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=Y0ZcmZtzDJYXIxa5wuP+zJgiw+MARnPcC3V3OMM2pVw=; b=TpaAA3xbA2NxgOQ/vnRBhQNTOaJfmlhTJ44RLEu/Z6/MrfqUEzmbvqKKsZYgqfPTOa vmgdtnvPt5CW8wARHXV8DsgkEoMBIaUilGl2VtDbvHMBgjfflnQLM9KxHaplFeYzuDTx I3Zd6MP7uOqC09/QP+7BR7GbyxYJzMzUibF5LaW+q7373VhKoJj8LEUh/Wa3x2pfXcz5 XMOQfnKjJthCHHleRwWI0VvnKy0ErWVOZ0ju81KvJJy0/zshsOKOX+Oe8JX/b8fZ6CPs 5NSxci6EJnMjcsqHF2RrPTUaElfs310st/qllPYSI3CSikz3pHXpi0q/LiYMgHAk+vxN vUPg== From: Jon Maxwell Date: Wed, 28 May 2014 08:45:49 +1000 Message-Id: <1401230749-19507-1-git-send-email-jmaxwell37@gmail.com> Subject: [Bridge] [PATCH net] bridge: notify user space after fdb update List-Id: Linux Ethernet Bridging List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 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, after a fdb has been updated to identify such port toggling. Signed-off-by: Jon Maxwell --- net/bridge/br_fdb.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c index 9203d5a..f3ee2da 100644 --- a/net/bridge/br_fdb.c +++ b/net/bridge/br_fdb.c @@ -487,6 +487,7 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, { struct hlist_head *head = &br->hash[br_mac_hash(addr, vid)]; struct net_bridge_fdb_entry *fdb; + bool fdb_modified = 0; /* some users want to always flood. */ if (hold_time(br) == 0) @@ -507,10 +508,15 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, source->dev->name); } else { /* fastpath: update of existing entry */ - fdb->dst = source; + if (unlikely(source != fdb->dst)) { + fdb->dst = source; + fdb_modified = 1; + } fdb->updated = jiffies; if (unlikely(added_by_user)) fdb->added_by_user = 1; + if (unlikely(fdb_modified)) + fdb_notify(br, fdb, RTM_NEWNEIGH); } } else { spin_lock(&br->hash_lock); -- 1.8.3.1