linux-kernel - Re: [PATCH] mm/page_alloc.c: Remove function return value

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Date:   Thu, 29 Dec 2022 15:54:22 +0800
From:   Baoquan He <bhe@...hat.com>
To:     lvqian@...china.com
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/page_alloc.c: Remove function return value

On 12/29/22 at 03:17pm, lvqian@...china.com wrote:
> From: lvqian <lvqian@...china.com>
> 
> The return value of this function has no meaning,
> so the original int type is replaced with a void type,
> which reduces the execution time of one return.
> 
> Signed-off-by: lvqian <lvqian@...china.com>
> ---
>  mm/page_alloc.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0745aedebb37..fffe16d854a9 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -828,17 +828,16 @@ static int __init early_debug_pagealloc(char *buf)
>  }
>  early_param("debug_pagealloc", early_debug_pagealloc);
>  
> -static int __init debug_guardpage_minorder_setup(char *buf)
> +static void __init debug_guardpage_minorder_setup(char *buf)
>  {
>  	unsigned long res;
>  
>  	if (kstrtoul(buf, 10, &res) < 0 ||  res > MAX_ORDER / 2) {
>  		pr_err("Bad debug_guardpage_minorder value\n");
> -		return 0;

This could be not right. Please see parse_args(), the returned value is
needed, otherwise you might get stuff you don't want in the switch case
handling.

parse_early_param()
  -->parse_early_options()
     -->parse_args()

> +	} else {
> +		_debug_guardpage_minorder = res;
> +		pr_info("Setting debug_guardpage_minorder to %lu\n", res);
>  	}
> -	_debug_guardpage_minorder = res;
> -	pr_info("Setting debug_guardpage_minorder to %lu\n", res);
> -	return 0;
>  }
>  early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup);
>  
> -- 
> 2.34.1
>