Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 64efade1 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds
Browse files

[PATCH] lockdep: fix delayacct locking bug 



Make the delayacct lock irqsave; this avoids the possible deadlock where
an interrupt is taken while holding the delayacct lock which needs to
take the delayacct lock.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e5b9a335

kernel/delayacct.c

+9 −6
Original line number Original line Diff line number Diff line
@@ -66,6 +66,7 @@ static void delayacct_end(struct timespec *start, struct timespec *end, 
{

{

	struct timespec ts;

	struct timespec ts;

	s64 ns;

	s64 ns;

	unsigned long flags;





	do_posix_clock_monotonic_gettime(end);

	do_posix_clock_monotonic_gettime(end);

	ts = timespec_sub(*end, *start);

	ts = timespec_sub(*end, *start);
@@ -73,10 +74,10 @@ static void delayacct_end(struct timespec *start, struct timespec *end, 
	if (ns < 0)

	if (ns < 0)

		return;

		return;





	spin_lock(&current->delays->lock);

	spin_lock_irqsave(&current->delays->lock, flags);

	*total += ns;

	*total += ns;

	(*count)++;

	(*count)++;

	spin_unlock(&current->delays->lock);

	spin_unlock_irqrestore(&current->delays->lock, flags);

}

}





void __delayacct_blkio_start(void)

void __delayacct_blkio_start(void)
@@ -104,6 +105,7 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 
	s64 tmp;

	s64 tmp;

	struct timespec ts;

	struct timespec ts;

	unsigned long t1,t2,t3;

	unsigned long t1,t2,t3;

	unsigned long flags;





	/* Though tsk->delays accessed later, early exit avoids

	/* Though tsk->delays accessed later, early exit avoids

	 * unnecessary returning of other data

	 * unnecessary returning of other data
@@ -136,14 +138,14 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 




	/* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */

	/* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */





	spin_lock(&tsk->delays->lock);

	spin_lock_irqsave(&tsk->delays->lock, flags);

	tmp = d->blkio_delay_total + tsk->delays->blkio_delay;

	tmp = d->blkio_delay_total + tsk->delays->blkio_delay;

	d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;

	d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;

	tmp = d->swapin_delay_total + tsk->delays->swapin_delay;

	tmp = d->swapin_delay_total + tsk->delays->swapin_delay;

	d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;

	d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;

	d->blkio_count += tsk->delays->blkio_count;

	d->blkio_count += tsk->delays->blkio_count;

	d->swapin_count += tsk->delays->swapin_count;

	d->swapin_count += tsk->delays->swapin_count;

	spin_unlock(&tsk->delays->lock);

	spin_unlock_irqrestore(&tsk->delays->lock, flags);





done:

done:

	return 0;

	return 0;
@@ -152,11 +154,12 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 
__u64 __delayacct_blkio_ticks(struct task_struct *tsk)

__u64 __delayacct_blkio_ticks(struct task_struct *tsk)

{

{

	__u64 ret;

	__u64 ret;

	unsigned long flags;





	spin_lock(&tsk->delays->lock);

	spin_lock_irqsave(&tsk->delays->lock, flags);

	ret = nsec_to_clock_t(tsk->delays->blkio_delay +

	ret = nsec_to_clock_t(tsk->delays->blkio_delay +

				tsk->delays->swapin_delay);

				tsk->delays->swapin_delay);

	spin_unlock(&tsk->delays->lock);

	spin_unlock_irqrestore(&tsk->delays->lock, flags);

	return ret;

	return ret;

}

}