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Message-ID: <20070608071841.GC30226@elte.hu>
Date: Fri, 8 Jun 2007 09:18:41 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
LKML <linux-kernel@...r.kernel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Alexey Kuznetsov <kuznet@....inr.ac.ru>,
Ulrich Drepper <drepper@...hat.com>
Subject: Re: [patch 2/4] rt-mutex: Fix chain walk early wakeup bug
* Thomas Gleixner <tglx@...utronix.de> wrote:
> +++ linux-2.6.22-rc4/kernel/rtmutex.c 2007-06-08 01:39:38.000000000 +0200
> @@ -189,6 +189,19 @@ int rt_mutex_adjust_prio_chain(struct ta
> 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;
nice fix! I'm wondering why we never triggered this case with in-kernel
locks in -rt?
Acked-by: Ingo Molnar <mingo@...e.hu>
Ingo
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