From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Eilon Greenstein" <eilong@broadcom.com>
Subject: Re: [PATCH] bnx2x: fix checksum validation
Date: Wed, 13 Jun 2012 17:21:03 +0300
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Cc: "David Miller" <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>,
	"Tom Herbert" <therbert@google.com>,
	"Robert Evans" <evansr@google.com>,
	"Willem de Bruijn" <willemb@google.com>,
	"Yaniv Rosner" <yanivr@broadcom.com>,
	"Merav Sicron" <meravs@broadcom.com>,
	"Yuval Mintz" <yuvalmin@broadcom.com>
To: "Eric Dumazet" <eric.dumazet@gmail.com>
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On Wed, 2012-06-13 at 16:10 +0200, Eric Dumazet wrote:
> On Wed, 2012-06-13 at 16:42 +0300, Eilon Greenstein wrote:
> 
> > So what you are saying is that the indication that the checksum is valid
> > is interpreted as the encapsulated checksum and not just the IP
> > header... This was not the intention of this code, it was meant to
> > indicate that the IP header is valid.
> > 
> 
> IP header is always checked by our stack.
> 
> Its so fast that there is no point spending a bit in skb, and testing
> this bit.
> 
> Yes, CHECKSUM_UNNECESSARY really means everything was checked up to L4
> 
> > I must admit that the code looks much better with this change. The only
> > down side is that there is no longer IP checksum offload for pure IP
> > packets, but that's negligible. The only thing that bothers me is that
> > there is no way to indicate anything about the encapsulated packet
> > separately from the outer header. Is that the way we want to keep it?
> 
> Some NIC allow for csum L3 offloading, providing the 16bit csum.
> 
> We then can :
> 
> skb->csum = csum;
> skb->ip_summed = CHECKSUM_COMPLETE;
> 
> Check drivers/net/ethernet/ibm/ehea/ehea_main.c,
> drivers/net/ethernet/marvell/skge.c ,
> drivers/net/ethernet/marvell/sky2.c , ... for examples.
> 
> 
> When a layer is removed(pulled), we can use skb_postpull_rcsum() and
> friends (check net/ipv4/ip_gre.c for example) to keep skb->csum up2date.
> 
> 
> If bnx2x provides this csum (for non TCP/UCP packets or fragments), you
> could fallback to this CHECKSUM_COMPLETE stuff.
> 
> 

Thanks Erik. This leaves me with just one thing to add:
Acked-by: Eilon Greenstein <eilong@broadcom.com>