netdev - Re: [PATCH] arp_notify: unconditionally send gratuitous ARP for NETDEV_NOTIFY

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Message-ID: <1297761225.21980.3663.camel@zakaz.uk.xensource.com>
Date:	Tue, 15 Feb 2011 09:13:45 +0000
From:	Ian Campbell <Ian.Campbell@...citrix.com>
To:	David Miller <davem@...emloft.net>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH] arp_notify: unconditionally send gratuitous ARP for
 NETDEV_NOTIFY_PEERS.

On Tue, 2011-02-15 at 01:46 +0000, David Miller wrote:
> From: Ian Campbell <ian.campbell@...rix.com>
> Date: Fri, 11 Feb 2011 17:44:16 +0000
> 
> > NETDEV_NOTIFY_PEER is an explicit request by the driver to send a link
> > notification while NETDEV_UP/NETDEV_CHANGEADDR generate link
> > notifications as a sort of side effect.
> > 
> > In the later cases the sysctl option is present because link
> > notification events can have undesired effects e.g. if the link is
> > flapping. I don't think this applies in the case of an explicit
> > request from a driver.
> > 
> > This patch makes NETDEV_NOTIFY_PEER unconditional, if preferred we
> > could add a new sysctl for this case which defaults to on.
> > 
> > This change causes Xen post-migration ARP notifications (which cause
> > switches to relearn their MAC tables etc) to be sent by default.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@...rix.com>
> 
> Ok, applied, thanks.

Thanks.

I nearly forgot -- the NETDEV_NOTIFY_PEER stuff was tagged for
stable/longterm backport (it appeared in 2.6.32.19 or so). I think this
change should likewise go back, what do you think?

Ian.

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