Re: [PATCH net] bridge: notify user space of fdb port change

Jon Maxwell
2014-05-16T08:13:05Z

Please use this patch. My bad, the previous one
incorrectly did the notify before fdb->added_by_user = 1.

----- Original Message -----
> From: "Jon Maxwell" <jmaxwell37@gmail.com>
> To: stephen@networkplumber.org
> Cc: davem@davemloft.net, "makita toshiaki" <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,
> jmaxwell@redhat.com, "Jon Maxwell" <jmaxwell37@gmail.com>
> Sent: Friday, May 16, 2014 6:08:39 PM
> Subject: [PATCH net] bridge: notify user space of fdb port change
>
> From: Jon Maxwell <jmaxwell37@gmail.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@gmail.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..67480c2 100644
> --- a/net/bridge/br_fdb.c
> +++ b/net/bridge/br_fdb.c
> @@ -511,6 +511,8 @@ void br_fdb_update(struct net_bridge *br, struct
> net_bridge_port *source,
> fdb->updated = jiffies;
> if (unlikely(added_by_user))
> fdb->added_by_user = 1;
> + if (unlikely(source->port_no != fdb->dst->port_no))
> + fdb_notify(br, fdb, RTM_NEWNEIGH);
> }
> } else {
> spin_lock(&br->hash_lock);
> --
> 1.8.3.1
>
>