+/* Local Checksum Offload.
+ * Compute outer checksum based on the assumption that the
+ * inner checksum will be offloaded later.
+ * Fill in outer checksum adjustment (e.g. with sum of outer
+ * pseudo-header) before calling.
+ * Also ensure that inner checksum is in linear data area.
+ */
+static inline __wsum lco_csum(struct sk_buff *skb)
+{
+ char *inner_csum_field;
+ __wsum csum;
+
+ /* Start with complement of inner checksum adjustment */
+ inner_csum_field = skb->data + skb_checksum_start_offset(skb) +
+ skb->csum_offset;
+ csum = ~csum_unfold(*(__force __sum16 *)inner_csum_field);
+ /* Add in checksum of our headers (incl. outer checksum
+ * adjustment filled in by caller)
+ */
+ csum = skb_checksum(skb, 0, skb_checksum_start_offset(skb), csum);
+ /* The result is the checksum from skb->data to end of packet */
+ return csum;
+}
+