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

From: Jon Maxwell <[email-masked]>
Date: Fri, 16 May 2014 04:12:51 -0400 (EDT)

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

----- Original Message -----
> From: "Jon Maxwell" <[email-masked]>
> To: [email-masked]
> Cc: [email-masked], "makita toshiaki" <[email-masked]>, [email-masked],
> [email-masked], [email-masked], [email-masked], [email-masked],
> [email-masked], "Jon Maxwell" <[email-masked]>
> Sent: Friday, May 16, 2014 6:08:39 PM
> Subject: [PATCH net] bridge: notify user space of fdb port change
> 
> From: Jon Maxwell <[email-masked]>
> 
> 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 <[email-masked]>
> ---
>  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
> 
>