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: releng/10.1/sys/kern/kern_mutex.c 255745 2013-09-20 23:06:21Z davide $");
38
39 #include "opt_adaptive_mutexes.h"
40 #include "opt_ddb.h"
41 #include "opt_global.h"
42 #include "opt_hwpmc_hooks.h"
43 #include "opt_kdtrace.h"
44 #include "opt_sched.h"
45
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/bus.h>
49 #include <sys/conf.h>
50 #include <sys/kdb.h>
51 #include <sys/kernel.h>
52 #include <sys/ktr.h>
53 #include <sys/lock.h>
54 #include <sys/malloc.h>
55 #include <sys/mutex.h>
56 #include <sys/proc.h>
57 #include <sys/resourcevar.h>
58 #include <sys/sched.h>
59 #include <sys/sbuf.h>
60 #include <sys/sysctl.h>
61 #include <sys/turnstile.h>
62 #include <sys/vmmeter.h>
63 #include <sys/lock_profile.h>
64
65 #include <machine/atomic.h>
66 #include <machine/bus.h>
67 #include <machine/cpu.h>
68
69 #include <ddb/ddb.h>
70
71 #include <fs/devfs/devfs_int.h>
72
73 #include <vm/vm.h>
74 #include <vm/vm_extern.h>
75
76 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
77 #define ADAPTIVE_MUTEXES
78 #endif
79
80 #ifdef HWPMC_HOOKS
81 #include <sys/pmckern.h>
82 PMC_SOFT_DEFINE( , , lock, failed);
83 #endif
84
85 /*
86 * Return the mutex address when the lock cookie address is provided.
87 * This functionality assumes that struct mtx* have a member named mtx_lock.
88 */
89 #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock))
90
91 /*
92 * Internal utility macros.
93 */
94 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
95
96 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
97
98 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK))
99
100 static void assert_mtx(const struct lock_object *lock, int what);
101 #ifdef DDB
102 static void db_show_mtx(const struct lock_object *lock);
103 #endif
104 static void lock_mtx(struct lock_object *lock, uintptr_t how);
105 static void lock_spin(struct lock_object *lock, uintptr_t how);
106 #ifdef KDTRACE_HOOKS
107 static int owner_mtx(const struct lock_object *lock,
108 struct thread **owner);
109 #endif
110 static uintptr_t unlock_mtx(struct lock_object *lock);
111 static uintptr_t unlock_spin(struct lock_object *lock);
112
113 /*
114 * Lock classes for sleep and spin mutexes.
115 */
116 struct lock_class lock_class_mtx_sleep = {
117 .lc_name = "sleep mutex",
118 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
119 .lc_assert = assert_mtx,
120 #ifdef DDB
121 .lc_ddb_show = db_show_mtx,
122 #endif
123 .lc_lock = lock_mtx,
124 .lc_unlock = unlock_mtx,
125 #ifdef KDTRACE_HOOKS
126 .lc_owner = owner_mtx,
127 #endif
128 };
129 struct lock_class lock_class_mtx_spin = {
130 .lc_name = "spin mutex",
131 .lc_flags = LC_SPINLOCK | LC_RECURSABLE,
132 .lc_assert = assert_mtx,
133 #ifdef DDB
134 .lc_ddb_show = db_show_mtx,
135 #endif
136 .lc_lock = lock_spin,
137 .lc_unlock = unlock_spin,
138 #ifdef KDTRACE_HOOKS
139 .lc_owner = owner_mtx,
140 #endif
141 };
142
143 /*
144 * System-wide mutexes
145 */
146 struct mtx blocked_lock;
147 struct mtx Giant;
148
149 void
150 assert_mtx(const struct lock_object *lock, int what)
151 {
152
153 mtx_assert((const struct mtx *)lock, what);
154 }
155
156 void
157 lock_mtx(struct lock_object *lock, uintptr_t how)
158 {
159
160 mtx_lock((struct mtx *)lock);
161 }
162
163 void
164 lock_spin(struct lock_object *lock, uintptr_t how)
165 {
166
167 panic("spin locks can only use msleep_spin");
168 }
169
170 uintptr_t
171 unlock_mtx(struct lock_object *lock)
172 {
173 struct mtx *m;
174
175 m = (struct mtx *)lock;
176 mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
177 mtx_unlock(m);
178 return (0);
179 }
180
181 uintptr_t
182 unlock_spin(struct lock_object *lock)
183 {
184
185 panic("spin locks can only use msleep_spin");
186 }
187
188 #ifdef KDTRACE_HOOKS
189 int
190 owner_mtx(const struct lock_object *lock, struct thread **owner)
191 {
192 const struct mtx *m = (const struct mtx *)lock;
193
194 *owner = mtx_owner(m);
195 return (mtx_unowned(m) == 0);
196 }
197 #endif
198
199 /*
200 * Function versions of the inlined __mtx_* macros. These are used by
201 * modules and can also be called from assembly language if needed.
202 */
203 void
204 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
205 {
206 struct mtx *m;
207
208 if (SCHEDULER_STOPPED())
209 return;
210
211 m = mtxlock2mtx(c);
212
213 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
214 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d",
215 curthread, m->lock_object.lo_name, file, line));
216 KASSERT(m->mtx_lock != MTX_DESTROYED,
217 ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
218 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
219 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
220 file, line));
221 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
222 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
223
224 __mtx_lock(m, curthread, opts, file, line);
225 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
226 line);
227 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
228 file, line);
229 curthread->td_locks++;
230 }
231
232 void
233 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
234 {
235 struct mtx *m;
236
237 if (SCHEDULER_STOPPED())
238 return;
239
240 m = mtxlock2mtx(c);
241
242 KASSERT(m->mtx_lock != MTX_DESTROYED,
243 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
244 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
245 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
246 file, line));
247 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
248 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
249 line);
250 mtx_assert(m, MA_OWNED);
251
252 if (m->mtx_recurse == 0)
253 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m);
254 __mtx_unlock(m, curthread, opts, file, line);
255 curthread->td_locks--;
256 }
257
258 void
259 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
260 int line)
261 {
262 struct mtx *m;
263
264 if (SCHEDULER_STOPPED())
265 return;
266
267 m = mtxlock2mtx(c);
268
269 KASSERT(m->mtx_lock != MTX_DESTROYED,
270 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
271 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
272 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
273 m->lock_object.lo_name, file, line));
274 if (mtx_owned(m))
275 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
276 (opts & MTX_RECURSE) != 0,
277 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
278 m->lock_object.lo_name, file, line));
279 opts &= ~MTX_RECURSE;
280 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
281 file, line, NULL);
282 __mtx_lock_spin(m, curthread, opts, file, line);
283 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
284 line);
285 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
286 }
287
288 void
289 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
290 int line)
291 {
292 struct mtx *m;
293
294 if (SCHEDULER_STOPPED())
295 return;
296
297 m = mtxlock2mtx(c);
298
299 KASSERT(m->mtx_lock != MTX_DESTROYED,
300 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
301 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
302 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
303 m->lock_object.lo_name, file, line));
304 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
305 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
306 line);
307 mtx_assert(m, MA_OWNED);
308
309 __mtx_unlock_spin(m);
310 }
311
312 /*
313 * The important part of mtx_trylock{,_flags}()
314 * Tries to acquire lock `m.' If this function is called on a mutex that
315 * is already owned, it will recursively acquire the lock.
316 */
317 int
318 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
319 {
320 struct mtx *m;
321 #ifdef LOCK_PROFILING
322 uint64_t waittime = 0;
323 int contested = 0;
324 #endif
325 int rval;
326
327 if (SCHEDULER_STOPPED())
328 return (1);
329
330 m = mtxlock2mtx(c);
331
332 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
333 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
334 curthread, m->lock_object.lo_name, file, line));
335 KASSERT(m->mtx_lock != MTX_DESTROYED,
336 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
337 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
338 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
339 file, line));
340
341 if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
342 (opts & MTX_RECURSE) != 0)) {
343 m->mtx_recurse++;
344 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
345 rval = 1;
346 } else
347 rval = _mtx_obtain_lock(m, (uintptr_t)curthread);
348 opts &= ~MTX_RECURSE;
349
350 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
351 if (rval) {
352 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
353 file, line);
354 curthread->td_locks++;
355 if (m->mtx_recurse == 0)
356 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE,
357 m, contested, waittime, file, line);
358
359 }
360
361 return (rval);
362 }
363
364 /*
365 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
366 *
367 * We call this if the lock is either contested (i.e. we need to go to
368 * sleep waiting for it), or if we need to recurse on it.
369 */
370 void
371 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts,
372 const char *file, int line)
373 {
374 struct mtx *m;
375 struct turnstile *ts;
376 uintptr_t v;
377 #ifdef ADAPTIVE_MUTEXES
378 volatile struct thread *owner;
379 #endif
380 #ifdef KTR
381 int cont_logged = 0;
382 #endif
383 #ifdef LOCK_PROFILING
384 int contested = 0;
385 uint64_t waittime = 0;
386 #endif
387 #ifdef KDTRACE_HOOKS
388 uint64_t spin_cnt = 0;
389 uint64_t sleep_cnt = 0;
390 int64_t sleep_time = 0;
391 #endif
392
393 if (SCHEDULER_STOPPED())
394 return;
395
396 m = mtxlock2mtx(c);
397
398 if (mtx_owned(m)) {
399 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
400 (opts & MTX_RECURSE) != 0,
401 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
402 m->lock_object.lo_name, file, line));
403 opts &= ~MTX_RECURSE;
404 m->mtx_recurse++;
405 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
406 if (LOCK_LOG_TEST(&m->lock_object, opts))
407 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
408 return;
409 }
410 opts &= ~MTX_RECURSE;
411
412 #ifdef HWPMC_HOOKS
413 PMC_SOFT_CALL( , , lock, failed);
414 #endif
415 lock_profile_obtain_lock_failed(&m->lock_object,
416 &contested, &waittime);
417 if (LOCK_LOG_TEST(&m->lock_object, opts))
418 CTR4(KTR_LOCK,
419 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
420 m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
421
422 while (!_mtx_obtain_lock(m, tid)) {
423 #ifdef KDTRACE_HOOKS
424 spin_cnt++;
425 #endif
426 #ifdef ADAPTIVE_MUTEXES
427 /*
428 * If the owner is running on another CPU, spin until the
429 * owner stops running or the state of the lock changes.
430 */
431 v = m->mtx_lock;
432 if (v != MTX_UNOWNED) {
433 owner = (struct thread *)(v & ~MTX_FLAGMASK);
434 if (TD_IS_RUNNING(owner)) {
435 if (LOCK_LOG_TEST(&m->lock_object, 0))
436 CTR3(KTR_LOCK,
437 "%s: spinning on %p held by %p",
438 __func__, m, owner);
439 while (mtx_owner(m) == owner &&
440 TD_IS_RUNNING(owner)) {
441 cpu_spinwait();
442 #ifdef KDTRACE_HOOKS
443 spin_cnt++;
444 #endif
445 }
446 continue;
447 }
448 }
449 #endif
450
451 ts = turnstile_trywait(&m->lock_object);
452 v = m->mtx_lock;
453
454 /*
455 * Check if the lock has been released while spinning for
456 * the turnstile chain lock.
457 */
458 if (v == MTX_UNOWNED) {
459 turnstile_cancel(ts);
460 continue;
461 }
462
463 #ifdef ADAPTIVE_MUTEXES
464 /*
465 * The current lock owner might have started executing
466 * on another CPU (or the lock could have changed
467 * owners) while we were waiting on the turnstile
468 * chain lock. If so, drop the turnstile lock and try
469 * again.
470 */
471 owner = (struct thread *)(v & ~MTX_FLAGMASK);
472 if (TD_IS_RUNNING(owner)) {
473 turnstile_cancel(ts);
474 continue;
475 }
476 #endif
477
478 /*
479 * If the mutex isn't already contested and a failure occurs
480 * setting the contested bit, the mutex was either released
481 * or the state of the MTX_RECURSED bit changed.
482 */
483 if ((v & MTX_CONTESTED) == 0 &&
484 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
485 turnstile_cancel(ts);
486 continue;
487 }
488
489 /*
490 * We definitely must sleep for this lock.
491 */
492 mtx_assert(m, MA_NOTOWNED);
493
494 #ifdef KTR
495 if (!cont_logged) {
496 CTR6(KTR_CONTENTION,
497 "contention: %p at %s:%d wants %s, taken by %s:%d",
498 (void *)tid, file, line, m->lock_object.lo_name,
499 WITNESS_FILE(&m->lock_object),
500 WITNESS_LINE(&m->lock_object));
501 cont_logged = 1;
502 }
503 #endif
504
505 /*
506 * Block on the turnstile.
507 */
508 #ifdef KDTRACE_HOOKS
509 sleep_time -= lockstat_nsecs();
510 #endif
511 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
512 #ifdef KDTRACE_HOOKS
513 sleep_time += lockstat_nsecs();
514 sleep_cnt++;
515 #endif
516 }
517 #ifdef KTR
518 if (cont_logged) {
519 CTR4(KTR_CONTENTION,
520 "contention end: %s acquired by %p at %s:%d",
521 m->lock_object.lo_name, (void *)tid, file, line);
522 }
523 #endif
524 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested,
525 waittime, file, line);
526 #ifdef KDTRACE_HOOKS
527 if (sleep_time)
528 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time);
529
530 /*
531 * Only record the loops spinning and not sleeping.
532 */
533 if (spin_cnt > sleep_cnt)
534 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt));
535 #endif
536 }
537
538 static void
539 _mtx_lock_spin_failed(struct mtx *m)
540 {
541 struct thread *td;
542
543 td = mtx_owner(m);
544
545 /* If the mutex is unlocked, try again. */
546 if (td == NULL)
547 return;
548
549 printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
550 m, m->lock_object.lo_name, td, td->td_tid);
551 #ifdef WITNESS
552 witness_display_spinlock(&m->lock_object, td, printf);
553 #endif
554 panic("spin lock held too long");
555 }
556
557 #ifdef SMP
558 /*
559 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
560 *
561 * This is only called if we need to actually spin for the lock. Recursion
562 * is handled inline.
563 */
564 void
565 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts,
566 const char *file, int line)
567 {
568 struct mtx *m;
569 int i = 0;
570 #ifdef LOCK_PROFILING
571 int contested = 0;
572 uint64_t waittime = 0;
573 #endif
574
575 if (SCHEDULER_STOPPED())
576 return;
577
578 m = mtxlock2mtx(c);
579
580 if (LOCK_LOG_TEST(&m->lock_object, opts))
581 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
582
583 #ifdef HWPMC_HOOKS
584 PMC_SOFT_CALL( , , lock, failed);
585 #endif
586 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
587 while (!_mtx_obtain_lock(m, tid)) {
588
589 /* Give interrupts a chance while we spin. */
590 spinlock_exit();
591 while (m->mtx_lock != MTX_UNOWNED) {
592 if (i++ < 10000000) {
593 cpu_spinwait();
594 continue;
595 }
596 if (i < 60000000 || kdb_active || panicstr != NULL)
597 DELAY(1);
598 else
599 _mtx_lock_spin_failed(m);
600 cpu_spinwait();
601 }
602 spinlock_enter();
603 }
604
605 if (LOCK_LOG_TEST(&m->lock_object, opts))
606 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
607
608 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m,
609 contested, waittime, (file), (line));
610 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i);
611 }
612 #endif /* SMP */
613
614 void
615 thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
616 {
617 struct mtx *m;
618 uintptr_t tid;
619 int i;
620 #ifdef LOCK_PROFILING
621 int contested = 0;
622 uint64_t waittime = 0;
623 #endif
624 #ifdef KDTRACE_HOOKS
625 uint64_t spin_cnt = 0;
626 #endif
627
628 i = 0;
629 tid = (uintptr_t)curthread;
630
631 if (SCHEDULER_STOPPED())
632 return;
633
634 for (;;) {
635 retry:
636 spinlock_enter();
637 m = td->td_lock;
638 KASSERT(m->mtx_lock != MTX_DESTROYED,
639 ("thread_lock() of destroyed mutex @ %s:%d", file, line));
640 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
641 ("thread_lock() of sleep mutex %s @ %s:%d",
642 m->lock_object.lo_name, file, line));
643 if (mtx_owned(m))
644 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
645 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
646 m->lock_object.lo_name, file, line));
647 WITNESS_CHECKORDER(&m->lock_object,
648 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
649 while (!_mtx_obtain_lock(m, tid)) {
650 #ifdef KDTRACE_HOOKS
651 spin_cnt++;
652 #endif
653 if (m->mtx_lock == tid) {
654 m->mtx_recurse++;
655 break;
656 }
657 #ifdef HWPMC_HOOKS
658 PMC_SOFT_CALL( , , lock, failed);
659 #endif
660 lock_profile_obtain_lock_failed(&m->lock_object,
661 &contested, &waittime);
662 /* Give interrupts a chance while we spin. */
663 spinlock_exit();
664 while (m->mtx_lock != MTX_UNOWNED) {
665 if (i++ < 10000000)
666 cpu_spinwait();
667 else if (i < 60000000 ||
668 kdb_active || panicstr != NULL)
669 DELAY(1);
670 else
671 _mtx_lock_spin_failed(m);
672 cpu_spinwait();
673 if (m != td->td_lock)
674 goto retry;
675 }
676 spinlock_enter();
677 }
678 if (m == td->td_lock)
679 break;
680 __mtx_unlock_spin(m); /* does spinlock_exit() */
681 #ifdef KDTRACE_HOOKS
682 spin_cnt++;
683 #endif
684 }
685 if (m->mtx_recurse == 0)
686 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE,
687 m, contested, waittime, (file), (line));
688 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
689 line);
690 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
691 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt);
692 }
693
694 struct mtx *
695 thread_lock_block(struct thread *td)
696 {
697 struct mtx *lock;
698
699 THREAD_LOCK_ASSERT(td, MA_OWNED);
700 lock = td->td_lock;
701 td->td_lock = &blocked_lock;
702 mtx_unlock_spin(lock);
703
704 return (lock);
705 }
706
707 void
708 thread_lock_unblock(struct thread *td, struct mtx *new)
709 {
710 mtx_assert(new, MA_OWNED);
711 MPASS(td->td_lock == &blocked_lock);
712 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
713 }
714
715 void
716 thread_lock_set(struct thread *td, struct mtx *new)
717 {
718 struct mtx *lock;
719
720 mtx_assert(new, MA_OWNED);
721 THREAD_LOCK_ASSERT(td, MA_OWNED);
722 lock = td->td_lock;
723 td->td_lock = new;
724 mtx_unlock_spin(lock);
725 }
726
727 /*
728 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
729 *
730 * We are only called here if the lock is recursed or contested (i.e. we
731 * need to wake up a blocked thread).
732 */
733 void
734 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line)
735 {
736 struct mtx *m;
737 struct turnstile *ts;
738
739 if (SCHEDULER_STOPPED())
740 return;
741
742 m = mtxlock2mtx(c);
743
744 if (mtx_recursed(m)) {
745 if (--(m->mtx_recurse) == 0)
746 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
747 if (LOCK_LOG_TEST(&m->lock_object, opts))
748 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
749 return;
750 }
751
752 /*
753 * We have to lock the chain before the turnstile so this turnstile
754 * can be removed from the hash list if it is empty.
755 */
756 turnstile_chain_lock(&m->lock_object);
757 ts = turnstile_lookup(&m->lock_object);
758 if (LOCK_LOG_TEST(&m->lock_object, opts))
759 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
760 MPASS(ts != NULL);
761 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
762 _mtx_release_lock_quick(m);
763
764 /*
765 * This turnstile is now no longer associated with the mutex. We can
766 * unlock the chain lock so a new turnstile may take it's place.
767 */
768 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
769 turnstile_chain_unlock(&m->lock_object);
770 }
771
772 /*
773 * All the unlocking of MTX_SPIN locks is done inline.
774 * See the __mtx_unlock_spin() macro for the details.
775 */
776
777 /*
778 * The backing function for the INVARIANTS-enabled mtx_assert()
779 */
780 #ifdef INVARIANT_SUPPORT
781 void
782 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line)
783 {
784 const struct mtx *m;
785
786 if (panicstr != NULL || dumping)
787 return;
788
789 m = mtxlock2mtx(c);
790
791 switch (what) {
792 case MA_OWNED:
793 case MA_OWNED | MA_RECURSED:
794 case MA_OWNED | MA_NOTRECURSED:
795 if (!mtx_owned(m))
796 panic("mutex %s not owned at %s:%d",
797 m->lock_object.lo_name, file, line);
798 if (mtx_recursed(m)) {
799 if ((what & MA_NOTRECURSED) != 0)
800 panic("mutex %s recursed at %s:%d",
801 m->lock_object.lo_name, file, line);
802 } else if ((what & MA_RECURSED) != 0) {
803 panic("mutex %s unrecursed at %s:%d",
804 m->lock_object.lo_name, file, line);
805 }
806 break;
807 case MA_NOTOWNED:
808 if (mtx_owned(m))
809 panic("mutex %s owned at %s:%d",
810 m->lock_object.lo_name, file, line);
811 break;
812 default:
813 panic("unknown mtx_assert at %s:%d", file, line);
814 }
815 }
816 #endif
817
818 /*
819 * The MUTEX_DEBUG-enabled mtx_validate()
820 *
821 * Most of these checks have been moved off into the LO_INITIALIZED flag
822 * maintained by the witness code.
823 */
824 #ifdef MUTEX_DEBUG
825
826 void mtx_validate(struct mtx *);
827
828 void
829 mtx_validate(struct mtx *m)
830 {
831
832 /*
833 * XXX: When kernacc() does not require Giant we can reenable this check
834 */
835 #ifdef notyet
836 /*
837 * Can't call kernacc() from early init386(), especially when
838 * initializing Giant mutex, because some stuff in kernacc()
839 * requires Giant itself.
840 */
841 if (!cold)
842 if (!kernacc((caddr_t)m, sizeof(m),
843 VM_PROT_READ | VM_PROT_WRITE))
844 panic("Can't read and write to mutex %p", m);
845 #endif
846 }
847 #endif
848
849 /*
850 * General init routine used by the MTX_SYSINIT() macro.
851 */
852 void
853 mtx_sysinit(void *arg)
854 {
855 struct mtx_args *margs = arg;
856
857 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL,
858 margs->ma_opts);
859 }
860
861 /*
862 * Mutex initialization routine; initialize lock `m' of type contained in
863 * `opts' with options contained in `opts' and name `name.' The optional
864 * lock type `type' is used as a general lock category name for use with
865 * witness.
866 */
867 void
868 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
869 {
870 struct mtx *m;
871 struct lock_class *class;
872 int flags;
873
874 m = mtxlock2mtx(c);
875
876 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
877 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0);
878 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
879 ("%s: mtx_lock not aligned for %s: %p", __func__, name,
880 &m->mtx_lock));
881
882 #ifdef MUTEX_DEBUG
883 /* Diagnostic and error correction */
884 mtx_validate(m);
885 #endif
886
887 /* Determine lock class and lock flags. */
888 if (opts & MTX_SPIN)
889 class = &lock_class_mtx_spin;
890 else
891 class = &lock_class_mtx_sleep;
892 flags = 0;
893 if (opts & MTX_QUIET)
894 flags |= LO_QUIET;
895 if (opts & MTX_RECURSE)
896 flags |= LO_RECURSABLE;
897 if ((opts & MTX_NOWITNESS) == 0)
898 flags |= LO_WITNESS;
899 if (opts & MTX_DUPOK)
900 flags |= LO_DUPOK;
901 if (opts & MTX_NOPROFILE)
902 flags |= LO_NOPROFILE;
903
904 /* Initialize mutex. */
905 lock_init(&m->lock_object, class, name, type, flags);
906
907 m->mtx_lock = MTX_UNOWNED;
908 m->mtx_recurse = 0;
909 }
910
911 /*
912 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
913 * passed in as a flag here because if the corresponding mtx_init() was
914 * called with MTX_QUIET set, then it will already be set in the mutex's
915 * flags.
916 */
917 void
918 _mtx_destroy(volatile uintptr_t *c)
919 {
920 struct mtx *m;
921
922 m = mtxlock2mtx(c);
923
924 if (!mtx_owned(m))
925 MPASS(mtx_unowned(m));
926 else {
927 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
928
929 /* Perform the non-mtx related part of mtx_unlock_spin(). */
930 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
931 spinlock_exit();
932 else
933 curthread->td_locks--;
934
935 lock_profile_release_lock(&m->lock_object);
936 /* Tell witness this isn't locked to make it happy. */
937 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
938 __LINE__);
939 }
940
941 m->mtx_lock = MTX_DESTROYED;
942 lock_destroy(&m->lock_object);
943 }
944
945 /*
946 * Intialize the mutex code and system mutexes. This is called from the MD
947 * startup code prior to mi_startup(). The per-CPU data space needs to be
948 * setup before this is called.
949 */
950 void
951 mutex_init(void)
952 {
953
954 /* Setup turnstiles so that sleep mutexes work. */
955 init_turnstiles();
956
957 /*
958 * Initialize mutexes.
959 */
960 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
961 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
962 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
963 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
964 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE);
965 mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
966 mtx_lock(&Giant);
967 }
968
969 #ifdef DDB
970 void
971 db_show_mtx(const struct lock_object *lock)
972 {
973 struct thread *td;
974 const struct mtx *m;
975
976 m = (const struct mtx *)lock;
977
978 db_printf(" flags: {");
979 if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
980 db_printf("SPIN");
981 else
982 db_printf("DEF");
983 if (m->lock_object.lo_flags & LO_RECURSABLE)
984 db_printf(", RECURSE");
985 if (m->lock_object.lo_flags & LO_DUPOK)
986 db_printf(", DUPOK");
987 db_printf("}\n");
988 db_printf(" state: {");
989 if (mtx_unowned(m))
990 db_printf("UNOWNED");
991 else if (mtx_destroyed(m))
992 db_printf("DESTROYED");
993 else {
994 db_printf("OWNED");
995 if (m->mtx_lock & MTX_CONTESTED)
996 db_printf(", CONTESTED");
997 if (m->mtx_lock & MTX_RECURSED)
998 db_printf(", RECURSED");
999 }
1000 db_printf("}\n");
1001 if (!mtx_unowned(m) && !mtx_destroyed(m)) {
1002 td = mtx_owner(m);
1003 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
1004 td->td_tid, td->td_proc->p_pid, td->td_name);
1005 if (mtx_recursed(m))
1006 db_printf(" recursed: %d\n", m->mtx_recurse);
1007 }
1008 }
1009 #endif
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