From e78d4833c03e28205b3d983f0c4e586ee34785fd Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Fri, 1 Jun 2012 00:42:06 +0200 Subject: [PATCH] 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 Signed-off-by: Fengguang Wu --- lib/flex_proportions.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/lib/flex_proportions.c b/lib/flex_proportions.c index e02a388..c785554 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; } -- 2.7.4