From mboxrd@z Thu Jan 1 00:00:00 1970 From: Veaceslav Falico Subject: Re: [net-next,1/3] bonding: fix vlan 0 addition and removal Date: Tue, 6 Aug 2013 10:59:41 +0200 Message-ID: <20130806085941.GM22756@redhat.com> References: <1375709304-16778-2-git-send-email-nikolay@redhat.com> <20130805215126.GB3859@redhat.com> <5200B63A.5070900@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Cc: netdev@vger.kernel.org, fubar@us.ibm.com, andy@greyhouse.net, davem@davemloft.net, kaber@trash.net To: Nikolay Aleksandrov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:34045 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754922Ab3HFJAo (ORCPT ); Tue, 6 Aug 2013 05:00:44 -0400 Content-Disposition: inline In-Reply-To: <5200B63A.5070900@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Aug 06, 2013 at 10:39:22AM +0200, Nikolay Aleksandrov wrote: >> From 1c89abefebe90568ed52d2df59fcfdd650bc4696 Mon Sep 17 00:00:00 2001 >> From: Veaceslav Falico >> Date: Mon, 5 Aug 2013 23:29:12 +0200 >> Subject: [PATCH] bonding: add vlan_uses_dev_rcu() and make bond_vlan_used() >> use it >> >> Currently, bond_vlan_used() looks for any vlan, including the pseudo-vlan >> id 0, and always returns true if 8021q is loaded. This creates several bad >> situations - some warnings in __bond_release_one() because it thinks that >> we still have vlans while removing, sending LB packets with vlan id 0 and, >> possibly, other caused by vlan id 0. >> >> Fix it by adding a new call, vlan_uses_dev_rcu(), which is the same as >> vlan_uses_dev(), but uses rcu_dereference() instead of rtnl, and thus we >> can use it in bond_vlan_used() wrapped in rcu_read_lock(). >> >> Also, use the pure vlan_uses_dev() in __bond_release_one() cause the rtnl >> lock is held there. >> >Just 1 more note, you can't trust nr_vlan_devs under RCU. Yes, you're right, however we actually don't care anyway if we race with (un)register_vlan_dev() - we'll end up either in using the (un)registered vlan or not, and in both cases it's ok. So I don't see a real problem here, tbh, though I'll look into this also.