From mboxrd@z Thu Jan  1 00:00:00 1970
From: Timo Teras <timo.teras@iki.fi>
Subject: net: Loosen constraints for recalculating checksum in skb_segment()
Date: Thu, 26 Dec 2013 09:18:51 +0200
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Cc: Simon Horman <horms@verge.net.au>, netdev@vger.kernel.org
To: David Miller <davem@davemloft.net>
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commit 1cdbcb7957cf9e5f841dbcde9b38fd18a804208b
Author: Simon Horman <horms@verge.net.au>
Date:   Sun May 19 15:46:49 2013 +0000

> net: Loosen constraints for recalculating checksum in skb_segment()
>
> This is a generic solution to resolve a specific problem that I have
> observed.
> 
> If the encapsulation of an skb changes then ability to offload
> checksums may also change. In particular it may be necessary to
> perform checksumming in software.
> 
> An example of such a case is where a non-GRE packet is received but
> is to be encapsulated and transmitted as GRE.

Dave, can you queue this for 3.10-stable.

It was around 3.9 when ip_gre got gso support. This added the bug that
forwarding non-gre to gre with gro+gso+tx offloads enabled does not
work properly - the TCP checksums are not calculated properly without
this patch.

Thanks,
 Timo