From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <5372BA1E.8000402@lab.ntt.co.jp> Date: Wed, 14 May 2014 09:34:38 +0900 From: Toshiaki Makita MIME-Version: 1.0 References: <1399967708-7283-1-git-send-email-jmaxwell@redhat.com> In-Reply-To: <1399967708-7283-1-git-send-email-jmaxwell@redhat.com> Content-Type: text/plain; charset=ISO-2022-JP 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: Jon Maxwell , 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, davem@davemloft.net (2014/05/13 16:55), Jon Maxwell 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) It seems that we don't need to fetch port_no and it is enough to compare source and fdb->dst. > + fdb_notify(br, fdb, RTM_NEWNEIGH); > fdb->dst = source; > fdb->updated = jiffies; > if (unlikely(added_by_user)) > This notifies fdb entry before updating existing entry. Is this on purpose? I think we should notify the updated fdb entry. Similar code fdb_add_entry() does after updating it. Also, isn't it better to move update of dst into "if" block? if (source != fdb->dst) { fdb->dst = source; modified = true; } ... if (modified) ... Thanks, Toshiaki Makita