From: Pavel Emelyanov <xemul@openvz.org>
Date: Tue, 11 Dec 2007 20:53:55 +0300

> Some handers and strategies of devinet sysctl tables need
> to know the net to propagate the ctl change to all the
> net devices.
> 
> I use the (currently unused) extra2 pointer on the tables
> to get it.
> 
> Holding the reference on the struct net is not possible,
> because otherwise we'll get a net->ctl_table->net circular
> dependency. But since the ctl tables are unregistered during 
> the net destruction, this is safe to get it w/o additional 
> protection.
> 
> Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

Applied.