udp: Clean up the use of flags in UDP segmentation offload

This patch goes though and cleans up the logic related to several of the
control flags used in UDP segmentation.  Specifically the use of dont_encap
isn't really needed as we can just check the skb for CHECKSUM_PARTIAL and
if it isn't set then we don't need to update the internal headers.  As such
we can just drop that value.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Acked-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp_offload.c

@@ -33,16 +33,13 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
 	__be16 new_protocol, bool is_ipv6)
 {
 	struct sk_buff *segs = ERR_PTR(-EINVAL);
+	bool remcsum, need_csum, offload_csum;
 	u16 mac_offset = skb->mac_header;
 	int mac_len = skb->mac_len;
 	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
 	__be16 protocol = skb->protocol;
 	int udp_offset, outer_hlen;
 	unsigned int oldlen;
-	bool need_csum = !!(skb_shinfo(skb)->gso_type &
-			    SKB_GSO_UDP_TUNNEL_CSUM);
-	bool remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
-	bool offload_csum = false, dont_encap = (need_csum || remcsum);
 
 	oldlen = (u16)~skb->len;
 
@@ -55,14 +52,18 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
 	skb_set_network_header(skb, skb_inner_network_offset(skb));
 	skb->mac_len = skb_inner_network_offset(skb);
 	skb->protocol = new_protocol;
+
+	need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
 	skb->encap_hdr_csum = need_csum;
+
+	remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
 	skb->remcsum_offload = remcsum;
 
 	/* Try to offload checksum if possible */
 	offload_csum = !!(need_csum &&
-			  ((skb->dev->features & NETIF_F_HW_CSUM) ||
-			   (skb->dev->features & (is_ipv6 ?
-			    NETIF_F_IPV6_CSUM : NETIF_F_IP_CSUM))));
+			  (skb->dev->features &
+			   (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) :
+				      (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
 
 	features &= skb->dev->hw_enc_features;
 
@@ -92,13 +93,11 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
 		int len;
 		__be32 delta;
 
-		if (dont_encap) {
-			skb->encapsulation = 0;
+		if (remcsum)
 			skb->ip_summed = CHECKSUM_NONE;
-		} else {
-			/* Only set up inner headers if we might be offloading
-			 * inner checksum.
-			 */
+
+		/* Set up inner headers if we are offloading inner checksum */
+		if (skb->ip_summed == CHECKSUM_PARTIAL) {
 			skb_reset_inner_headers(skb);
 			skb->encapsulation = 1;
 		}
@@ -122,15 +121,15 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
 		uh->check = ~csum_fold((__force __wsum)
 				       ((__force u32)uh->check +
 					(__force u32)delta));
-		if (offload_csum) {
-			skb->ip_summed = CHECKSUM_PARTIAL;
-			skb->csum_start = skb_transport_header(skb) - skb->head;
-			skb->csum_offset = offsetof(struct udphdr, check);
-		} else {
-			uh->check = gso_make_checksum(skb, ~uh->check);
 
+		if (skb->encapsulation || !offload_csum) {
+			uh->check = gso_make_checksum(skb, ~uh->check);
 			if (uh->check == 0)
 				uh->check = CSUM_MANGLED_0;
+		} else {
+			skb->ip_summed = CHECKSUM_PARTIAL;
+			skb->csum_start = skb_transport_header(skb) - skb->head;
+			skb->csum_offset = offsetof(struct udphdr, check);
 		}
 	} while ((skb = skb->next));
 out: