Re: [NET]: Allow forwarding of ip_summed except CHECKSUM_COMPLETE
Herbert Xu wrote: Hi Dave: [NET]: Allow forwarding of ip_summed except CHECKSUM_COMPLETE Right now Xen has a horrible hack that lets it forward packets with partial checksums. One of the reasons that CHECKSUM_PARTIAL and CHECKSUM_COMPLETE were added is so that we can get rid of this hack (where it creates two extra bits in the skbuff to essentially mirror ip_summed without being destroyed by the forwarding code). I had forgotten that I've already gone through all the deivce drivers last time around to make sure that they're looking at ip_summed == CHECKSUM_PARTIAL rather than ip_summed != 0 on transmit. In any case, I've now done that again so it should definitely be safe. Unfortunately nobody has yet added any code to update CHECKSUM_COMPLETE values on forward so we I'm setting that to CHECKSUM_NONE. This should be safe to remove for bridging but I'd like to check that code path first. So here is the patch that lets us get rid of the hack by preserving ip_summed (mostly) on forwarded packets. Just wondering, how does Xen know whether a packet will be forwarded? The input path doesn't seem to deal with CHECKSUM_PARTIAL correctly, ip_defrag for example resets them to CHECKSUM_NONE, so further checks will fail, others seem to either ignore them or handle them together with CHECKSUM_NONE. - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [NET]: Allow forwarding of ip_summed except CHECKSUM_COMPLETE
On Tue, Mar 27, 2007 at 10:51:53PM +0200, Patrick McHardy wrote:
Just wondering, how does Xen know whether a packet will be forwarded?
It's up to Linux to handle it correctly.
The input path doesn't seem to deal with CHECKSUM_PARTIAL correctly,
ip_defrag for example resets them to CHECKSUM_NONE, so further checks
will fail, others seem to either ignore them or handle them together
with CHECKSUM_NONE.
That's OK, Linux/Xen never generates any CHECKSUM_PARTIAL fragments.
Cheers,
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Re: [NET]: Allow forwarding of ip_summed except CHECKSUM_COMPLETE
From: Herbert Xu [EMAIL PROTECTED] Date: Tue, 27 Mar 2007 15:38:21 +1000 [NET]: Allow forwarding of ip_summed except CHECKSUM_COMPLETE Right now Xen has a horrible hack that lets it forward packets with partial checksums. One of the reasons that CHECKSUM_PARTIAL and CHECKSUM_COMPLETE were added is so that we can get rid of this hack (where it creates two extra bits in the skbuff to essentially mirror ip_summed without being destroyed by the forwarding code). I had forgotten that I've already gone through all the deivce drivers last time around to make sure that they're looking at ip_summed == CHECKSUM_PARTIAL rather than ip_summed != 0 on transmit. In any case, I've now done that again so it should definitely be safe. Unfortunately nobody has yet added any code to update CHECKSUM_COMPLETE values on forward so we I'm setting that to CHECKSUM_NONE. This should be safe to remove for bridging but I'd like to check that code path first. So here is the patch that lets us get rid of the hack by preserving ip_summed (mostly) on forwarded packets. Signed-off-by: Herbert Xu [EMAIL PROTECTED] Applied to net-2.6.22, thanks Herbert. - To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
