art of the code
it is called with a NULL socket parameter. We want to rely on the socket
to retrieve the network namespace, so we always pass a valid socket in all
cases.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: Benjamin Thery <benjamin.thery@bull.net>
Signed-off-by: David S. Miller <davem@davemloft.net>