macvlan: Support creating macvlans from macvlans
When running in a network namespace whose only link to
the outside world is a macvlan device, not being
able to create another macvlan is a real pain.
So modify macvlan creation to allow automatically forward
a creation of a macvlan on a macvlan to become a creation
of a macvlan on the underlying network device.
Signed-off-by: Eric Biederman <ebiederm@aristanetworks.com>
Acked-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 7e24b50..b5241fc 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -461,12 +461,13 @@
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.
+ /* When creating macvlans on top of other macvlans - use
+ * the real device as the lowerdev.
*/
- if (lowerdev->rtnl_link_ops == dev->rtnl_link_ops)
- return -ENODEV;
+ if (lowerdev->rtnl_link_ops == dev->rtnl_link_ops) {
+ struct macvlan_dev *lowervlan = netdev_priv(lowerdev);
+ lowerdev = lowervlan->lowerdev;
+ }
if (!tb[IFLA_MTU])
dev->mtu = lowerdev->mtu;
