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>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index f3496e995302..73e255788fae 100644
--- 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;