net: dsa: move netdevice notifier registration

Move the netdevice notifier block register code in slave.c and provide
helpers for dsa.c to register and unregister it.

At the same time, check for errors since (un)register_netdevice_notifier
may fail.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/dsa.c

@@ -903,10 +903,6 @@ static struct packet_type dsa_pack_type __read_mostly = {
 	.func	= dsa_switch_rcv,
 };
 
-static struct notifier_block dsa_netdevice_nb __read_mostly = {
-	.notifier_call	= dsa_slave_netdevice_event,
-};
-
 #ifdef CONFIG_PM_SLEEP
 static int dsa_suspend(struct device *d)
 {
@@ -964,7 +960,9 @@ static int __init dsa_init_module(void)
 {
 	int rc;
 
-	register_netdevice_notifier(&dsa_netdevice_nb);
+	rc = dsa_slave_register_notifier();
+	if (rc)
+		return rc;
 
 	rc = platform_driver_register(&dsa_driver);
 	if (rc)
@@ -978,7 +976,7 @@ module_init(dsa_init_module);
 
 static void __exit dsa_cleanup_module(void)
 {
-	unregister_netdevice_notifier(&dsa_netdevice_nb);
+	dsa_slave_unregister_notifier();
 	dev_remove_pack(&dsa_pack_type);
 	platform_driver_unregister(&dsa_driver);
 }

net/dsa/dsa_priv.h

@@ -63,8 +63,8 @@ int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
 void dsa_slave_destroy(struct net_device *slave_dev);
 int dsa_slave_suspend(struct net_device *slave_dev);
 int dsa_slave_resume(struct net_device *slave_dev);
-int dsa_slave_netdevice_event(struct notifier_block *unused,
-			      unsigned long event, void *ptr);
+int dsa_slave_register_notifier(void);
+void dsa_slave_unregister_notifier(void);
 
 /* tag_dsa.c */
 extern const struct dsa_device_ops dsa_netdev_ops;

net/dsa/slave.c

@@ -1524,7 +1524,7 @@ static int dsa_slave_port_event(struct net_device *dev, unsigned long event,
 	return NOTIFY_DONE;
 }
 
-int dsa_slave_netdevice_event(struct notifier_block *unused,
+static int dsa_slave_netdevice_event(struct notifier_block *nb,
 				     unsigned long event, void *ptr)
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
@@ -1534,3 +1534,21 @@ int dsa_slave_netdevice_event(struct notifier_block *unused,
 
 	return NOTIFY_DONE;
 }
+
+static struct notifier_block dsa_slave_nb __read_mostly = {
+	.notifier_call	= dsa_slave_netdevice_event,
+};
+
+int dsa_slave_register_notifier(void)
+{
+	return register_netdevice_notifier(&dsa_slave_nb);
+}
+
+void dsa_slave_unregister_notifier(void)
+{
+	int err;
+
+	err = unregister_netdevice_notifier(&dsa_slave_nb);
+	if (err)
+		pr_err("DSA: failed to unregister slave notifier (%d)\n", err);
+}