netdev - Re: deadlocks if use htb

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, 15 Jan 2009 09:01:20 +0000
From:	Jarek Poplawski <jarkao2@...il.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Denys Fedoryschenko <denys@...p.net.lb>,
	Chris Caputo <ccaputo@....net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Badalian Vyacheslav <slavon@...telecom.ru>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: deadlocks if use htb

On Wed, Jan 14, 2009 at 03:28:03PM +0100, Peter Zijlstra wrote:
...
> Right, found all that...
> 
> Can't spot anything obviously wrong though.. hrtimer_start*() does
> remove_hrtimer() which checks STATE_ENQUEUED, STATE_PENDING and pulls it
> off the relevant list before it continues the enqueue.
> 
> However a loop in enqueue_hrtimer() would suggest a corrupted RB-tree,
> but I cannot find an RB-op that doesn't hold base-lock.
> 

I've revisited it yesterday, and if I don't miss something, there is
possible a scenario similar to this:

cpu1:				cpu2:

run_hrtimer_pending
spin_unlock
restart = fn(timer)

				hrtimer_start
				enqueue_hrtimer

				hrtimer_start
				remove_hrtimer
				(the HRTIMER_STATE_CALLBACK is removed)

				switch_hrtimer_base
spin_lock
(not this hrtimer's anymore)
__remove_hrtimer
list_add_tail			enqueue_hrtimer


Jarek P.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html