On 10/17/2016 07:01 PM, Tom Herbert wrote: >> > + >> > + if (skb->ip_summed == CHECKSUM_COMPLETE) >> > + skb->ip_summed = CHECKSUM_NONE; >> > + > Because the packet is being changed? Would it make sense to update the > checksum complete value based on the changes being made. Consider the > case that the next hop is local to the host (someone may try to > implement network virtualization this way). >
Rethinking about that: even if the next hop is local, I am not sure to see the benefits of updating the checksum instead of setting CHECKSUM_NONE. For example, if the next and final hop is local and the packet carries a TCP payload, tcp_checksum_complete() would force the recomputation of the checksum anyway (unless ip_summed == CHECKSUM_UNNECESSARY). So I fail to see a path where updating the checksum would be beneficial. Am I missing something ? David
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