net/sched: add net device refcount tracker to struct Qdisc

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

include/net/sch_generic.h

@@ -125,7 +125,7 @@ struct Qdisc {
 	spinlock_t		seqlock;
 
 	struct rcu_head		rcu;
-
+	netdevice_tracker	dev_tracker;
 	/* private data */
 	long privdata[] ____cacheline_aligned;
 };

net/sched/sch_generic.c

@@ -973,7 +973,7 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 	sch->enqueue = ops->enqueue;
 	sch->dequeue = ops->dequeue;
 	sch->dev_queue = dev_queue;
-	dev_hold(dev);
+	dev_hold_track(dev, &sch->dev_tracker, GFP_KERNEL);
 	refcount_set(&sch->refcnt, 1);
 
 	return sch;
@@ -1073,7 +1073,7 @@ static void qdisc_destroy(struct Qdisc *qdisc)
 		ops->destroy(qdisc);
 
 	module_put(ops->owner);
-	dev_put(qdisc_dev(qdisc));
+	dev_put_track(qdisc_dev(qdisc), &qdisc->dev_tracker);
 
 	trace_qdisc_destroy(qdisc);