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freebsd-dev/sys/kern/kern_mutex.c
jhb 6f9cde3aa5 Add an implementation of turnstiles and change the sleep mutex code to use 
turnstiles to implement blocking isntead of implementing a thread queue
directly.  These turnstiles are somewhat similar to those used in Solaris 7
as described in Solaris Internals but are also different.

Turnstiles do not come out of a fixed-sized pool.  Rather, each thread is
assigned a turnstile when it is created that it frees when it is destroyed.
When a thread blocks on a lock, it donates its turnstile to that lock to
serve as queue of blocked threads.  The queue associated with a given lock
is found by a lookup in a simple hash table.  The turnstile itself is
protected by a lock associated with its entry in the hash table.  This
means that sched_lock is no longer needed to contest on a mutex.  Instead,
sched_lock is only used when manipulating run queues or thread priorities.
Turnstiles also implement priority propagation inherently.

Currently turnstiles only support mutexes.  Eventually, however, turnstiles
may grow two queue's to support a non-sleepable reader/writer lock
implementation.  For more details, see the comments in sys/turnstile.h and
kern/subr_turnstile.c.

The two primary advantages from the turnstile code include: 1) the size
of struct mutex shrinks by four pointers as it no longer stores the
thread queue linkages directly, and 2) less contention on sched_lock in
SMP systems including the ability for multiple CPUs to contend on different
locks simultaneously (not that this last detail is necessarily that much of
a big win).  Note that 1) means that this commit is a kernel ABI breaker,
so don't mix old modules with a new kernel and vice versa.

Tested on:	i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00

817 lines
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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 <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.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 <machine/atomic.h>
#include <machine/bus.h>
#include <machine/clock.h>
#include <machine/cpu.h>
#include <ddb/ddb.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
/*
* Internal utility macros.
*/
#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
#define mtx_owner(m) (mtx_unowned((m)) ? NULL \
: (struct thread *)((m)->mtx_lock & MTX_FLAGMASK))
/*
* Lock classes for sleep and spin mutexes.
*/
struct lock_class lock_class_mtx_sleep = {
"sleep mutex",
LC_SLEEPLOCK | LC_RECURSABLE
};
struct lock_class lock_class_mtx_spin = {
"spin mutex",
LC_SPINLOCK | LC_RECURSABLE
};
/*
* System-wide mutexes
*/
struct mtx sched_lock;
struct mtx Giant;
#ifdef MUTEX_PROFILING
SYSCTL_NODE(_debug, OID_AUTO, mutex, CTLFLAG_RD, NULL, "mutex debugging");
SYSCTL_NODE(_debug_mutex, OID_AUTO, prof, CTLFLAG_RD, NULL, "mutex profiling");
static int mutex_prof_enable = 0;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, enable, CTLFLAG_RW,
&mutex_prof_enable, 0, "Enable tracing of mutex holdtime");
struct mutex_prof {
const char *name;
const char *file;
int line;
uintmax_t cnt_max;
uintmax_t cnt_tot;
uintmax_t cnt_cur;
struct mutex_prof *next;
};
/*
* mprof_buf is a static pool of profiling records to avoid possible
* reentrance of the memory allocation functions.
*
* Note: NUM_MPROF_BUFFERS must be smaller than MPROF_HASH_SIZE.
*/
#define NUM_MPROF_BUFFERS 1000
static struct mutex_prof mprof_buf[NUM_MPROF_BUFFERS];
static int first_free_mprof_buf;
#define MPROF_HASH_SIZE 1009
static struct mutex_prof *mprof_hash[MPROF_HASH_SIZE];
/* SWAG: sbuf size = avg stat. line size * number of locks */
#define MPROF_SBUF_SIZE 256 * 400
static int mutex_prof_acquisitions;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, acquisitions, CTLFLAG_RD,
&mutex_prof_acquisitions, 0, "Number of mutex acquistions recorded");
static int mutex_prof_records;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, records, CTLFLAG_RD,
&mutex_prof_records, 0, "Number of profiling records");
static int mutex_prof_maxrecords = NUM_MPROF_BUFFERS;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, maxrecords, CTLFLAG_RD,
&mutex_prof_maxrecords, 0, "Maximum number of profiling records");
static int mutex_prof_rejected;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, rejected, CTLFLAG_RD,
&mutex_prof_rejected, 0, "Number of rejected profiling records");
static int mutex_prof_hashsize = MPROF_HASH_SIZE;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, hashsize, CTLFLAG_RD,
&mutex_prof_hashsize, 0, "Hash size");
static int mutex_prof_collisions = 0;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, collisions, CTLFLAG_RD,
&mutex_prof_collisions, 0, "Number of hash collisions");
/*
* mprof_mtx protects the profiling buffers and the hash.
*/
static struct mtx mprof_mtx;
MTX_SYSINIT(mprof, &mprof_mtx, "mutex profiling lock", MTX_SPIN | MTX_QUIET);
static u_int64_t
nanoseconds(void)
{
struct timespec tv;
nanotime(&tv);
return (tv.tv_sec * (u_int64_t)1000000000 + tv.tv_nsec);
}
static int
dump_mutex_prof_stats(SYSCTL_HANDLER_ARGS)
{
struct sbuf *sb;
int error, i;
static int multiplier = 1;
if (first_free_mprof_buf == 0)
return (SYSCTL_OUT(req, "No locking recorded",
sizeof("No locking recorded")));
retry_sbufops:
sb = sbuf_new(NULL, NULL, MPROF_SBUF_SIZE * multiplier, SBUF_FIXEDLEN);
sbuf_printf(sb, "%6s %12s %11s %5s %s\n",
"max", "total", "count", "avg", "name");
/*
* XXX this spinlock seems to be by far the largest perpetrator
* of spinlock latency (1.6 msec on an Athlon1600 was recorded
* even before I pessimized it further by moving the average
* computation here).
*/
mtx_lock_spin(&mprof_mtx);
for (i = 0; i < first_free_mprof_buf; ++i) {
sbuf_printf(sb, "%6ju %12ju %11ju %5ju %s:%d (%s)\n",
mprof_buf[i].cnt_max / 1000,
mprof_buf[i].cnt_tot / 1000,
mprof_buf[i].cnt_cur,
mprof_buf[i].cnt_cur == 0 ? (uintmax_t)0 :
mprof_buf[i].cnt_tot / (mprof_buf[i].cnt_cur * 1000),
mprof_buf[i].file, mprof_buf[i].line, mprof_buf[i].name);
if (sbuf_overflowed(sb)) {
mtx_unlock_spin(&mprof_mtx);
sbuf_delete(sb);
multiplier++;
goto retry_sbufops;
}
}
mtx_unlock_spin(&mprof_mtx);
sbuf_finish(sb);
error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
sbuf_delete(sb);
return (error);
}
SYSCTL_PROC(_debug_mutex_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
NULL, 0, dump_mutex_prof_stats, "A", "Mutex profiling statistics");
#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(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
("mtx_lock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
file, line));
_get_sleep_lock(m, curthread, opts, file, line);
LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
#ifdef MUTEX_PROFILING
/* don't reset the timer when/if recursing */
if (m->mtx_acqtime == 0) {
m->mtx_filename = file;
m->mtx_lineno = line;
m->mtx_acqtime = mutex_prof_enable ? nanoseconds() : 0;
++mutex_prof_acquisitions;
}
#endif
}
void
_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
("mtx_unlock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
file, line));
WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
mtx_assert(m, MA_OWNED);
#ifdef MUTEX_PROFILING
if (m->mtx_acqtime != 0) {
static const char *unknown = "(unknown)";
struct mutex_prof *mpp;
u_int64_t acqtime, now;
const char *p, *q;
volatile u_int hash;
now = nanoseconds();
acqtime = m->mtx_acqtime;
m->mtx_acqtime = 0;
if (now <= acqtime)
goto out;
for (p = m->mtx_filename;
p != NULL && strncmp(p, "../", 3) == 0; p += 3)
/* nothing */ ;
if (p == NULL || *p == '\0')
p = unknown;
for (hash = m->mtx_lineno, q = p; *q != '\0'; ++q)
hash = (hash * 2 + *q) % MPROF_HASH_SIZE;
mtx_lock_spin(&mprof_mtx);
for (mpp = mprof_hash[hash]; mpp != NULL; mpp = mpp->next)
if (mpp->line == m->mtx_lineno &&
strcmp(mpp->file, p) == 0)
break;
if (mpp == NULL) {
/* Just exit if we cannot get a trace buffer */
if (first_free_mprof_buf >= NUM_MPROF_BUFFERS) {
++mutex_prof_rejected;
goto unlock;
}
mpp = &mprof_buf[first_free_mprof_buf++];
mpp->name = mtx_name(m);
mpp->file = p;
mpp->line = m->mtx_lineno;
mpp->next = mprof_hash[hash];
if (mprof_hash[hash] != NULL)
++mutex_prof_collisions;
mprof_hash[hash] = mpp;
++mutex_prof_records;
}
/*
* Record if the mutex has been held longer now than ever
* before.
*/
if (now - acqtime > mpp->cnt_max)
mpp->cnt_max = now - acqtime;
mpp->cnt_tot += now - acqtime;
mpp->cnt_cur++;
unlock:
mtx_unlock_spin(&mprof_mtx);
}
out:
#endif
_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_object.lo_class == &lock_class_mtx_spin,
("mtx_lock_spin() of sleep mutex %s @ %s:%d",
m->mtx_object.lo_name, file, line));
#if defined(SMP) || LOCK_DEBUG > 0 || 1
_get_spin_lock(m, curthread, opts, file, line);
#else
critical_enter();
#endif
LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
WITNESS_LOCK(&m->mtx_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_object.lo_class == &lock_class_mtx_spin,
("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
m->mtx_object.lo_name, file, line));
WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
mtx_assert(m, MA_OWNED);
#if defined(SMP) || LOCK_DEBUG > 0 || 1
_rel_spin_lock(m);
#else
critical_exit();
#endif
}
/*
* The important part of mtx_trylock{,_flags}()
* Tries to acquire lock `m.' We do NOT handle recursion here. If this
* function is called on a recursed mutex, it will return failure and
* will not recursively acquire the lock. You are expected to know what
* you are doing.
*/
int
_mtx_trylock(struct mtx *m, int opts, const char *file, int line)
{
int rval;
MPASS(curthread != NULL);
rval = _obtain_lock(m, curthread);
LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line);
if (rval)
WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
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, int opts, const char *file, int line)
{
struct turnstile *ts;
struct thread *td = curthread;
#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
struct thread *owner;
#endif
uintptr_t v;
#ifdef KTR
int cont_logged = 0;
#endif
if (mtx_owned(m)) {
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
return;
}
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR4(KTR_LOCK,
"_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
m->mtx_object.lo_name, (void *)m->mtx_lock, file, line);
while (!_obtain_lock(m, td)) {
ts = turnstile_lookup(&m->mtx_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->mtx_object);
#ifdef __i386__
ia32_pause();
#endif
continue;
}
/*
* 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) {
MPASS(ts != NULL);
m->mtx_lock = (uintptr_t)td | MTX_CONTESTED;
turnstile_claim(ts);
return;
}
/*
* 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, (void *)v,
(void *)(v | MTX_CONTESTED))) {
turnstile_release(&m->mtx_object);
#ifdef __i386__
ia32_pause();
#endif
continue;
}
#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
/*
* If the current owner of the lock is executing on another
* CPU, spin instead of blocking.
*/
owner = (struct thread *)(v & MTX_FLAGMASK);
if (m != &Giant && TD_IS_RUNNING(owner)) {
turnstile_release(&m->mtx_object);
while (mtx_owner(m) == owner && TD_IS_RUNNING(owner)) {
#ifdef __i386__
ia32_pause();
#endif
}
continue;
}
#endif /* SMP && 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",
td, file, line, m->mtx_object.lo_name,
WITNESS_FILE(&m->mtx_object),
WITNESS_LINE(&m->mtx_object));
cont_logged = 1;
}
#endif
/*
* Block on the turnstile.
*/
turnstile_wait(ts, &m->mtx_object, mtx_owner(m));
}
#ifdef KTR
if (cont_logged) {
CTR4(KTR_CONTENTION,
"contention end: %s acquired by %p at %s:%d",
m->mtx_object.lo_name, td, file, line);
}
#endif
return;
}
/*
* _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, int opts, const char *file, int line)
{
int i = 0;
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
for (;;) {
if (_obtain_lock(m, curthread))
break;
/* Give interrupts a chance while we spin. */
critical_exit();
while (m->mtx_lock != MTX_UNOWNED) {
if (i++ < 10000000) {
#ifdef __i386__
ia32_pause();
#endif
continue;
}
if (i < 60000000)
DELAY(1);
#ifdef DDB
else if (!db_active) {
#else
else {
#endif
printf("spin lock %s held by %p for > 5 seconds\n",
m->mtx_object.lo_name, (void *)m->mtx_lock);
#ifdef WITNESS
witness_display_spinlock(&m->mtx_object,
mtx_owner(m));
#endif
panic("spin lock held too long");
}
#ifdef __i386__
ia32_pause();
#endif
}
critical_enter();
}
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
return;
}
/*
* _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;
struct thread *td, *td1;
if (mtx_recursed(m)) {
if (--(m->mtx_recurse) == 0)
atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
return;
}
ts = turnstile_lookup(&m->mtx_object);
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
if (ts == NULL) {
_release_lock_quick(m);
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m);
turnstile_release(&m->mtx_object);
return;
}
#else
MPASS(ts != NULL);
#endif
/* XXX */
td1 = turnstile_head(ts);
if (turnstile_signal(ts)) {
_release_lock_quick(m);
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m);
} else {
m->mtx_lock = MTX_CONTESTED;
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p still contested",
m);
}
turnstile_unpend(ts);
/*
* 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->mtx_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->mtx_object, opts))
CTR2(KTR_LOCK,
"_mtx_unlock_sleep: %p switching out lock=%p", m,
(void *)m->mtx_lock);
td->td_proc->p_stats->p_ru.ru_nivcsw++;
mi_switch();
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p",
m, (void *)m->mtx_lock);
}
mtx_unlock_spin(&sched_lock);
return;
}
/*
* 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)
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->mtx_object.lo_name, file, line);
if (mtx_recursed(m)) {
if ((what & MA_NOTRECURSED) != 0)
panic("mutex %s recursed at %s:%d",
m->mtx_object.lo_name, file, line);
} else if ((what & MA_RECURSED) != 0) {
panic("mutex %s unrecursed at %s:%d",
m->mtx_object.lo_name, file, line);
}
break;
case MA_NOTOWNED:
if (mtx_owned(m))
panic("mutex %s owned at %s:%d",
m->mtx_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
/*
* XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly
* we can re-enable the kernacc() checks.
*/
#ifndef __alpha__
/*
* 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
}
#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_object *lock;
MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
MTX_NOWITNESS | MTX_DUPOK)) == 0);
#ifdef MUTEX_DEBUG
/* Diagnostic and error correction */
mtx_validate(m);
#endif
lock = &m->mtx_object;
KASSERT((lock->lo_flags & LO_INITIALIZED) == 0,
("mutex \"%s\" %p already initialized", name, m));
bzero(m, sizeof(*m));
if (opts & MTX_SPIN)
lock->lo_class = &lock_class_mtx_spin;
else
lock->lo_class = &lock_class_mtx_sleep;
lock->lo_name = name;
lock->lo_type = type != NULL ? type : name;
if (opts & MTX_QUIET)
lock->lo_flags = LO_QUIET;
if (opts & MTX_RECURSE)
lock->lo_flags |= LO_RECURSABLE;
if ((opts & MTX_NOWITNESS) == 0)
lock->lo_flags |= LO_WITNESS;
if (opts & MTX_DUPOK)
lock->lo_flags |= LO_DUPOK;
m->mtx_lock = MTX_UNOWNED;
LOCK_LOG_INIT(lock, opts);
WITNESS_INIT(lock);
}
/*
* 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)
{
LOCK_LOG_DESTROY(&m->mtx_object, 0);
if (!mtx_owned(m))
MPASS(mtx_unowned(m));
else {
MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
/* Tell witness this isn't locked to make it happy. */
WITNESS_UNLOCK(&m->mtx_object, LOP_EXCLUSIVE, __FILE__,
__LINE__);
}
WITNESS_DESTROY(&m->mtx_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 thread0 so that mutexes work. */
LIST_INIT(&thread0.td_contested);
/* 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_lock(&Giant);
}
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