staging: fsl-dpaa2: ethsw: Add missing netdevice check

port_switchdev_event() does not check that the target network device is
actually backed by the ethsw driver, this could be problematic in a
stacked environment case.

Fixes: 44baaa43 ("staging: fsl-dpaa2/ethsw: Add Freescale DPAA2 Ethernet Switch driver")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fsl-dpaa2/ethsw/ethsw.c

@@ -1047,6 +1047,9 @@ static int port_switchdev_event(struct notifier_block *unused,
 	struct ethsw_switchdev_event_work *switchdev_work;
 	struct switchdev_notifier_fdb_info *fdb_info = ptr;
 
+	if (!ethsw_port_dev_check(dev))
+		return NOTIFY_DONE;
+
 	switchdev_work = kzalloc(sizeof(*switchdev_work), GFP_ATOMIC);
 	if (!switchdev_work)
 		return NOTIFY_BAD;