netdev - Re: [PATCH 1/1] ipv4: arp: update neighbour address when a gratuitous arp is received and arp

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Date:	Wed, 1 Jan 2014 21:06:10 -0800
From:	Salam Noureddine <noureddine@...stanetworks.com>
To:	David Miller <davem@...emloft.net>
Cc:	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	netdev@...r.kernel.org
Subject: Re: [PATCH 1/1] ipv4: arp: update neighbour address when a gratuitous
 arp is received and arp_accept is set

Hi David,

This patch is against net-next, sorry forgot to mention it in the
subject. Hannes pointed changes made to arp.c in net-next so I
generated this patch accordingly.

Thanks,

Salam

On Wed, Jan 1, 2014 at 8:38 PM, David Miller <davem@...emloft.net> wrote:
> From: Salam Noureddine <noureddine@...stanetworks.com>
> Date: Tue, 24 Dec 2013 14:17:02 -0800
>
>> Gratuitous arp packets are useful in switchover scenarios to update
>> client arp tables as quickly as possible. Currently, the mac address
>> of a neighbour is only updated after a locktime period has elapsed
>> since the last update. In most use cases such delays are unacceptable
>> for network admins. Moreover, the "updated" field of the neighbour
>> stucture doesn't record the last time the address of a neighbour
>> changed but records any change that happens to the neighbour. This is
>> clearly a bug since locktime uses that field as meaning "addr_updated".
>> With this observation, I was able to perpetuate a stale address by
>> sending a stream of gratuitous arp packets spaced less than locktime
>> apart. With this change the address is updated when a gratuitous arp
>> is received and the arp_accept sysctl is set.
>>
>> Signed-off-by: Salam Noureddine <noureddine@...stanetworks.com>
>
> This patch doesn't apply, please regenerate this patch against current
> sources.
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