net/sched: sch_hfsc: warn about class in use while deleting

Add extack to warn that delete was rejected because
the class is still in use
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/sched/sch_hfsc.c

@@ -1094,8 +1094,10 @@ hfsc_delete_class(struct Qdisc *sch, unsigned long arg,
 	struct hfsc_class *cl = (struct hfsc_class *)arg;
 
 	if (cl->level > 0 || qdisc_class_in_use(&cl->cl_common) ||
-	    cl == &q->root)
+	    cl == &q->root) {
+		NL_SET_ERR_MSG(extack, "HFSC class in use");
 		return -EBUSY;
+	}
 
 	sch_tree_lock(sch);