udp checksum issue in netpoll mode.

["Aubrey Li" <aubreylee@gmail.com>]

I think we discussed this issue before.

The current checksum function doesn't consider the kind of packet
which is padded to reach a specific minimum length. I believe that's
the problem caused my test case failed. Is this issue fixed? Or is it
acceptable if I make a patch not calculating this kind of packet?

Thanks,
-Aubrey
===============================================
static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
                            unsigned short ulen, __be32 saddr, __be32 daddr)
{
        __wsum psum;

        if (uh->check == 0 || skb->ip_summed == CHECKSUM_UNNECESSARY)
                return 0;

        psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
        if (skb->ip_summed == CHECKSUM_COMPLETE &&
            !csum_fold(csum_add(psum, skb->csum)))
                return 0;

        skb->csum = psum;

        return __skb_checksum_complete(skb);
}
===============================================