linux-kernel - Re: workqueue destruction BUG

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]

Message-ID: <4C739DC6.1040309@kernel.org>
Date:	Tue, 24 Aug 2010 12:24:06 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Johannes Berg <johannes@...solutions.net>
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: workqueue destruction BUG_ON

Hello,

On 08/24/2010 10:55 AM, Johannes Berg wrote:
> In our testing with iwlwifi, we keep running into this BUG_ON:
> 
> 	BUG_ON(cwq->nr_active);
> 
> in destroy_workqueue(). This is quite unhelpful, and since the code
> flushes the workqueue I really don't see how this could be happening,
> unless maybe there's cross-talk between this and other workqueues?

Flushing the workqueue doesn't guarantee that the workqueue stays
empty.  It just flushes the currently pending works.  If there are
requeueing works or something else is queueing new works, workqueue
won't be empty.  The check is new.  Previously, workqueue code didn't
check whether the workqueue is actually empty.  Now that the worklist
is shared, we need such check in place.  There was also a similar
report on ath9k.  I think it's most likely that something is queueing
works on a dying wokrqueue in the wireless common code.  I'll prep a
debug patch to print out some details.

Thanks.

-- 
tejun
--
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/