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[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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Peter Zijlstra 2006-11-05 23:52:10 -08:00 committed by Linus Torvalds
parent e5b9a335fd
commit 64efade11c
1 changed files with 9 additions and 6 deletions
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15
kernel/delayacct.c
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@ -66,6 +66,7 @@ static void delayacct_end(struct timespec *start, struct timespec *end,
{
struct timespec ts;
s64 ns;
unsigned long flags;
do_posix_clock_monotonic_gettime(end);
ts = timespec_sub(*end, *start);
@ -73,10 +74,10 @@ static void delayacct_end(struct timespec *start, struct timespec *end,
if (ns < 0)
return;
spin_lock(&current->delays->lock);
spin_lock_irqsave(&current->delays->lock, flags);
*total += ns;
(*count)++;
spin_unlock(&current->delays->lock);
spin_unlock_irqrestore(&current->delays->lock, flags);
}
void __delayacct_blkio_start(void)
@ -104,6 +105,7 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
s64 tmp;
struct timespec ts;
unsigned long t1,t2,t3;
unsigned long flags;
/* Though tsk->delays accessed later, early exit avoids
* 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 */
spin_lock(&tsk->delays->lock);
spin_lock_irqsave(&tsk->delays->lock, flags);
tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
d->blkio_count += tsk->delays->blkio_count;
d->swapin_count += tsk->delays->swapin_count;
spin_unlock(&tsk->delays->lock);
spin_unlock_irqrestore(&tsk->delays->lock, flags);
done:
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 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 +
tsk->delays->swapin_delay);
spin_unlock(&tsk->delays->lock);
spin_unlock_irqrestore(&tsk->delays->lock, flags);
return ret;
}