Return-path: Received: from mail-ob0-f180.google.com ([209.85.214.180]:43756 "EHLO mail-ob0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751129AbaCTHMy convert rfc822-to-8bit (ORCPT ); Thu, 20 Mar 2014 03:12:54 -0400 Received: by mail-ob0-f180.google.com with SMTP id wn1so446606obc.25 for ; Thu, 20 Mar 2014 00:12:53 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1395238008.4142.15.camel@jlt4.sipsolutions.net> References: <1394021648-22605-1-git-send-email-michal.kazior@tieto.com> <1395238008.4142.15.camel@jlt4.sipsolutions.net> Date: Thu, 20 Mar 2014 08:12:53 +0100 Message-ID: (sfid-20140320_081257_818075_D49E2EF8) Subject: Re: [PATCH] mac80211: protect AP VLAN list with local->mtx From: Michal Kazior To: Johannes Berg Cc: linux-wireless Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 19 March 2014 15:06, Johannes Berg wrote: > On Wed, 2014-03-05 at 13:14 +0100, Michal Kazior wrote: >> It was impossible to change chanctx of master AP >> for AP VLANs because the copy function requires >> RTNL which can't be simply taken in mac80211 code >> due to possible deadlocks. >> >> This is required for future chanctx reservation >> that re-bind vifs to new chanctx. This requires >> safe AP VLAN iteration without RTNL. >> >> Now VLANs can be iterated while holding either >> RTNL or local->mtx because the list is modified >> while holding both of these locks. > > No objection really, but maybe it would make more sense to use > iflist_mtx? I used local->mtx because it seemed easier at the time (the lock is already used on all related codepaths). Using local->iflist_mtx would add another mutex to for csa/reservation. I think it shouldn't be hard to do it though. Should I re-spin? (this will probably need a re-spin of Luca's reservation patchset and my RFC). Michał