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freebsd-skq/sys/kern/kern_mutex.c

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/*-
* Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Berkeley Software Design Inc's name may not be used to endorse or
* promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
* and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
*/
/*
* Machine independent bits of mutex implementation.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_adaptive_mutexes.h"
#include "opt_ddb.h"
#include "opt_hwpmc_hooks.h"
#include "opt_sched.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sbuf.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/turnstile.h>
#include <sys/vmmeter.h>
#include <sys/lock_profile.h>
#include <machine/atomic.h>
#include <machine/bus.h>
#include <machine/cpu.h>
#include <ddb/ddb.h>
#include <fs/devfs/devfs_int.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
#define ADAPTIVE_MUTEXES
#endif
#ifdef HWPMC_HOOKS
#include <sys/pmckern.h>
PMC_SOFT_DEFINE( , , lock, failed);
#endif
/*
* Return the mutex address when the lock cookie address is provided.
* This functionality assumes that struct mtx* have a member named mtx_lock.
*/
#define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock))
/*
* Internal utility macros.
*/
#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
#define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
static void assert_mtx(const struct lock_object *lock, int what);
#ifdef DDB
static void db_show_mtx(const struct lock_object *lock);
#endif
static void lock_mtx(struct lock_object *lock, uintptr_t how);
static void lock_spin(struct lock_object *lock, uintptr_t how);
#ifdef KDTRACE_HOOKS
static int owner_mtx(const struct lock_object *lock,
struct thread **owner);
#endif
static uintptr_t unlock_mtx(struct lock_object *lock);
static uintptr_t unlock_spin(struct lock_object *lock);
/*
* Lock classes for sleep and spin mutexes.
*/
struct lock_class lock_class_mtx_sleep = {
.lc_name = "sleep mutex",
.lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
.lc_assert = assert_mtx,
#ifdef DDB
.lc_ddb_show = db_show_mtx,
#endif
.lc_lock = lock_mtx,
.lc_unlock = unlock_mtx,
#ifdef KDTRACE_HOOKS
.lc_owner = owner_mtx,
#endif
};
struct lock_class lock_class_mtx_spin = {
.lc_name = "spin mutex",
.lc_flags = LC_SPINLOCK | LC_RECURSABLE,
.lc_assert = assert_mtx,
#ifdef DDB
.lc_ddb_show = db_show_mtx,
#endif
.lc_lock = lock_spin,
.lc_unlock = unlock_spin,
#ifdef KDTRACE_HOOKS
.lc_owner = owner_mtx,
#endif
};
#ifdef ADAPTIVE_MUTEXES
static SYSCTL_NODE(_debug, OID_AUTO, mtx, CTLFLAG_RD, NULL, "mtx debugging");
static struct lock_delay_config __read_mostly mtx_delay;
SYSCTL_INT(_debug_mtx, OID_AUTO, delay_base, CTLFLAG_RW, &mtx_delay.base,
0, "");
SYSCTL_INT(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max,
0, "");
LOCK_DELAY_SYSINIT_DEFAULT(mtx_delay);
#endif
static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin, CTLFLAG_RD, NULL,
"mtx spin debugging");
static struct lock_delay_config __read_mostly mtx_spin_delay;
SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_base, CTLFLAG_RW,
&mtx_spin_delay.base, 0, "");
SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_max, CTLFLAG_RW,
&mtx_spin_delay.max, 0, "");
LOCK_DELAY_SYSINIT_DEFAULT(mtx_spin_delay);
/*
* System-wide mutexes
*/
struct mtx blocked_lock;
struct mtx Giant;
void
assert_mtx(const struct lock_object *lock, int what)
{
mtx_assert((const struct mtx *)lock, what);
}
void
lock_mtx(struct lock_object *lock, uintptr_t how)
{
mtx_lock((struct mtx *)lock);
}
void
lock_spin(struct lock_object *lock, uintptr_t how)
{
panic("spin locks can only use msleep_spin");
}
uintptr_t
unlock_mtx(struct lock_object *lock)
{
struct mtx *m;
m = (struct mtx *)lock;
mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
mtx_unlock(m);
return (0);
}
uintptr_t
unlock_spin(struct lock_object *lock)
{
panic("spin locks can only use msleep_spin");
}
#ifdef KDTRACE_HOOKS
int
owner_mtx(const struct lock_object *lock, struct thread **owner)
{
const struct mtx *m;
uintptr_t x;
m = (const struct mtx *)lock;
x = m->mtx_lock;
*owner = (struct thread *)(x & ~MTX_FLAGMASK);
return (x != MTX_UNOWNED);
}
#endif
/*
* Function versions of the inlined __mtx_* macros. These are used by
* modules and can also be called from assembly language if needed.
*/
void
__mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
{
struct mtx *m;
uintptr_t tid, v;
m = mtxlock2mtx(c);
KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d",
curthread, m->lock_object.lo_name, file, line));
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_lock() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
file, line));
WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
tid = (uintptr_t)curthread;
v = MTX_UNOWNED;
if (!_mtx_obtain_lock_fetch(m, &v, tid))
_mtx_lock_sleep(m, v, tid, opts, file, line);
else
LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
m, 0, 0, file, line);
LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
line);
WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
file, line);
TD_LOCKS_INC(curthread);
}
void
__mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
{
struct mtx *m;
m = mtxlock2mtx(c);
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
file, line));
WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
line);
mtx_assert(m, MA_OWNED);
#ifdef LOCK_PROFILING
__mtx_unlock_sleep(c, opts, file, line);
#else
__mtx_unlock(m, curthread, opts, file, line);
#endif
TD_LOCKS_DEC(curthread);
}
void
__mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
int line)
{
struct mtx *m;
if (SCHEDULER_STOPPED())
return;
m = mtxlock2mtx(c);
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
("mtx_lock_spin() of sleep mutex %s @ %s:%d",
m->lock_object.lo_name, file, line));
if (mtx_owned(m))
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
(opts & MTX_RECURSE) != 0,
("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
m->lock_object.lo_name, file, line));
opts &= ~MTX_RECURSE;
WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
file, line, NULL);
__mtx_lock_spin(m, curthread, opts, file, line);
LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
line);
WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
}
int
__mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
int line)
{
struct mtx *m;
if (SCHEDULER_STOPPED())
return (1);
m = mtxlock2mtx(c);
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
("mtx_trylock_spin() of sleep mutex %s @ %s:%d",
m->lock_object.lo_name, file, line));
KASSERT((opts & MTX_RECURSE) == 0,
("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n",
m->lock_object.lo_name, file, line));
if (__mtx_trylock_spin(m, curthread, opts, file, line)) {
LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line);
WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
return (1);
}
LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line);
return (0);
}
void
__mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
int line)
{
struct mtx *m;
if (SCHEDULER_STOPPED())
return;
m = mtxlock2mtx(c);
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
m->lock_object.lo_name, file, line));
WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
line);
mtx_assert(m, MA_OWNED);
__mtx_unlock_spin(m);
}
/*
* The important part of mtx_trylock{,_flags}()
* Tries to acquire lock `m.' If this function is called on a mutex that
* is already owned, it will recursively acquire the lock.
*/
int
_mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
{
struct mtx *m;
#ifdef LOCK_PROFILING
uint64_t waittime = 0;
int contested = 0;
#endif
int rval;
if (SCHEDULER_STOPPED())
return (1);
m = mtxlock2mtx(c);
KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
curthread, m->lock_object.lo_name, file, line));
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
file, line));
if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
(opts & MTX_RECURSE) != 0)) {
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
rval = 1;
} else
rval = _mtx_obtain_lock(m, (uintptr_t)curthread);
opts &= ~MTX_RECURSE;
LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
if (rval) {
WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
file, line);
TD_LOCKS_INC(curthread);
if (m->mtx_recurse == 0)
LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
m, contested, waittime, file, line);
}
return (rval);
}
/*
* __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
*
* We call this if the lock is either contested (i.e. we need to go to
* sleep waiting for it), or if we need to recurse on it.
*/
#if LOCK_DEBUG > 0
void
__mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, int opts,
const char *file, int line)
#else
void
__mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, int opts)
#endif
{
struct mtx *m;
struct turnstile *ts;
#ifdef ADAPTIVE_MUTEXES
volatile struct thread *owner;
#endif
#ifdef KTR
int cont_logged = 0;
#endif
#ifdef LOCK_PROFILING
int contested = 0;
uint64_t waittime = 0;
#endif
#if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS)
struct lock_delay_arg lda;
#endif
#ifdef KDTRACE_HOOKS
u_int sleep_cnt = 0;
int64_t sleep_time = 0;
int64_t all_time = 0;
int doing_lockstat;
#endif
if (SCHEDULER_STOPPED())
return;
#if defined(ADAPTIVE_MUTEXES)
lock_delay_arg_init(&lda, &mtx_delay);
#elif defined(KDTRACE_HOOKS)
lock_delay_arg_init(&lda, NULL);
#endif
m = mtxlock2mtx(c);
if (__predict_false(v == MTX_UNOWNED))
v = MTX_READ_VALUE(m);
if (__predict_false(lv_mtx_owner(v) == (struct thread *)tid)) {
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
(opts & MTX_RECURSE) != 0,
("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
m->lock_object.lo_name, file, line));
opts &= ~MTX_RECURSE;
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
return;
}
opts &= ~MTX_RECURSE;
#ifdef HWPMC_HOOKS
PMC_SOFT_CALL( , , lock, failed);
#endif
lock_profile_obtain_lock_failed(&m->lock_object,
&contested, &waittime);
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR4(KTR_LOCK,
"_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
#ifdef KDTRACE_HOOKS
#ifdef LOCK_PROFILING
doing_lockstat = 1;
#else
doing_lockstat = lockstat_enabled;
#endif
if (__predict_false(doing_lockstat))
all_time -= lockstat_nsecs(&m->lock_object);
#endif
for (;;) {
if (v == MTX_UNOWNED) {
if (_mtx_obtain_lock_fetch(m, &v, tid))
break;
continue;
}
#ifdef KDTRACE_HOOKS
lda.spin_cnt++;
#endif
#ifdef ADAPTIVE_MUTEXES
/*
* If the owner is running on another CPU, spin until the
* owner stops running or the state of the lock changes.
*/
owner = lv_mtx_owner(v);
if (TD_IS_RUNNING(owner)) {
if (LOCK_LOG_TEST(&m->lock_object, 0))
CTR3(KTR_LOCK,
"%s: spinning on %p held by %p",
__func__, m, owner);
KTR_STATE1(KTR_SCHED, "thread",
sched_tdname((struct thread *)tid),
"spinning", "lockname:\"%s\"",
m->lock_object.lo_name);
do {
lock_delay(&lda);
v = MTX_READ_VALUE(m);
owner = lv_mtx_owner(v);
} while (v != MTX_UNOWNED && TD_IS_RUNNING(owner));
KTR_STATE0(KTR_SCHED, "thread",
sched_tdname((struct thread *)tid),
"running");
continue;
}
#endif
ts = turnstile_trywait(&m->lock_object);
v = MTX_READ_VALUE(m);
/*
* Check if the lock has been released while spinning for
* the turnstile chain lock.
*/
if (v == MTX_UNOWNED) {
turnstile_cancel(ts);
continue;
}
#ifdef ADAPTIVE_MUTEXES
/*
* The current lock owner might have started executing
* on another CPU (or the lock could have changed
* owners) while we were waiting on the turnstile
* chain lock. If so, drop the turnstile lock and try
* again.
*/
owner = lv_mtx_owner(v);
if (TD_IS_RUNNING(owner)) {
turnstile_cancel(ts);
continue;
}
#endif
/*
* If the mutex isn't already contested and a failure occurs
* setting the contested bit, the mutex was either released
* or the state of the MTX_RECURSED bit changed.
*/
if ((v & MTX_CONTESTED) == 0 &&
!atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
turnstile_cancel(ts);
v = MTX_READ_VALUE(m);
continue;
}
/*
* We definitely must sleep for this lock.
*/
mtx_assert(m, MA_NOTOWNED);
#ifdef KTR
if (!cont_logged) {
CTR6(KTR_CONTENTION,
"contention: %p at %s:%d wants %s, taken by %s:%d",
(void *)tid, file, line, m->lock_object.lo_name,
WITNESS_FILE(&m->lock_object),
WITNESS_LINE(&m->lock_object));
cont_logged = 1;
}
#endif
/*
* Block on the turnstile.
*/
#ifdef KDTRACE_HOOKS
sleep_time -= lockstat_nsecs(&m->lock_object);
#endif
turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
#ifdef KDTRACE_HOOKS
sleep_time += lockstat_nsecs(&m->lock_object);
sleep_cnt++;
#endif
v = MTX_READ_VALUE(m);
}
#ifdef KTR
if (cont_logged) {
CTR4(KTR_CONTENTION,
"contention end: %s acquired by %p at %s:%d",
m->lock_object.lo_name, (void *)tid, file, line);
}
#endif
#ifdef KDTRACE_HOOKS
if (__predict_true(!doing_lockstat))
return;
all_time += lockstat_nsecs(&m->lock_object);
#endif
LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested,
waittime, file, line);
#ifdef KDTRACE_HOOKS
if (sleep_time)
LOCKSTAT_RECORD1(adaptive__block, m, sleep_time);
/*
* Only record the loops spinning and not sleeping.
*/
if (lda.spin_cnt > sleep_cnt)
LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time);
#endif
}
static void
_mtx_lock_spin_failed(struct mtx *m)
{
struct thread *td;
td = mtx_owner(m);
/* If the mutex is unlocked, try again. */
if (td == NULL)
return;
printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
m, m->lock_object.lo_name, td, td->td_tid);
#ifdef WITNESS
witness_display_spinlock(&m->lock_object, td, printf);
#endif
panic("spin lock held too long");
}
#ifdef SMP
/*
* _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
*
* This is only called if we need to actually spin for the lock. Recursion
* is handled inline.
*/
void
_mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v, uintptr_t tid,
int opts, const char *file, int line)
{
struct mtx *m;
struct lock_delay_arg lda;
#ifdef LOCK_PROFILING
int contested = 0;
uint64_t waittime = 0;
#endif
#ifdef KDTRACE_HOOKS
int64_t spin_time = 0;
#endif
if (SCHEDULER_STOPPED())
return;
lock_delay_arg_init(&lda, &mtx_spin_delay);
m = mtxlock2mtx(c);
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
"spinning", "lockname:\"%s\"", m->lock_object.lo_name);
#ifdef HWPMC_HOOKS
PMC_SOFT_CALL( , , lock, failed);
#endif
lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
#ifdef KDTRACE_HOOKS
spin_time -= lockstat_nsecs(&m->lock_object);
#endif
for (;;) {
if (v == MTX_UNOWNED) {
if (_mtx_obtain_lock_fetch(m, &v, tid))
break;
continue;
}
/* Give interrupts a chance while we spin. */
spinlock_exit();
do {
if (lda.spin_cnt < 10000000) {
lock_delay(&lda);
} else {
lda.spin_cnt++;
if (lda.spin_cnt < 60000000 || kdb_active ||
panicstr != NULL)
DELAY(1);
else
_mtx_lock_spin_failed(m);
cpu_spinwait();
}
v = MTX_READ_VALUE(m);
} while (v != MTX_UNOWNED);
spinlock_enter();
}
#ifdef KDTRACE_HOOKS
spin_time += lockstat_nsecs(&m->lock_object);
#endif
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
"running");
#ifdef KDTRACE_HOOKS
LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
contested, waittime, file, line);
if (spin_time != 0)
LOCKSTAT_RECORD1(spin__spin, m, spin_time);
#endif
}
#endif /* SMP */
void
thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
{
struct mtx *m;
uintptr_t tid, v;
struct lock_delay_arg lda;
#ifdef LOCK_PROFILING
int contested = 0;
uint64_t waittime = 0;
#endif
#ifdef KDTRACE_HOOKS
int64_t spin_time = 0;
#endif
tid = (uintptr_t)curthread;
if (SCHEDULER_STOPPED()) {
/*
* Ensure that spinlock sections are balanced even when the
* scheduler is stopped, since we may otherwise inadvertently
* re-enable interrupts while dumping core.
*/
spinlock_enter();
return;
}
lock_delay_arg_init(&lda, &mtx_spin_delay);
#ifdef KDTRACE_HOOKS
spin_time -= lockstat_nsecs(&td->td_lock->lock_object);
#endif
for (;;) {
retry:
v = MTX_UNOWNED;
spinlock_enter();
m = td->td_lock;
KASSERT(m->mtx_lock != MTX_DESTROYED,
("thread_lock() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
("thread_lock() of sleep mutex %s @ %s:%d",
m->lock_object.lo_name, file, line));
if (mtx_owned(m))
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
m->lock_object.lo_name, file, line));
WITNESS_CHECKORDER(&m->lock_object,
opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
for (;;) {
if (_mtx_obtain_lock_fetch(m, &v, tid))
break;
if (v == MTX_UNOWNED)
continue;
if (v == tid) {
m->mtx_recurse++;
break;
}
#ifdef HWPMC_HOOKS
PMC_SOFT_CALL( , , lock, failed);
#endif
lock_profile_obtain_lock_failed(&m->lock_object,
&contested, &waittime);
/* Give interrupts a chance while we spin. */
spinlock_exit();
do {
if (lda.spin_cnt < 10000000) {
lock_delay(&lda);
} else {
lda.spin_cnt++;
if (lda.spin_cnt < 60000000 ||
kdb_active || panicstr != NULL)
DELAY(1);
else
_mtx_lock_spin_failed(m);
cpu_spinwait();
}
if (m != td->td_lock)
goto retry;
v = MTX_READ_VALUE(m);
} while (v != MTX_UNOWNED);
spinlock_enter();
}
if (m == td->td_lock)
break;
__mtx_unlock_spin(m); /* does spinlock_exit() */
}
#ifdef KDTRACE_HOOKS
spin_time += lockstat_nsecs(&m->lock_object);
#endif
if (m->mtx_recurse == 0)
LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
contested, waittime, file, line);
LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
line);
WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
#ifdef KDTRACE_HOOKS
if (spin_time != 0)
LOCKSTAT_RECORD1(thread__spin, m, spin_time);
#endif
}
struct mtx *
thread_lock_block(struct thread *td)
{
struct mtx *lock;
THREAD_LOCK_ASSERT(td, MA_OWNED);
lock = td->td_lock;
td->td_lock = &blocked_lock;
mtx_unlock_spin(lock);
return (lock);
}
void
thread_lock_unblock(struct thread *td, struct mtx *new)
{
mtx_assert(new, MA_OWNED);
MPASS(td->td_lock == &blocked_lock);
atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
}
void
thread_lock_set(struct thread *td, struct mtx *new)
{
struct mtx *lock;
mtx_assert(new, MA_OWNED);
THREAD_LOCK_ASSERT(td, MA_OWNED);
lock = td->td_lock;
td->td_lock = new;
mtx_unlock_spin(lock);
}
/*
* __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
*
* We are only called here if the lock is recursed, contested (i.e. we
* need to wake up a blocked thread) or lockstat probe is active.
*/
#if LOCK_DEBUG > 0
void
__mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line)
#else
void
__mtx_unlock_sleep(volatile uintptr_t *c, int opts)
#endif
{
struct mtx *m;
struct turnstile *ts;
uintptr_t tid, v;
if (SCHEDULER_STOPPED())
return;
tid = (uintptr_t)curthread;
m = mtxlock2mtx(c);
v = MTX_READ_VALUE(m);
if (v & MTX_RECURSED) {
if (--(m->mtx_recurse) == 0)
atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
return;
}
LOCKSTAT_PROFILE_RELEASE_LOCK(adaptive__release, m);
if (v == tid && _mtx_release_lock(m, tid))
return;
/*
* We have to lock the chain before the turnstile so this turnstile
* can be removed from the hash list if it is empty.
*/
turnstile_chain_lock(&m->lock_object);
ts = turnstile_lookup(&m->lock_object);
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
MPASS(ts != NULL);
turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
_mtx_release_lock_quick(m);
/*
* This turnstile is now no longer associated with the mutex. We can
* unlock the chain lock so a new turnstile may take it's place.
*/
turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
turnstile_chain_unlock(&m->lock_object);
}
/*
* All the unlocking of MTX_SPIN locks is done inline.
* See the __mtx_unlock_spin() macro for the details.
*/
/*
* The backing function for the INVARIANTS-enabled mtx_assert()
*/
#ifdef INVARIANT_SUPPORT
void
__mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line)
{
const struct mtx *m;
if (panicstr != NULL || dumping || SCHEDULER_STOPPED())
return;
m = mtxlock2mtx(c);
switch (what) {
case MA_OWNED:
case MA_OWNED | MA_RECURSED:
case MA_OWNED | MA_NOTRECURSED:
if (!mtx_owned(m))
panic("mutex %s not owned at %s:%d",
m->lock_object.lo_name, file, line);
if (mtx_recursed(m)) {
if ((what & MA_NOTRECURSED) != 0)
panic("mutex %s recursed at %s:%d",
m->lock_object.lo_name, file, line);
} else if ((what & MA_RECURSED) != 0) {
panic("mutex %s unrecursed at %s:%d",
m->lock_object.lo_name, file, line);
}
break;
case MA_NOTOWNED:
if (mtx_owned(m))
panic("mutex %s owned at %s:%d",
m->lock_object.lo_name, file, line);
break;
default:
panic("unknown mtx_assert at %s:%d", file, line);
}
}
#endif
/*
* General init routine used by the MTX_SYSINIT() macro.
*/
void
mtx_sysinit(void *arg)
{
struct mtx_args *margs = arg;
mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL,
margs->ma_opts);
}
/*
* Mutex initialization routine; initialize lock `m' of type contained in
* `opts' with options contained in `opts' and name `name.' The optional
* lock type `type' is used as a general lock category name for use with
* witness.
*/
void
_mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
{
struct mtx *m;
struct lock_class *class;
int flags;
m = mtxlock2mtx(c);
MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0);
ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
("%s: mtx_lock not aligned for %s: %p", __func__, name,
&m->mtx_lock));
/* Determine lock class and lock flags. */
if (opts & MTX_SPIN)
class = &lock_class_mtx_spin;
else
class = &lock_class_mtx_sleep;
flags = 0;
if (opts & MTX_QUIET)
flags |= LO_QUIET;
if (opts & MTX_RECURSE)
flags |= LO_RECURSABLE;
if ((opts & MTX_NOWITNESS) == 0)
flags |= LO_WITNESS;
if (opts & MTX_DUPOK)
flags |= LO_DUPOK;
if (opts & MTX_NOPROFILE)
flags |= LO_NOPROFILE;
if (opts & MTX_NEW)
flags |= LO_NEW;
/* Initialize mutex. */
lock_init(&m->lock_object, class, name, type, flags);
m->mtx_lock = MTX_UNOWNED;
m->mtx_recurse = 0;
}
/*
* Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
* passed in as a flag here because if the corresponding mtx_init() was
* called with MTX_QUIET set, then it will already be set in the mutex's
* flags.
*/
void
_mtx_destroy(volatile uintptr_t *c)
{
struct mtx *m;
m = mtxlock2mtx(c);
if (!mtx_owned(m))
MPASS(mtx_unowned(m));
else {
MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
/* Perform the non-mtx related part of mtx_unlock_spin(). */
if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
spinlock_exit();
else
TD_LOCKS_DEC(curthread);
lock_profile_release_lock(&m->lock_object);
/* Tell witness this isn't locked to make it happy. */
WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
__LINE__);
}
m->mtx_lock = MTX_DESTROYED;
lock_destroy(&m->lock_object);
}
/*
* Intialize the mutex code and system mutexes. This is called from the MD
* startup code prior to mi_startup(). The per-CPU data space needs to be
* setup before this is called.
*/
void
mutex_init(void)
{
/* Setup turnstiles so that sleep mutexes work. */
init_turnstiles();
/*
* Initialize mutexes.
*/
mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN);
mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN);
mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN);
mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN);
mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
mtx_lock(&Giant);
}
#ifdef DDB
void
db_show_mtx(const struct lock_object *lock)
{
struct thread *td;
const struct mtx *m;
m = (const struct mtx *)lock;
db_printf(" flags: {");
if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
db_printf("SPIN");
else
db_printf("DEF");
if (m->lock_object.lo_flags & LO_RECURSABLE)
db_printf(", RECURSE");
if (m->lock_object.lo_flags & LO_DUPOK)
db_printf(", DUPOK");
db_printf("}\n");
db_printf(" state: {");
if (mtx_unowned(m))
db_printf("UNOWNED");
else if (mtx_destroyed(m))
db_printf("DESTROYED");
else {
db_printf("OWNED");
if (m->mtx_lock & MTX_CONTESTED)
db_printf(", CONTESTED");
if (m->mtx_lock & MTX_RECURSED)
db_printf(", RECURSED");
}
db_printf("}\n");
if (!mtx_unowned(m) && !mtx_destroyed(m)) {
td = mtx_owner(m);
db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
td->td_tid, td->td_proc->p_pid, td->td_name);
if (mtx_recursed(m))
db_printf(" recursed: %d\n", m->mtx_recurse);
}
}
#endif
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