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 mtx_delay = {
150 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_initial, CTLFLAG_RW, &mtx_delay.initial,
152 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_step, CTLFLAG_RW, &mtx_delay.step,
154 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_min, CTLFLAG_RW, &mtx_delay.min,
156 SYSCTL_INT(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max,
160 mtx_delay_sysinit(void *dummy)
163 mtx_delay.initial = mp_ncpus * 25;
164 mtx_delay.step = (mp_ncpus * 25) / 2;
165 mtx_delay.min = mp_ncpus * 5;
166 mtx_delay.max = mp_ncpus * 25 * 10;
168 LOCK_DELAY_SYSINIT(mtx_delay_sysinit);
171 static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin, CTLFLAG_RD, NULL,
172 "mtx spin debugging");
174 static struct lock_delay_config mtx_spin_delay = {
181 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_initial, CTLFLAG_RW,
182 &mtx_spin_delay.initial, 0, "");
183 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_step, CTLFLAG_RW, &mtx_spin_delay.step,
185 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_min, CTLFLAG_RW, &mtx_spin_delay.min,
187 SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_spin_delay.max,
191 mtx_spin_delay_sysinit(void *dummy)
194 mtx_spin_delay.initial = mp_ncpus * 25;
195 mtx_spin_delay.step = (mp_ncpus * 25) / 2;
196 mtx_spin_delay.min = mp_ncpus * 5;
197 mtx_spin_delay.max = mp_ncpus * 25 * 10;
199 LOCK_DELAY_SYSINIT(mtx_spin_delay_sysinit);
202 * System-wide mutexes
204 struct mtx blocked_lock;
208 assert_mtx(const struct lock_object *lock, int what)
211 mtx_assert((const struct mtx *)lock, what);
215 lock_mtx(struct lock_object *lock, uintptr_t how)
218 mtx_lock((struct mtx *)lock);
222 lock_spin(struct lock_object *lock, uintptr_t how)
225 panic("spin locks can only use msleep_spin");
229 unlock_mtx(struct lock_object *lock)
233 m = (struct mtx *)lock;
234 mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
240 unlock_spin(struct lock_object *lock)
243 panic("spin locks can only use msleep_spin");
248 owner_mtx(const struct lock_object *lock, struct thread **owner)
253 m = (const struct mtx *)lock;
255 *owner = (struct thread *)(x & ~MTX_FLAGMASK);
256 return (x != MTX_UNOWNED);
261 * Function versions of the inlined __mtx_* macros. These are used by
262 * modules and can also be called from assembly language if needed.
265 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
269 if (SCHEDULER_STOPPED())
274 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
275 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d",
276 curthread, m->lock_object.lo_name, file, line));
277 KASSERT(m->mtx_lock != MTX_DESTROYED,
278 ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
279 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
280 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
282 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
283 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
285 __mtx_lock(m, curthread, opts, file, line);
286 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
288 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
290 TD_LOCKS_INC(curthread);
294 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
298 if (SCHEDULER_STOPPED())
303 KASSERT(m->mtx_lock != MTX_DESTROYED,
304 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
305 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
306 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
308 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
309 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
311 mtx_assert(m, MA_OWNED);
313 __mtx_unlock(m, curthread, opts, file, line);
314 TD_LOCKS_DEC(curthread);
318 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
323 if (SCHEDULER_STOPPED())
328 KASSERT(m->mtx_lock != MTX_DESTROYED,
329 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
330 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
331 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
332 m->lock_object.lo_name, file, line));
334 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
335 (opts & MTX_RECURSE) != 0,
336 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
337 m->lock_object.lo_name, file, line));
338 opts &= ~MTX_RECURSE;
339 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
341 __mtx_lock_spin(m, curthread, opts, file, line);
342 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
344 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
348 __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
353 if (SCHEDULER_STOPPED())
358 KASSERT(m->mtx_lock != MTX_DESTROYED,
359 ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line));
360 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
361 ("mtx_trylock_spin() of sleep mutex %s @ %s:%d",
362 m->lock_object.lo_name, file, line));
363 KASSERT((opts & MTX_RECURSE) == 0,
364 ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n",
365 m->lock_object.lo_name, file, line));
366 if (__mtx_trylock_spin(m, curthread, opts, file, line)) {
367 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line);
368 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
371 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line);
376 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
381 if (SCHEDULER_STOPPED())
386 KASSERT(m->mtx_lock != MTX_DESTROYED,
387 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
388 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
389 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
390 m->lock_object.lo_name, file, line));
391 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
392 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
394 mtx_assert(m, MA_OWNED);
396 __mtx_unlock_spin(m);
400 * The important part of mtx_trylock{,_flags}()
401 * Tries to acquire lock `m.' If this function is called on a mutex that
402 * is already owned, it will recursively acquire the lock.
405 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
408 #ifdef LOCK_PROFILING
409 uint64_t waittime = 0;
414 if (SCHEDULER_STOPPED())
419 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
420 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
421 curthread, m->lock_object.lo_name, file, line));
422 KASSERT(m->mtx_lock != MTX_DESTROYED,
423 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
424 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
425 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
428 if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
429 (opts & MTX_RECURSE) != 0)) {
431 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
434 rval = _mtx_obtain_lock(m, (uintptr_t)curthread);
435 opts &= ~MTX_RECURSE;
437 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
439 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
441 TD_LOCKS_INC(curthread);
442 if (m->mtx_recurse == 0)
443 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
444 m, contested, waittime, file, line);
452 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
454 * We call this if the lock is either contested (i.e. we need to go to
455 * sleep waiting for it), or if we need to recurse on it.
458 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts,
459 const char *file, int line)
462 struct turnstile *ts;
464 #ifdef ADAPTIVE_MUTEXES
465 volatile struct thread *owner;
470 #ifdef LOCK_PROFILING
472 uint64_t waittime = 0;
474 #if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS)
475 struct lock_delay_arg lda;
479 int64_t sleep_time = 0;
480 int64_t all_time = 0;
483 if (SCHEDULER_STOPPED())
486 #if defined(ADAPTIVE_MUTEXES)
487 lock_delay_arg_init(&lda, &mtx_delay);
488 #elif defined(KDTRACE_HOOKS)
489 lock_delay_arg_init(&lda, NULL);
492 v = MTX_READ_VALUE(m);
494 if (__predict_false(lv_mtx_owner(v) == (struct thread *)tid)) {
495 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
496 (opts & MTX_RECURSE) != 0,
497 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
498 m->lock_object.lo_name, file, line));
499 opts &= ~MTX_RECURSE;
501 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
502 if (LOCK_LOG_TEST(&m->lock_object, opts))
503 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
506 opts &= ~MTX_RECURSE;
509 PMC_SOFT_CALL( , , lock, failed);
511 lock_profile_obtain_lock_failed(&m->lock_object,
512 &contested, &waittime);
513 if (LOCK_LOG_TEST(&m->lock_object, opts))
515 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
516 m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
518 all_time -= lockstat_nsecs(&m->lock_object);
522 if (v == MTX_UNOWNED) {
523 if (_mtx_obtain_lock(m, tid))
525 v = MTX_READ_VALUE(m);
531 #ifdef ADAPTIVE_MUTEXES
533 * If the owner is running on another CPU, spin until the
534 * owner stops running or the state of the lock changes.
536 owner = lv_mtx_owner(v);
537 if (TD_IS_RUNNING(owner)) {
538 if (LOCK_LOG_TEST(&m->lock_object, 0))
540 "%s: spinning on %p held by %p",
542 KTR_STATE1(KTR_SCHED, "thread",
543 sched_tdname((struct thread *)tid),
544 "spinning", "lockname:\"%s\"",
545 m->lock_object.lo_name);
548 v = MTX_READ_VALUE(m);
549 owner = lv_mtx_owner(v);
550 } while (v != MTX_UNOWNED && TD_IS_RUNNING(owner));
551 KTR_STATE0(KTR_SCHED, "thread",
552 sched_tdname((struct thread *)tid),
558 ts = turnstile_trywait(&m->lock_object);
559 v = MTX_READ_VALUE(m);
562 * Check if the lock has been released while spinning for
563 * the turnstile chain lock.
565 if (v == MTX_UNOWNED) {
566 turnstile_cancel(ts);
570 #ifdef ADAPTIVE_MUTEXES
572 * The current lock owner might have started executing
573 * on another CPU (or the lock could have changed
574 * owners) while we were waiting on the turnstile
575 * chain lock. If so, drop the turnstile lock and try
578 owner = lv_mtx_owner(v);
579 if (TD_IS_RUNNING(owner)) {
580 turnstile_cancel(ts);
586 * If the mutex isn't already contested and a failure occurs
587 * setting the contested bit, the mutex was either released
588 * or the state of the MTX_RECURSED bit changed.
590 if ((v & MTX_CONTESTED) == 0 &&
591 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
592 turnstile_cancel(ts);
593 v = MTX_READ_VALUE(m);
598 * We definitely must sleep for this lock.
600 mtx_assert(m, MA_NOTOWNED);
605 "contention: %p at %s:%d wants %s, taken by %s:%d",
606 (void *)tid, file, line, m->lock_object.lo_name,
607 WITNESS_FILE(&m->lock_object),
608 WITNESS_LINE(&m->lock_object));
614 * Block on the turnstile.
617 sleep_time -= lockstat_nsecs(&m->lock_object);
619 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
621 sleep_time += lockstat_nsecs(&m->lock_object);
624 v = MTX_READ_VALUE(m);
627 all_time += lockstat_nsecs(&m->lock_object);
632 "contention end: %s acquired by %p at %s:%d",
633 m->lock_object.lo_name, (void *)tid, file, line);
636 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested,
637 waittime, file, line);
640 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time);
643 * Only record the loops spinning and not sleeping.
645 if (lda.spin_cnt > sleep_cnt)
646 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time);
651 _mtx_lock_spin_failed(struct mtx *m)
657 /* If the mutex is unlocked, try again. */
661 printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
662 m, m->lock_object.lo_name, td, td->td_tid);
664 witness_display_spinlock(&m->lock_object, td, printf);
666 panic("spin lock held too long");
671 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
673 * This is only called if we need to actually spin for the lock. Recursion
677 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts,
678 const char *file, int line)
681 struct lock_delay_arg lda;
683 #ifdef LOCK_PROFILING
685 uint64_t waittime = 0;
688 int64_t spin_time = 0;
691 if (SCHEDULER_STOPPED())
694 lock_delay_arg_init(&lda, &mtx_spin_delay);
697 if (LOCK_LOG_TEST(&m->lock_object, opts))
698 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
699 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
700 "spinning", "lockname:\"%s\"", m->lock_object.lo_name);
703 PMC_SOFT_CALL( , , lock, failed);
705 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
707 spin_time -= lockstat_nsecs(&m->lock_object);
709 v = MTX_READ_VALUE(m);
711 if (v == MTX_UNOWNED) {
712 if (_mtx_obtain_lock(m, tid))
714 v = MTX_READ_VALUE(m);
717 /* Give interrupts a chance while we spin. */
720 if (lda.spin_cnt < 10000000) {
724 if (lda.spin_cnt < 60000000 || kdb_active ||
728 _mtx_lock_spin_failed(m);
731 v = MTX_READ_VALUE(m);
732 } while (v != MTX_UNOWNED);
736 spin_time += lockstat_nsecs(&m->lock_object);
739 if (LOCK_LOG_TEST(&m->lock_object, opts))
740 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
741 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
745 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
746 contested, waittime, file, line);
748 LOCKSTAT_RECORD1(spin__spin, m, spin_time);
754 thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
758 struct lock_delay_arg lda;
759 #ifdef LOCK_PROFILING
761 uint64_t waittime = 0;
764 int64_t spin_time = 0;
767 tid = (uintptr_t)curthread;
769 if (SCHEDULER_STOPPED()) {
771 * Ensure that spinlock sections are balanced even when the
772 * scheduler is stopped, since we may otherwise inadvertently
773 * re-enable interrupts while dumping core.
779 lock_delay_arg_init(&lda, &mtx_spin_delay);
782 spin_time -= lockstat_nsecs(&td->td_lock->lock_object);
788 KASSERT(m->mtx_lock != MTX_DESTROYED,
789 ("thread_lock() of destroyed mutex @ %s:%d", file, line));
790 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
791 ("thread_lock() of sleep mutex %s @ %s:%d",
792 m->lock_object.lo_name, file, line));
794 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
795 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
796 m->lock_object.lo_name, file, line));
797 WITNESS_CHECKORDER(&m->lock_object,
798 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
799 v = MTX_READ_VALUE(m);
801 if (v == MTX_UNOWNED) {
802 if (_mtx_obtain_lock(m, tid))
804 v = MTX_READ_VALUE(m);
812 PMC_SOFT_CALL( , , lock, failed);
814 lock_profile_obtain_lock_failed(&m->lock_object,
815 &contested, &waittime);
816 /* Give interrupts a chance while we spin. */
819 if (lda.spin_cnt < 10000000) {
823 if (lda.spin_cnt < 60000000 ||
824 kdb_active || panicstr != NULL)
827 _mtx_lock_spin_failed(m);
830 if (m != td->td_lock)
832 v = MTX_READ_VALUE(m);
833 } while (v != MTX_UNOWNED);
836 if (m == td->td_lock)
838 __mtx_unlock_spin(m); /* does spinlock_exit() */
841 spin_time += lockstat_nsecs(&m->lock_object);
843 if (m->mtx_recurse == 0)
844 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
845 contested, waittime, file, line);
846 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
848 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
851 LOCKSTAT_RECORD1(thread__spin, m, spin_time);
856 thread_lock_block(struct thread *td)
860 THREAD_LOCK_ASSERT(td, MA_OWNED);
862 td->td_lock = &blocked_lock;
863 mtx_unlock_spin(lock);
869 thread_lock_unblock(struct thread *td, struct mtx *new)
871 mtx_assert(new, MA_OWNED);
872 MPASS(td->td_lock == &blocked_lock);
873 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
877 thread_lock_set(struct thread *td, struct mtx *new)
881 mtx_assert(new, MA_OWNED);
882 THREAD_LOCK_ASSERT(td, MA_OWNED);
885 mtx_unlock_spin(lock);
889 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
891 * We are only called here if the lock is recursed or contested (i.e. we
892 * need to wake up a blocked thread).
895 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line)
898 struct turnstile *ts;
900 if (SCHEDULER_STOPPED())
905 if (mtx_recursed(m)) {
906 if (--(m->mtx_recurse) == 0)
907 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
908 if (LOCK_LOG_TEST(&m->lock_object, opts))
909 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
914 * We have to lock the chain before the turnstile so this turnstile
915 * can be removed from the hash list if it is empty.
917 turnstile_chain_lock(&m->lock_object);
918 ts = turnstile_lookup(&m->lock_object);
919 if (LOCK_LOG_TEST(&m->lock_object, opts))
920 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
922 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
923 _mtx_release_lock_quick(m);
926 * This turnstile is now no longer associated with the mutex. We can
927 * unlock the chain lock so a new turnstile may take it's place.
929 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
930 turnstile_chain_unlock(&m->lock_object);
934 * All the unlocking of MTX_SPIN locks is done inline.
935 * See the __mtx_unlock_spin() macro for the details.
939 * The backing function for the INVARIANTS-enabled mtx_assert()
941 #ifdef INVARIANT_SUPPORT
943 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line)
947 if (panicstr != NULL || dumping || SCHEDULER_STOPPED())
954 case MA_OWNED | MA_RECURSED:
955 case MA_OWNED | MA_NOTRECURSED:
957 panic("mutex %s not owned at %s:%d",
958 m->lock_object.lo_name, file, line);
959 if (mtx_recursed(m)) {
960 if ((what & MA_NOTRECURSED) != 0)
961 panic("mutex %s recursed at %s:%d",
962 m->lock_object.lo_name, file, line);
963 } else if ((what & MA_RECURSED) != 0) {
964 panic("mutex %s unrecursed at %s:%d",
965 m->lock_object.lo_name, file, line);
970 panic("mutex %s owned at %s:%d",
971 m->lock_object.lo_name, file, line);
974 panic("unknown mtx_assert at %s:%d", file, line);
980 * General init routine used by the MTX_SYSINIT() macro.
983 mtx_sysinit(void *arg)
985 struct mtx_args *margs = arg;
987 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL,
992 * Mutex initialization routine; initialize lock `m' of type contained in
993 * `opts' with options contained in `opts' and name `name.' The optional
994 * lock type `type' is used as a general lock category name for use with
998 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
1001 struct lock_class *class;
1006 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
1007 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0);
1008 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
1009 ("%s: mtx_lock not aligned for %s: %p", __func__, name,
1012 /* Determine lock class and lock flags. */
1013 if (opts & MTX_SPIN)
1014 class = &lock_class_mtx_spin;
1016 class = &lock_class_mtx_sleep;
1018 if (opts & MTX_QUIET)
1020 if (opts & MTX_RECURSE)
1021 flags |= LO_RECURSABLE;
1022 if ((opts & MTX_NOWITNESS) == 0)
1023 flags |= LO_WITNESS;
1024 if (opts & MTX_DUPOK)
1026 if (opts & MTX_NOPROFILE)
1027 flags |= LO_NOPROFILE;
1031 /* Initialize mutex. */
1032 lock_init(&m->lock_object, class, name, type, flags);
1034 m->mtx_lock = MTX_UNOWNED;
1039 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
1040 * passed in as a flag here because if the corresponding mtx_init() was
1041 * called with MTX_QUIET set, then it will already be set in the mutex's
1045 _mtx_destroy(volatile uintptr_t *c)
1052 MPASS(mtx_unowned(m));
1054 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
1056 /* Perform the non-mtx related part of mtx_unlock_spin(). */
1057 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
1060 TD_LOCKS_DEC(curthread);
1062 lock_profile_release_lock(&m->lock_object);
1063 /* Tell witness this isn't locked to make it happy. */
1064 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
1068 m->mtx_lock = MTX_DESTROYED;
1069 lock_destroy(&m->lock_object);
1073 * Intialize the mutex code and system mutexes. This is called from the MD
1074 * startup code prior to mi_startup(). The per-CPU data space needs to be
1075 * setup before this is called.
1081 /* Setup turnstiles so that sleep mutexes work. */
1085 * Initialize mutexes.
1087 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
1088 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
1089 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
1090 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
1091 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN);
1092 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN);
1093 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN);
1094 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN);
1095 mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
1101 db_show_mtx(const struct lock_object *lock)
1104 const struct mtx *m;
1106 m = (const struct mtx *)lock;
1108 db_printf(" flags: {");
1109 if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
1113 if (m->lock_object.lo_flags & LO_RECURSABLE)
1114 db_printf(", RECURSE");
1115 if (m->lock_object.lo_flags & LO_DUPOK)
1116 db_printf(", DUPOK");
1118 db_printf(" state: {");
1120 db_printf("UNOWNED");
1121 else if (mtx_destroyed(m))
1122 db_printf("DESTROYED");
1125 if (m->mtx_lock & MTX_CONTESTED)
1126 db_printf(", CONTESTED");
1127 if (m->mtx_lock & MTX_RECURSED)
1128 db_printf(", RECURSED");
1131 if (!mtx_unowned(m) && !mtx_destroyed(m)) {
1133 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
1134 td->td_tid, td->td_proc->p_pid, td->td_name);
1135 if (mtx_recursed(m))
1136 db_printf(" recursed: %d\n", m->mtx_recurse);