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> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Darren Hart <dvhltc@us.ibm.com> Cc: stable-2.6.31 <stable@kernel.org> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -916,8 +916,8 @@ futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
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hb1 = hash_futex(&key1);
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hb2 = hash_futex(&key2);
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double_lock_hb(hb1, hb2);
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retry_private:
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double_lock_hb(hb1, hb2);
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op_ret = futex_atomic_op_inuser(op, uaddr2);
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if (unlikely(op_ret < 0)) {
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