netdev - Re: [PATCH net-next] net: relax expensive skb_unclone() in iptunnel_handle

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Message-Id: <20160503.002327.1415458450222416618.davem@davemloft.net>
Date:	Tue, 03 May 2016 00:23:27 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: relax expensive skb_unclone() in
 iptunnel_handle_offloads()

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Sat, 30 Apr 2016 10:19:29 -0700

> From: Eric Dumazet <edumazet@...gle.com>
> 
> Locally generated TCP GSO packets having to go through a GRE/SIT/IPIP
> tunnel have to go through an expensive skb_unclone()
> 
> Reallocating skb->head is a lot of work.
> 
> Test should really check if a 'real clone' of the packet was done.
> 
> TCP does not care if the original gso_type is changed while the packet
> travels in the stack.
> 
> This adds skb_header_unclone() which is a variant of skb_clone()
> using skb_header_cloned() check instead of skb_cloned().
> 
> This variant can probably be used from other points.
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Nice observation, applied, thanks Eric.