net/sched: cbs: Fix error path of cbs_module_init

If register_qdisc fails, we should unregister
netdevice notifier.
Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: e0a7683d ("net/sched: cbs: fix port_rate miscalculation")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_cbs.c

@@ -549,12 +549,17 @@ static struct notifier_block cbs_device_notifier = {
 
 static int __init cbs_module_init(void)
 {
-	int err = register_netdevice_notifier(&cbs_device_notifier);
+	int err;
 
+	err = register_netdevice_notifier(&cbs_device_notifier);
 	if (err)
 		return err;
 
-	return register_qdisc(&cbs_qdisc_ops);
+	err = register_qdisc(&cbs_qdisc_ops);
+	if (err)
+		unregister_netdevice_notifier(&cbs_device_notifier);
+
+	return err;
 }
 
 static void __exit cbs_module_exit(void)