From 23f1a0e55f78484e82fbffebfd44b860d9a348ed Mon Sep 17 00:00:00 2001
From: Aaro Koskinen <aaro.koskinen@nokia.com>
Date: Wed, 26 Feb 2020 18:49:01 +0200
Subject: [PATCH] net: stmmac: fix notifier registration

commit 474a31e13a4e9749fb3ee55794d69d0f17ee0998 upstream.

We cannot register the same netdev notifier multiple times when probing
stmmac devices. Register the notifier only once in module init, and also
make debugfs creation/deletion safe against simultaneous notifier call.

Fixes: 481a7d154cbb ("stmmac: debugfs entry name is not be changed when udev rename device name.")
Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 75696c62537e..0a8dc66e00e6 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4086,6 +4086,8 @@ static int stmmac_init_fs(struct net_device *dev)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
 
+	rtnl_lock();
+
 	/* Create per netdev entries */
 	priv->dbgfs_dir = debugfs_create_dir(dev->name, stmmac_fs_dir);
 
@@ -4120,7 +4122,7 @@ static int stmmac_init_fs(struct net_device *dev)
 		return -ENOMEM;
 	}
 
-	register_netdevice_notifier(&stmmac_notifier);
+	rtnl_unlock();
 
 	return 0;
 }
@@ -4129,7 +4131,6 @@ 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 */
@@ -4507,14 +4508,14 @@ int stmmac_dvr_remove(struct device *dev)
 
 	netdev_info(priv->dev, "%s: removing driver", __func__);
 
-#ifdef CONFIG_DEBUG_FS
-	stmmac_exit_fs(ndev);
-#endif
 	stmmac_stop_all_dma(priv);
 
 	stmmac_mac_set(priv, priv->ioaddr, false);
 	netif_carrier_off(ndev);
 	unregister_netdev(ndev);
+#ifdef CONFIG_DEBUG_FS
+	stmmac_exit_fs(ndev);
+#endif
 	if (priv->plat->stmmac_rst)
 		reset_control_assert(priv->plat->stmmac_rst);
 	clk_disable_unprepare(priv->plat->pclk);
@@ -4734,6 +4735,7 @@ static int __init stmmac_init(void)
 			return -ENOMEM;
 		}
 	}
+	register_netdevice_notifier(&stmmac_notifier);
 #endif
 
 	return 0;
@@ -4742,6 +4744,7 @@ static int __init stmmac_init(void)
 static void __exit stmmac_exit(void)
 {
 #ifdef CONFIG_DEBUG_FS
+	unregister_netdevice_notifier(&stmmac_notifier);
 	debugfs_remove_recursive(stmmac_fs_dir);
 #endif
 }
-- 
2.7.4