udptunnels: Call handle_offloads after inserting vlan tag.

handle_offloads() calls skb_reset_inner_headers() to store
the layer pointers to the encapsulated packet. However, we
currently push the vlag tag (if there is one) onto the packet
afterwards. This changes the MAC header for the encapsulated
packet but it is not reflected in skb->inner_mac_header, which
breaks GSO and drivers which attempt to use this for encapsulation
offloads.

Fixes: 1eaa8178 ("vxlan: Add tx-vlan offload support.")
Signed-off-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index f8528a4..fceb637 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1713,12 +1713,6 @@
 		}
 	}
 
-	skb = iptunnel_handle_offloads(skb, udp_sum, type);
-	if (IS_ERR(skb)) {
-		err = -EINVAL;
-		goto err;
-	}
-
 	skb_scrub_packet(skb, xnet);
 
 	min_headroom = LL_RESERVED_SPACE(dst->dev) + dst->header_len
@@ -1738,6 +1732,12 @@
 		goto err;
 	}
 
+	skb = iptunnel_handle_offloads(skb, udp_sum, type);
+	if (IS_ERR(skb)) {
+		err = -EINVAL;
+		goto err;
+	}
+
 	vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
 	vxh->vx_flags = htonl(VXLAN_HF_VNI);
 	vxh->vx_vni = md->vni;
@@ -1798,10 +1798,6 @@
 		}
 	}
 
-	skb = iptunnel_handle_offloads(skb, udp_sum, type);
-	if (IS_ERR(skb))
-		return PTR_ERR(skb);
-
 	min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
 			+ VXLAN_HLEN + sizeof(struct iphdr)
 			+ (skb_vlan_tag_present(skb) ? VLAN_HLEN : 0);
@@ -1817,6 +1813,10 @@
 	if (WARN_ON(!skb))
 		return -ENOMEM;
 
+	skb = iptunnel_handle_offloads(skb, udp_sum, type);
+	if (IS_ERR(skb))
+		return PTR_ERR(skb);
+
 	vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
 	vxh->vx_flags = htonl(VXLAN_HF_VNI);
 	vxh->vx_vni = md->vni;