net: move __skb_checksum_complete*() to skbuff.c

__skb_checksum_complete_head() and __skb_checksum_complete()
are both declared in skbuff.h, they fit better in skbuff.c
than datagram.c.

Cc: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index b4ee5c8..5cb4b34 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2645,6 +2645,49 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
 }
 EXPORT_SYMBOL(skb_copy_and_csum_bits);
 
+__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
+{
+	__sum16 sum;
+
+	sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
+	if (likely(!sum)) {
+		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+		    !skb->csum_complete_sw)
+			netdev_rx_csum_fault(skb->dev);
+	}
+	if (!skb_shared(skb))
+		skb->csum_valid = !sum;
+	return sum;
+}
+EXPORT_SYMBOL(__skb_checksum_complete_head);
+
+__sum16 __skb_checksum_complete(struct sk_buff *skb)
+{
+	__wsum csum;
+	__sum16 sum;
+
+	csum = skb_checksum(skb, 0, skb->len, 0);
+
+	/* skb->csum holds pseudo checksum */
+	sum = csum_fold(csum_add(skb->csum, csum));
+	if (likely(!sum)) {
+		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+		    !skb->csum_complete_sw)
+			netdev_rx_csum_fault(skb->dev);
+	}
+
+	if (!skb_shared(skb)) {
+		/* Save full packet checksum */
+		skb->csum = csum;
+		skb->ip_summed = CHECKSUM_COMPLETE;
+		skb->csum_complete_sw = 1;
+		skb->csum_valid = !sum;
+	}
+
+	return sum;
+}
+EXPORT_SYMBOL(__skb_checksum_complete);
+
 static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
 {
 	net_warn_ratelimited(