From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 13 May 2014 08:28:53 -0700 From: Stephen Hemminger Message-ID: <20140513082853.25e99c67@nehalam.linuxnetplumber.net> In-Reply-To: <20140513151611.GA2966@minipsycho.orion> References: <1399967708-7283-1-git-send-email-jmaxwell@redhat.com> <20140513151611.GA2966@minipsycho.orion> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Bridge] [PATCH net] bridge: notify user space of fdb port change List-Id: Linux Ethernet Bridging List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jiri Pirko Cc: vyasevic@redhat.com, jpirko@redhat.com, netdev@vger.kernel.org, jmaxwell@redhat.com, bridge@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Jon Maxwell , davem@davemloft.net On Tue, 13 May 2014 17:16:11 +0200 Jiri Pirko wrote: > Tue, May 13, 2014 at 09:55:08AM CEST, jmaxwell37@gmail.com wrote: > >From: Jon Maxwell > > > >There has been a number incidents recently where customers running KVM have > >reported that VM hosts on different Hypervisors are unreachable. Based on > >pcap traces we found that the bridge was broadcasting the ARP request out > >onto the network. However some NICs have an inbuilt switch which on occasions > >were broadcasting the VMs ARP request back through the physical NIC on the > >Hypervisor. This resulted in the bridge changing ports and incorrectly learning > >that the VMs mac address was external. As a result the ARP reply was directed > >back onto the external network and VM never updated it's ARP cache. This patch > >will notify the bridge command to identify such port toggling. > > > >Signed-off-by: Jon Maxwell > >--- > > net/bridge/br_fdb.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > >diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c > >index 9203d5a..37742e2 100644 > >--- a/net/bridge/br_fdb.c > >+++ b/net/bridge/br_fdb.c > >@@ -507,6 +507,8 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, > > source->dev->name); > > } else { > > /* fastpath: update of existing entry */ > >+ if (source->port_no != fdb->dst->port_no) > >+ fdb_notify(br, fdb, RTM_NEWNEIGH); > > fdb->dst = source; > > fdb->updated = jiffies; > > if (unlikely(added_by_user)) > >-- > >1.8.3.1 > > > Reviewed-by: Jiri Pirko I like the patch, but please add unlikely() to this conditional. This is in the fast path code for bridge learning.