/*-
* 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_global.h"
#include "opt_mutex_wake_all.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/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>
/*
* Force MUTEX_WAKE_ALL for now.
* single thread wakeup needs fixes to avoid race conditions with
* priority inheritance.
*/
#ifndef MUTEX_WAKE_ALL
#define MUTEX_WAKE_ALL
#endif
#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
#define ADAPTIVE_MUTEXES
#endif
/*
* Internal utility macros.
*/
#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
#define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK))
#ifdef DDB
static void db_show_mtx(struct lock_object *lock);
#endif
static void lock_mtx(struct lock_object *lock, int how);
static void lock_spin(struct lock_object *lock, int how);
static int unlock_mtx(struct lock_object *lock);
static int 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,
#ifdef DDB
.lc_ddb_show = db_show_mtx,
#endif
.lc_lock = lock_mtx,
.lc_unlock = unlock_mtx,
};
struct lock_class lock_class_mtx_spin = {
.lc_name = "spin mutex",
.lc_flags = LC_SPINLOCK | LC_RECURSABLE,
#ifdef DDB
.lc_ddb_show = db_show_mtx,
#endif
.lc_lock = lock_spin,
.lc_unlock = unlock_spin,
};
/*
* System-wide mutexes
*/
struct mtx sched_lock;
struct mtx Giant;
#ifdef LOCK_PROFILING
static inline void lock_profile_init(void)
{
int i;
/* Initialize the mutex profiling locks */
for (i = 0; i < LPROF_LOCK_SIZE; i++) {
mtx_init(&lprof_locks[i], "mprof lock",
NULL, MTX_SPIN|MTX_QUIET|MTX_NOPROFILE);
}
}
#else
static inline void lock_profile_init(void) {;}
#endif
void
lock_mtx(struct lock_object *lock, int how)
{
mtx_lock((struct mtx *)lock);
}
void
lock_spin(struct lock_object *lock, int how)
{
panic("spin locks can only use msleep_spin");
}
int
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);
}
int
unlock_spin(struct lock_object *lock)
{
panic("spin locks can only use msleep_spin");
}
/*
* 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(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
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 | LOP_NEWORDER | LOP_EXCLUSIVE,
file, line);
_get_sleep_lock(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);
curthread->td_locks++;
}
void
_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
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));
curthread->td_locks--;
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);
if (m->mtx_recurse == 0)
lock_profile_release_lock(&m->lock_object);
_rel_sleep_lock(m, curthread, opts, file, line);
}
void
_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
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));
WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
file, line);
_get_spin_lock(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);
}
void
_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
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);
_rel_spin_lock(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(struct mtx *m, int opts, const char *file, int line)
{
int rval, contested = 0;
uint64_t waittime = 0;
MPASS(curthread != NULL);
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) {
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
rval = 1;
} else
rval = _obtain_lock(m, (uintptr_t)curthread);
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);
curthread->td_locks++;
if (m->mtx_recurse == 0)
lock_profile_obtain_lock_success(&m->lock_object, 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.
*/
void
_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file,
int line)
{
#ifdef ADAPTIVE_MUTEXES
volatile struct thread *owner;
#endif
#ifdef KTR
int cont_logged = 0;
#endif
int contested = 0;
uint64_t waittime = 0;
uintptr_t v;
if (mtx_owned(m)) {
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
m->lock_object.lo_name, file, line));
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;
}
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);
while (!_obtain_lock(m, tid)) {
turnstile_lock(&m->lock_object);
v = m->mtx_lock;
/*
* Check if the lock has been released while spinning for
* the turnstile chain lock.
*/
if (v == MTX_UNOWNED) {
turnstile_release(&m->lock_object);
cpu_spinwait();
continue;
}
#ifdef MUTEX_WAKE_ALL
MPASS(v != MTX_CONTESTED);
#else
/*
* The mutex was marked contested on release. This means that
* there are other threads blocked on it. Grab ownership of
* it and propagate its priority to the current thread if
* necessary.
*/
if (v == MTX_CONTESTED) {
m->mtx_lock = tid | MTX_CONTESTED;
turnstile_claim(&m->lock_object);
break;
}
#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_release(&m->lock_object);
cpu_spinwait();
continue;
}
#ifdef ADAPTIVE_MUTEXES
/*
* If the current owner of the lock is executing on another
* CPU, spin instead of blocking.
*/
owner = (struct thread *)(v & ~MTX_FLAGMASK);
#ifdef ADAPTIVE_GIANT
if (TD_IS_RUNNING(owner))
#else
if (m != &Giant && TD_IS_RUNNING(owner))
#endif
{
turnstile_release(&m->lock_object);
while (mtx_owner(m) == owner && TD_IS_RUNNING(owner)) {
cpu_spinwait();
}
continue;
}
#endif /* ADAPTIVE_MUTEXES */
/*
* 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.
*/
turnstile_wait(&m->lock_object, mtx_owner(m),
TS_EXCLUSIVE_QUEUE);
}
#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
lock_profile_obtain_lock_success(&m->lock_object, contested,
waittime, (file), (line));
}
#ifdef SMP
/*
* _mtx_lock_spin: 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(struct mtx *m, uintptr_t tid, int opts, const char *file,
int line)
{
int i = 0, contested = 0;
struct thread *td;
uint64_t waittime = 0;
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
while (!_obtain_lock(m, tid)) {
/* Give interrupts a chance while we spin. */
spinlock_exit();
while (m->mtx_lock != MTX_UNOWNED) {
if (i++ < 10000000) {
cpu_spinwait();
continue;
}
if (i < 60000000 || kdb_active || panicstr != NULL)
DELAY(1);
else {
td = mtx_owner(m);
/* If the mutex is unlocked, try again. */
if (td == NULL)
continue;
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);
#endif
panic("spin lock held too long");
}
cpu_spinwait();
}
spinlock_enter();
}
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
lock_profile_obtain_lock_success(&m->lock_object, contested,
waittime, (file), (line));
}
#endif /* SMP */
/*
* _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
*
* We are only called here if the lock is recursed or contested (i.e. we
* need to wake up a blocked thread).
*/
void
_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line)
{
struct turnstile *ts;
#ifndef PREEMPTION
struct thread *td, *td1;
#endif
if (mtx_recursed(m)) {
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;
}
turnstile_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);
#ifdef ADAPTIVE_MUTEXES
if (ts == NULL) {
_release_lock_quick(m);
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m);
turnstile_release(&m->lock_object);
return;
}
#else
MPASS(ts != NULL);
#endif
#ifndef PREEMPTION
/* XXX */
td1 = turnstile_head(ts, TS_EXCLUSIVE_QUEUE);
#endif
#ifdef MUTEX_WAKE_ALL
turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
_release_lock_quick(m);
#else
if (turnstile_signal(ts, TS_EXCLUSIVE_QUEUE)) {
_release_lock_quick(m);
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m);
} else {
m->mtx_lock = MTX_CONTESTED;
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p still contested",
m);
}
#endif
turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
#ifndef PREEMPTION
/*
* XXX: This is just a hack until preemption is done. However,
* once preemption is done we need to either wrap the
* turnstile_signal() and release of the actual lock in an
* extra critical section or change the preemption code to
* always just set a flag and never do instant-preempts.
*/
td = curthread;
if (td->td_critnest > 0 || td1->td_priority >= td->td_priority)
return;
mtx_lock_spin(&sched_lock);
if (!TD_IS_RUNNING(td1)) {
#ifdef notyet
if (td->td_ithd != NULL) {
struct ithd *it = td->td_ithd;
if (it->it_interrupted) {
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR2(KTR_LOCK,
"_mtx_unlock_sleep: %p interrupted %p",
it, it->it_interrupted);
intr_thd_fixup(it);
}
}
#endif
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR2(KTR_LOCK,
"_mtx_unlock_sleep: %p switching out lock=%p", m,
(void *)m->mtx_lock);
mi_switch(SW_INVOL, NULL);
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p",
m, (void *)m->mtx_lock);
}
mtx_unlock_spin(&sched_lock);
#endif
}
/*
* All the unlocking of MTX_SPIN locks is done inline.
* See the _rel_spin_lock() macro for the details.
*/
/*
* The backing function for the INVARIANTS-enabled mtx_assert()
*/
#ifdef INVARIANT_SUPPORT
void
_mtx_assert(struct mtx *m, int what, const char *file, int line)
{
if (panicstr != NULL || dumping)
return;
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
/*
* The MUTEX_DEBUG-enabled mtx_validate()
*
* Most of these checks have been moved off into the LO_INITIALIZED flag
* maintained by the witness code.
*/
#ifdef MUTEX_DEBUG
void mtx_validate(struct mtx *);
void
mtx_validate(struct mtx *m)
{
/*
* XXX: When kernacc() does not require Giant we can reenable this check
*/
#ifdef notyet
/*
* Can't call kernacc() from early init386(), especially when
* initializing Giant mutex, because some stuff in kernacc()
* requires Giant itself.
*/
if (!cold)
if (!kernacc((caddr_t)m, sizeof(m),
VM_PROT_READ | VM_PROT_WRITE))
panic("Can't read and write to mutex %p", m);
#endif
}
#endif
/*
* General init routine used by the MTX_SYSINIT() macro.
*/
void
mtx_sysinit(void *arg)
{
struct mtx_args *margs = arg;
mtx_init(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(struct mtx *m, const char *name, const char *type, int opts)
{
struct lock_class *class;
int flags;
MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0);
#ifdef MUTEX_DEBUG
/* Diagnostic and error correction */
mtx_validate(m);
#endif
/* 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;
/* Initialize mutex. */
m->mtx_lock = MTX_UNOWNED;
m->mtx_recurse = 0;
lock_profile_object_init(&m->lock_object, class, name);
lock_init(&m->lock_object, class, name, type, flags);
}
/*
* 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(struct mtx *m)
{
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
curthread->td_locks--;
/* 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_profile_object_destroy(&m->lock_object);
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(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
mtx_lock(&Giant);
lock_profile_init();
}
#ifdef DDB
void
db_show_mtx(struct lock_object *lock)
{
struct thread *td;
struct mtx *m;
m = (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 {
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)) {
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_proc->p_comm);
if (mtx_recursed(m))
db_printf(" recursed: %d\n", m->mtx_recurse);
}
}
#endif
