From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758939AbaEMHzv (ORCPT ); Tue, 13 May 2014 03:55:51 -0400 Received: from mail-pb0-f43.google.com ([209.85.160.43]:41896 "EHLO mail-pb0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756506AbaEMHzs (ORCPT ); Tue, 13 May 2014 03:55:48 -0400 X-Google-Original-From: Jon Maxwell From: Jon Maxwell To: stephen@networkplumber.org Cc: davem@davemloft.net, makita.toshiaki@lab.ntt.co.jp, vyasevic@redhat.com, bridge@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jpirko@redhat.com, jmaxwell37@gmail.com, jmaxwell@redhat.com Subject: [PATCH net] bridge: notify user space of fdb port change Date: Tue, 13 May 2014 17:55:08 +1000 Message-Id: <1399967708-7283-1-git-send-email-jmaxwell@redhat.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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