[net] GRE: enable offloads for GRE

[net] GRE: enable offloads for GRE

[Jeff Kirsher]

From: Amritha Nambiar <amritha.nambiar@intel.com>

To get offloads to work with Generic Routing Encapsulation (GRE), the
outer transport header has to be reset after skb_push is done. This
patch has the support for this fix and hence GRE offloading.

Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Signed-off-by: Joseph Gasparakis <joseph.gasparakis@intel.com>
Tested-By: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---
 net/ipv4/gre_demux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index 4e9619b..0485bf7 100644
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -68,6 +68,7 @@ void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
 
 	skb_push(skb, hdr_len);
 
+	skb_reset_transport_header(skb);
 	greh = (struct gre_base_hdr *)skb->data;
 	greh->flags = tnl_flags_to_gre_flags(tpi->flags);
 	greh->protocol = tpi->proto;
-- 
1.9.3

Re: [net] GRE: enable offloads for GRE

[David Miller]

From: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Date: Thu, 10 Jul 2014 17:29:21 -0700

> From: Amritha Nambiar <amritha.nambiar@intel.com>
> 
> To get offloads to work with Generic Routing Encapsulation (GRE), the
> outer transport header has to be reset after skb_push is done. This
> patch has the support for this fix and hence GRE offloading.
> 
> Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
> Signed-off-by: Joseph Gasparakis <joseph.gasparakis@intel.com>
> Tested-By: Jim Young <jamesx.m.young@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

I think, generally speaking, this is more about making sure the
SKB is in a proper state.  If that happens to make offloads over
GRE work properly, that's certainly a nice side effect :)

Applied, thanks.