Re: [Xen-devel] [PATCH] Fix checksum errors when firewalling in domU

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 9 May 2006, at 20:22, James Dykman wrote:

> @@ -819,7 +819,10 @@
>                  * can infer it from csum_blank so test both flags.
>                  */
>                 if (rx->flags & 
> (NETRXF_data_validated|NETRXF_csum_blank))
> {
> -                       skb->ip_summed = CHECKSUM_UNNECESSARY;
> +                       if (rx->flags & NETRXF_csum_blank)
> +                               skb->ip_summed = CHECKSUM_HW;
> +                       else
> +                               skb->ip_summed = CHECKSUM_UNNECESSARY;
>                         skb->proto_data_valid = 1;
>                 } else {
>                         skb->ip_summed = CHECKSUM_NONE;
This hunk seems dodgy to me. According to the comment in linux/skbuff.h 
we shouldn't be passing up CHECKSUM_HW unless we have set skb->csum to 
the 1s-complement sum of the packet contents. You added code to do this 
in both netfront and netback, and it doesn't seem right in either case.
 -- Keir


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