Messages in this thread Patch in this message | | | Date | Fri, 08 Jun 2007 10:29:29 -0000 | From | Thomas Gleixner <> | Subject | [patch-stable 2/3] rt-mutex: Fix chain walk early wakeup bug |
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Alexey Kuznetsov found some problems in the pi-futex code.
One of the root causes is:
When a wakeup happens, we do not to stop the chain walk so we we follow a non existing locking chain.
Drop out when this happens.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu>
--- kernel/rtmutex.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
Index: linux-2.6.21/kernel/rtmutex.c =================================================================== --- linux-2.6.21.orig/kernel/rtmutex.c 2007-06-08 11:56:10.000000000 +0200 +++ linux-2.6.21/kernel/rtmutex.c 2007-06-08 11:56:10.000000000 +0200 @@ -212,6 +212,19 @@ static int rt_mutex_adjust_prio_chain(st if (!waiter || !waiter->task) goto out_unlock_pi; + /* + * Check the orig_waiter state. After we dropped the locks, + * the previous owner of the lock might have released the lock + * and made us the pending owner: + */ + if (orig_waiter && !orig_waiter->task) + goto out_unlock_pi; + + /* + * Drop out, when the task has no waiters. Note, + * top_waiter can be NULL, when we are in the deboosting + * mode! + */ if (top_waiter && (!task_has_pi_waiters(task) || top_waiter != task_top_pi_waiter(task))) goto out_unlock_pi; --
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