linux-kernel - Re: [PATCH 5/5] staging: pi433: Remove duplicated code using the "goto" error recovery scheme.

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Date: Thu, 28 Mar 2024 17:03:17 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Shahar Avidar <ikobh7@...il.com>
Cc: gregkh@...uxfoundation.org, hverkuil-cisco@...all.nl,
	andriy.shevchenko@...ux.intel.com, robh@...nel.org,
	felixkimbu1@...il.com, linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] staging: pi433: Remove duplicated code using the
 "goto" error recovery scheme.

On Thu, Mar 28, 2024 at 02:12:44PM +0200, Shahar Avidar wrote:
> pi433_init had "unregister_chrdev" called twice.
> Remove it using goto statements.
> 
> Signed-off-by: Shahar Avidar <ikobh7@...il.com>
> ---
>  drivers/staging/pi433/pi433_if.c | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/pi433/pi433_if.c b/drivers/staging/pi433/pi433_if.c
> index 62ce75b07bf0..e538f1d4e787 100644
> --- a/drivers/staging/pi433/pi433_if.c
> +++ b/drivers/staging/pi433/pi433_if.c
> @@ -1400,24 +1400,25 @@ static int __init pi433_init(void)
>  	 */
>  	status = alloc_chrdev_region(&pi433_devt, 0, N_PI433_MINORS, "pi433");
>  	if (status < 0)
> -		return status;
> +		goto fail;

Just return directly.  Do nothing gotos are bad for readability and they
create Forgot to Set the Error Code bugs.  Also there was a direct
return earlier in the function so it's better to do things consistently.

>  
>  	status = class_register(&pi433_class);
> -	if (status) {
> -		unregister_chrdev(MAJOR(pi433_devt),
> -				  pi433_spi_driver.driver.name);
> -		return status;
> -	}
> +	if (status)
> +		goto unreg_chrdev;
>  
>  	root_dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
>  
>  	status = spi_register_driver(&pi433_spi_driver);
> -	if (status < 0) {
> -		class_unregister(&pi433_class);
> -		unregister_chrdev(MAJOR(pi433_devt),
> -				  pi433_spi_driver.driver.name);
> -	}
> +	if (status < 0)
> +		goto unreg_class;
>  
> +	return 0;
> +
> +unreg_class:
> +	class_unregister(&pi433_class);

There is a debugfs_remove() missing.  I have written a blog that might
be helpful:

https://staticthinking.wordpress.com/2022/04/28/free-the-last-thing-style/

regards,
dan carpenter

> +unreg_chrdev:
> +	unregister_chrdev(MAJOR(pi433_devt), pi433_spi_driver.driver.name);
> +fail:
>  	return status;
>  }