Commit 1a539a87 authored Jun 08, 2007 by Thomas Gleixner Committed by Linus Torvalds Jun 08, 2007

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>

parent c0d1d2bf

kernel/rtmutex.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -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;