11f9ca696e
r282971 attempted to fix this problem by decrementing cv_waiters after waking up from sleeping on a condition variable, but this can result in a use-after-free if the CV is freed before all woken threads have had a chance to run. Instead, avoid incrementing cv_waiters past INT_MAX, and have cv_signal() explicitly check for sleeping threads once cv_waiters has reached this bound. Reviewed by: jhb MFC after: 2 weeks Sponsored by: EMC / Isilon Storage Division Differential Revision: https://reviews.freebsd.org/D4822
477 lines
12 KiB
C
477 lines
12 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/limits.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
|
|
|
|
/*
|
|
* A bound below which cv_waiters is valid. Once cv_waiters reaches this bound,
|
|
* cv_signal must manually check the wait queue for threads.
|
|
*/
|
|
#define CV_WAITERS_BOUND INT_MAX
|
|
|
|
#define CV_WAITERS_INC(cvp) do { \
|
|
if ((cvp)->cv_waiters < CV_WAITERS_BOUND) \
|
|
(cvp)->cv_waiters++; \
|
|
} while (0)
|
|
|
|
/*
|
|
* Common sanity checks for cv_wait* functions.
|
|
*/
|
|
#define CV_ASSERT(cvp, lock, td) do { \
|
|
KASSERT((td) != NULL, ("%s: td NULL", __func__)); \
|
|
KASSERT(TD_IS_RUNNING(td), ("%s: not TDS_RUNNING", __func__)); \
|
|
KASSERT((cvp) != NULL, ("%s: cvp NULL", __func__)); \
|
|
KASSERT((lock) != NULL, ("%s: lock NULL", __func__)); \
|
|
} 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 lock_object *lock)
|
|
{
|
|
WITNESS_SAVE_DECL(lock_witness);
|
|
struct lock_class *class;
|
|
struct thread *td;
|
|
uintptr_t lock_state;
|
|
|
|
td = curthread;
|
|
lock_state = 0;
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(1, 0, cv_wmesg(cvp));
|
|
#endif
|
|
CV_ASSERT(cvp, lock, td);
|
|
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
|
|
"Waiting on \"%s\"", cvp->cv_description);
|
|
class = LOCK_CLASS(lock);
|
|
|
|
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;
|
|
}
|
|
|
|
sleepq_lock(cvp);
|
|
|
|
CV_WAITERS_INC(cvp);
|
|
if (lock == &Giant.lock_object)
|
|
mtx_assert(&Giant, MA_OWNED);
|
|
DROP_GIANT();
|
|
|
|
sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
|
|
if (lock != &Giant.lock_object) {
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_release(cvp);
|
|
WITNESS_SAVE(lock, lock_witness);
|
|
lock_state = class->lc_unlock(lock);
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_lock(cvp);
|
|
}
|
|
sleepq_wait(cvp, 0);
|
|
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(0, 0, cv_wmesg(cvp));
|
|
#endif
|
|
PICKUP_GIANT();
|
|
if (lock != &Giant.lock_object) {
|
|
class->lc_lock(lock, lock_state);
|
|
WITNESS_RESTORE(lock, lock_witness);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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 lock_object *lock)
|
|
{
|
|
struct lock_class *class;
|
|
struct thread *td;
|
|
|
|
td = curthread;
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(1, 0, cv_wmesg(cvp));
|
|
#endif
|
|
CV_ASSERT(cvp, lock, td);
|
|
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
|
|
"Waiting on \"%s\"", cvp->cv_description);
|
|
KASSERT(lock != &Giant.lock_object,
|
|
("cv_wait_unlock cannot be used with Giant"));
|
|
class = LOCK_CLASS(lock);
|
|
|
|
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.
|
|
*/
|
|
class->lc_unlock(lock);
|
|
return;
|
|
}
|
|
|
|
sleepq_lock(cvp);
|
|
|
|
CV_WAITERS_INC(cvp);
|
|
DROP_GIANT();
|
|
|
|
sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_release(cvp);
|
|
class->lc_unlock(lock);
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_lock(cvp);
|
|
sleepq_wait(cvp, 0);
|
|
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(0, 0, cv_wmesg(cvp));
|
|
#endif
|
|
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 lock_object *lock)
|
|
{
|
|
WITNESS_SAVE_DECL(lock_witness);
|
|
struct lock_class *class;
|
|
struct thread *td;
|
|
uintptr_t lock_state;
|
|
int rval;
|
|
|
|
td = curthread;
|
|
lock_state = 0;
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(1, 0, cv_wmesg(cvp));
|
|
#endif
|
|
CV_ASSERT(cvp, lock, td);
|
|
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
|
|
"Waiting on \"%s\"", cvp->cv_description);
|
|
class = LOCK_CLASS(lock);
|
|
|
|
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);
|
|
|
|
CV_WAITERS_INC(cvp);
|
|
if (lock == &Giant.lock_object)
|
|
mtx_assert(&Giant, MA_OWNED);
|
|
DROP_GIANT();
|
|
|
|
sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
|
|
SLEEPQ_INTERRUPTIBLE, 0);
|
|
if (lock != &Giant.lock_object) {
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_release(cvp);
|
|
WITNESS_SAVE(lock, lock_witness);
|
|
lock_state = class->lc_unlock(lock);
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_lock(cvp);
|
|
}
|
|
rval = sleepq_wait_sig(cvp, 0);
|
|
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(0, 0, cv_wmesg(cvp));
|
|
#endif
|
|
PICKUP_GIANT();
|
|
if (lock != &Giant.lock_object) {
|
|
class->lc_lock(lock, lock_state);
|
|
WITNESS_RESTORE(lock, lock_witness);
|
|
}
|
|
|
|
return (rval);
|
|
}
|
|
|
|
/*
|
|
* Wait on a condition variable for (at most) the value specified in sbt
|
|
* argument. Returns 0 if the process was resumed by cv_signal or cv_broadcast,
|
|
* EWOULDBLOCK if the timeout expires.
|
|
*/
|
|
int
|
|
_cv_timedwait_sbt(struct cv *cvp, struct lock_object *lock, sbintime_t sbt,
|
|
sbintime_t pr, int flags)
|
|
{
|
|
WITNESS_SAVE_DECL(lock_witness);
|
|
struct lock_class *class;
|
|
struct thread *td;
|
|
int lock_state, rval;
|
|
|
|
td = curthread;
|
|
lock_state = 0;
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(1, 0, cv_wmesg(cvp));
|
|
#endif
|
|
CV_ASSERT(cvp, lock, td);
|
|
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
|
|
"Waiting on \"%s\"", cvp->cv_description);
|
|
class = LOCK_CLASS(lock);
|
|
|
|
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);
|
|
|
|
CV_WAITERS_INC(cvp);
|
|
if (lock == &Giant.lock_object)
|
|
mtx_assert(&Giant, MA_OWNED);
|
|
DROP_GIANT();
|
|
|
|
sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
|
|
sleepq_set_timeout_sbt(cvp, sbt, pr, flags);
|
|
if (lock != &Giant.lock_object) {
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_release(cvp);
|
|
WITNESS_SAVE(lock, lock_witness);
|
|
lock_state = class->lc_unlock(lock);
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_lock(cvp);
|
|
}
|
|
rval = sleepq_timedwait(cvp, 0);
|
|
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(0, 0, cv_wmesg(cvp));
|
|
#endif
|
|
PICKUP_GIANT();
|
|
if (lock != &Giant.lock_object) {
|
|
class->lc_lock(lock, lock_state);
|
|
WITNESS_RESTORE(lock, lock_witness);
|
|
}
|
|
|
|
return (rval);
|
|
}
|
|
|
|
/*
|
|
* Wait on a condition variable for (at most) the value specified in sbt
|
|
* argument, 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_sbt(struct cv *cvp, struct lock_object *lock,
|
|
sbintime_t sbt, sbintime_t pr, int flags)
|
|
{
|
|
WITNESS_SAVE_DECL(lock_witness);
|
|
struct lock_class *class;
|
|
struct thread *td;
|
|
int lock_state, rval;
|
|
|
|
td = curthread;
|
|
lock_state = 0;
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(1, 0, cv_wmesg(cvp));
|
|
#endif
|
|
CV_ASSERT(cvp, lock, td);
|
|
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
|
|
"Waiting on \"%s\"", cvp->cv_description);
|
|
class = LOCK_CLASS(lock);
|
|
|
|
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);
|
|
|
|
CV_WAITERS_INC(cvp);
|
|
if (lock == &Giant.lock_object)
|
|
mtx_assert(&Giant, MA_OWNED);
|
|
DROP_GIANT();
|
|
|
|
sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
|
|
SLEEPQ_INTERRUPTIBLE, 0);
|
|
sleepq_set_timeout_sbt(cvp, sbt, pr, flags);
|
|
if (lock != &Giant.lock_object) {
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_release(cvp);
|
|
WITNESS_SAVE(lock, lock_witness);
|
|
lock_state = class->lc_unlock(lock);
|
|
if (class->lc_flags & LC_SLEEPABLE)
|
|
sleepq_lock(cvp);
|
|
}
|
|
rval = sleepq_timedwait_sig(cvp, 0);
|
|
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_CSW))
|
|
ktrcsw(0, 0, cv_wmesg(cvp));
|
|
#endif
|
|
PICKUP_GIANT();
|
|
if (lock != &Giant.lock_object) {
|
|
class->lc_lock(lock, lock_state);
|
|
WITNESS_RESTORE(lock, lock_witness);
|
|
}
|
|
|
|
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)
|
|
{
|
|
int wakeup_swapper;
|
|
|
|
wakeup_swapper = 0;
|
|
sleepq_lock(cvp);
|
|
if (cvp->cv_waiters > 0) {
|
|
if (cvp->cv_waiters == CV_WAITERS_BOUND &&
|
|
sleepq_lookup(cvp) == NULL) {
|
|
cvp->cv_waiters = 0;
|
|
} else {
|
|
if (cvp->cv_waiters < CV_WAITERS_BOUND)
|
|
cvp->cv_waiters--;
|
|
wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0,
|
|
0);
|
|
}
|
|
}
|
|
sleepq_release(cvp);
|
|
if (wakeup_swapper)
|
|
kick_proc0();
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
int wakeup_swapper;
|
|
|
|
/*
|
|
* XXX sleepq_broadcast pri argument changed from -1 meaning
|
|
* no pri to 0 meaning no pri.
|
|
*/
|
|
wakeup_swapper = 0;
|
|
if (pri == -1)
|
|
pri = 0;
|
|
sleepq_lock(cvp);
|
|
if (cvp->cv_waiters > 0) {
|
|
cvp->cv_waiters = 0;
|
|
wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0);
|
|
}
|
|
sleepq_release(cvp);
|
|
if (wakeup_swapper)
|
|
kick_proc0();
|
|
}
|