On Wed, Jun 15, 2011 at 11:00:09AM -0700, Jesse Gross wrote:
> Older kernels (those before 2.6.22) rely on implicit assumptions
> to determine checksum offloading status.  These assumptions tend
> to break down when doing switching because it sits in the middle
> of the transmit and receive path.  Newer kernels deal with this
> problem by adding more explicit information about how to checksum.
> This replicates that behavior by mirroring the state from newer
> kernels in private OVS storage on the kernels that lack it.  On
> ingress and egress we then map that state onto the appropriate
> location for the given kernel and can consistently manipulate it
> within OVS.  Some of this was already done for the checksum type
> but this makes it more robust and expands it to the checksum start
> and offset as well.
> 
> Signed-off-by: Jesse Gross <[email protected]>

I didn't see any problems, but I don't understand this code very well.
I think that it would help my understanding if compute_ip_summed() and
forward_ip_summed() had comments that explained why one would call
them and what they do.  compute_ip_summed() does have a large comment
already, but it explains only the details, not the "big picture"
rationale behind what it does.

Thanks,

Ben.
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