Messages in this thread Patch in this message | | | Date | Fri, 09 Oct 2009 16:08:46 -0700 | From | Greg KH <> | Subject | [patch 10/26] futex: Fix locking imbalance |
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2.6.31-stable review patch. If anyone has any objections, please let us know.
------------------ From: Thomas Gleixner <tglx@linutronix.de>
commit eaaea8036d0261d87d7072c5bc88c7ea730c18ac upstream.
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> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/futex.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/futex.c +++ b/kernel/futex.c @@ -912,8 +912,8 @@ 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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