[ARP]: Introduce the arp_hdr_len helper.

There are some place, that calculate the ARP header length. These
calculations are correct, but 
 a) some operate with "magic" constants,
 b) enlarge the code length (sometimes at the cost of coding style),
 c) are not informative from the first glance.

The proposal is to introduce a helper, that includes all the good
sides of these calculations.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 4 deletions

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 6faa128a4c8..7ae98659d79 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -384,9 +384,7 @@ static void arp_reply(struct sk_buff *skb)
         if (skb->dev->flags & IFF_NOARP)
                 return;
 
-        if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
-                                 (2 * skb->dev->addr_len) +
-                                 (2 * sizeof(u32)))))
+        if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
                 return;
 
         skb_reset_network_header(skb);
@@ -414,7 +412,7 @@ static void arp_reply(struct sk_buff *skb)
             ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
                 return;
 
-        size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
+        size = arp_hdr_len(skb->dev);
         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
                             LL_RESERVED_SPACE(np->dev));