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Date: Wed, 14 May 2014 09:34:38 +0900 From: Toshiaki Makita <makita.toshiaki@....ntt.co.jp> To: Jon Maxwell <jmaxwell37@...il.com>, stephen@...workplumber.org CC: davem@...emloft.net, vyasevic@...hat.com, bridge@...ts.linux-foundation.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, jpirko@...hat.com, jmaxwell@...hat.com Subject: Re: [PATCH net] bridge: notify user space of fdb port change (2014/05/13 16:55), Jon Maxwell wrote: > From: Jon Maxwell <jmaxwell37@...il.com> > > 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 <jmaxwell37@...il.com> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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