net: add net device refcount tracker to ethtool_phys_id()

This helper might hold a netdev reference for a long time,
lets add reference tracking.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ethtool/ioctl.c

@@ -1989,6 +1989,7 @@ static int ethtool_phys_id(struct net_device *dev, void __user *useraddr)
 	struct ethtool_value id;
 	static bool busy;
 	const struct ethtool_ops *ops = dev->ethtool_ops;
+	netdevice_tracker dev_tracker;
 	int rc;
 
 	if (!ops->set_phys_id)
@@ -2008,7 +2009,7 @@ static int ethtool_phys_id(struct net_device *dev, void __user *useraddr)
 	 * removal of the device.
 	 */
 	busy = true;
-	dev_hold(dev);
+	dev_hold_track(dev, &dev_tracker, GFP_KERNEL);
 	rtnl_unlock();
 
 	if (rc == 0) {
@@ -2032,7 +2033,7 @@ static int ethtool_phys_id(struct net_device *dev, void __user *useraddr)
 	}
 
 	rtnl_lock();
-	dev_put(dev);
+	dev_put_track(dev, &dev_tracker);
 	busy = false;
 
 	(void) ops->set_phys_id(dev, ETHTOOL_ID_INACTIVE);