Messages in this thread Patch in this message | | | From | Willy Tarreau <> | Date | Sat, 11 Aug 2007 21:48:03 +0200 | Subject | [2.6.20.16 review 11/28] 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.
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- kernel/rtmutex.c | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index 9b08847..dd5feae 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c @@ -212,6 +212,19 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task, 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; -- 1.5.2.4 -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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