ipv4: Use 32-bit loads for ID and length in GRO

This patch optimises the IPv4 GRO code by using 32-bit loads
(instead of 16-bit ones) on the ID and length checks in the receive
function.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 644cc55..5abee4c 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1248,9 +1248,9 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head,
        struct iphdr *iph;
        unsigned int hlen;
        unsigned int off;
+       unsigned int id;
        int flush = 1;
        int proto;
-       int id;
 
        off = skb_gro_offset(skb);
        hlen = off + sizeof(*iph);
@@ -1274,9 +1274,9 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head,
        if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
                goto out_unlock;
 
-       flush = ntohs(iph->tot_len) != skb_gro_len(skb) ||
-               iph->frag_off != htons(IP_DF);
-       id = ntohs(iph->id);
+       id = ntohl(*(u32 *)&iph->id);
+       flush = (u16)((ntohl(*(u32 *)iph) ^ skb_gro_len(skb)) | (id ^ IP_DF));
+       id >>= 16;
 
        for (p = *head; p; p = p->next) {
                struct iphdr *iph2;