Commit 9f2e0f63 authored by Linus Torvalds's avatar Linus Torvalds

Merge branch 'for-3.18-fixes' of git://

Pull percpu fix from Tejun Heo:
 "This contains one patch to fix a race condition which can lead to
  percpu_ref using a percpu pointer which is corrupted with a set DEAD
  bit.  The bug was introduced while separating out the ATOMIC mode flag
  from the DEAD flag.  The fix is pretty straight forward.

  I just committed the patch to the percpu tree but am sending out the
  pull request early as I'll be on vacation for a week.  The patch
  should be fairly safe and while the latency will be higher I'll be
  checking emails"

* 'for-3.18-fixes' of git://
  percpu-ref: fix DEAD flag contamination of percpu pointer
parents d038a63a 4aab3b5b
......@@ -133,7 +133,13 @@ static inline bool __ref_is_percpu(struct percpu_ref *ref,
/* paired with smp_store_release() in percpu_ref_reinit() */
if (unlikely(percpu_ptr & __PERCPU_REF_ATOMIC))
* Theoretically, the following could test just ATOMIC; however,
* then we'd have to mask off DEAD separately as DEAD may be
* visible without ATOMIC if we race with percpu_ref_kill(). DEAD
* implies ATOMIC anyway. Test them together.
if (unlikely(percpu_ptr & __PERCPU_REF_ATOMIC_DEAD))
return false;
*percpu_countp = (unsigned long __percpu *)percpu_ptr;
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