[PATCH/RFC net] gre: set inner_protocol on xmit

Ensure that the inner_protocol is set on transmit so that GSO segmentation,
which relies on that field, works correctly.

I have observed this is not the case when OvS transmits GRE using
lwtunnel metadata (which it always does).

Fixes: 38720352412a ("gre: Use inner_proto to obtain inner header protocol")
Cc: Alexander Duyck <redacted>
Reviewed-by: Dinan Gunawardena <redacted>
Acked-by: Jakub Kicinski <redacted>
Signed-off-by: Simon Horman <redacted>
---
 net/ipv4/ip_gre.c | 1 +
 1 file changed, 1 insertion(+)
---
 Repost with correct domain vger address

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 5b1481be0282..1571b71448a0 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c

@@ -451,6 +451,7 @@ static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev,
 
 	df = key->tun_flags & TUNNEL_DONT_FRAGMENT ?  htons(IP_DF) : 0;
 
+	skb_set_inner_protocol(skb, proto);
 	iptunnel_xmit(skb->sk, rt, skb, fl.saddr, key->u.ipv4.dst, IPPROTO_GRE,
 		      key->tos, key->ttl, df, false);
 	return;

-- 
2.7.0.rc3.207.g0ac5344