xen-netback: switch to use skb_partial_csum_set()

Switch to use skb_partial_csum_set() to simplify the codes.

Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 01a33cc58cf1adf454afd662fba7f72776aae2aa..9f71844042634e06af148b872e6a343c54a789f1 100644 (file)
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1156,7 +1156,6 @@ static int netbk_set_skb_gso(struct xenvif *vif,
 static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
 {
        struct iphdr *iph;
-       unsigned char *th;
        int err = -EPROTO;
        int recalculate_partial_csum = 0;
 
@@ -1180,28 +1179,26 @@ static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
                goto out;
 
        iph = (void *)skb->data;
-       th = skb->data + 4 * iph->ihl;
-       if (th >= skb_tail_pointer(skb))
-               goto out;
-
-       skb_set_transport_header(skb, 4 * iph->ihl);
-       skb->csum_start = th - skb->head;
        switch (iph->protocol) {
        case IPPROTO_TCP:
-               skb->csum_offset = offsetof(struct tcphdr, check);
+               if (!skb_partial_csum_set(skb, 4 * iph->ihl,
+                                         offsetof(struct tcphdr, check)))
+                       goto out;
 
                if (recalculate_partial_csum) {
-                       struct tcphdr *tcph = (struct tcphdr *)th;
+                       struct tcphdr *tcph = tcp_hdr(skb);
                        tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
                                                         skb->len - iph->ihl*4,
                                                         IPPROTO_TCP, 0);
                }
                break;
        case IPPROTO_UDP:
-               skb->csum_offset = offsetof(struct udphdr, check);
+               if (!skb_partial_csum_set(skb, 4 * iph->ihl,
+                                         offsetof(struct udphdr, check)))
+                       goto out;
 
                if (recalculate_partial_csum) {
-                       struct udphdr *udph = (struct udphdr *)th;
+                       struct udphdr *udph = udp_hdr(skb);
                        udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
                                                         skb->len - iph->ihl*4,
                                                         IPPROTO_UDP, 0);
@@ -1215,9 +1212,6 @@ static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
                goto out;
        }
 
-       if ((th + skb->csum_offset + 2) > skb_tail_pointer(skb))
-               goto out;
-
        err = 0;
 
 out: