From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754885AbaIBSEm (ORCPT ); Tue, 2 Sep 2014 14:04:42 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:63837 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754342AbaIBSEk (ORCPT ); Tue, 2 Sep 2014 14:04:40 -0400 MIME-Version: 1.0 In-Reply-To: <1409680684.972417.162793869.03CF8A61@webmail.messagingengine.com> References: <20140829195339.GA9780@kria> <1409363489.2980.17.camel@localhost> <1409680684.972417.162793869.03CF8A61@webmail.messagingengine.com> Date: Tue, 2 Sep 2014 11:04:38 -0700 Message-ID: Subject: Re: RTNL: assertion failed at net/ipv6/addrconf.c (1699) From: Cong Wang To: Hannes Frederic Sowa Cc: Sabrina Dubroca , Tommi Rantala , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev , LKML , trinity@vger.kernel.org, Dave Jones Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 2, 2014 at 10:58 AM, Hannes Frederic Sowa wrote: > Hi Cong, > > On Tue, Sep 2, 2014, at 18:50, Cong Wang wrote: >> On Fri, Aug 29, 2014 at 6:51 PM, Hannes Frederic Sowa >> wrote: >> > >> > Also rtnl_lock and rcu_read_lock compose in that order, so we don't need >> > to change dev_get_by_flags, but as this is the only user it sure is >> > possible. RCU locked version is just easier composeable, so I wouldn't >> > touch that if needed in future, just also take rcu lock as before. >> >> There is no point to keep RCU read lock if we have rtnl lock, >> I don't know why you don't want to change dev_get_by_flags(), >> it is pretty easy to do since it only has one caller. > > I definitely don't have a problem cleaning this up in net-next. I wanted > a minimal patch for stable because I didn't check history where and when > additional users of dev_get_by_flags_rcu were removed. `git grep` should show you we only have one caller. Apparently we don't care about any out-of-tree module. > >> Even if you really need RCU in future, you are always welcome >> to bring it back when you do, sorry we should never be blocked by >> code NOT merged yet. >> >> > >> > Also we should move ASSERT_RTNL checks from addrconf_join_solict to >> > ipv6_dev_mc_inc/dec. >> > >> >> Make it another patch. > > It is just one logical change, moving ASSERT_RTNLs to places where they > better catch invalid callstacks. > Conflicts with what you claimed above. :)