From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from he.sipsolutions.net ([78.46.109.217]:41884 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935040Ab0KQTCG (ORCPT ); Wed, 17 Nov 2010 14:02:06 -0500 Subject: Re: [PATCH] mac80211: Fix deadlock in ieee80211_do_stop. From: Johannes Berg To: Ben Greear Cc: Tejun Heo , linux-wireless@vger.kernel.org In-Reply-To: <4CE4260F.80603@candelatech.com> References: <1289592426-5367-1-git-send-email-greearb@candelatech.com> <1289594998.3736.11.camel@jlt3.sipsolutions.net> <4CDDAA3B.9090007@candelatech.com> <1289596096.3736.13.camel@jlt3.sipsolutions.net> <4CDE699B.70401@kernel.org> <4CE1A344.7040201@candelatech.com> <4CE292F7.4090200@kernel.org> <1289929258.3673.1.camel@jlt3.sipsolutions.net> <4CE396A9.1050908@kernel.org> <1290020005.3777.6.camel@jlt3.sipsolutions.net> <4CE4260F.80603@candelatech.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 17 Nov 2010 11:03:37 -0800 Message-ID: <1290020617.3777.7.camel@jlt3.sipsolutions.net> Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, 2010-11-17 at 10:59 -0800, Ben Greear wrote: > On 11/17/2010 10:53 AM, Johannes Berg wrote: > > On Wed, 2010-11-17 at 09:47 +0100, Tejun Heo wrote: > > > >> WQ_NON_REENTRANT doesn't guarantee ordered execution but it guarantees > >> that a single work is not executed concurrently on multiple CPUs. I'm > >> not sure whether this would be safe for the workqueue used by mac80211 > >> but it should let us know whether the workqueue is choked due to a > >> work which is executing for long time. In the long run, if using non > >> reentrant is safe for mac80211, using it would be much better. > > > > No, I don't think it's safe for mac80211. > > So maybe my patch is a good enough way to fix this? Not before we get to the bottom of it, I think, and somebody goes and analyses _all_ the work items that might be there. johannes