Messages in this thread Patch in this message | | | Date | Sun, 4 Oct 2009 07:54:41 GMT | From | tip-bot for Thomas Gleixner <> | Subject | [tip:core/futexes] futex: Fix locking imbalance |
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Commit-ID: 9694d494b7f462bffb86654fabe9e1ec2b2b0c47 Gitweb: http://git.kernel.org/tip/9694d494b7f462bffb86654fabe9e1ec2b2b0c47 Author: Thomas Gleixner <tglx@linutronix.de> AuthorDate: Sun, 4 Oct 2009 09:34:17 +0200 Committer: Thomas Gleixner <tglx@linutronix.de> 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@acm.jhu.edu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> LKML-Reference: <new-submission> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Darren Hart <dvhltc@us.ibm.com> Cc: stable-2.6.31 <stable@kernel.org>
--- 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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