[PATCH v4 4/4] staging: rtl8192u: fix rmmod warn when device is renamed

Tong Zhang
2022-07-30T03:35:08Z

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. Also note that we cannot
simply do debugfs_lookup to find out old dentry since by the time the
notifier is called, netdev->name is already changed to new name.

Reported-by: Zheyu Ma <zheyuma97@gmail.com>
Tested-by: Zheyu Ma <zheyuma97@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tong Zhang <ztong0001@gmail.com>
---
drivers/staging/rtl8192u/r8192U.h | 1 +
drivers/staging/rtl8192u/r8192U_core.c | 32 +++++++++++++++++++++++
drivers/staging/rtl8192u/r8192U_debugfs.c | 8 ++++++
3 files changed, 41 insertions(+)

diff --git a/drivers/staging/rtl8192u/r8192U.h b/drivers/staging/rtl8192u/r8192U.h
index 920a6a154860..420ab696fc3e 100644
--- a/drivers/staging/rtl8192u/r8192U.h
+++ b/drivers/staging/rtl8192u/r8192U.h
@@ -1122,6 +1122,7 @@ void setKey(struct net_device *dev, u8 EntryNo, u8 KeyIndex, u16 KeyType,

void rtl8192_debugfs_init_one(struct net_device *dev);
void rtl8192_debugfs_exit_one(struct net_device *dev);
+void rtl8192_debugfs_rename_one(struct net_device *dev);
void rtl8192_debugfs_init(void);
void rtl8192_debugfs_exit(void);

diff --git a/drivers/staging/rtl8192u/r8192U_core.c b/drivers/staging/rtl8192u/r8192U_core.c
index 865bc0dc7c71..0a60ef20107c 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_one(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;
@@ -4615,6 +4639,12 @@ 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;
+ }
+
rtl8192_debugfs_init();
ret = ieee80211_debug_init();
if (ret) {
@@ -4663,6 +4693,7 @@ static int __init rtl8192_usb_module_init(void)
ieee80211_debug_exit();
debugfs_exit:
rtl8192_debugfs_exit();
+ unregister_netdevice_notifier(&rtl8192_usb_netdev_notifier);
return ret;
}

@@ -4675,6 +4706,7 @@ static void __exit rtl8192_usb_module_exit(void)
ieee80211_crypto_deinit();
ieee80211_debug_exit();
rtl8192_debugfs_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 c64504346657..fe8ef72506ee 100644
--- a/drivers/staging/rtl8192u/r8192U_debugfs.c
+++ b/drivers/staging/rtl8192u/r8192U_debugfs.c
@@ -169,6 +169,14 @@ void rtl8192_debugfs_exit_one(struct net_device *dev)
debugfs_remove_recursive(priv->debugfs_dir);
}

+void rtl8192_debugfs_rename_one(struct net_device *dev)
+{
+ struct r8192_priv *priv = ieee80211_priv(dev);
+ struct dentry *parent_dir = debugfs_lookup(KBUILD_MODNAME, NULL);
+
+ debugfs_rename(parent_dir, priv->debugfs_dir, parent_dir, dev->name);
+}
+
void rtl8192_debugfs_init(void)
{
debugfs_create_dir(KBUILD_MODNAME, NULL);
--
2.25.1