[PATCH net-next 2/4] ipvlan: play well with macvlan device

[Mahesh Bandewar <maheshb@google.com>]

If a device is already a macvlan port then refuse to use it as
an ipvlan port in the early stage of port creation.

	thost1:~# ip link add link eth0 mvl0 type macvlan
	thost1:~# echo $?
	0
	thost1:~# ip link add link eth0 ipvl0 type ipvlan
	RTNETLINK answers: Device or resource busy
	thost1:~# echo $?
	2
	thost1:~#

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
---
 drivers/net/ipvlan/ipvlan_main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 96b71b0d78f6..a706a547d811 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -38,6 +38,12 @@ static int ipvlan_port_create(struct net_device *dev)
 		netdev_err(dev, "Master is either lo or non-ether device\n");
 		return -EINVAL;
 	}
+
+	if (netif_is_macvlan_port(dev)) {
+		netdev_err(dev, "Master is a macvlan port.\n");
+		return -EBUSY;
+	}
+
 	port = kzalloc(sizeof(struct ipvl_port), GFP_KERNEL);
 	if (!port)
 		return -ENOMEM;
-- 
2.2.0.rc0.207.ga3a616c