netdev - Re: Does CHECKSUM_COMPLETE work at all?

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Date:	Sat, 22 Feb 2014 13:31:04 +0100
From:	Daniel Borkmann <dborkman@...hat.com>
To:	Tom Herbert <therbert@...gle.com>
CC:	Linux Netdev List <netdev@...r.kernel.org>,
	Thomas Graf <tgraf@...hat.com>
Subject: Re: Does CHECKSUM_COMPLETE work at all?

On 02/22/2014 03:11 AM, Tom Herbert wrote:
> If a driver sets CHECKSUM_COMPLETE in a packet, I don't see anywhere
> in either the Ethernet rcv path or ip_rcv where the skb->csum is being
> pulled (no *pull_rcsum calls). I believe CHECKSUM_COMPLETE means the
> checksum is over the whole packet (L2, L3, and L4), so it looks like
> TCP would never see a usable value.

Funny you ask, we had recently similar question [1]. ;) So, yes, it
should be over the whole packet as seen by Linux, and is therefore not
usable as is by protocols like TCP.

  [1] http://thread.gmane.org/gmane.linux.network/292443/
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