linux-kernel - [PATCH v2 3/3] staging: rtl8192u: fix rmmod warn when wlan0 is renamed

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Date:   Mon, 18 Jul 2022 22:50:38 -0700
From:   Tong Zhang <ztong0001@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tong Zhang <ztong0001@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Colin Ian King <colin.king@...el.com>,
        Saurav Girepunje <saurav.girepunje@...il.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Johan Hovold <johan@...nel.org>, linux-kernel@...r.kernel.org,
        linux-staging@...ts.linux.dev
Cc:     dan.carpenter@...cle.com, Zheyu Ma <zheyuma97@...il.com>
Subject: [PATCH v2 3/3] staging: rtl8192u: fix rmmod warn when wlan0 is renamed

This driver creates 4 debug files under [devname] folder. The devname
could be wlan0 initially, however it could be renamed later to e.g.
enx00e04c00000. This will cause problem during debug file teardown since
it uses  netdev->name which is no longer wlan0. To solve this problem,
add a notifier to handle device renaming.

Reported-by: Zheyu Ma <zheyuma97@...il.com>
Tested-by: Zheyu Ma <zheyuma97@...il.com>
Signed-off-by: Tong Zhang <ztong0001@...il.com>
---
 drivers/staging/rtl8192u/r8192U.h         |  1 +
 drivers/staging/rtl8192u/r8192U_core.c    | 35 ++++++++++++++++++++++-
 drivers/staging/rtl8192u/r8192U_debugfs.c | 13 +++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8192u/r8192U.h b/drivers/staging/rtl8192u/r8192U.h
index e8860bb2b607..ccce37b7e2ae 100644
--- a/drivers/staging/rtl8192u/r8192U.h
+++ b/drivers/staging/rtl8192u/r8192U.h
@@ -1122,4 +1122,5 @@ void setKey(struct net_device *dev, u8 EntryNo, u8 KeyIndex, u16 KeyType,
 
 void rtl8192_debugfs_init(struct net_device *dev);
 void rtl8192_debugfs_exit(struct net_device *dev);
+void rtl8192_debugfs_rename(struct net_device *dev);
 #endif
diff --git a/drivers/staging/rtl8192u/r8192U_core.c b/drivers/staging/rtl8192u/r8192U_core.c
index ac3716550505..5cc78c5bd706 100644
--- a/drivers/staging/rtl8192u/r8192U_core.c
+++ b/drivers/staging/rtl8192u/r8192U_core.c
@@ -4606,6 +4606,30 @@ static void rtl8192_usb_disconnect(struct usb_interface *intf)
 	RT_TRACE(COMP_DOWN, "wlan driver removed\n");
 }
 
+static int rtl8192_usb_netdev_event(struct notifier_block *nb, unsigned long event,
+				    void *data)
+{
+	struct net_device *netdev = netdev_notifier_info_to_dev(data);
+
+	if (netdev->netdev_ops != &rtl8192_netdev_ops)
+		goto out;
+
+	switch (event) {
+	case NETDEV_CHANGENAME:
+		rtl8192_debugfs_rename(netdev);
+		break;
+	default:
+		break;
+	}
+
+out:
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block rtl8192_usb_netdev_notifier = {
+	.notifier_call = rtl8192_usb_netdev_event,
+};
+
 static int __init rtl8192_usb_module_init(void)
 {
 	int ret;
@@ -4615,10 +4639,16 @@ static int __init rtl8192_usb_module_init(void)
 	RT_TRACE(COMP_INIT, "Initializing module");
 	RT_TRACE(COMP_INIT, "Wireless extensions version %d", WIRELESS_EXT);
 
+	ret = register_netdevice_notifier(&rtl8192_usb_netdev_notifier);
+	if (ret) {
+		pr_err("register_netdevice_notifier failed %d\n", ret);
+		return ret;
+	}
+
 	ret = ieee80211_debug_init();
 	if (ret) {
 		pr_err("ieee80211_debug_init() failed %d\n", ret);
-		return ret;
+		goto unregister_notifier;
 	}
 
 	ret = ieee80211_crypto_init();
@@ -4660,6 +4690,8 @@ static int __init rtl8192_usb_module_init(void)
 	ieee80211_crypto_deinit();
 debug_exit:
 	ieee80211_debug_exit();
+unregister_notifier:
+	unregister_netdevice_notifier(&rtl8192_usb_netdev_notifier);
 	return ret;
 }
 
@@ -4671,6 +4703,7 @@ static void __exit rtl8192_usb_module_exit(void)
 	ieee80211_crypto_tkip_exit();
 	ieee80211_crypto_deinit();
 	ieee80211_debug_exit();
+	unregister_netdevice_notifier(&rtl8192_usb_netdev_notifier);
 	RT_TRACE(COMP_DOWN, "Exiting");
 }
 
diff --git a/drivers/staging/rtl8192u/r8192U_debugfs.c b/drivers/staging/rtl8192u/r8192U_debugfs.c
index 5c9376e50889..c94f5dfac96b 100644
--- a/drivers/staging/rtl8192u/r8192U_debugfs.c
+++ b/drivers/staging/rtl8192u/r8192U_debugfs.c
@@ -173,3 +173,16 @@ void rtl8192_debugfs_exit(struct net_device *dev)
 	priv->debugfs_dir = NULL;
 }
 
+void rtl8192_debugfs_rename(struct net_device *dev)
+{
+	struct r8192_priv *priv = (struct r8192_priv *)ieee80211_priv(dev);
+
+	if (!priv->debugfs_dir)
+		return;
+
+	if (!strcmp(priv->debugfs_dir->d_name.name, dev->name))
+		return;
+
+	debugfs_rename(priv->debugfs_dir->d_parent, priv->debugfs_dir,
+		       priv->debugfs_dir->d_parent, dev->name);
+}
-- 
2.25.1