udp: Offload outer UDP tunnel csum if available

In __skb_udp_tunnel_segment if outer UDP checksums are enabled and
ip_summed is not already CHECKSUM_PARTIAL, set up checksum offload
if device features allow it.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 6480cea..a774711 100644 (file)
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -29,7 +29,7 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
        netdev_features_t features,
        struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
                                             netdev_features_t features),
-       __be16 new_protocol)
+       __be16 new_protocol, bool is_ipv6)
 {
        struct sk_buff *segs = ERR_PTR(-EINVAL);
        u16 mac_offset = skb->mac_header;
@@ -39,7 +39,9 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
        netdev_features_t enc_features;
        int udp_offset, outer_hlen;
        unsigned int oldlen;
-       bool need_csum;
+       bool need_csum = !!(skb_shinfo(skb)->gso_type &
+                           SKB_GSO_UDP_TUNNEL_CSUM);
+       bool offload_csum = false, dont_encap = need_csum;
 
        oldlen = (u16)~skb->len;
 
@@ -52,10 +54,12 @@ 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;
+       skb->encap_hdr_csum = need_csum;
 
-       need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
-       if (need_csum)
-               skb->encap_hdr_csum = 1;
+       /* Try to offload checksum if possible */
+       offload_csum = !!(need_csum &&
+                         (skb->dev->features &
+                          (is_ipv6 ? NETIF_F_V6_CSUM : NETIF_F_V4_CSUM)));
 
        /* segment inner packet. */
        enc_features = skb->dev->hw_enc_features & features;
@@ -72,11 +76,21 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
        do {
                struct udphdr *uh;
                int len;
-
-               skb_reset_inner_headers(skb);
-               skb->encapsulation = 1;
+               __be32 delta;
+
+               if (dont_encap) {
+                       skb->encapsulation = 0;
+                       skb->ip_summed = CHECKSUM_NONE;
+               } else {
+                       /* Only set up inner headers if we might be offloading
+                        * inner checksum.
+                        */
+                       skb_reset_inner_headers(skb);
+                       skb->encapsulation = 1;
+               }
 
                skb->mac_len = mac_len;
+               skb->protocol = protocol;
 
                skb_push(skb, outer_hlen);
                skb_reset_mac_header(skb);
@@ -86,19 +100,25 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
                uh = udp_hdr(skb);
                uh->len = htons(len);
 
-               if (need_csum) {
-                       __be32 delta = htonl(oldlen + len);
+               if (!need_csum)
+                       continue;
+
+               delta = htonl(oldlen + len);
+
+               uh->check = ~csum_fold((__force __wsum)
+                                      ((__force u32)uh->check +
+                                       (__force u32)delta));
 
-                       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 (uh->check == 0)
                                uh->check = CSUM_MANGLED_0;
                }
-
-               skb->protocol = protocol;
        } while ((skb = skb->next));
 out:
        return segs;
@@ -134,7 +154,7 @@ struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
        }
 
        segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
-                                       protocol);
+                                       protocol, is_ipv6);
 
 out_unlock:
        rcu_read_unlock();