vxlan: Improve vxlan headroom calculation.

Rather than having static headroom calculation, adjust headroom
according to target device.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index f3496e9..73e2557 100644 (file)
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1130,6 +1130,7 @@ int vxlan_xmit_skb(struct net *net, struct vxlan_sock *vs,
 {
        struct vxlanhdr *vxh;
        struct udphdr *uh;
+       int min_headroom;
        int err;
 
        if (!skb->encapsulation) {
@@ -1137,6 +1138,14 @@ int vxlan_xmit_skb(struct net *net, struct vxlan_sock *vs,
                skb->encapsulation = 1;
        }
 
+       min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
+                       + VXLAN_HLEN + sizeof(struct iphdr);
+
+       /* Need space for new headers (invalidates iph ptr) */
+       err = skb_cow_head(skb, min_headroom);
+       if (unlikely(err))
+               return err;
+
        vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
        vxh->vx_flags = htonl(VXLAN_FLAGS);
        vxh->vx_vni = vni;
@@ -1220,10 +1229,6 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                goto drop;
        }
 
-       /* Need space for new headers (invalidates iph ptr) */
-       if (skb_cow_head(skb, VXLAN_HEADROOM))
-               goto drop;
-
        old_iph = ip_hdr(skb);
 
        ttl = vxlan->ttl;