diff options
| author | Jason Baron <jbaron@akamai.com> | 2014-07-02 17:52:44 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-07-16 13:38:21 +0200 |
| commit | 5cd08fbfdb6baa9fe98f530b76898fc5725a6289 (patch) | |
| tree | b4f9df78a954c306cacea7372d920d1eb373140f /kernel/sched | |
| parent | sched: Remove extra static_key*() function indirection (diff) | |
| download | linux-5cd08fbfdb6baa9fe98f530b76898fc5725a6289.tar.xz linux-5cd08fbfdb6baa9fe98f530b76898fc5725a6289.zip | |
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>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2f960813c582..8705125bb9b1 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -245,6 +245,7 @@ sched_feat_write(struct file *filp, const char __user *ubuf, char buf[64]; char *cmp; int i; + struct inode *inode; if (cnt > 63) cnt = 63; @@ -255,7 +256,11 @@ sched_feat_write(struct file *filp, const char __user *ubuf, buf[cnt] = 0; cmp = strstrip(buf); + /* Ensure the static_key remains in a consistent state */ + inode = file_inode(filp); + mutex_lock(&inode->i_mutex); i = sched_feat_set(cmp); + mutex_unlock(&inode->i_mutex); if (i == __SCHED_FEAT_NR) return -EINVAL; |