2 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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
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
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 $
33 * Machine independent bits of mutex implementation.
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
39 #include "opt_adaptive_mutexes.h"
41 #include "opt_global.h"
42 #include "opt_kdtrace.h"
43 #include "opt_sched.h"
45 #include <sys/param.h>
46 #include <sys/systm.h>
50 #include <sys/kernel.h>
53 #include <sys/malloc.h>
54 #include <sys/mutex.h>
56 #include <sys/resourcevar.h>
57 #include <sys/sched.h>
59 #include <sys/sysctl.h>
60 #include <sys/turnstile.h>
61 #include <sys/vmmeter.h>
62 #include <sys/lock_profile.h>
64 #include <machine/atomic.h>
65 #include <machine/bus.h>
66 #include <machine/cpu.h>
70 #include <fs/devfs/devfs_int.h>
73 #include <vm/vm_extern.h>
75 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
76 #define ADAPTIVE_MUTEXES
80 * Internal utility macros.
82 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
84 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
86 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK))
88 static void assert_mtx(struct lock_object *lock, int what);
90 static void db_show_mtx(struct lock_object *lock);
92 static void lock_mtx(struct lock_object *lock, int how);
93 static void lock_spin(struct lock_object *lock, int how);
95 static int owner_mtx(struct lock_object *lock, struct thread **owner);
97 static int unlock_mtx(struct lock_object *lock);
98 static int unlock_spin(struct lock_object *lock);
101 * Lock classes for sleep and spin mutexes.
103 struct lock_class lock_class_mtx_sleep = {
104 .lc_name = "sleep mutex",
105 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
106 .lc_assert = assert_mtx,
108 .lc_ddb_show = db_show_mtx,
111 .lc_unlock = unlock_mtx,
113 .lc_owner = owner_mtx,
116 struct lock_class lock_class_mtx_spin = {
117 .lc_name = "spin mutex",
118 .lc_flags = LC_SPINLOCK | LC_RECURSABLE,
119 .lc_assert = assert_mtx,
121 .lc_ddb_show = db_show_mtx,
123 .lc_lock = lock_spin,
124 .lc_unlock = unlock_spin,
126 .lc_owner = owner_mtx,
131 * System-wide mutexes
133 struct mtx blocked_lock;
137 assert_mtx(struct lock_object *lock, int what)
140 mtx_assert((struct mtx *)lock, what);
144 lock_mtx(struct lock_object *lock, int how)
147 mtx_lock((struct mtx *)lock);
151 lock_spin(struct lock_object *lock, int how)
154 panic("spin locks can only use msleep_spin");
158 unlock_mtx(struct lock_object *lock)
162 m = (struct mtx *)lock;
163 mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
169 unlock_spin(struct lock_object *lock)
172 panic("spin locks can only use msleep_spin");
177 owner_mtx(struct lock_object *lock, struct thread **owner)
179 struct mtx *m = (struct mtx *)lock;
181 *owner = mtx_owner(m);
182 return (mtx_unowned(m) == 0);
187 * Function versions of the inlined __mtx_* macros. These are used by
188 * modules and can also be called from assembly language if needed.
191 _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line)
194 if (SCHEDULER_STOPPED())
196 MPASS(curthread != NULL);
197 KASSERT(m->mtx_lock != MTX_DESTROYED,
198 ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
199 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
200 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
202 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
205 _get_sleep_lock(m, curthread, opts, file, line);
206 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
208 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
209 curthread->td_locks++;
213 _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
216 if (SCHEDULER_STOPPED())
218 MPASS(curthread != NULL);
219 KASSERT(m->mtx_lock != MTX_DESTROYED,
220 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
221 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
222 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
224 curthread->td_locks--;
225 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
226 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
228 mtx_assert(m, MA_OWNED);
230 if (m->mtx_recurse == 0)
231 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m);
232 _rel_sleep_lock(m, curthread, opts, file, line);
236 _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
239 if (SCHEDULER_STOPPED())
241 MPASS(curthread != NULL);
242 KASSERT(m->mtx_lock != MTX_DESTROYED,
243 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
244 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
245 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
246 m->lock_object.lo_name, file, line));
248 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
249 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
250 m->lock_object.lo_name, file, line));
251 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
253 _get_spin_lock(m, curthread, opts, file, line);
254 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
256 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
260 _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
263 if (SCHEDULER_STOPPED())
265 MPASS(curthread != NULL);
266 KASSERT(m->mtx_lock != MTX_DESTROYED,
267 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
268 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
269 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
270 m->lock_object.lo_name, file, line));
271 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
272 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
274 mtx_assert(m, MA_OWNED);
280 * The important part of mtx_trylock{,_flags}()
281 * Tries to acquire lock `m.' If this function is called on a mutex that
282 * is already owned, it will recursively acquire the lock.
285 _mtx_trylock(struct mtx *m, int opts, const char *file, int line)
287 #ifdef LOCK_PROFILING
288 uint64_t waittime = 0;
293 if (SCHEDULER_STOPPED())
296 MPASS(curthread != NULL);
297 KASSERT(m->mtx_lock != MTX_DESTROYED,
298 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
299 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
300 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
303 if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) {
305 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
308 rval = _obtain_lock(m, (uintptr_t)curthread);
310 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
312 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
314 curthread->td_locks++;
315 if (m->mtx_recurse == 0)
316 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE,
317 m, contested, waittime, file, line);
325 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
327 * We call this if the lock is either contested (i.e. we need to go to
328 * sleep waiting for it), or if we need to recurse on it.
331 _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file,
334 struct turnstile *ts;
336 #ifdef ADAPTIVE_MUTEXES
337 volatile struct thread *owner;
342 #ifdef LOCK_PROFILING
344 uint64_t waittime = 0;
347 uint64_t spin_cnt = 0;
348 uint64_t sleep_cnt = 0;
349 int64_t sleep_time = 0;
352 if (SCHEDULER_STOPPED())
356 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
357 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
358 m->lock_object.lo_name, file, line));
360 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
361 if (LOCK_LOG_TEST(&m->lock_object, opts))
362 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
366 lock_profile_obtain_lock_failed(&m->lock_object,
367 &contested, &waittime);
368 if (LOCK_LOG_TEST(&m->lock_object, opts))
370 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
371 m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
373 while (!_obtain_lock(m, tid)) {
377 #ifdef ADAPTIVE_MUTEXES
379 * If the owner is running on another CPU, spin until the
380 * owner stops running or the state of the lock changes.
383 if (v != MTX_UNOWNED) {
384 owner = (struct thread *)(v & ~MTX_FLAGMASK);
385 if (TD_IS_RUNNING(owner)) {
386 if (LOCK_LOG_TEST(&m->lock_object, 0))
388 "%s: spinning on %p held by %p",
390 while (mtx_owner(m) == owner &&
391 TD_IS_RUNNING(owner)) {
402 ts = turnstile_trywait(&m->lock_object);
406 * Check if the lock has been released while spinning for
407 * the turnstile chain lock.
409 if (v == MTX_UNOWNED) {
410 turnstile_cancel(ts);
414 #ifdef ADAPTIVE_MUTEXES
416 * The current lock owner might have started executing
417 * on another CPU (or the lock could have changed
418 * owners) while we were waiting on the turnstile
419 * chain lock. If so, drop the turnstile lock and try
422 owner = (struct thread *)(v & ~MTX_FLAGMASK);
423 if (TD_IS_RUNNING(owner)) {
424 turnstile_cancel(ts);
430 * If the mutex isn't already contested and a failure occurs
431 * setting the contested bit, the mutex was either released
432 * or the state of the MTX_RECURSED bit changed.
434 if ((v & MTX_CONTESTED) == 0 &&
435 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
436 turnstile_cancel(ts);
441 * We definitely must sleep for this lock.
443 mtx_assert(m, MA_NOTOWNED);
448 "contention: %p at %s:%d wants %s, taken by %s:%d",
449 (void *)tid, file, line, m->lock_object.lo_name,
450 WITNESS_FILE(&m->lock_object),
451 WITNESS_LINE(&m->lock_object));
457 * Block on the turnstile.
460 sleep_time -= lockstat_nsecs();
462 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
464 sleep_time += lockstat_nsecs();
471 "contention end: %s acquired by %p at %s:%d",
472 m->lock_object.lo_name, (void *)tid, file, line);
475 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested,
476 waittime, file, line);
479 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time);
482 * Only record the loops spinning and not sleeping.
484 if (spin_cnt > sleep_cnt)
485 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt));
490 _mtx_lock_spin_failed(struct mtx *m)
496 /* If the mutex is unlocked, try again. */
500 printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
501 m, m->lock_object.lo_name, td, td->td_tid);
503 witness_display_spinlock(&m->lock_object, td, printf);
505 panic("spin lock held too long");
510 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock.
512 * This is only called if we need to actually spin for the lock. Recursion
516 _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file,
520 #ifdef LOCK_PROFILING
522 uint64_t waittime = 0;
525 if (SCHEDULER_STOPPED())
528 if (LOCK_LOG_TEST(&m->lock_object, opts))
529 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
531 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
532 while (!_obtain_lock(m, tid)) {
534 /* Give interrupts a chance while we spin. */
536 while (m->mtx_lock != MTX_UNOWNED) {
537 if (i++ < 10000000) {
541 if (i < 60000000 || kdb_active || panicstr != NULL)
544 _mtx_lock_spin_failed(m);
550 if (LOCK_LOG_TEST(&m->lock_object, opts))
551 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
553 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m,
554 contested, waittime, (file), (line));
555 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i);
560 _thread_lock_flags(struct thread *td, int opts, const char *file, int line)
565 #ifdef LOCK_PROFILING
567 uint64_t waittime = 0;
570 uint64_t spin_cnt = 0;
574 tid = (uintptr_t)curthread;
576 if (SCHEDULER_STOPPED())
583 KASSERT(m->mtx_lock != MTX_DESTROYED,
584 ("thread_lock() of destroyed mutex @ %s:%d", file, line));
585 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
586 ("thread_lock() of sleep mutex %s @ %s:%d",
587 m->lock_object.lo_name, file, line));
589 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
590 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
591 m->lock_object.lo_name, file, line));
592 WITNESS_CHECKORDER(&m->lock_object,
593 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
594 while (!_obtain_lock(m, tid)) {
598 if (m->mtx_lock == tid) {
602 lock_profile_obtain_lock_failed(&m->lock_object,
603 &contested, &waittime);
604 /* Give interrupts a chance while we spin. */
606 while (m->mtx_lock != MTX_UNOWNED) {
609 else if (i < 60000000 ||
610 kdb_active || panicstr != NULL)
613 _mtx_lock_spin_failed(m);
615 if (m != td->td_lock)
620 if (m == td->td_lock)
622 _rel_spin_lock(m); /* does spinlock_exit() */
627 if (m->mtx_recurse == 0)
628 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE,
629 m, contested, waittime, (file), (line));
630 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
632 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
633 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt);
637 thread_lock_block(struct thread *td)
641 THREAD_LOCK_ASSERT(td, MA_OWNED);
643 td->td_lock = &blocked_lock;
644 mtx_unlock_spin(lock);
650 thread_lock_unblock(struct thread *td, struct mtx *new)
652 mtx_assert(new, MA_OWNED);
653 MPASS(td->td_lock == &blocked_lock);
654 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
658 thread_lock_set(struct thread *td, struct mtx *new)
662 mtx_assert(new, MA_OWNED);
663 THREAD_LOCK_ASSERT(td, MA_OWNED);
666 mtx_unlock_spin(lock);
670 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
672 * We are only called here if the lock is recursed or contested (i.e. we
673 * need to wake up a blocked thread).
676 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line)
678 struct turnstile *ts;
680 if (SCHEDULER_STOPPED())
683 if (mtx_recursed(m)) {
684 if (--(m->mtx_recurse) == 0)
685 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
686 if (LOCK_LOG_TEST(&m->lock_object, opts))
687 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
692 * We have to lock the chain before the turnstile so this turnstile
693 * can be removed from the hash list if it is empty.
695 turnstile_chain_lock(&m->lock_object);
696 ts = turnstile_lookup(&m->lock_object);
697 if (LOCK_LOG_TEST(&m->lock_object, opts))
698 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
700 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
701 _release_lock_quick(m);
704 * This turnstile is now no longer associated with the mutex. We can
705 * unlock the chain lock so a new turnstile may take it's place.
707 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
708 turnstile_chain_unlock(&m->lock_object);
712 * All the unlocking of MTX_SPIN locks is done inline.
713 * See the _rel_spin_lock() macro for the details.
717 * The backing function for the INVARIANTS-enabled mtx_assert()
719 #ifdef INVARIANT_SUPPORT
721 _mtx_assert(struct mtx *m, int what, const char *file, int line)
724 if (panicstr != NULL || dumping)
728 case MA_OWNED | MA_RECURSED:
729 case MA_OWNED | MA_NOTRECURSED:
731 panic("mutex %s not owned at %s:%d",
732 m->lock_object.lo_name, file, line);
733 if (mtx_recursed(m)) {
734 if ((what & MA_NOTRECURSED) != 0)
735 panic("mutex %s recursed at %s:%d",
736 m->lock_object.lo_name, file, line);
737 } else if ((what & MA_RECURSED) != 0) {
738 panic("mutex %s unrecursed at %s:%d",
739 m->lock_object.lo_name, file, line);
744 panic("mutex %s owned at %s:%d",
745 m->lock_object.lo_name, file, line);
748 panic("unknown mtx_assert at %s:%d", file, line);
754 * The MUTEX_DEBUG-enabled mtx_validate()
756 * Most of these checks have been moved off into the LO_INITIALIZED flag
757 * maintained by the witness code.
761 void mtx_validate(struct mtx *);
764 mtx_validate(struct mtx *m)
768 * XXX: When kernacc() does not require Giant we can reenable this check
772 * Can't call kernacc() from early init386(), especially when
773 * initializing Giant mutex, because some stuff in kernacc()
774 * requires Giant itself.
777 if (!kernacc((caddr_t)m, sizeof(m),
778 VM_PROT_READ | VM_PROT_WRITE))
779 panic("Can't read and write to mutex %p", m);
785 * General init routine used by the MTX_SYSINIT() macro.
788 mtx_sysinit(void *arg)
790 struct mtx_args *margs = arg;
792 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts);
796 * Mutex initialization routine; initialize lock `m' of type contained in
797 * `opts' with options contained in `opts' and name `name.' The optional
798 * lock type `type' is used as a general lock category name for use with
802 mtx_init(struct mtx *m, const char *name, const char *type, int opts)
804 struct lock_class *class;
807 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
808 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0);
809 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
810 ("%s: mtx_lock not aligned for %s: %p", __func__, name,
814 /* Diagnostic and error correction */
818 /* Determine lock class and lock flags. */
820 class = &lock_class_mtx_spin;
822 class = &lock_class_mtx_sleep;
824 if (opts & MTX_QUIET)
826 if (opts & MTX_RECURSE)
827 flags |= LO_RECURSABLE;
828 if ((opts & MTX_NOWITNESS) == 0)
830 if (opts & MTX_DUPOK)
832 if (opts & MTX_NOPROFILE)
833 flags |= LO_NOPROFILE;
835 /* Initialize mutex. */
836 m->mtx_lock = MTX_UNOWNED;
839 lock_init(&m->lock_object, class, name, type, flags);
843 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
844 * passed in as a flag here because if the corresponding mtx_init() was
845 * called with MTX_QUIET set, then it will already be set in the mutex's
849 mtx_destroy(struct mtx *m)
853 MPASS(mtx_unowned(m));
855 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
857 /* Perform the non-mtx related part of mtx_unlock_spin(). */
858 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
861 curthread->td_locks--;
863 lock_profile_release_lock(&m->lock_object);
864 /* Tell witness this isn't locked to make it happy. */
865 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
869 m->mtx_lock = MTX_DESTROYED;
870 lock_destroy(&m->lock_object);
874 * Intialize the mutex code and system mutexes. This is called from the MD
875 * startup code prior to mi_startup(). The per-CPU data space needs to be
876 * setup before this is called.
882 /* Setup turnstiles so that sleep mutexes work. */
886 * Initialize mutexes.
888 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
889 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
890 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
891 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
892 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE);
893 mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
899 db_show_mtx(struct lock_object *lock)
904 m = (struct mtx *)lock;
906 db_printf(" flags: {");
907 if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
911 if (m->lock_object.lo_flags & LO_RECURSABLE)
912 db_printf(", RECURSE");
913 if (m->lock_object.lo_flags & LO_DUPOK)
914 db_printf(", DUPOK");
916 db_printf(" state: {");
918 db_printf("UNOWNED");
919 else if (mtx_destroyed(m))
920 db_printf("DESTROYED");
923 if (m->mtx_lock & MTX_CONTESTED)
924 db_printf(", CONTESTED");
925 if (m->mtx_lock & MTX_RECURSED)
926 db_printf(", RECURSED");
929 if (!mtx_unowned(m) && !mtx_destroyed(m)) {
931 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
932 td->td_tid, td->td_proc->p_pid, td->td_name);
934 db_printf(" recursed: %d\n", m->mtx_recurse);