macvtap: check minor when unregistering

macvtap_device_event(NETDEV_UNREGISTER) should check vlan->minor to
determine if it is being invoked in the context of a macvtap_newlink
that failed, for example in this code sequence:

macvtap_newlink
  macvlan_common_newlink
    register_netdevice
      call_netdevice_notifiers(NETDEV_REGISTER, dev)
        macvtap_device_event(NETDEV_REGISTER)
          <fail here, vlan->minor = 0>
      rollback_registered(dev);
        rollback_registered_many
          call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
            macvtap_device_event(NETDEV_UNREGISTER)
              <nothing to clean up here>

Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 95394edd1ed528fc9cf94fb39aadeaa28c47fb26..74cb15a2e032a42fe84b7112543e5c270def60e7 100644 (file)
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -1303,6 +1303,9 @@ static int macvtap_device_event(struct notifier_block *unused,
                }
                break;
        case NETDEV_UNREGISTER:
+               /* vlan->minor == 0 if NETDEV_REGISTER above failed */
+               if (vlan->minor == 0)
+                       break;
                devt = MKDEV(MAJOR(macvtap_major), vlan->minor);
                device_destroy(macvtap_class, devt);
                macvtap_free_minor(vlan);