linux-kernel - Re: [PATCH 5/5] futex: fix miss ordered wakeups

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Date:	Thu, 12 Jun 2008 10:56:15 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Daniel Walker <dwalker@...sta.com>
cc:	linux-kernel@...r.kernel.org, Ulrich Drepper <drepper@...il.com>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [PATCH 5/5] futex: fix miss ordered wakeups

On Wed, 11 Jun 2008, Daniel Walker wrote:
> Adds an additional function call to the sched_setscheduler to update the
> waiter position of a task if it happens to be waiting on a futex. This
> ensures that the kernel level waiter ordering is correctly maintained
> based on the changed priority of the task.
> 
> I fixed the locking issue noticed by Thomas Gleixner.
> 
> This doesn't address userspace at all, only the kernel level wakeups and
> kernel level ordering.
> 
> The additional locking added to the futex_wait function has no visible speed
> impact, and only effects waiters which actual enter the kernel.

The additional locking is just broken and you did not even bother to
test your changes with lockdep.

Aside of this, these patches still add 100 lines of code to achieve
nothing - as dicussed when you previously submitted your changes. 

Please stop wasting everyone's time with that.

Thanks,

	tglx
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