Merge branch 'net-allow-per-net-notifier-to-follow-netdev-into-namespace'

Merge branch 'net-allow-per-net-notifier-to-follow-netdev-into-namespace'

Jiri Pirko says:

====================
net: allow per-net notifier to follow netdev into namespace

Currently we have per-net notifier, which allows to get only
notifications relevant to particular network namespace. That is enough
for drivers that have netdevs local in a particular namespace (cannot
move elsewhere).

However if netdev can change namespace, per-net notifier cannot be used.
Introduce dev_net variant that is basically per-net notifier with an
extension that re-registers the per-net notifier upon netdev namespace
change. Basically the per-net notifier follows the netdev into
namespace.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>