leds: trigger: netdev: fix refcnt leak on interface rename

Rafał Miłecki · jacek-anaszewski · commit 4cb6560514fa · 2019-03-26T20:25:37.000+01:00
Renaming a netdev-trigger-tracked interface was resulting in an unbalanced dev_hold(). Example: > iw phy phy0 interface add foo type __ap > echo netdev > trigger > echo foo > device_name > ip link set foo name bar > iw dev bar del [ 237.355366] unregister_netdevice: waiting for bar to become free. Usage count = 1 [ 247.435362] unregister_netdevice: waiting for bar to become free. Usage count = 1 [ 257.545366] unregister_netdevice: waiting for bar to become free. Usage count = 1 Above problem was caused by trigger checking a dev->name which obviously changes after renaming an interface. It meant missing all further events including the NETDEV_UNREGISTER which is required for calling dev_put(). This change fixes that by: 1) Comparing device struct *address* for notification-filtering purposes 2) Dropping unneeded NETDEV_CHANGENAME code (no behavior change) Fixes: 06f502f ("leds: trigger: Introduce a NETDEV trigger") Signed-off-by: Rafał Miłecki <rafal@milecki.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c
@@ -301,11 +301,11 @@ static int netdev_trig_notify(struct notifier_block *nb,
 		container_of(nb, struct led_netdev_data, notifier);
 
 	if (evt != NETDEV_UP && evt != NETDEV_DOWN && evt != NETDEV_CHANGE
-	    && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER
-	    && evt != NETDEV_CHANGENAME)
+	    && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER)
 		return NOTIFY_DONE;
 
-	if (strcmp(dev->name, trigger_data->device_name))
+	if (!(dev == trigger_data->net_dev ||
+	      (evt == NETDEV_REGISTER && !strcmp(dev->name, trigger_data->device_name))))
 		return NOTIFY_DONE;
 
 	cancel_delayed_work_sync(&trigger_data->work);
@@ -320,12 +320,9 @@ static int netdev_trig_notify(struct notifier_block *nb,
 		dev_hold(dev);
 		trigger_data->net_dev = dev;
 		break;
-	case NETDEV_CHANGENAME:
 	case NETDEV_UNREGISTER:
-		if (trigger_data->net_dev) {
-			dev_put(trigger_data->net_dev);
-			trigger_data->net_dev = NULL;
-		}
+		dev_put(trigger_data->net_dev);
+		trigger_data->net_dev = NULL;
 		break;
 	case NETDEV_UP:
 	case NETDEV_CHANGE:
