile.
629 */
630 #ifdef KDTRACE_HOOKS
631 sleep_time -= lockstat_nsecs(&m->lock_object);
632 #endif
633 #ifndef ADAPTIVE_MUTEXES
634 owner = mtx_owner(m);
635 #endif
636 MPASS(owner == mtx_owner(m));
637 turnstile_wait(ts, owner, TS_EXCLUSIVE_QUEUE);
638 #ifdef KDTRACE_HOOKS
639 sleep_time += lockstat_nsecs(&m->lock_object);
640 sleep_cnt++;
641 #endif
642 v = MTX_READ_VALUE(m);
643 }
644 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
645 if (__predict_true(!doing_lockprof))
646 return;
647 #endif
648 #ifdef KDTRACE_HOOKS
649 all_time += lockstat_nsecs(&m->lock_object);
650 if (sleep_time)
651 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time);
652
653 /*
654 * Only record the loops spinning and not sleeping.
655 */
656 if (lda.spin_cnt > sleep_cnt)
657 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time);
658 out_lockstat:
659 #endif
660 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested,
661 waittime, file, line);
662 }
663
664 #ifdef SMP
665 /*
666 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
667 *
668 * This is only called if we need to actually spin for the lock. Recursion
669 * is handled inline.
670 */
671 #if LOCK_DEBUG > 0
672 void
_mtx_lock_spin_cookie(volatile uintptr_t * c,uintptr_t v,int opts,const char * file,int line)673 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v, int opts,
674 const char *file, int line)
675 #else
676 void
677 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v)
678 #endif
679 {
680 struct mtx *m;
681 struct lock_delay_arg lda;
682 uintptr_t tid;
683 #ifdef LOCK_PROFILING
684 int contested = 0;
685 uint64_t waittime = 0;
686 #endif
687 #ifdef KDTRACE_HOOKS
688 int64_t spin_time = 0;
689 #endif
690 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
691 int doing_lockprof;
692 #endif
693
694 tid = (uintptr_t)curthread;
695 m = mtxlock2mtx(c);
696
697 #ifdef KDTRACE_HOOKS
698 if (LOCKSTAT_PROFILE_ENABLED(adaptive__acquire)) {
699 while (v == MTX_UNOWNED) {
700 if (_mtx_obtain_lock_fetch(m, &v, tid))
701 goto out_lockstat;
702 }
703 doing_lockprof = 1;
704 spin_time -= lockstat_nsecs(&m->lock_object);
705 }
706 #endif
707 #ifdef LOCK_PROFILING
708 doing_lockprof = 1;
709 #endif
710
711 if (__predict_false(v == MTX_UNOWNED))
712 v = MTX_READ_VALUE(m);
713
714 if (__predict_false(v == tid)) {
715 m->mtx_recurse++;
716 return;
717 }
718
719 if (SCHEDULER_STOPPED())
720 return;
721
722 lock_delay_arg_init(&lda, &mtx_spin_delay);
723
724 if (LOCK_LOG_TEST(&m->lock_object, opts))
725 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
726 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
727 "spinning", "lockname:\"%s\"", m->lock_object.lo_name);
728
729 #ifdef HWPMC_HOOKS
730 PMC_SOFT_CALL( , , lock, failed);
731 #endif
732 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
733
734 for (;;) {
735 if (v == MTX_UNOWNED) {
736 if (_mtx_obtain_lock_fetch(m, &v, tid))
737 break;
738 continue;
739 }
740 /* Give interrupts a chance while we spin. */
741 spinlock_exit();
742 do {
743 if (__predict_true(lda.spin_cnt < 10000000)) {
744 lock_delay(&lda);
745 } else {
746 _mtx_lock_indefinite_check(m, &lda);
747 }
748 v = MTX_READ_VALUE(m);
749 } while (v != MTX_UNOWNED);
750 spinlock_enter();
751 }
752
753 if (LOCK_LOG_TEST(&m->lock_object, opts))
754 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
755 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
756 "running");
757
758 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
759 if (__predict_true(!doing_lockprof))
760 return;
761 #endif
762 #ifdef KDTRACE_HOOKS
763 spin_time += lockstat_nsecs(&m->lock_object);
764 if (lda.spin_cnt != 0)
765 LOCKSTAT_RECORD1(spin__spin, m, spin_time);
766 out_lockstat:
767 #endif
768 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
769 contested, waittime, file, line);
770 }
771 #endif /* SMP */
772
773 #ifdef INVARIANTS
774 static void
thread_lock_validate(struct mtx * m,int opts,const char * file,int line)775 thread_lock_validate(struct mtx *m, int opts, const char *file, int line)
776 {
777
778 KASSERT(m->mtx_lock != MTX_DESTROYED,
779 ("thread_lock() of destroyed mutex @ %s:%d", file, line));
780 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
781 ("thread_lock() of sleep mutex %s @ %s:%d",
782 m->lock_object.lo_name, file, line));
783 if (mtx_owned(m))
784 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
785 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
786 m->lock_object.lo_name, file, line));
787 WITNESS_CHECKORDER(&m->lock_object,
788 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
789 }
790 #else
791 #define thread_lock_validate(m, opts, file, line) do { } while (0)
792 #endif
793
794 #ifndef LOCK_PROFILING
795 #if LOCK_DEBUG > 0
796 void
_thread_lock(struct thread * td,int opts,const char * file,int line)797 _thread_lock(struct thread *td, int opts, const char *file, int line)
798 #else
799 void
800 _thread_lock(struct thread *td)
801 #endif
802 {
803 struct mtx *m;
804 uintptr_t tid, v;
805
806 tid = (uintptr_t)curthread;
807
808 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(spin__acquire)))
809 goto slowpath_noirq;
810 spinlock_enter();
811 m = td->td_lock;
812 thread_lock_validate(m, 0, file, line);
813 v = MTX_READ_VALUE(m);
814 if (__predict_true(v == MTX_UNOWNED)) {
815 if (__predict_false(!_mtx_obtain_lock(m, tid)))
816 goto slowpath_unlocked;
817 } else if (v == tid) {
818 m->mtx_recurse++;
819 } else
820 goto slowpath_unlocked;
821 if (__predict_true(m == td->td_lock)) {
822 WITNESS_LOCK(&m->lock_object, LOP_EXCLUSIVE, file, line);
823 return;
824 }
825 MPASS(m->mtx_recurse == 0);
826 _mtx_release_lock_quick(m);
827 slowpath_unlocked:
828 spinlock_exit();
829 slowpath_noirq:
830 #if LOCK_DEBUG > 0
831 thread_lock_flags_(td, opts, file, line);
832 #else
833 thread_lock_flags_(td, 0, 0, 0);
834 #endif
835 }
836 #endif
837
838 void
thread_lock_flags_(struct thread * td,int opts,const char * file,int line)839 thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
840 {
841 struct mtx *m;
842 uintptr_t tid, v;
843 struct lock_delay_arg lda;
844 #ifdef LOCK_PROFILING
845 int contested = 0;
846 uint64_t waittime = 0;
847 #endif
848 #ifdef KDTRACE_HOOKS
849 int64_t spin_time = 0;
850 #endif
851 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
852 int doing_lockprof = 1;
853 #endif
854
855 tid = (uintptr_t)curthread;
856
857 if (SCHEDULER_STOPPED()) {
858 /*
859 * Ensure that spinlock sections are balanced even when the
860 * scheduler is stopped, since we may otherwise inadvertently
861 * re-enable interrupts while dumping core.
862 */
863 spinlock_enter();
864 return;
865 }
866
867 lock_delay_arg_init(&lda, &mtx_spin_delay);
868
869 #ifdef HWPMC_HOOKS
870 PMC_SOFT_CALL( , , lock, failed);
871 #endif
872
873 #ifdef LOCK_PROFILING
874 doing_lockprof = 1;
875 #elif defined(KDTRACE_HOOKS)
876 doing_lockprof = lockstat_enabled;
877 if (__predict_false(doing_lockprof))
878 spin_time -= lockstat_nsecs(&td->td_lock->lock_object);
879 #endif
880 spinlock_enter();
881
882 for (;;) {
883 retry:
884 m = td->td_lock;
885 thread_lock_validate(m, opts, file, line);
886 v = MTX_READ_VALUE(m);
887 for (;;) {
888 if (v == MTX_UNOWNED) {
889 if (_mtx_obtain_lock_fetch(m, &v, tid))
890 break;
891 continue;
892 }
893 if (v == tid) {
894 m->mtx_recurse++;
895 MPASS(m == td->td_lock);
896 break;
897 }
898 lock_profile_obtain_lock_failed(&m->lock_object,
899 &contested, &waittime);
900 /* Give interrupts a chance while we spin. */
901 spinlock_exit();
902 do {
903 if (__predict_true(lda.spin_cnt < 10000000)) {
904 lock_delay(&lda);
905 } else {
906 _mtx_lock_indefinite_check(m, &lda);
907 }
908 if (m != td->td_lock) {
909 spinlock_enter();
910 goto retry;
911 }
912 v = MTX_READ_VALUE(m);
913 } while (v != MTX_UNOWNED);
914 spinlock_enter();
915 }
916 if (m == td->td_lock)
917 break;
918 MPASS(m->mtx_recurse == 0);
919 _mtx_release_lock_quick(m);
920 }
921 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
922 line);
923 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
924
925 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
926 if (__predict_true(!doing_lockprof))
927 return;
928 #endif
929 #ifdef KDTRACE_HOOKS
930 spin_time += lockstat_nsecs(&m->lock_object);
931 #endif
932 if (m->mtx_recurse == 0)
933 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
934 contested, waittime, file, line);
935 #ifdef KDTRACE_HOOKS
936 if (lda.spin_cnt != 0)
937 LOCKSTAT_RECORD1(thread__spin, m, spin_time);
938 #endif
939 }
940
941 struct mtx *
thread_lock_block(struct thread * td)942 thread_lock_block(struct thread *td)
943 {
944 struct mtx *lock;
945
946 THREAD_LOCK_ASSERT(td, MA_OWNED);
947 lock = td->td_lock;
948 td->td_lock = &blocked_lock;
949 mtx_unlock_spin(lock);
950
951 return (lock);
952 }
953
954 void
thread_lock_unblock(struct thread * td,struct mtx * new)955 thread_lock_unblock(struct thread *td, struct mtx *new)
956 {
957 mtx_assert(new, MA_OWNED);
958 MPASS(td->td_lock == &blocked_lock);
959 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
960 }
961
962 void
thread_lock_set(struct thread * td,struct mtx * new)963 thread_lock_set(struct thread *td, struct mtx *new)
964 {
965 struct mtx *lock;
966
967 mtx_assert(new, MA_OWNED);
968 THREAD_LOCK_ASSERT(td, MA_OWNED);
969 lock = td->td_lock;
970 td->td_lock = new;
971 mtx_unlock_spin(lock);
972 }
973
974 /*
975 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
976 *
977 * We are only called here if the lock is recursed, contested (i.e. we
978 * need to wake up a blocked thread) or lockstat probe is active.
979 */
980 #if LOCK_DEBUG > 0
981 void
__mtx_unlock_sleep(volatile uintptr_t * c,uintptr_t v,int opts,const char * file,int line)982 __mtx_unlock_sleep(volatile uintptr_t *c, uintptr_t v, int opts,
983 const char *file, int line)
984 #else
985 void
986 __mtx_unlock_sleep(volatile uintptr_t *c, uintptr_t v)
987 #endif
988 {
989 struct mtx *m;
990 struct turnstile *ts;
991 uintptr_t tid;
992
993 if (SCHEDULER_STOPPED())
994 return;
995
996 tid = (uintptr_t)curthread;
997 m = mtxlock2mtx(c);
998
999 if (__predict_false(v == tid))
1000 v = MTX_READ_VALUE(m);
1001
1002 if (__predict_false(v & MTX_RECURSED)) {
1003 if (--(m->mtx_recurse) == 0)
1004 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
1005 if (LOCK_LOG_TEST(&m->lock_object, opts))
1006 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
1007 return;
1008 }
1009
1010 LOCKSTAT_PROFILE_RELEASE_LOCK(adaptive__release, m);
1011 if (v == tid && _mtx_release_lock(m, tid))
1012 return;
1013
1014 /*
1015 * We have to lock the chain before the turnstile so this turnstile
1016 * can be removed from the hash list if it is empty.
1017 */
1018 turnstile_chain_lock(&m->lock_object);
1019 _mtx_release_lock_quick(m);
1020 ts = turnstile_lookup(&m->lock_object);
1021 MPASS(ts != NULL);
1022 if (LOCK_LOG_TEST(&m->lock_object, opts))
1023 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
1024 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
1025
1026 /*
1027 * This turnstile is now no longer associated with the mutex. We can
1028 * unlock the chain lock so a new turnstile may take it's place.
1029 */
1030 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
1031 turnstile_chain_unlock(&m->lock_object);
1032 }
1033
1034 /*
1035 * All the unlocking of MTX_SPIN locks is done inline.
1036 * See the __mtx_unlock_spin() macro for the details.
1037 */
1038
1039 /*
1040 * The backing function for the INVARIANTS-enabled mtx_assert()
1041 */
1042 #ifdef INVARIANT_SUPPORT
1043 void
__mtx_assert(const volatile uintptr_t * c,int what,const char * file,int line)1044 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line)
1045 {
1046 const struct mtx *m;
1047
1048 if (panicstr != NULL || dumping || SCHEDULER_STOPPED())
1049 return;
1050
1051 m = mtxlock2mtx(c);
1052
1053 switch (what) {
1054 case MA_OWNED:
1055 case MA_OWNED | MA_RECURSED:
1056 case MA_OWNED | MA_NOTRECURSED:
1057 if (!mtx_owned(m))
1058 panic("mutex %s not owned at %s:%d",
1059 m->lock_object.lo_name, file, line);
1060 if (mtx_recursed(m)) {
1061 if ((what & MA_NOTRECURSED) != 0)
1062 panic("mutex %s recursed at %s:%d",
1063 m->lock_object.lo_name, file, line);
1064 } else if ((what & MA_RECURSED) != 0) {
1065 panic("mutex %s unrecursed at %s:%d",
1066 m->lock_object.lo_name, file, line);
1067 }
1068 break;
1069 case MA_NOTOWNED:
1070 if (mtx_owned(m))
1071 panic("mutex %s owned at %s:%d",
1072 m->lock_object.lo_name, file, line);
1073 break;
1074 default:
1075 panic("unknown mtx_assert at %s:%d", file, line);
1076 }
1077 }
1078 #endif
1079
1080 /*
1081 * General init routine used by the MTX_SYSINIT() macro.
1082 */
1083 void
mtx_sysinit(void * arg)1084 mtx_sysinit(void *arg)
1085 {
1086 struct mtx_args *margs = arg;
1087
1088 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL,
1089 margs->ma_opts);
1090 }
1091
1092 /*
1093 * Mutex initialization routine; initialize lock `m' of type contained in
1094 * `opts' with options contained in `opts' and name `name.' The optional
1095 * lock type `type' is used as a general lock category name for use with
1096 * witness.
1097 */
1098 void
_mtx_init(volatile uintptr_t * c,const char * name,const char * type,int opts)1099 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
1100 {
1101 struct mtx *m;
1102 struct lock_class *class;
1103 int flags;
1104
1105 m = mtxlock2mtx(c);
1106
1107 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
1108 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0);
1109 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
1110 ("%s: mtx_lock not aligned for %s: %p", __func__, name,
1111 &m->mtx_lock));
1112
1113 /* Determine lock class and lock flags. */
1114 if (opts & MTX_SPIN)
1115 class = &lock_class_mtx_spin;
1116 else
1117 class = &lock_class_mtx_sleep;
1118 flags = 0;
1119 if (opts & MTX_QUIET)
1120 flags |= LO_QUIET;
1121 if (opts & MTX_RECURSE)
1122 flags |= LO_RECURSABLE;
1123 if ((opts & MTX_NOWITNESS) == 0)
1124 flags |= LO_WITNESS;
1125 if (opts & MTX_DUPOK)
1126 flags |= LO_DUPOK;
1127 if (opts & MTX_NOPROFILE)
1128 flags |= LO_NOPROFILE;
1129 if (opts & MTX_NEW)
1130 flags |= LO_NEW;
1131
1132 /* Initialize mutex. */
1133 lock_init(&m->lock_object, class, name, type, flags);
1134
1135 m->mtx_lock = MTX_UNOWNED;
1136 m->mtx_recurse = 0;
1137 }
1138
1139 /*
1140 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
1141 * passed in as a flag here because if the corresponding mtx_init() was
1142 * called with MTX_QUIET set, then it will already be set in the mutex's
1143 * flags.
1144 */
1145 void
_mtx_destroy(volatile uintptr_t * c)1146 _mtx_destroy(volatile uintptr_t *c)
1147 {
1148 struct mtx *m;
1149
1150 m = mtxlock2mtx(c);
1151
1152 if (!mtx_owned(m))
1153 MPASS(mtx_unowned(m));
1154 else {
1155 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
1156
1157 /* Perform the non-mtx related part of mtx_unlock_spin(). */
1158 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
1159 spinlock_exit();
1160 else
1161 TD_LOCKS_DEC(curthread);
1162
1163 lock_profile_release_lock(&m->lock_object);
1164 /* Tell witness this isn't locked to make it happy. */
1165 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
1166 __LINE__);
1167 }
1168
1169 m->mtx_lock = MTX_DESTROYED;
1170 lock_destroy(&m->lock_object);
1171 }
1172
1173 /*
1174 * Intialize the mutex code and system mutexes. This is called from the MD
1175 * startup code prior to mi_startup(). The per-CPU data space needs to be
1176 * setup before this is called.
1177 */
1178 void
mutex_init(void)1179 mutex_init(void)
1180 {
1181
1182 /* Setup turnstiles so that sleep mutexes work. */
1183 init_turnstiles();
1184
1185 /*
1186 * Initialize mutexes.
1187 */
1188 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
1189 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
1190 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
1191 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
1192 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN);
1193 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN);
1194 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN);
1195 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN);
1196 mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
1197 mtx_lock(&Giant);
1198 }
1199
1200 static void __noinline
_mtx_lock_indefinite_check(struct mtx * m,struct lock_delay_arg * ldap)1201 _mtx_lock_indefinite_check(struct mtx *m, struct lock_delay_arg *ldap)
1202 {
1203 struct thread *td;
1204
1205 ldap->spin_cnt++;
1206 if (ldap->spin_cnt < 60000000 || kdb_active || panicstr != NULL)
1207 cpu_lock_delay();
1208 else {
1209 td = mtx_owner(m);
1210
1211 /* If the mutex is unlocked, try again. */
1212 if (td == NULL)
1213 return;
1214
1215 printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
1216 m, m->lock_object.lo_name, td, td->td_tid);
1217 #ifdef WITNESS
1218 witness_display_spinlock(&m->lock_object, td, printf);
1219 #endif
1220 panic("spin lock held too long");
1221 }
1222 cpu_spinwait();
1223 }
1224
1225 #ifdef DDB
1226 void
db_show_mtx(const struct lock_object * lock)1227 db_show_mtx(const struct lock_object *lock)
1228 {
1229 struct thread *td;
1230 const struct mtx *m;
1231
1232 m = (const struct mtx *)lock;
1233
1234 db_printf(" flags: {");
1235 if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
1236 db_printf("SPIN");
1237 else
1238 db_printf("DEF");
1239 if (m->lock_object.lo_flags & LO_RECURSABLE)
1240 db_printf(", RECURSE");
1241 if (m->lock_object.lo_flags & LO_DUPOK)
1242 db_printf(", DUPOK");
1243 db_printf("}\n");
1244 db_printf(" state: {");
1245 if (mtx_unowned(m))
1246 db_printf("UNOWNED");
1247 else if (mtx_destroyed(m))
1248 db_printf("DESTROYED");
1249 else {
1250 db_printf("OWNED");
1251 if (m->mtx_lock & MTX_CONTESTED)
1252 db_printf(", CONTESTED");
1253 if (m->mtx_lock & MTX_RECURSED)
1254 db_printf(", RECURSED");
1255 }
1256 db_printf("}\n");
1257 if (!mtx_unowned(m) && !mtx_destroyed(m)) {
1258 td = mtx_owner(m);
1259 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
1260 td->td_tid, td->td_proc->p_pid, td->td_name);
1261 if (mtx_recursed(m))
1262 db_printf(" recursed: %d\n", m->mtx_recurse);
1263 }
1264 }
1265 #endif
1266