sched: Fix static_key race with sched_feat()
authorJason Baron <jbaron@akamai.com>
Wed, 2 Jul 2014 15:52:44 +0000 (15:52 +0000)
committerIngo Molnar <mingo@kernel.org>
Wed, 16 Jul 2014 11:38:21 +0000 (13:38 +0200)
commit5cd08fbfdb6baa9fe98f530b76898fc5725a6289
treeb4f9df78a954c306cacea7372d920d1eb373140f
parent6e76ea8a8209386c3cc7ee5594e6ea5d25525cf2
sched: Fix static_key race with sched_feat()

As pointed out by Andi Kleen, the usage of static keys can be racy in
sched_feat_disable() vs. sched_feat_enable(). Currently, we first check the
value of keys->enabled, and subsequently update the branch direction. This,
can be racy and can potentially leave the keys in an inconsistent state.

Take the i_mutex around these calls to resolve the race.

Reported-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/9d7780c83db26683955cd01e6bc654ee2586e67f.1404315388.git.jbaron@akamai.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/sched/core.c