Re: [PATCH 02/13] USB: ULPI: fix memory leak with using debugfs_lookup()

[Heikki Krogerus]

On Thu, Feb 02, 2023 at 04:32:24PM +0100, Greg Kroah-Hartman wrote:
> When calling debugfs_lookup() the result must have dput() called on it,
> otherwise the memory will leak over time.  To make things simpler, just
> call debugfs_lookup_and_remove() instead which handles all of the logic
> at once.
> 
> Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Cc: linux-usb@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

> ---
>  drivers/usb/common/ulpi.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/usb/common/ulpi.c b/drivers/usb/common/ulpi.c
> index 67b780b256a9..a98b2108376a 100644
> --- a/drivers/usb/common/ulpi.c
> +++ b/drivers/usb/common/ulpi.c
> @@ -271,7 +271,7 @@ static int ulpi_regs_show(struct seq_file *seq, void *data)
>  }
>  DEFINE_SHOW_ATTRIBUTE(ulpi_regs);
>  
> -#define ULPI_ROOT debugfs_lookup(KBUILD_MODNAME, NULL)
> +static struct dentry *ulpi_root;
>  
>  static int ulpi_register(struct device *dev, struct ulpi *ulpi)
>  {
> @@ -301,7 +301,7 @@ static int ulpi_register(struct device *dev, struct ulpi *ulpi)
>  		return ret;
>  	}
>  
> -	root = debugfs_create_dir(dev_name(dev), ULPI_ROOT);
> +	root = debugfs_create_dir(dev_name(dev), ulpi_root);
>  	debugfs_create_file("regs", 0444, root, ulpi, &ulpi_regs_fops);
>  
>  	dev_dbg(&ulpi->dev, "registered ULPI PHY: vendor %04x, product %04x\n",
> @@ -349,8 +349,7 @@ EXPORT_SYMBOL_GPL(ulpi_register_interface);
>   */
>  void ulpi_unregister_interface(struct ulpi *ulpi)
>  {
> -	debugfs_remove_recursive(debugfs_lookup(dev_name(&ulpi->dev),
> -						ULPI_ROOT));
> +	debugfs_lookup_and_remove(dev_name(&ulpi->dev), ulpi_root);
>  	device_unregister(&ulpi->dev);
>  }
>  EXPORT_SYMBOL_GPL(ulpi_unregister_interface);
> @@ -360,12 +359,11 @@ EXPORT_SYMBOL_GPL(ulpi_unregister_interface);
>  static int __init ulpi_init(void)
>  {
>  	int ret;
> -	struct dentry *root;
>  
> -	root = debugfs_create_dir(KBUILD_MODNAME, NULL);
> +	ulpi_root = debugfs_create_dir(KBUILD_MODNAME, NULL);
>  	ret = bus_register(&ulpi_bus);
>  	if (ret)
> -		debugfs_remove(root);
> +		debugfs_remove(ulpi_root);
>  	return ret;
>  }
>  subsys_initcall(ulpi_init);
> @@ -373,7 +371,7 @@ subsys_initcall(ulpi_init);
>  static void __exit ulpi_exit(void)
>  {
>  	bus_unregister(&ulpi_bus);
> -	debugfs_remove_recursive(ULPI_ROOT);
> +	debugfs_remove(ulpi_root);
>  }
>  module_exit(ulpi_exit);
>  
> -- 
> 2.39.1

-- 
heikki