Merge branch 'l2tp-tunnel-refs'

Guillaume Nault says:

====================
l2tp: fix some l2tp_tunnel_find() issues in l2tp_netlink

Since l2tp_tunnel_find() doesn't take a reference on the tunnel it
returns, its users are almost guaranteed to be racy.

This series defines l2tp_tunnel_get() which can be used as a safe
replacement, and converts some of l2tp_tunnel_find() users in the
l2tp_netlink module.

Other users often combine this issue with other more or less subtle
races. They will be fixed incrementally in followup series.
====================

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