]> pilppa.com Git - linux-2.6-omap-h63xx.git/commitdiff
rt-mutex: fix chain walk early wakeup bug
authorThomas Gleixner <tglx@linutronix.de>
Fri, 8 Jun 2007 20:46:58 +0000 (13:46 -0700)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Sat, 9 Jun 2007 00:23:34 +0000 (17:23 -0700)
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 <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/rtmutex.c

index a273183c37a037307b1f1915171fffcce1ff413f..a6fbb41305210c9d3d45c56a670f3fe96af6ce64 100644 (file)
@@ -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;