netdev - Re: [PATCH net-next 3/3] GRE: Add TCP segmentation offload for GRE

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Date:	Thu, 14 Feb 2013 19:19:29 -0800
From:	Pravin Shelar <pshelar@...ira.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev@...r.kernel.org, edumazet@...gle.com, jesse@...ira.com,
	bhutchings@...arflare.com, mirqus@...il.com
Subject: Re: [PATCH net-next 3/3] GRE: Add TCP segmentation offload for GRE

On Thu, Feb 14, 2013 at 5:39 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Thu, 2013-02-14 at 11:45 -0800, Pravin B Shelar wrote:
>> Following patch adds GRE protocol offload handler so that
>> skb_gso_segment() can segment GRE packets.
>> SKB GSO CB is added to keep track of total header length so that
>> skb_segment can push entire header. e.g. in case of GRE, skb_segment
>> need to push inner and outer headers to every segment.
>> New NETIF_F_GRE_GSO feature is added for devices which support HW
>> GRE TSO offload. Currently none of devices support it therefore GRE GSO
>> always fall backs to software GSO.
>>
>> Signed-off-by: Pravin B Shelar <pshelar@...ira.com>
>> ---
>> Fixed according to comments from Jesse and Eric.
>> v2-v3:
>>  - Use device features to segment inner packet.
>>  - Moved skb_mac_gso_segment to separate patch.
>>  - simplified gre_gso_segment().
>>  - Added NETIF_F_GRE_GSO feature.
>>
>> v1-v2:
>>  - Factored a MAC layer handler out of skb_gso_segment().
>>  - Eliminated copy operation from gre_gso_segment().
>>  - Refresh header pointer after pskb_may_pull().
>> ---
>
> Seems very good to me, thanks !
>
> The only thing that puzzles me is the ip_select_ident() in
> ipgre_tunnel_xmit()
>
> Do we care of the IP identifiers being 0, 1, 2, 3, ... on the outer
> headers ?
>
> Without TSO, we are using 0 IP identifiers (DF being set)
>
right. I will keep id as zero for all cases.

> Also if we can't unclone the skb in handle_offloads(), we should
> increment tx_dropped or tx_errors.
>
ok.

>
>
>
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