From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id; bh=Kxx/F5I4sUf+A88knP4oliNe1NWBRQvTxNuOIgbUQiU=; b=gfvtS5dIIWj0R/wIzlUUpcbJE2m7saWeV7VZJty8KmOqpmGlFFUiWzyFSH8WC1QwOV BaAXd/sB186WV+i8avTUaer4Crl/927Fj8yUkbBTlE9EwltDBfvRhS2wNk2Ub6a7K83x YMCSpj+7z+WHIEmEPHDfRHcqTAYrzG0Hg8cDjxi5PBM0wMPZ8KyZ/a0SIzzyWSKWhh6X LOcnKWYY7PC1XWmplIHs7VIi6FU33MuGfkohZOrCJTmhmg0/vro6As6e6EdwCMc1v15g MBfJYPVk8huzmiqoE/CYyyoNo6hRAQcdKvSht0jBqKOC6HOPrpniA++lx9HxWL3ZQNzh h8Qw== From: Jon Maxwell Message-Id: <1399967708-7283-1-git-send-email-jmaxwell@redhat.com> Subject: [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: , Date: Tue, 13 May 2014 07:55:48 -0000 To: stephen@networkplumber.org Cc: vyasevic@redhat.com, jpirko@redhat.com, netdev@vger.kernel.org, jmaxwell@redhat.com, bridge@lists.linux-foundation.org, linux-kernel@vger.kernel.org, jmaxwell37@gmail.com, davem@davemloft.net 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