Commit:     1a539a87280b3032fd12bc93a4a82f1d8aa97ca8
Parent:     c0d1d2bf5a28f78def7b68ca1eb5ba31aafd43a1
Author:     Thomas Gleixner <[EMAIL PROTECTED]>
AuthorDate: Fri Jun 8 13:46:58 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri Jun 8 17:23:34 2007 -0700

    rt-mutex: fix chain walk early wakeup bug
    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 follow a not
    longer relevant locking chain.
    Drop out when this happens.
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
    Acked-by: Ingo Molnar <[EMAIL PROTECTED]>
    Cc: Steven Rostedt <[EMAIL PROTECTED]>
    Cc: Alexey Kuznetsov <[EMAIL PROTECTED]>
    Cc: Ulrich Drepper <[EMAIL PROTECTED]>
    Cc: Eric Dumazet <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 kernel/rtmutex.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index a273183..a6fbb41 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -189,6 +189,19 @@ 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;
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