Re: [PATCH net v3 2/2] udp_offload: Set encapsulation before inner completes.

From: Jarno Rajahalme <redacted>
Date: Tue,  3 May 2016 16:10:21 -0700

UDP tunnel segmentation code relies on the inner offsets being set for
an UDP tunnel GSO packet, but the inner *_complete() functions will
set the inner offsets only if 'encapsulation' is set before calling
them.  Currently, udp_gro_complete() sets 'encapsulation' only after
the inner *_complete() functions are done.  This causes the inner
offsets having invalid values after udp_gro_complete() returns, which
in turn will make it impossible to properly segment the packet in case
it needs to be forwarded, which would be visible to the user either as
invalid packets being sent or as packet loss.

This patch fixes this by setting skb's 'encapsulation' in
udp_gro_complete() before calling into the inner complete functions,
and by making each possible UDP tunnel gro_complete() callback set the
inner_mac_header to the beginning of the tunnel payload.

Signed-off-by: Jarno Rajahalme <redacted>
---
v3: Added setting inner_mac_header from all possible callbacks to cover
    cases where there is no inner mac header.

Alex and Tom, can you please review this new version since you guys had
so much feedback for v2?

THanks.