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

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Message-ID: <255115023.7295678.1400227971937.JavaMail.zimbra@redhat.com>
Date:	Fri, 16 May 2014 04:12:51 -0400 (EDT)
From:	Jon Maxwell <jmaxwell@...hat.com>
To:	stephen@...workplumber.org
Cc:	davem@...emloft.net,
	makita toshiaki <makita.toshiaki@....ntt.co.jp>,
	vyasevic@...hat.com, bridge@...ts.linux-foundation.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	jpirko@...hat.com
Subject: Re: [PATCH net] bridge: notify user space of fdb port change

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@...il.com>
> To: stephen@...workplumber.org
> Cc: davem@...emloft.net, "makita toshiaki" <makita.toshiaki@....ntt.co.jp>, vyasevic@...hat.com,
> bridge@...ts.linux-foundation.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, jpirko@...hat.com,
> jmaxwell@...hat.com, "Jon Maxwell" <jmaxwell37@...il.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@...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..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
> 
> 
--
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