hsr: fix error handling routine in hsr_dev_finalize()

hsr_dev_finalize() is called to create new hsr interface.
There are some wrong error handling codes.

1. wrong checking return value of debugfs_create_{dir/file}.
These function doesn't return NULL. If error occurs in there,
it returns error pointer.
So, it should check error pointer instead of NULL.

2. It doesn't unregister interface if it fails to setup hsr interface.
If it fails to initialize hsr interface after register_netdevice(),
it should call unregister_netdevice().

3. Ignore failure of creation of debugfs
If creating of debugfs dir and file is failed, creating hsr interface
will be failed. But debugfs doesn't affect actual logic of hsr module.
So, ignoring this is more correct and this behavior is more general.

Fixes: c5a75911 ("net/hsr: Use list_head (and rcu) instead of array for slave devices.")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/hsr/hsr_debugfs.c

@@ -77,15 +77,14 @@ static const struct file_operations hsr_fops = {
  * When debugfs is configured this routine sets up the node_table file per
  * hsr device for dumping the node_table entries
  */
-int hsr_debugfs_init(struct hsr_priv *priv, struct net_device *hsr_dev)
+void hsr_debugfs_init(struct hsr_priv *priv, struct net_device *hsr_dev)
 {
-	int rc = -1;
 	struct dentry *de = NULL;
 
 	de = debugfs_create_dir(hsr_dev->name, NULL);
-	if (!de) {
+	if (IS_ERR(de)) {
 		pr_err("Cannot create hsr debugfs root\n");
-		return rc;
+		return;
 	}
 
 	priv->node_tbl_root = de;
@@ -93,13 +92,13 @@ int hsr_debugfs_init(struct hsr_priv *priv, struct net_device *hsr_dev)
 	de = debugfs_create_file("node_table", S_IFREG | 0444,
 				 priv->node_tbl_root, priv,
 				 &hsr_fops);
-	if (!de) {
+	if (IS_ERR(de)) {
 		pr_err("Cannot create hsr node_table directory\n");
-		return rc;
+		debugfs_remove(priv->node_tbl_root);
+		priv->node_tbl_root = NULL;
+		return;
 	}
 	priv->node_tbl_file = de;
-
-	return 0;
 }
 
 /* hsr_debugfs_term - Tear down debugfs intrastructure

net/hsr/hsr_device.c

@@ -477,30 +477,31 @@ int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2],
 
 	res = hsr_add_port(hsr, hsr_dev, HSR_PT_MASTER);
 	if (res)
-		goto err_add_port;
+		goto err_add_master;
 
 	res = register_netdevice(hsr_dev);
 	if (res)
-		goto fail;
+		goto err_unregister;
 
 	res = hsr_add_port(hsr, slave[0], HSR_PT_SLAVE_A);
 	if (res)
-		goto fail;
+		goto err_add_slaves;
+
 	res = hsr_add_port(hsr, slave[1], HSR_PT_SLAVE_B);
 	if (res)
-		goto fail;
+		goto err_add_slaves;
 
+	hsr_debugfs_init(hsr, hsr_dev);
 	mod_timer(&hsr->prune_timer, jiffies + msecs_to_jiffies(PRUNE_PERIOD));
-	res = hsr_debugfs_init(hsr, hsr_dev);
-	if (res)
-		goto fail;
 
 	return 0;
 
-fail:
+err_add_slaves:
+	unregister_netdevice(hsr_dev);
+err_unregister:
 	list_for_each_entry_safe(port, tmp, &hsr->ports, port_list)
 		hsr_del_port(port);
-err_add_port:
+err_add_master:
 	hsr_del_self_node(&hsr->self_node_db);
 
 	return res;

net/hsr/hsr_main.h

@@ -184,15 +184,12 @@ static inline u16 hsr_get_skb_sequence_nr(struct sk_buff *skb)
 }
 
 #if IS_ENABLED(CONFIG_DEBUG_FS)
-int hsr_debugfs_init(struct hsr_priv *priv, struct net_device *hsr_dev);
+void hsr_debugfs_init(struct hsr_priv *priv, struct net_device *hsr_dev);
 void hsr_debugfs_term(struct hsr_priv *priv);
 #else
-static inline int hsr_debugfs_init(struct hsr_priv *priv,
-				   struct net_device *hsr_dev)
-{
-	return 0;
-}
-
+static inline void hsr_debugfs_init(struct hsr_priv *priv,
+				    struct net_device *hsr_dev)
+{}
 static inline void hsr_debugfs_term(struct hsr_priv *priv)
 {}
 #endif