Messages in this thread Patch in this message | | | Date | Mon, 5 Oct 2009 19:11:41 GMT | From | tip-bot for Thomas Gleixner <> | Subject | [tip:core/urgent] futex: Fix locking imbalance |
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Commit-ID: eaaea8036d0261d87d7072c5bc88c7ea730c18ac Gitweb: http://git.kernel.org/tip/eaaea8036d0261d87d7072c5bc88c7ea730c18ac Author: Thomas Gleixner <tglx@linutronix.de> AuthorDate: Sun, 4 Oct 2009 09:34:17 +0200 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Mon, 5 Oct 2009 21:08:14 +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> 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>
--- kernel/futex.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c index 463af2e..1e176f3 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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