stmmac: debugfs entry name is not be changed when udev rename device name.

Add one notifier for udev changes net device name.
Fixes: b6601323ef9e ("net: stmmac: debugfs entry name is not be changed when udev rename")
Signed-off-by: Jiping Ma <jiping.ma2@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -106,6 +106,7 @@ MODULE_PARM_DESC(chain_mode, "To use chain instead of ring mode");
 static irqreturn_t stmmac_interrupt(int irq, void *dev_id);
 
 #ifdef CONFIG_DEBUG_FS
+static const struct net_device_ops stmmac_netdev_ops;
 static void stmmac_init_fs(struct net_device *dev);
 static void stmmac_exit_fs(struct net_device *dev);
 #endif
@@ -4256,6 +4257,34 @@ static int stmmac_dma_cap_show(struct seq_file *seq, void *v)
 }
 DEFINE_SHOW_ATTRIBUTE(stmmac_dma_cap);
 
+/* Use network device events to rename debugfs file entries.
+ */
+static int stmmac_device_event(struct notifier_block *unused,
+			       unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct stmmac_priv *priv = netdev_priv(dev);
+
+	if (dev->netdev_ops != &stmmac_netdev_ops)
+		goto done;
+
+	switch (event) {
+	case NETDEV_CHANGENAME:
+		if (priv->dbgfs_dir)
+			priv->dbgfs_dir = debugfs_rename(stmmac_fs_dir,
+							 priv->dbgfs_dir,
+							 stmmac_fs_dir,
+							 dev->name);
+		break;
+	}
+done:
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block stmmac_notifier = {
+	.notifier_call = stmmac_device_event,
+};
+
 static void stmmac_init_fs(struct net_device *dev)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
@@ -4270,12 +4299,15 @@ static void stmmac_init_fs(struct net_device *dev)
 	/* Entry to report the DMA HW features */
 	debugfs_create_file("dma_cap", 0444, priv->dbgfs_dir, dev,
 			    &stmmac_dma_cap_fops);
+
+	register_netdevice_notifier(&stmmac_notifier);
 }
 
 static void stmmac_exit_fs(struct net_device *dev)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
 
+	unregister_netdevice_notifier(&stmmac_notifier);
 	debugfs_remove_recursive(priv->dbgfs_dir);
 }
 #endif /* CONFIG_DEBUG_FS */