[ovs-dev] [Patch] datapath: fix checksum after putting vlan tag

[Jesse Gross]

On Tue, Feb 26, 2013 at 1:46 AM, Cong Wang <amwang at redhat.com> wrote:
> After inserting the VLAN tag with __vlan_put_tag(), we should
> re-calculate the skb checksum if it is done.
>
> Cc: Jesse Gross <jesse at nicira.com>
> Signed-off-by: Cong Wang <amwang at redhat.com>

This code path is supposed to be emulate dev_hard_start_xmit() on
older kernels.  However, the current upstream code doesn't have the
behavior that you are proposing because CHECKSUM_COMPLETE is generally
not significant on the transmit path (it seems only likely to be
useful if a packet is looped back through something like a veth).  At
the very least, the behavior of the upstream and backported versions
should match.