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authorThomas Gleixner <tglx@linutronix.de>2007-06-08 20:46:58 (GMT)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-06-09 00:23:34 (GMT)
commit1a539a87280b3032fd12bc93a4a82f1d8aa97ca8 (patch)
tree6dea1610ba5ff54f0e3f845d83bfc68ffc162e31 /kernel/rtmutex.c
parentc0d1d2bf5a28f78def7b68ca1eb5ba31aafd43a1 (diff)
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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 <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>
Diffstat (limited to 'kernel/rtmutex.c')
-rw-r--r--kernel/rtmutex.c13
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;