freebsd-dev/sys/kern/kern_condvar.c
Pawel Jakub Dawidek 7ee07175af Change sleepq_add(9) argument from 'struct mtx *' to 'struct lock_object *',
which allows to use it with different kinds of locks. For example it allows
to implement Solaris conditions variables which will be used in ZFS port on
top of sx(9) locks.

Reviewed by:	jhb
2006-11-16 01:02:00 +00:00

360 lines
8.9 KiB
C

/*-
* Copyright (c) 2000 Jake Burkholder <jake@freebsd.org>.
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR OR CONTRIBUTORS 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/condvar.h>
#include <sys/sched.h>
#include <sys/signalvar.h>
#include <sys/sleepqueue.h>
#include <sys/resourcevar.h>
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
/*
* Common sanity checks for cv_wait* functions.
*/
#define CV_ASSERT(cvp, mp, td) do { \
KASSERT((td) != NULL, ("%s: curthread NULL", __func__)); \
KASSERT(TD_IS_RUNNING(td), ("%s: not TDS_RUNNING", __func__)); \
KASSERT((cvp) != NULL, ("%s: cvp NULL", __func__)); \
KASSERT((mp) != NULL, ("%s: mp NULL", __func__)); \
mtx_assert((mp), MA_OWNED | MA_NOTRECURSED); \
} while (0)
/*
* Initialize a condition variable. Must be called before use.
*/
void
cv_init(struct cv *cvp, const char *desc)
{
cvp->cv_description = desc;
cvp->cv_waiters = 0;
}
/*
* Destroy a condition variable. The condition variable must be re-initialized
* in order to be re-used.
*/
void
cv_destroy(struct cv *cvp)
{
#ifdef INVARIANTS
struct sleepqueue *sq;
sleepq_lock(cvp);
sq = sleepq_lookup(cvp);
sleepq_release(cvp);
KASSERT(sq == NULL, ("%s: associated sleep queue non-empty", __func__));
#endif
}
/*
* Wait on a condition variable. The current thread is placed on the condition
* variable's wait queue and suspended. A cv_signal or cv_broadcast on the same
* condition variable will resume the thread. The mutex is released before
* sleeping and will be held on return. It is recommended that the mutex be
* held when cv_signal or cv_broadcast are called.
*/
void
cv_wait(struct cv *cvp, struct mtx *mp)
{
WITNESS_SAVE_DECL(mp);
WITNESS_SAVE(&mp->mtx_object, mp);
if (cold || panicstr) {
/*
* During autoconfiguration, just give interrupts
* a chance, then just return. Don't run any other
* thread or panic below, in case this is the idle
* process and already asleep.
*/
return;
}
cv_wait_unlock(cvp, mp);
mtx_lock(mp);
WITNESS_RESTORE(&mp->mtx_object, mp);
}
/*
* Wait on a condition variable. This function differs from cv_wait by
* not aquiring the mutex after condition variable was signaled.
*/
void
cv_wait_unlock(struct cv *cvp, struct mtx *mp)
{
struct thread *td;
td = curthread;
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(1, 0);
#endif
CV_ASSERT(cvp, mp, td);
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
"Waiting on \"%s\"", cvp->cv_description);
if (cold || panicstr) {
/*
* During autoconfiguration, just give interrupts
* a chance, then just return. Don't run any other
* thread or panic below, in case this is the idle
* process and already asleep.
*/
mtx_unlock(mp);
return;
}
sleepq_lock(cvp);
cvp->cv_waiters++;
DROP_GIANT();
mtx_unlock(mp);
sleepq_add(cvp, &mp->mtx_object, cvp->cv_description, SLEEPQ_CONDVAR);
sleepq_wait(cvp);
PICKUP_GIANT();
}
/*
* Wait on a condition variable, allowing interruption by signals. Return 0 if
* the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if
* a signal was caught. If ERESTART is returned the system call should be
* restarted if possible.
*/
int
cv_wait_sig(struct cv *cvp, struct mtx *mp)
{
struct thread *td;
struct proc *p;
int rval;
WITNESS_SAVE_DECL(mp);
td = curthread;
p = td->td_proc;
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(1, 0);
#endif
CV_ASSERT(cvp, mp, td);
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
"Waiting on \"%s\"", cvp->cv_description);
WITNESS_SAVE(&mp->mtx_object, mp);
if (cold || panicstr) {
/*
* After a panic, or during autoconfiguration, just give
* interrupts a chance, then just return; don't run any other
* procs or panic below, in case this is the idle process and
* already asleep.
*/
return (0);
}
sleepq_lock(cvp);
cvp->cv_waiters++;
DROP_GIANT();
mtx_unlock(mp);
sleepq_add(cvp, &mp->mtx_object, cvp->cv_description, SLEEPQ_CONDVAR |
SLEEPQ_INTERRUPTIBLE);
rval = sleepq_wait_sig(cvp);
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(0, 0);
#endif
PICKUP_GIANT();
mtx_lock(mp);
WITNESS_RESTORE(&mp->mtx_object, mp);
return (rval);
}
/*
* Wait on a condition variable for at most timo/hz seconds. Returns 0 if the
* process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout
* expires.
*/
int
cv_timedwait(struct cv *cvp, struct mtx *mp, int timo)
{
struct thread *td;
int rval;
WITNESS_SAVE_DECL(mp);
td = curthread;
rval = 0;
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(1, 0);
#endif
CV_ASSERT(cvp, mp, td);
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
"Waiting on \"%s\"", cvp->cv_description);
WITNESS_SAVE(&mp->mtx_object, mp);
if (cold || panicstr) {
/*
* After a panic, or during autoconfiguration, just give
* interrupts a chance, then just return; don't run any other
* thread or panic below, in case this is the idle process and
* already asleep.
*/
return 0;
}
sleepq_lock(cvp);
cvp->cv_waiters++;
DROP_GIANT();
mtx_unlock(mp);
sleepq_add(cvp, &mp->mtx_object, cvp->cv_description, SLEEPQ_CONDVAR);
sleepq_set_timeout(cvp, timo);
rval = sleepq_timedwait(cvp);
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(0, 0);
#endif
PICKUP_GIANT();
mtx_lock(mp);
WITNESS_RESTORE(&mp->mtx_object, mp);
return (rval);
}
/*
* Wait on a condition variable for at most timo/hz seconds, allowing
* interruption by signals. Returns 0 if the thread was resumed by cv_signal
* or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if
* a signal was caught.
*/
int
cv_timedwait_sig(struct cv *cvp, struct mtx *mp, int timo)
{
struct thread *td;
struct proc *p;
int rval;
WITNESS_SAVE_DECL(mp);
td = curthread;
p = td->td_proc;
rval = 0;
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(1, 0);
#endif
CV_ASSERT(cvp, mp, td);
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
"Waiting on \"%s\"", cvp->cv_description);
WITNESS_SAVE(&mp->mtx_object, mp);
if (cold || panicstr) {
/*
* After a panic, or during autoconfiguration, just give
* interrupts a chance, then just return; don't run any other
* thread or panic below, in case this is the idle process and
* already asleep.
*/
return 0;
}
sleepq_lock(cvp);
cvp->cv_waiters++;
DROP_GIANT();
mtx_unlock(mp);
sleepq_add(cvp, &mp->mtx_object, cvp->cv_description, SLEEPQ_CONDVAR |
SLEEPQ_INTERRUPTIBLE);
sleepq_set_timeout(cvp, timo);
rval = sleepq_timedwait_sig(cvp);
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(0, 0);
#endif
PICKUP_GIANT();
mtx_lock(mp);
WITNESS_RESTORE(&mp->mtx_object, mp);
return (rval);
}
/*
* Signal a condition variable, wakes up one waiting thread. Will also wakeup
* the swapper if the process is not in memory, so that it can bring the
* sleeping process in. Note that this may also result in additional threads
* being made runnable. Should be called with the same mutex as was passed to
* cv_wait held.
*/
void
cv_signal(struct cv *cvp)
{
sleepq_lock(cvp);
if (cvp->cv_waiters > 0) {
cvp->cv_waiters--;
sleepq_signal(cvp, SLEEPQ_CONDVAR, -1);
} else
sleepq_release(cvp);
}
/*
* Broadcast a signal to a condition variable. Wakes up all waiting threads.
* Should be called with the same mutex as was passed to cv_wait held.
*/
void
cv_broadcastpri(struct cv *cvp, int pri)
{
sleepq_lock(cvp);
if (cvp->cv_waiters > 0) {
cvp->cv_waiters = 0;
sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri);
} else
sleepq_release(cvp);
}