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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 12 Jun 2008 06:30:02 -0700
From:	Daniel Walker <dwalker@...sta.com>
To:	Thomas Gleixner <tglx@...utronix.de>
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 Thu, 2008-06-12 at 10:56 +0200, Thomas Gleixner wrote:
> 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.

I ran it with lockdep enabled , I didn't get any warnings..

> 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.

It achieves correct ordering of the futex waiters inside the kernel,
that is in fact _something_ ..

Daniel


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/