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lib: Fix possible deadlock in flexible proportion code 

When percpu counter function in fprop_new_period() is interrupted by an
interrupt while holding counter lock, it can cause deadlock when the
interrupt wants to take the lock as well. Fix the problem by disabling
interrupts when calling percpu counter functions.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
This commit is contained in:
Jan Kara 2012-06-01 00:42:06 +02:00 committed by Fengguang Wu
parent f3109a51f8
commit e78d4833c0
1 changed files with 8 additions and 2 deletions
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10
lib/flex_proportions.c
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@ -62,13 +62,18 @@ void fprop_global_destroy(struct fprop_global *p)
*/
bool fprop_new_period(struct fprop_global *p, int periods)
{
u64 events = percpu_counter_sum(&p->events);
u64 events;
unsigned long flags;
local_irq_save(flags);
events = percpu_counter_sum(&p->events);
/*
* Don't do anything if there are no events.
*/
if (events <= 1)
if (events <= 1) {
local_irq_restore(flags);
return false;
}
write_seqcount_begin(&p->sequence);
if (periods < 64)
events -= events >> periods;
@ -76,6 +81,7 @@ bool fprop_new_period(struct fprop_global *p, int periods)
percpu_counter_add(&p->events, -events);
p->period += periods;
write_seqcount_end(&p->sequence);
local_irq_restore(flags);
return true;
}