linux-kernel - Re: [PATCH] bitops: use the same mechanism for get_count_order[

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Message-ID: <20200526070457.GI1634618@smile.fi.intel.com>
Date:   Tue, 26 May 2020 10:04:57 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Wei Yang <richard.weiyang@...il.com>
Cc:     akpm@...ux-foundation.org, christian.brauner@...ntu.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bitops: use the same mechanism for get_count_order[_long]

On Mon, May 25, 2020 at 09:59:58PM +0000, Wei Yang wrote:
> These two functions share the same logic.

So, same comment. Please, add test first, make sure it works on current kernel,
then after your patch applied, and send it as a series, thanks!

P.S. W/o test code looks good, but based on my experience I'm very suspicious
about "small" changes that may lead to big issues. Hope you understand my point.

> Signed-off-by: Wei Yang <richard.weiyang@...il.com>
> ---
>  include/linux/bitops.h | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> index 5b5609e81a84..80703ef27aee 100644
> --- a/include/linux/bitops.h
> +++ b/include/linux/bitops.h
> @@ -188,12 +188,10 @@ static inline unsigned fls_long(unsigned long l)
>  
>  static inline int get_count_order(unsigned int count)
>  {
> -	int order;
> +	if (count == 0)
> +		return -1;
>  
> -	order = fls(count) - 1;
> -	if (count & (count - 1))
> -		order++;
> -	return order;
> +	return fls(--count);
>  }
>  
>  /**
> -- 
> 2.23.0
> 

-- 
With Best Regards,
Andy Shevchenko