ip_gre: fix ipgre_header to return correct offset
ip_gre: fix ipgre_header to return correct offset

Fix ipgre_header() (header_ops->create) to return the correct
amount of bytes pushed. Most callers of dev_hard_header() seem
to care only if it was success, but af_packet.c uses it as
offset to the skb to copy from userspace only once. In practice
this fixes packet socket sendto()/sendmsg() to gre tunnels.

Regression introduced in c54419321455631079c7d6e60bc732dd0c5914c5
("GRE: Refactor GRE tunneling code.")

Cc: Pravin B Shelar <95dcc1879f3489c0d5163907cdd946775296b2dd@nicira.com>
Signed-off-by: Timo Teräs <266f729f1f620250264df63d5dfd302c2a88080e@iki.fi>
Acked-by: Eric Dumazet <312c7d941f03386814be517ffdb3e0eb6624e275@google.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs