gro: Clean up tcpX_gro_receive checksum verification

This patch simplifies the checksum verification in tcpX_gro_receive
by reusing the CHECKSUM_COMPLETE code for CHECKSUM_NONE.  All it
does for CHECKSUM_NONE is compute the partial checksum and then
treat it as if it came from the hardware (CHECKSUM_COMPLETE).

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Cheers,
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 20 insertions, 33 deletions

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index 55aeec930140..05606353c7e7 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -274,35 +274,29 @@ static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *
 {
         const struct iphdr *iph = skb_gro_network_header(skb);
         __wsum wsum;
-        __sum16 sum;
 
         /* Don't bother verifying checksum if we're going to flush anyway. */
         if (NAPI_GRO_CB(skb)->flush)
                 goto skip_csum;
 
+        wsum = skb->csum;
+
         switch (skb->ip_summed) {
+        case CHECKSUM_NONE:
+                wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb),
+                                    0);
+
+                /* fall through */
+
         case CHECKSUM_COMPLETE:
                 if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
-                                  skb->csum)) {
+                                  wsum)) {
                         skb->ip_summed = CHECKSUM_UNNECESSARY;
                         break;
                 }
-flush:
+
                 NAPI_GRO_CB(skb)->flush = 1;
                 return NULL;
-
-        case CHECKSUM_NONE:
-                wsum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
-                                          skb_gro_len(skb), IPPROTO_TCP, 0);
-                sum = csum_fold(skb_checksum(skb,
-                                             skb_gro_offset(skb),
-                                             skb_gro_len(skb),
-                                             wsum));
-                if (sum)
-                        goto flush;
-
-                skb->ip_summed = CHECKSUM_UNNECESSARY;
-                break;
         }
 
 skip_csum:
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index 71923d14127a..6d18157dc32c 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -37,36 +37,29 @@ static struct sk_buff **tcp6_gro_receive(struct sk_buff **head,
 {
         const struct ipv6hdr *iph = skb_gro_network_header(skb);
         __wsum wsum;
-        __sum16 sum;
 
         /* Don't bother verifying checksum if we're going to flush anyway. */
         if (NAPI_GRO_CB(skb)->flush)
                 goto skip_csum;
 
+        wsum = skb->csum;
+
         switch (skb->ip_summed) {
+        case CHECKSUM_NONE:
+                wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb),
+                                    wsum);
+
+                /* fall through */
+
         case CHECKSUM_COMPLETE:
                 if (!tcp_v6_check(skb_gro_len(skb), &iph->saddr, &iph->daddr,
-                                  skb->csum)) {
+                                  wsum)) {
                         skb->ip_summed = CHECKSUM_UNNECESSARY;
                         break;
                 }
-flush:
+
                 NAPI_GRO_CB(skb)->flush = 1;
                 return NULL;
-
-        case CHECKSUM_NONE:
-                wsum = ~csum_unfold(csum_ipv6_magic(&iph->saddr, &iph->daddr,
-                                                    skb_gro_len(skb),
-                                                    IPPROTO_TCP, 0));
-                sum = csum_fold(skb_checksum(skb,
-                                             skb_gro_offset(skb),
-                                             skb_gro_len(skb),
-                                             wsum));
-                if (sum)
-                        goto flush;
-
-                skb->ip_summed = CHECKSUM_UNNECESSARY;
-                break;
         }
 
 skip_csum: