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authorJan Kara <jack@suse.cz>2012-06-01 00:42:06 +0200
committerFengguang Wu <fengguang.wu@intel.com>2012-06-09 08:37:55 +0900
commite78d4833c03e28205b3d983f0c4e586ee34785fd (patch)
treea0c91fbb027dd2cafce11c3fa699efca0d4fb52a /lib/flex_proportions.c
parentf3109a51f8dc88e8a94f620240b7474b91bed37a (diff)
downloadlinux-e78d4833c03e28205b3d983f0c4e586ee34785fd.tar.gz
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>
Diffstat (limited to 'lib/flex_proportions.c')
-rw-r--r--lib/flex_proportions.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/lib/flex_proportions.c b/lib/flex_proportions.c
index e02a3883ae0..c785554f952 100644
--- a/lib/flex_proportions.c
+++ b/lib/flex_proportions.c
@@ -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;
}