drop_monitor: add net device refcount tracker

We want to track all dev_hold()/dev_put() to ease leak hunting.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/devlink.h

@@ -664,13 +664,17 @@ struct devlink_health_reporter_ops {
  * @trap_name: Trap name.
  * @trap_group_name: Trap group name.
  * @input_dev: Input netdevice.
+ * @dev_tracker: refcount tracker for @input_dev.
  * @fa_cookie: Flow action user cookie.
  * @trap_type: Trap type.
  */
 struct devlink_trap_metadata {
 	const char *trap_name;
 	const char *trap_group_name;
+
 	struct net_device *input_dev;
+	netdevice_tracker dev_tracker;
+
 	const struct flow_action_cookie *fa_cookie;
 	enum devlink_trap_type trap_type;
 };