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_hwpmc_hooks.h"
42 #include "opt_sched.h"
44 #include <sys/param.h>
45 #include <sys/systm.h>
49 #include <sys/kernel.h>
52 #include <sys/malloc.h>
53 #include <sys/mutex.h>
55 #include <sys/resourcevar.h>
56 #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 #include <sys/pmckern.h>
81 PMC_SOFT_DEFINE( , , lock, failed);
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.
88 #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock))
91 * Internal utility macros.
93 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
95 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
97 static void assert_mtx(const struct lock_object *lock, int what);
99 static void db_show_mtx(const struct lock_object *lock);
101 static void lock_mtx(struct lock_object *lock, uintptr_t how);
102 static void lock_spin(struct lock_object *lock, uintptr_t how);
104 static int owner_mtx(const struct lock_object *lock,
105 struct thread **owner);
107 static uintptr_t unlock_mtx(struct lock_object *lock);
108 static uintptr_t unlock_spin(struct lock_object *lock);
111 * Lock classes for sleep and spin mutexes.
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,
118 .lc_ddb_show = db_show_mtx,
121 .lc_unlock = unlock_mtx,
123 .lc_owner = owner_mtx,
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,
131 .lc_ddb_show = db_show_mtx,
133 .lc_lock = lock_spin,
134 .lc_unlock = unlock_spin,
136 .lc_owner = owner_mtx,
140 #ifdef ADAPTIVE_MUTEXES
141 static SYSCTL_NODE(_debug, OID_AUTO, mtx, CTLFLAG_RD, NULL, "mtx debugging");
143 static struct lock_delay_config __read_mostly mtx_delay;
145 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_base, CTLFLAG_RW, &mtx_delay.base,
147 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max,
150 LOCK_DELAY_SYSINIT_DEFAULT(mtx_delay);
153 static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin, CTLFLAG_RD, NULL,
154 "mtx spin debugging");
156 static struct lock_delay_config __read_mostly mtx_spin_delay;
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, "");
163 LOCK_DELAY_SYSINIT_DEFAULT(mtx_spin_delay);
166 * System-wide mutexes
168 struct mtx blocked_lock;
172 assert_mtx(const struct lock_object *lock, int what)
175 mtx_assert((const struct mtx *)lock, what);
179 lock_mtx(struct lock_object *lock, uintptr_t how)
182 mtx_lock((struct mtx *)lock);
186 lock_spin(struct lock_object *lock, uintptr_t how)
189 panic("spin locks can only use msleep_spin");
193 unlock_mtx(struct lock_object *lock)
197 m = (struct mtx *)lock;
198 mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
204 unlock_spin(struct lock_object *lock)
207 panic("spin locks can only use msleep_spin");
212 owner_mtx(const struct lock_object *lock, struct thread **owner)
217 m = (const struct mtx *)lock;
219 *owner = (struct thread *)(x & ~MTX_FLAGMASK);
220 return (x != MTX_UNOWNED);
225 * Function versions of the inlined __mtx_* macros. These are used by
226 * modules and can also be called from assembly language if needed.
229 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
236 KASSERT(kdb_active != 0 || SCHEDULER_STOPPED() ||
237 !TD_IS_IDLETHREAD(curthread),
238 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d",
239 curthread, m->lock_object.lo_name, file, line));
240 KASSERT(m->mtx_lock != MTX_DESTROYED,
241 ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
242 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
243 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
245 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
246 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
248 tid = (uintptr_t)curthread;
250 if (!_mtx_obtain_lock_fetch(m, &v, tid))
251 _mtx_lock_sleep(m, v, tid, opts, file, line);
253 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
254 m, 0, 0, file, line);
255 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
257 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
259 TD_LOCKS_INC(curthread);
263 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
269 KASSERT(m->mtx_lock != MTX_DESTROYED,
270 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
271 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
272 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
274 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
275 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
277 mtx_assert(m, MA_OWNED);
279 #ifdef LOCK_PROFILING
280 __mtx_unlock_sleep(c, opts, file, line);
282 __mtx_unlock(m, curthread, opts, file, line);
284 TD_LOCKS_DEC(curthread);
288 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
293 if (SCHEDULER_STOPPED())
298 KASSERT(m->mtx_lock != MTX_DESTROYED,
299 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
300 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
301 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
302 m->lock_object.lo_name, file, line));
304 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
305 (opts & MTX_RECURSE) != 0,
306 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
307 m->lock_object.lo_name, file, line));
308 opts &= ~MTX_RECURSE;
309 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
311 __mtx_lock_spin(m, curthread, opts, file, line);
312 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
314 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
318 __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
323 if (SCHEDULER_STOPPED())
328 KASSERT(m->mtx_lock != MTX_DESTROYED,
329 ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line));
330 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
331 ("mtx_trylock_spin() of sleep mutex %s @ %s:%d",
332 m->lock_object.lo_name, file, line));
333 KASSERT((opts & MTX_RECURSE) == 0,
334 ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n",
335 m->lock_object.lo_name, file, line));
336 if (__mtx_trylock_spin(m, curthread, opts, file, line)) {
337 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line);
338 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
341 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line);
346 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
351 if (SCHEDULER_STOPPED())
356 KASSERT(m->mtx_lock != MTX_DESTROYED,
357 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
358 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
359 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
360 m->lock_object.lo_name, file, line));
361 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
362 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
364 mtx_assert(m, MA_OWNED);
366 __mtx_unlock_spin(m);
370 * The important part of mtx_trylock{,_flags}()
371 * Tries to acquire lock `m.' If this function is called on a mutex that
372 * is already owned, it will recursively acquire the lock.
375 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
380 #ifdef LOCK_PROFILING
381 uint64_t waittime = 0;
389 if (SCHEDULER_STOPPED_TD(td))
394 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(td),
395 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
396 curthread, m->lock_object.lo_name, file, line));
397 KASSERT(m->mtx_lock != MTX_DESTROYED,
398 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
399 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
400 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
407 if (_mtx_obtain_lock_fetch(m, &v, tid))
409 if (v == MTX_UNOWNED)
412 ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
413 (opts & MTX_RECURSE) != 0)) {
415 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
423 opts &= ~MTX_RECURSE;
425 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
427 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
429 TD_LOCKS_INC(curthread);
431 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
432 m, contested, waittime, file, line);
439 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
441 * We call this if the lock is either contested (i.e. we need to go to
442 * sleep waiting for it), or if we need to recurse on it.
446 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, int opts,
447 const char *file, int line)
450 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, uintptr_t tid)
454 struct turnstile *ts;
455 #ifdef ADAPTIVE_MUTEXES
456 volatile struct thread *owner;
461 #ifdef LOCK_PROFILING
463 uint64_t waittime = 0;
465 #if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS)
466 struct lock_delay_arg lda;
470 int64_t sleep_time = 0;
471 int64_t all_time = 0;
473 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
477 if (SCHEDULER_STOPPED())
480 #if defined(ADAPTIVE_MUTEXES)
481 lock_delay_arg_init(&lda, &mtx_delay);
482 #elif defined(KDTRACE_HOOKS)
483 lock_delay_arg_init(&lda, NULL);
486 if (__predict_false(v == MTX_UNOWNED))
487 v = MTX_READ_VALUE(m);
489 if (__predict_false(lv_mtx_owner(v) == (struct thread *)tid)) {
490 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
491 (opts & MTX_RECURSE) != 0,
492 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
493 m->lock_object.lo_name, file, line));
495 opts &= ~MTX_RECURSE;
498 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
499 if (LOCK_LOG_TEST(&m->lock_object, opts))
500 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
504 opts &= ~MTX_RECURSE;
508 PMC_SOFT_CALL( , , lock, failed);
510 lock_profile_obtain_lock_failed(&m->lock_object,
511 &contested, &waittime);
512 if (LOCK_LOG_TEST(&m->lock_object, opts))
514 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
515 m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
516 #ifdef LOCK_PROFILING
518 #elif defined(KDTRACE_HOOKS)
519 doing_lockprof = lockstat_enabled;
520 if (__predict_false(doing_lockprof))
521 all_time -= lockstat_nsecs(&m->lock_object);
525 if (v == MTX_UNOWNED) {
526 if (_mtx_obtain_lock_fetch(m, &v, tid))
533 #ifdef ADAPTIVE_MUTEXES
535 * If the owner is running on another CPU, spin until the
536 * owner stops running or the state of the lock changes.
538 owner = lv_mtx_owner(v);
539 if (TD_IS_RUNNING(owner)) {
540 if (LOCK_LOG_TEST(&m->lock_object, 0))
542 "%s: spinning on %p held by %p",
544 KTR_STATE1(KTR_SCHED, "thread",
545 sched_tdname((struct thread *)tid),
546 "spinning", "lockname:\"%s\"",
547 m->lock_object.lo_name);
550 v = MTX_READ_VALUE(m);
551 owner = lv_mtx_owner(v);
552 } while (v != MTX_UNOWNED && TD_IS_RUNNING(owner));
553 KTR_STATE0(KTR_SCHED, "thread",
554 sched_tdname((struct thread *)tid),
560 ts = turnstile_trywait(&m->lock_object);
561 v = MTX_READ_VALUE(m);
564 * Check if the lock has been released while spinning for
565 * the turnstile chain lock.
567 if (v == MTX_UNOWNED) {
568 turnstile_cancel(ts);
572 #ifdef ADAPTIVE_MUTEXES
574 * The current lock owner might have started executing
575 * on another CPU (or the lock could have changed
576 * owners) while we were waiting on the turnstile
577 * chain lock. If so, drop the turnstile lock and try
580 owner = lv_mtx_owner(v);
581 if (TD_IS_RUNNING(owner)) {
582 turnstile_cancel(ts);
588 * If the mutex isn't already contested and a failure occurs
589 * setting the contested bit, the mutex was either released
590 * or the state of the MTX_RECURSED bit changed.
592 if ((v & MTX_CONTESTED) == 0 &&
593 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
594 turnstile_cancel(ts);
595 v = MTX_READ_VALUE(m);
600 * We definitely must sleep for this lock.
602 mtx_assert(m, MA_NOTOWNED);
607 "contention: %p at %s:%d wants %s, taken by %s:%d",
608 (void *)tid, file, line, m->lock_object.lo_name,
609 WITNESS_FILE(&m->lock_object),
610 WITNESS_LINE(&m->lock_object));
616 * Block on the turnstile.
619 sleep_time -= lockstat_nsecs(&m->lock_object);
621 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
623 sleep_time += lockstat_nsecs(&m->lock_object);
626 v = MTX_READ_VALUE(m);
631 "contention end: %s acquired by %p at %s:%d",
632 m->lock_object.lo_name, (void *)tid, file, line);
635 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
636 if (__predict_true(!doing_lockprof))
640 all_time += lockstat_nsecs(&m->lock_object);
642 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested,
643 waittime, file, line);
646 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time);
649 * Only record the loops spinning and not sleeping.
651 if (lda.spin_cnt > sleep_cnt)
652 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time);
657 _mtx_lock_spin_failed(struct mtx *m)
663 /* If the mutex is unlocked, try again. */
667 printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
668 m, m->lock_object.lo_name, td, td->td_tid);
670 witness_display_spinlock(&m->lock_object, td, printf);
672 panic("spin lock held too long");
677 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
679 * This is only called if we need to actually spin for the lock. Recursion
683 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v, uintptr_t tid,
684 int opts, const char *file, int line)
687 struct lock_delay_arg lda;
688 #ifdef LOCK_PROFILING
690 uint64_t waittime = 0;
693 int64_t spin_time = 0;
695 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
699 if (SCHEDULER_STOPPED())
702 lock_delay_arg_init(&lda, &mtx_spin_delay);
705 if (__predict_false(v == MTX_UNOWNED))
706 v = MTX_READ_VALUE(m);
708 if (__predict_false(v == tid)) {
713 if (LOCK_LOG_TEST(&m->lock_object, opts))
714 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
715 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
716 "spinning", "lockname:\"%s\"", m->lock_object.lo_name);
719 PMC_SOFT_CALL( , , lock, failed);
721 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
722 #ifdef LOCK_PROFILING
724 #elif defined(KDTRACE_HOOKS)
725 doing_lockprof = lockstat_enabled;
726 if (__predict_false(doing_lockprof))
727 spin_time -= lockstat_nsecs(&m->lock_object);
730 if (v == MTX_UNOWNED) {
731 if (_mtx_obtain_lock_fetch(m, &v, tid))
735 /* Give interrupts a chance while we spin. */
738 if (lda.spin_cnt < 10000000) {
742 if (lda.spin_cnt < 60000000 || kdb_active ||
746 _mtx_lock_spin_failed(m);
749 v = MTX_READ_VALUE(m);
750 } while (v != MTX_UNOWNED);
754 if (LOCK_LOG_TEST(&m->lock_object, opts))
755 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
756 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
759 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
760 if (__predict_true(!doing_lockprof))
764 spin_time += lockstat_nsecs(&m->lock_object);
766 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
767 contested, waittime, file, line);
770 LOCKSTAT_RECORD1(spin__spin, m, spin_time);
776 thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
780 struct lock_delay_arg lda;
781 #ifdef LOCK_PROFILING
783 uint64_t waittime = 0;
786 int64_t spin_time = 0;
788 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
789 int doing_lockprof = 1;
792 tid = (uintptr_t)curthread;
794 if (SCHEDULER_STOPPED()) {
796 * Ensure that spinlock sections are balanced even when the
797 * scheduler is stopped, since we may otherwise inadvertently
798 * re-enable interrupts while dumping core.
804 lock_delay_arg_init(&lda, &mtx_spin_delay);
806 #ifdef LOCK_PROFILING
808 #elif defined(KDTRACE_HOOKS)
809 doing_lockprof = lockstat_enabled;
810 if (__predict_false(doing_lockprof))
811 spin_time -= lockstat_nsecs(&td->td_lock->lock_object);
818 KASSERT(m->mtx_lock != MTX_DESTROYED,
819 ("thread_lock() of destroyed mutex @ %s:%d", file, line));
820 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
821 ("thread_lock() of sleep mutex %s @ %s:%d",
822 m->lock_object.lo_name, file, line));
824 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
825 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
826 m->lock_object.lo_name, file, line));
827 WITNESS_CHECKORDER(&m->lock_object,
828 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
830 if (_mtx_obtain_lock_fetch(m, &v, tid))
832 if (v == MTX_UNOWNED)
839 PMC_SOFT_CALL( , , lock, failed);
841 lock_profile_obtain_lock_failed(&m->lock_object,
842 &contested, &waittime);
843 /* Give interrupts a chance while we spin. */
846 if (lda.spin_cnt < 10000000) {
850 if (lda.spin_cnt < 60000000 ||
851 kdb_active || panicstr != NULL)
854 _mtx_lock_spin_failed(m);
857 if (m != td->td_lock)
859 v = MTX_READ_VALUE(m);
860 } while (v != MTX_UNOWNED);
863 if (m == td->td_lock)
865 __mtx_unlock_spin(m); /* does spinlock_exit() */
867 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
869 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
871 #if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
872 if (__predict_true(!doing_lockprof))
876 spin_time += lockstat_nsecs(&m->lock_object);
878 if (m->mtx_recurse == 0)
879 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
880 contested, waittime, file, line);
883 LOCKSTAT_RECORD1(thread__spin, m, spin_time);
888 thread_lock_block(struct thread *td)
892 THREAD_LOCK_ASSERT(td, MA_OWNED);
894 td->td_lock = &blocked_lock;
895 mtx_unlock_spin(lock);
901 thread_lock_unblock(struct thread *td, struct mtx *new)
903 mtx_assert(new, MA_OWNED);
904 MPASS(td->td_lock == &blocked_lock);
905 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
909 thread_lock_set(struct thread *td, struct mtx *new)
913 mtx_assert(new, MA_OWNED);
914 THREAD_LOCK_ASSERT(td, MA_OWNED);
917 mtx_unlock_spin(lock);
921 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
923 * We are only called here if the lock is recursed, contested (i.e. we
924 * need to wake up a blocked thread) or lockstat probe is active.
928 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line)
931 __mtx_unlock_sleep(volatile uintptr_t *c)
935 struct turnstile *ts;
938 if (SCHEDULER_STOPPED())
941 tid = (uintptr_t)curthread;
943 v = MTX_READ_VALUE(m);
945 if (v & MTX_RECURSED) {
946 if (--(m->mtx_recurse) == 0)
947 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
948 if (LOCK_LOG_TEST(&m->lock_object, opts))
949 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
953 LOCKSTAT_PROFILE_RELEASE_LOCK(adaptive__release, m);
954 if (v == tid && _mtx_release_lock(m, tid))
958 * We have to lock the chain before the turnstile so this turnstile
959 * can be removed from the hash list if it is empty.
961 turnstile_chain_lock(&m->lock_object);
962 ts = turnstile_lookup(&m->lock_object);
963 if (LOCK_LOG_TEST(&m->lock_object, opts))
964 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
966 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
967 _mtx_release_lock_quick(m);
970 * This turnstile is now no longer associated with the mutex. We can
971 * unlock the chain lock so a new turnstile may take it's place.
973 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
974 turnstile_chain_unlock(&m->lock_object);
978 * All the unlocking of MTX_SPIN locks is done inline.
979 * See the __mtx_unlock_spin() macro for the details.
983 * The backing function for the INVARIANTS-enabled mtx_assert()
985 #ifdef INVARIANT_SUPPORT
987 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line)
991 if (panicstr != NULL || dumping || SCHEDULER_STOPPED())
998 case MA_OWNED | MA_RECURSED:
999 case MA_OWNED | MA_NOTRECURSED:
1001 panic("mutex %s not owned at %s:%d",
1002 m->lock_object.lo_name, file, line);
1003 if (mtx_recursed(m)) {
1004 if ((what & MA_NOTRECURSED) != 0)
1005 panic("mutex %s recursed at %s:%d",
1006 m->lock_object.lo_name, file, line);
1007 } else if ((what & MA_RECURSED) != 0) {
1008 panic("mutex %s unrecursed at %s:%d",
1009 m->lock_object.lo_name, file, line);
1014 panic("mutex %s owned at %s:%d",
1015 m->lock_object.lo_name, file, line);
1018 panic("unknown mtx_assert at %s:%d", file, line);
1024 * General init routine used by the MTX_SYSINIT() macro.
1027 mtx_sysinit(void *arg)
1029 struct mtx_args *margs = arg;
1031 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL,
1036 * Mutex initialization routine; initialize lock `m' of type contained in
1037 * `opts' with options contained in `opts' and name `name.' The optional
1038 * lock type `type' is used as a general lock category name for use with
1042 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
1045 struct lock_class *class;
1050 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
1051 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0);
1052 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
1053 ("%s: mtx_lock not aligned for %s: %p", __func__, name,
1056 /* Determine lock class and lock flags. */
1057 if (opts & MTX_SPIN)
1058 class = &lock_class_mtx_spin;
1060 class = &lock_class_mtx_sleep;
1062 if (opts & MTX_QUIET)
1064 if (opts & MTX_RECURSE)
1065 flags |= LO_RECURSABLE;
1066 if ((opts & MTX_NOWITNESS) == 0)
1067 flags |= LO_WITNESS;
1068 if (opts & MTX_DUPOK)
1070 if (opts & MTX_NOPROFILE)
1071 flags |= LO_NOPROFILE;
1075 /* Initialize mutex. */
1076 lock_init(&m->lock_object, class, name, type, flags);
1078 m->mtx_lock = MTX_UNOWNED;
1083 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
1084 * passed in as a flag here because if the corresponding mtx_init() was
1085 * called with MTX_QUIET set, then it will already be set in the mutex's
1089 _mtx_destroy(volatile uintptr_t *c)
1096 MPASS(mtx_unowned(m));
1098 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
1100 /* Perform the non-mtx related part of mtx_unlock_spin(). */
1101 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
1104 TD_LOCKS_DEC(curthread);
1106 lock_profile_release_lock(&m->lock_object);
1107 /* Tell witness this isn't locked to make it happy. */
1108 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
1112 m->mtx_lock = MTX_DESTROYED;
1113 lock_destroy(&m->lock_object);
1117 * Intialize the mutex code and system mutexes. This is called from the MD
1118 * startup code prior to mi_startup(). The per-CPU data space needs to be
1119 * setup before this is called.
1125 /* Setup turnstiles so that sleep mutexes work. */
1129 * Initialize mutexes.
1131 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
1132 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
1133 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
1134 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
1135 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN);
1136 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN);
1137 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN);
1138 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN);
1139 mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
1145 db_show_mtx(const struct lock_object *lock)
1148 const struct mtx *m;
1150 m = (const struct mtx *)lock;
1152 db_printf(" flags: {");
1153 if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
1157 if (m->lock_object.lo_flags & LO_RECURSABLE)
1158 db_printf(", RECURSE");
1159 if (m->lock_object.lo_flags & LO_DUPOK)
1160 db_printf(", DUPOK");
1162 db_printf(" state: {");
1164 db_printf("UNOWNED");
1165 else if (mtx_destroyed(m))
1166 db_printf("DESTROYED");
1169 if (m->mtx_lock & MTX_CONTESTED)
1170 db_printf(", CONTESTED");
1171 if (m->mtx_lock & MTX_RECURSED)
1172 db_printf(", RECURSED");
1175 if (!mtx_unowned(m) && !mtx_destroyed(m)) {
1177 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
1178 td->td_tid, td->td_proc->p_pid, td->td_name);
1179 if (mtx_recursed(m))
1180 db_printf(" recursed: %d\n", m->mtx_recurse);