net: udp: always set up for CHECKSUM_PARTIAL offload

If the dst device doesn't support it, it'll get fixed up later anyway
 by validate_xmit_skb().  Also, this allows us to take advantage of LCO
 to avoid summing the payload multiple times.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: ecree-solarflare

net/ipv4/udp.c

@@ -857,23 +857,11 @@ void udp_set_csum(bool nocheck, struct sk_buff *skb,
 		uh->check = udp_v4_check(len, saddr, daddr, lco_csum(skb));
 		if (uh->check == 0)
 			uh->check = CSUM_MANGLED_0;
-	} else if (skb_dst(skb) && skb_dst(skb)->dev &&
-		   (skb_dst(skb)->dev->features &
-		    (NETIF_F_IP_CSUM | NETIF_F_HW_CSUM))) {
+	} else {
 		skb->ip_summed = CHECKSUM_PARTIAL;
 		skb->csum_start = skb_transport_header(skb) - skb->head;
 		skb->csum_offset = offsetof(struct udphdr, check);
 		uh->check = ~udp_v4_check(len, saddr, daddr, 0);
-	} else {
-		__wsum csum;
-
-		uh->check = 0;
-		csum = skb_checksum(skb, 0, len, 0);
-		uh->check = udp_v4_check(len, saddr, daddr, csum);
-		if (uh->check == 0)
-			uh->check = CSUM_MANGLED_0;
-
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
 	}
 }
 EXPORT_SYMBOL(udp_set_csum);

net/ipv6/ip6_checksum.c

@@ -103,22 +103,11 @@ void udp6_set_csum(bool nocheck, struct sk_buff *skb,
 		uh->check = udp_v6_check(len, saddr, daddr, lco_csum(skb));
 		if (uh->check == 0)
 			uh->check = CSUM_MANGLED_0;
-	} else if (skb_dst(skb) && skb_dst(skb)->dev &&
-		   (skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
+	} else {
 		skb->ip_summed = CHECKSUM_PARTIAL;
 		skb->csum_start = skb_transport_header(skb) - skb->head;
 		skb->csum_offset = offsetof(struct udphdr, check);
 		uh->check = ~udp_v6_check(len, saddr, daddr, 0);
-	} else {
-		__wsum csum;
-
-		uh->check = 0;
-		csum = skb_checksum(skb, 0, len, 0);
-		uh->check = udp_v6_check(len, saddr, daddr, csum);
-		if (uh->check == 0)
-			uh->check = CSUM_MANGLED_0;
-
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
 	}
 }
 EXPORT_SYMBOL(udp6_set_csum);