[MACVLAN]: Prevent nesting macvlan devices
Don't allow to nest macvlan devices since it will cause lockdep
warnings and isn't really useful for anything.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 2e4bcd5..e8dc2f4 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -384,6 +384,13 @@
if (lowerdev == NULL)
return -ENODEV;
+ /* Don't allow macvlans on top of other macvlans - its not really
+ * wrong, but lockdep can't handle it and its not useful for anything
+ * you couldn't do directly on top of the real device.
+ */
+ if (lowerdev->rtnl_link_ops == dev->rtnl_link_ops)
+ return -ENODEV;
+
if (!tb[IFLA_MTU])
dev->mtu = lowerdev->mtu;
else if (dev->mtu > lowerdev->mtu)