Return-path: Received: from ebb05.tieto.com ([131.207.168.36]:55667 "EHLO ebb05.tieto.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750839Ab2GDMeD (ORCPT ); Wed, 4 Jul 2012 08:34:03 -0400 Message-ID: <4FF43838.4010908@tieto.com> (sfid-20120704_143408_257481_761F26DD) Date: Wed, 4 Jul 2012 14:34:00 +0200 From: Michal Kazior MIME-Version: 1.0 To: Johannes Berg CC: "linux-wireless@vger.kernel.org" , "Manoharan, Rajkumar" Subject: Re: [PATCH 06/13] cfg80211: track monitor interfaces count References: <1340966828-22874-1-git-send-email-michal.kazior@tieto.com> <1340966828-22874-7-git-send-email-michal.kazior@tieto.com> <1341400378.12432.4.camel@jlt3.sipsolutions.net> (sfid-20120704_131306_010478_4A0DA490) <1341400632.12432.5.camel@jlt3.sipsolutions.net> (sfid-20120704_131718_037897_66E57863) <1341401180.12432.6.camel@jlt3.sipsolutions.net> (sfid-20120704_132627_061268_46C684C8) <1341401264.12432.7.camel@jlt3.sipsolutions.net> In-Reply-To: <1341401264.12432.7.camel@jlt3.sipsolutions.net> Content-Type: text/plain; charset="UTF-8"; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: Johannes Berg wrote: > On Wed, 2012-07-04 at 13:26 +0200, Johannes Berg wrote: >> On Wed, 2012-07-04 at 13:17 +0200, Johannes Berg wrote: >>> On Wed, 2012-07-04 at 13:12 +0200, Johannes Berg wrote: >>>> Hi Michal, >>>> >>>> A few people noticed that these patches cause deadlocks. I think the >>>> reason is that it's not allowed to lock the device here: >>>> >>>>> case NETDEV_DOWN: >>>>> dev_hold(dev); >>>>> + cfg80211_lock_rdev(rdev); >>>> >>>> This causes a deadlock since the interface is set down inside mac80211 >>>> when inside a handler from cfg80211 already, or so. >>> >>> I just reproduce it -- it's because we come from nl80211_del_interface() >> >> Ok ... we don't really need to hold the rdev lock since it's all under >> rtnl. Can you please confirm this is safe? >> >> http://p.sipsolutions.net/bde4760671f3e250.txt > > I guess we can remove more locking: > http://p.sipsolutions.net/8a1b875a431e72a0.txt I can't really test it right now, but it looks good to me. -- Pozdrawiam / Best regards, Michal Kazior.