xen-netfront: use skb_partial_csum_set() to simplify the codes

use skb_partial_csum_set() to simplify the codes

Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 62238a08cb517e6ed30d8df58c33c49dcf95286b..76a22365d4e9ebfecdb20ea8270ca3760c07c36c 100644 (file)
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -858,7 +858,6 @@ static RING_IDX xennet_fill_frags(struct netfront_info *np,
 static int checksum_setup(struct net_device *dev, struct sk_buff *skb)
 {
        struct iphdr *iph;
-       unsigned char *th;
        int err = -EPROTO;
        int recalculate_partial_csum = 0;
 
@@ -883,27 +882,27 @@ static int checksum_setup(struct net_device *dev, 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->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);
@@ -917,9 +916,6 @@ static int checksum_setup(struct net_device *dev, struct sk_buff *skb)
                goto out;
        }
 
-       if ((th + skb->csum_offset + 2) > skb_tail_pointer(skb))
-               goto out;
-
        err = 0;
 
 out: