netdev - Re: [PATCH net-next 0/3] net: Eliminate gso_send

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Message-Id: <20140926.002343.1473744968675123105.davem@davemloft.net>
Date:	Fri, 26 Sep 2014 00:23:43 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	therbert@...gle.com
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH net-next 0/3] net: Eliminate gso_send_check

From: Tom Herbert <therbert@...gle.com>
Date: Sat, 20 Sep 2014 14:52:27 -0700

> gso_send_check presents a lot of complexity for what it is being used
> for. It seems that there are only two cases where it might be effective:
> TCP and UFO paths. In these cases, the gso_send_check function
> initializes the TCP or UDP checksum respectively to the pseudo header
> checksum so that the checksum computation is appropriately offloaded or
> computed in the gso_segment functions. The gso_send_check functions
> are only called from dev.c in skb_mac_gso_segment when ip_summed !=
> CHECKSUM_PARTIAL (which seems very unlikely in TCP case). We can move
> the logic of this into the respective gso_segment functions where the
> checksum is initialized if ip_summed != CHECKSUM_PARTIAL.
> 
> With the above cases handled, gso_send_check is no longer needed, so
> we can remove all uses of it and the fields in the offload callbacks.
> With this change, ip_summed in the skb should be preserved though all
> the layers of gso_segment calls.
> 
> In follow-on patches, we may be able to remove the check setup code in
> tcp_gso_segment if we can guarantee that ip_summed will always be
> CHECKSUM_PARTIAL (verify all paths and probably add an assert in
> tcp_gro_segment).
> 
> Tested these patches by:
>   - netperf TCP_STREAM test with GSO enabled
>   - Forced ip_summed != CHECKSUM_PARTIAL with above
>   - Ran UDP_RR with 10000 request size over GRE tunnel. This exercised
>     UFO path.

Series applied, thanks Tom.
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