Commit-ID: 9694d494b7f462bffb86654fabe9e1ec2b2b0c47
Gitweb: http://git.kernel.org/tip/9694d494b7f462bffb86654fabe9e1ec2b2b0c47
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Sun, 4 Oct 2009 09:34:17 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sun, 4 Oct 2009 09:46:56 +0200
futex: Fix locking imbalance
Rich reported a lock imbalance in the futex code.
(http://bugzilla.kernel.org/show_bug.cgi?id=14288)
It's caused by the displacement of the retry_private label in
futex_wake_op(). The code unlocks the hash bucket locks in the error
handling path and retries without locking them again which makes the
next unlock fail.
Move retry_private so we lock the hash bucket locks when we retry.
Reported-by: Rich Ercolany <rercola@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
LKML-Reference: <new-submission>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Darren Hart <dvhltc@xxxxxxxxxx>
Cc: stable-2.6.31 <stable@xxxxxxxxxx>
---
kernel/futex.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index b911adc..a2f7538 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -916,8 +916,8 @@ retry:
hb1 = hash_futex(&key1);
hb2 = hash_futex(&key2);
- double_lock_hb(hb1, hb2);
retry_private:
+ double_lock_hb(hb1, hb2);
op_ret = futex_atomic_op_inuser(op, uaddr2);
if (unlikely(op_ret < 0)) {
--
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