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_hwpmc_hooks.h"
43 #include "opt_kdtrace.h"
44 #include "opt_sched.h"
46 #include <sys/param.h>
47 #include <sys/systm.h>
51 #include <sys/kernel.h>
54 #include <sys/malloc.h>
55 #include <sys/mutex.h>
57 #include <sys/resourcevar.h>
58 #include <sys/sched.h>
60 #include <sys/sysctl.h>
61 #include <sys/turnstile.h>
62 #include <sys/vmmeter.h>
63 #include <sys/lock_profile.h>
65 #include <machine/atomic.h>
66 #include <machine/bus.h>
67 #include <machine/cpu.h>
71 #include <fs/devfs/devfs_int.h>
74 #include <vm/vm_extern.h>
76 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
77 #define ADAPTIVE_MUTEXES
81 #include <sys/pmckern.h>
82 PMC_SOFT_DEFINE( , , lock, failed);
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.
89 #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock))
92 * Internal utility macros.
94 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
96 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
98 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK))
100 static void assert_mtx(const struct lock_object *lock, int what);
102 static void db_show_mtx(const struct lock_object *lock);
104 static void lock_mtx(struct lock_object *lock, uintptr_t how);
105 static void lock_spin(struct lock_object *lock, uintptr_t how);
107 static int owner_mtx(const struct lock_object *lock,
108 struct thread **owner);
110 static uintptr_t unlock_mtx(struct lock_object *lock);
111 static uintptr_t unlock_spin(struct lock_object *lock);
114 * Lock classes for sleep and spin mutexes.
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,
121 .lc_ddb_show = db_show_mtx,
124 .lc_unlock = unlock_mtx,
126 .lc_owner = owner_mtx,
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,
134 .lc_ddb_show = db_show_mtx,
136 .lc_lock = lock_spin,
137 .lc_unlock = unlock_spin,
139 .lc_owner = owner_mtx,
144 * System-wide mutexes
146 struct mtx blocked_lock;
150 assert_mtx(const struct lock_object *lock, int what)
153 mtx_assert((const struct mtx *)lock, what);
157 lock_mtx(struct lock_object *lock, uintptr_t how)
160 mtx_lock((struct mtx *)lock);
164 lock_spin(struct lock_object *lock, uintptr_t how)
167 panic("spin locks can only use msleep_spin");
171 unlock_mtx(struct lock_object *lock)
175 m = (struct mtx *)lock;
176 mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
182 unlock_spin(struct lock_object *lock)
185 panic("spin locks can only use msleep_spin");
190 owner_mtx(const struct lock_object *lock, struct thread **owner)
192 const struct mtx *m = (const struct mtx *)lock;
194 *owner = mtx_owner(m);
195 return (mtx_unowned(m) == 0);
200 * Function versions of the inlined __mtx_* macros. These are used by
201 * modules and can also be called from assembly language if needed.
204 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
208 if (SCHEDULER_STOPPED())
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,
221 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
222 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
224 __mtx_lock(m, curthread, opts, file, line);
225 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
227 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
229 curthread->td_locks++;
233 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
237 if (SCHEDULER_STOPPED())
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,
247 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
248 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
250 mtx_assert(m, MA_OWNED);
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--;
259 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
264 if (SCHEDULER_STOPPED())
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));
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,
282 __mtx_lock_spin(m, curthread, opts, file, line);
283 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
285 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
289 __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
294 if (SCHEDULER_STOPPED())
299 KASSERT(m->mtx_lock != MTX_DESTROYED,
300 ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line));
301 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
302 ("mtx_trylock_spin() of sleep mutex %s @ %s:%d",
303 m->lock_object.lo_name, file, line));
304 KASSERT((opts & MTX_RECURSE) == 0,
305 ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n",
306 m->lock_object.lo_name, file, line));
307 if (__mtx_trylock_spin(m, curthread, opts, file, line)) {
308 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line);
309 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
312 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line);
317 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
322 if (SCHEDULER_STOPPED())
327 KASSERT(m->mtx_lock != MTX_DESTROYED,
328 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
329 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
330 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
331 m->lock_object.lo_name, file, line));
332 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
333 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
335 mtx_assert(m, MA_OWNED);
337 __mtx_unlock_spin(m);
341 * The important part of mtx_trylock{,_flags}()
342 * Tries to acquire lock `m.' If this function is called on a mutex that
343 * is already owned, it will recursively acquire the lock.
346 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
349 #ifdef LOCK_PROFILING
350 uint64_t waittime = 0;
355 if (SCHEDULER_STOPPED())
360 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
361 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
362 curthread, m->lock_object.lo_name, file, line));
363 KASSERT(m->mtx_lock != MTX_DESTROYED,
364 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
365 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
366 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
369 if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
370 (opts & MTX_RECURSE) != 0)) {
372 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
375 rval = _mtx_obtain_lock(m, (uintptr_t)curthread);
376 opts &= ~MTX_RECURSE;
378 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
380 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
382 curthread->td_locks++;
383 if (m->mtx_recurse == 0)
384 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE,
385 m, contested, waittime, file, line);
393 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
395 * We call this if the lock is either contested (i.e. we need to go to
396 * sleep waiting for it), or if we need to recurse on it.
399 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts,
400 const char *file, int line)
403 struct turnstile *ts;
405 #ifdef ADAPTIVE_MUTEXES
406 volatile struct thread *owner;
411 #ifdef LOCK_PROFILING
413 uint64_t waittime = 0;
416 uint64_t spin_cnt = 0;
417 uint64_t sleep_cnt = 0;
418 int64_t sleep_time = 0;
419 int64_t all_time = 0;
422 if (SCHEDULER_STOPPED())
428 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
429 (opts & MTX_RECURSE) != 0,
430 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
431 m->lock_object.lo_name, file, line));
432 opts &= ~MTX_RECURSE;
434 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
435 if (LOCK_LOG_TEST(&m->lock_object, opts))
436 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
439 opts &= ~MTX_RECURSE;
442 PMC_SOFT_CALL( , , lock, failed);
444 lock_profile_obtain_lock_failed(&m->lock_object,
445 &contested, &waittime);
446 if (LOCK_LOG_TEST(&m->lock_object, opts))
448 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
449 m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
451 all_time -= lockstat_nsecs(&m->lock_object);
454 while (!_mtx_obtain_lock(m, tid)) {
458 #ifdef ADAPTIVE_MUTEXES
460 * If the owner is running on another CPU, spin until the
461 * owner stops running or the state of the lock changes.
464 if (v != MTX_UNOWNED) {
465 owner = (struct thread *)(v & ~MTX_FLAGMASK);
466 if (TD_IS_RUNNING(owner)) {
467 if (LOCK_LOG_TEST(&m->lock_object, 0))
469 "%s: spinning on %p held by %p",
471 KTR_STATE1(KTR_SCHED, "thread",
472 sched_tdname((struct thread *)tid),
473 "spinning", "lockname:\"%s\"",
474 m->lock_object.lo_name);
475 while (mtx_owner(m) == owner &&
476 TD_IS_RUNNING(owner)) {
482 KTR_STATE0(KTR_SCHED, "thread",
483 sched_tdname((struct thread *)tid),
490 ts = turnstile_trywait(&m->lock_object);
494 * Check if the lock has been released while spinning for
495 * the turnstile chain lock.
497 if (v == MTX_UNOWNED) {
498 turnstile_cancel(ts);
502 #ifdef ADAPTIVE_MUTEXES
504 * The current lock owner might have started executing
505 * on another CPU (or the lock could have changed
506 * owners) while we were waiting on the turnstile
507 * chain lock. If so, drop the turnstile lock and try
510 owner = (struct thread *)(v & ~MTX_FLAGMASK);
511 if (TD_IS_RUNNING(owner)) {
512 turnstile_cancel(ts);
518 * If the mutex isn't already contested and a failure occurs
519 * setting the contested bit, the mutex was either released
520 * or the state of the MTX_RECURSED bit changed.
522 if ((v & MTX_CONTESTED) == 0 &&
523 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
524 turnstile_cancel(ts);
529 * We definitely must sleep for this lock.
531 mtx_assert(m, MA_NOTOWNED);
536 "contention: %p at %s:%d wants %s, taken by %s:%d",
537 (void *)tid, file, line, m->lock_object.lo_name,
538 WITNESS_FILE(&m->lock_object),
539 WITNESS_LINE(&m->lock_object));
545 * Block on the turnstile.
548 sleep_time -= lockstat_nsecs(&m->lock_object);
550 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
552 sleep_time += lockstat_nsecs(&m->lock_object);
557 all_time += lockstat_nsecs(&m->lock_object);
562 "contention end: %s acquired by %p at %s:%d",
563 m->lock_object.lo_name, (void *)tid, file, line);
566 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested,
567 waittime, file, line);
570 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time);
573 * Only record the loops spinning and not sleeping.
575 if (spin_cnt > sleep_cnt)
576 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (all_time - sleep_time));
581 _mtx_lock_spin_failed(struct mtx *m)
587 /* If the mutex is unlocked, try again. */
591 printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
592 m, m->lock_object.lo_name, td, td->td_tid);
594 witness_display_spinlock(&m->lock_object, td, printf);
596 panic("spin lock held too long");
601 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
603 * This is only called if we need to actually spin for the lock. Recursion
607 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts,
608 const char *file, int line)
612 #ifdef LOCK_PROFILING
614 uint64_t waittime = 0;
617 int64_t spin_time = 0;
620 if (SCHEDULER_STOPPED())
625 if (LOCK_LOG_TEST(&m->lock_object, opts))
626 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
627 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
628 "spinning", "lockname:\"%s\"", m->lock_object.lo_name);
631 PMC_SOFT_CALL( , , lock, failed);
633 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
635 spin_time -= lockstat_nsecs(&m->lock_object);
637 while (!_mtx_obtain_lock(m, tid)) {
639 /* Give interrupts a chance while we spin. */
641 while (m->mtx_lock != MTX_UNOWNED) {
642 if (i++ < 10000000) {
646 if (i < 60000000 || kdb_active || panicstr != NULL)
649 _mtx_lock_spin_failed(m);
655 spin_time += lockstat_nsecs(&m->lock_object);
658 if (LOCK_LOG_TEST(&m->lock_object, opts))
659 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
660 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
663 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m,
664 contested, waittime, (file), (line));
667 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, spin_time);
673 thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
678 #ifdef LOCK_PROFILING
680 uint64_t waittime = 0;
683 int64_t spin_time = 0;
687 tid = (uintptr_t)curthread;
689 if (SCHEDULER_STOPPED()) {
691 * Ensure that spinlock sections are balanced even when the
692 * scheduler is stopped, since we may otherwise inadvertently
693 * re-enable interrupts while dumping core.
700 spin_time -= lockstat_nsecs(&td->td_lock->lock_object);
706 KASSERT(m->mtx_lock != MTX_DESTROYED,
707 ("thread_lock() of destroyed mutex @ %s:%d", file, line));
708 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
709 ("thread_lock() of sleep mutex %s @ %s:%d",
710 m->lock_object.lo_name, file, line));
712 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
713 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
714 m->lock_object.lo_name, file, line));
715 WITNESS_CHECKORDER(&m->lock_object,
716 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
717 while (!_mtx_obtain_lock(m, tid)) {
718 if (m->mtx_lock == tid) {
723 PMC_SOFT_CALL( , , lock, failed);
725 lock_profile_obtain_lock_failed(&m->lock_object,
726 &contested, &waittime);
727 /* Give interrupts a chance while we spin. */
729 while (m->mtx_lock != MTX_UNOWNED) {
732 else if (i < 60000000 ||
733 kdb_active || panicstr != NULL)
736 _mtx_lock_spin_failed(m);
738 if (m != td->td_lock)
743 if (m == td->td_lock)
745 __mtx_unlock_spin(m); /* does spinlock_exit() */
748 spin_time += lockstat_nsecs(&m->lock_object);
750 if (m->mtx_recurse == 0)
751 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE,
752 m, contested, waittime, (file), (line));
753 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
755 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
756 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_time);
760 thread_lock_block(struct thread *td)
764 THREAD_LOCK_ASSERT(td, MA_OWNED);
766 td->td_lock = &blocked_lock;
767 mtx_unlock_spin(lock);
773 thread_lock_unblock(struct thread *td, struct mtx *new)
775 mtx_assert(new, MA_OWNED);
776 MPASS(td->td_lock == &blocked_lock);
777 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
781 thread_lock_set(struct thread *td, struct mtx *new)
785 mtx_assert(new, MA_OWNED);
786 THREAD_LOCK_ASSERT(td, MA_OWNED);
789 mtx_unlock_spin(lock);
793 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
795 * We are only called here if the lock is recursed or contested (i.e. we
796 * need to wake up a blocked thread).
799 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line)
802 struct turnstile *ts;
804 if (SCHEDULER_STOPPED())
809 if (mtx_recursed(m)) {
810 if (--(m->mtx_recurse) == 0)
811 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
812 if (LOCK_LOG_TEST(&m->lock_object, opts))
813 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
818 * We have to lock the chain before the turnstile so this turnstile
819 * can be removed from the hash list if it is empty.
821 turnstile_chain_lock(&m->lock_object);
822 ts = turnstile_lookup(&m->lock_object);
823 if (LOCK_LOG_TEST(&m->lock_object, opts))
824 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
826 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
827 _mtx_release_lock_quick(m);
830 * This turnstile is now no longer associated with the mutex. We can
831 * unlock the chain lock so a new turnstile may take it's place.
833 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
834 turnstile_chain_unlock(&m->lock_object);
838 * All the unlocking of MTX_SPIN locks is done inline.
839 * See the __mtx_unlock_spin() macro for the details.
843 * The backing function for the INVARIANTS-enabled mtx_assert()
845 #ifdef INVARIANT_SUPPORT
847 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line)
851 if (panicstr != NULL || dumping)
858 case MA_OWNED | MA_RECURSED:
859 case MA_OWNED | MA_NOTRECURSED:
861 panic("mutex %s not owned at %s:%d",
862 m->lock_object.lo_name, file, line);
863 if (mtx_recursed(m)) {
864 if ((what & MA_NOTRECURSED) != 0)
865 panic("mutex %s recursed at %s:%d",
866 m->lock_object.lo_name, file, line);
867 } else if ((what & MA_RECURSED) != 0) {
868 panic("mutex %s unrecursed at %s:%d",
869 m->lock_object.lo_name, file, line);
874 panic("mutex %s owned at %s:%d",
875 m->lock_object.lo_name, file, line);
878 panic("unknown mtx_assert at %s:%d", file, line);
884 * The MUTEX_DEBUG-enabled mtx_validate()
886 * Most of these checks have been moved off into the LO_INITIALIZED flag
887 * maintained by the witness code.
891 void mtx_validate(struct mtx *);
894 mtx_validate(struct mtx *m)
898 * XXX: When kernacc() does not require Giant we can reenable this check
902 * Can't call kernacc() from early init386(), especially when
903 * initializing Giant mutex, because some stuff in kernacc()
904 * requires Giant itself.
907 if (!kernacc((caddr_t)m, sizeof(m),
908 VM_PROT_READ | VM_PROT_WRITE))
909 panic("Can't read and write to mutex %p", m);
915 * General init routine used by the MTX_SYSINIT() macro.
918 mtx_sysinit(void *arg)
920 struct mtx_args *margs = arg;
922 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL,
927 * Mutex initialization routine; initialize lock `m' of type contained in
928 * `opts' with options contained in `opts' and name `name.' The optional
929 * lock type `type' is used as a general lock category name for use with
933 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
936 struct lock_class *class;
941 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
942 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0);
943 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
944 ("%s: mtx_lock not aligned for %s: %p", __func__, name,
948 /* Diagnostic and error correction */
952 /* Determine lock class and lock flags. */
954 class = &lock_class_mtx_spin;
956 class = &lock_class_mtx_sleep;
958 if (opts & MTX_QUIET)
960 if (opts & MTX_RECURSE)
961 flags |= LO_RECURSABLE;
962 if ((opts & MTX_NOWITNESS) == 0)
964 if (opts & MTX_DUPOK)
966 if (opts & MTX_NOPROFILE)
967 flags |= LO_NOPROFILE;
969 /* Initialize mutex. */
970 lock_init(&m->lock_object, class, name, type, flags);
972 m->mtx_lock = MTX_UNOWNED;
977 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
978 * passed in as a flag here because if the corresponding mtx_init() was
979 * called with MTX_QUIET set, then it will already be set in the mutex's
983 _mtx_destroy(volatile uintptr_t *c)
990 MPASS(mtx_unowned(m));
992 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
994 /* Perform the non-mtx related part of mtx_unlock_spin(). */
995 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
998 curthread->td_locks--;
1000 lock_profile_release_lock(&m->lock_object);
1001 /* Tell witness this isn't locked to make it happy. */
1002 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
1006 m->mtx_lock = MTX_DESTROYED;
1007 lock_destroy(&m->lock_object);
1011 * Intialize the mutex code and system mutexes. This is called from the MD
1012 * startup code prior to mi_startup(). The per-CPU data space needs to be
1013 * setup before this is called.
1019 /* Setup turnstiles so that sleep mutexes work. */
1023 * Initialize mutexes.
1025 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
1026 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
1027 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
1028 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
1029 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE);
1030 mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
1036 db_show_mtx(const struct lock_object *lock)
1039 const struct mtx *m;
1041 m = (const struct mtx *)lock;
1043 db_printf(" flags: {");
1044 if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
1048 if (m->lock_object.lo_flags & LO_RECURSABLE)
1049 db_printf(", RECURSE");
1050 if (m->lock_object.lo_flags & LO_DUPOK)
1051 db_printf(", DUPOK");
1053 db_printf(" state: {");
1055 db_printf("UNOWNED");
1056 else if (mtx_destroyed(m))
1057 db_printf("DESTROYED");
1060 if (m->mtx_lock & MTX_CONTESTED)
1061 db_printf(", CONTESTED");
1062 if (m->mtx_lock & MTX_RECURSED)
1063 db_printf(", RECURSED");
1066 if (!mtx_unowned(m) && !mtx_destroyed(m)) {
1068 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
1069 td->td_tid, td->td_proc->p_pid, td->td_name);
1070 if (mtx_recursed(m))
1071 db_printf(" recursed: %d\n", m->mtx_recurse);