Merge branch 'udp-gso-cleanups'

Alexander Duyck says:

====================
UDP GSO Segmentation clean-ups

This patch set addresses a number of issues I found while sorting out
enabling UDP GSO Segmentation support for ixgbe/ixgbevf. Specifically there
were a number of issues related to the checksum and such that seemed to
cause either minor irregularities or kernel panics in the case of the
offload request being allowed to traverse between name spaces.

With this set applied I am was able to get UDP GSO traffic to pass over
vxlan tunnels in both offloaded modes and non-offloaded modes for ixgbe and
ixgbevf.

I submitted the driver specific patches earlier as an RFC:
https://patchwork.ozlabs.org/project/netdev/list/?series=42477&archive=both&state=*

v2: Updated patches based on feedback from Eric Dumazet
    Split first patch into several patches based on feedback from Eric
v3: Drop patch that was calling pskb_may_pull as it was redundant.
    Added code to use MANGLED_0 in case of UDP checksum
    Drop patch adding NETIF_F_GSO_UDP_L4 to list of GSO software offloads
    Added Acked-by for patches reviewed by Willem and not changed
====================

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