Return-path: Received: from he.sipsolutions.net ([78.46.109.217]:42015 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751495Ab2GDL1q (ORCPT ); Wed, 4 Jul 2012 07:27:46 -0400 Message-ID: <1341401264.12432.7.camel@jlt3.sipsolutions.net> (sfid-20120704_132749_752933_DD7057D2) Subject: Re: [PATCH 06/13] cfg80211: track monitor interfaces count From: Johannes Berg To: Michal Kazior Cc: linux-wireless@vger.kernel.org, "Manoharan, Rajkumar" Date: Wed, 04 Jul 2012 13:27:44 +0200 In-Reply-To: <1341401180.12432.6.camel@jlt3.sipsolutions.net> (sfid-20120704_132627_061268_46C684C8) 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) Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: 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 johannes