From 1a539a87280b3032fd12bc93a4a82f1d8aa97ca8 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 8 Jun 2007 13:46:58 -0700 Subject: [PATCH] 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 Acked-by: Ingo Molnar Cc: Steven Rostedt Cc: Alexey Kuznetsov Cc: Ulrich Drepper Cc: Eric Dumazet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/rtmutex.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index a273183c37..a6fbb41305 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; -- 2.39.5