From: Antonio Quartulli <redacted>
Date: Sat, 30 Mar 2013 18:07:37 +0100

iflink is currently set to 0 in __gre_tunnel_init(). This
function is invoked in gre_tap_init() and
ipgre_tunnel_init() which are both used to initialise the
ndo_init field of the respective net_device_ops structs
(ipgre.. and gre_tap..) used by GRE interfaces.

However, in netdevice_register() iflink is first set to -1,
then ndo_init is invoked and then iflink is assigned to a
proper value if and only if it still was -1.

Assigning 0 to iflink in ndo_init is therefore first
preventing netdev_register() to correctly assign it a proper
value and then breaking iflink at all since 0 has not
correct meaning.

Fix this by removing the iflink assignment in
__gre_tunnel_init().

Introduced by c54419321455631079c7d6e60bc732dd0c5914c5
("GRE: Refactor GRE tunneling code.")

Reported-by: Fengguang Wu <redacted>
Signed-off-by: Antonio Quartulli <redacted>

Please always indicate, in the subject line inside of the [] brackets,
what tree the patch is targetted at.

I can use "git describe" on the guilty commit, but why take a chance?

Applied to net-next, thanks.