[PATCH] phy: realtek: usb: Fix the NULL vs IS_ERR() bug for debugfs_create_dir()

[Greg Kroah-Hartman]

On Thu, Aug 31, 2023 at 10:05:59PM +0800, Jinjie Ruan wrote:
> Since both debugfs_create_dir() and debugfs_create_file() return
> ERR_PTR and never return NULL, So use IS_ERR() to check it
> instead of checking NULL.
> 
> Fixes: 134e6d25f6bd ("phy: realtek: usb: Add driver for the Realtek SoC USB 2.0 PHY")
> Fixes: adda6e82a7de ("phy: realtek: usb: Add driver for the Realtek SoC USB 3.0 PHY")
> Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
> ---
>  drivers/phy/realtek/phy-rtk-usb2.c | 6 +++---
>  drivers/phy/realtek/phy-rtk-usb3.c | 6 +++---
>  2 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/phy/realtek/phy-rtk-usb2.c b/drivers/phy/realtek/phy-rtk-usb2.c
> index 5e7ee060b404..67ca78762c80 100644
> --- a/drivers/phy/realtek/phy-rtk-usb2.c
> +++ b/drivers/phy/realtek/phy-rtk-usb2.c
> @@ -853,11 +853,11 @@ static inline void create_debug_files(struct rtk_phy *rtk_phy)
>  
>  	rtk_phy->debug_dir = debugfs_create_dir(dev_name(rtk_phy->dev),
>  						phy_debug_root);
> -	if (!rtk_phy->debug_dir)
> +	if (IS_ERR(rtk_phy->debug_dir))
>  		return;

No, please just drop this check.

>  
> -	if (!debugfs_create_file("parameter", 0444, rtk_phy->debug_dir, rtk_phy,
> -				 &rtk_usb2_parameter_fops))
> +	if (IS_ERR(debugfs_create_file("parameter", 0444, rtk_phy->debug_dir, rtk_phy,
> +				 &rtk_usb2_parameter_fops)))

Again, no, please never check the return value of debugfs_create_file(),
it's not needed at all, and no kernel code should ever do something
different if debugfs returns an error.

debugfs calls should not be checked, they can just be safely passed back
into other debugfs calls, if needed.  That is it.  This api is supposed
to be simple and safe, please don't make it harder than it needs to be :)

thanks,

greg k-h