netdev - [PATCH net-next 6/8] vxlan: Improve vxlan headroom calculation.

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Date:	Thu, 20 Jun 2013 00:26:52 -0700
From:	Pravin B Shelar <pshelar@...ira.com>
To:	netdev@...r.kernel.org, dev@...nvswitch.org
Cc:	Pravin B Shelar <pshelar@...ira.com>
Subject: [PATCH net-next 6/8] vxlan: Improve vxlan headroom calculation.

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

Signed-off-by: Pravin B Shelar <pshelar@...ira.com>
---
 drivers/net/vxlan.c |   13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 6ca2632..e53c947 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1040,6 +1040,7 @@ int vxlan_xmit_skb(struct net *net, struct vxlan_handler *vh,
 {
 	struct vxlanhdr *vxh;
 	struct udphdr *uh;
+	int min_headroom;
 	int err;
 
 	if (!skb->encapsulation) {
@@ -1047,6 +1048,14 @@ int vxlan_xmit_skb(struct net *net, struct vxlan_handler *vh,
 		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;
@@ -1099,10 +1108,6 @@ static netdev_tx_t __vxlan_xmit(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;
-- 
1.7.1

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