[PATCH 3.16.y-ckt 058/104] vxlan: set needed headroom correctly

[Luis Henriques]

3.16.7-ckt19 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jiri Benc <jbenc at redhat.com>

commit 9dc2ad1008c9f91f55ec6c89ec0f8639dfc91596 upstream.

vxlan_setup is called when allocating the net_device, i.e. way before
vxlan_newlink (or vxlan_dev_configure) is called. This means
vxlan->default_dst is actually unset in vxlan_setup and the condition that
sets needed_headroom always takes the else branch.

Set the needed_headrom at the point when we have the information about
the address family available.

Fixes: e4c7ed415387c ("vxlan: add ipv6 support")
Fixes: 2853af6a2ea1a ("vxlan: use dev->needed_headroom instead of dev->hard_header_len")
CC: Cong Wang <cwang at twopensource.com>
Signed-off-by: Jiri Benc <jbenc at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
[ luis: backported to 3.16:
  - initialise needed_headrom in vxlan_newlink() instead of
    vxlan_dev_configure() ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/vxlan.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 40bf8a87b3d9..8a7a35c4f6bd 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2251,10 +2251,6 @@ static void vxlan_setup(struct net_device *dev)
 
 	eth_hw_addr_random(dev);
 	ether_setup(dev);
-	if (vxlan->default_dst.remote_ip.sa.sa_family == AF_INET6)
-		dev->needed_headroom = ETH_HLEN + VXLAN6_HEADROOM;
-	else
-		dev->needed_headroom = ETH_HLEN + VXLAN_HEADROOM;
 
 	dev->netdev_ops = &vxlan_netdev_ops;
 	dev->destructor = free_netdev;
@@ -2651,8 +2647,12 @@ static int vxlan_newlink(struct net *net, struct net_device *dev,
 
 		dev->needed_headroom = lowerdev->hard_header_len +
 				       (use_ipv6 ? VXLAN6_HEADROOM : VXLAN_HEADROOM);
-	} else if (use_ipv6)
+	} else if (use_ipv6) {
 		vxlan->flags |= VXLAN_F_IPV6;
+		dev->needed_headroom = ETH_HLEN + VXLAN6_HEADROOM;
+	} else {
+		dev->needed_headroom = ETH_HLEN + VXLAN_HEADROOM;
+	}
 
 	if (data[IFLA_VXLAN_TOS])
 		vxlan->tos  = nla_get_u8(data[IFLA_VXLAN_TOS]);