+
+void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
+ __be32 from, __be32 to, int pseudohdr)
+{
+ __be32 diff[] = { ~from, to };
+ if (skb->ip_summed != CHECKSUM_PARTIAL) {
+ *sum = csum_fold(csum_partial(diff, sizeof(diff),
+ ~csum_unfold(*sum)));
+ if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
+ skb->csum = ~csum_partial(diff, sizeof(diff),
+ ~skb->csum);
+ } else if (pseudohdr)
+ *sum = ~csum_fold(csum_partial(diff, sizeof(diff),
+ csum_unfold(*sum)));
+}
+EXPORT_SYMBOL(inet_proto_csum_replace4);