linux-kernel - Re: [PATCH V1] mm/damon: Modify damon_rand() macro to static inline function

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Message-Id: <20211206124523.6259-1-sj@kernel.org>
Date:   Mon,  6 Dec 2021 12:45:23 +0000
From:   SeongJae Park <sj@...nel.org>
To:     Xin Hao <xhao@...ux.alibaba.com>
Cc:     sj@...nel.org, akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V1] mm/damon: Modify damon_rand() macro to static inline function

On Mon, 6 Dec 2021 20:41:29 +0800 Xin Hao <xhao@...ux.alibaba.com> wrote:

> The damon_rand() func can not be implemented as a macro.
> Example:
> 	damon_rand(a++, b);
> The value of 'a' will be incremented twice, This is obviously
> unreasonable, So there fix it.
> 
> Fixes: b9a6ac4e4ede ("mm/damon: adaptively adjust regions")
> Reported-by: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Xin Hao <xhao@...ux.alibaba.com>
> ---
>  include/linux/damon.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/damon.h b/include/linux/damon.h
> index c6df025d8704..bc9c8932b1e8 100644
> --- a/include/linux/damon.h
> +++ b/include/linux/damon.h
> @@ -19,7 +19,10 @@
>  #define DAMOS_MAX_SCORE		(99)
> 
>  /* Get a random number in [l, r) */
> -#define damon_rand(l, r) (l + prandom_u32_max(r - l))
> +static inline unsigned long damon_rand(unsigned long l, unsigned long r)
> +{
> +	return l + (r - l);

Seems prandom_u32_max() is missed?


Thanks,
SJ

> +}
> 
>  /**
>   * struct damon_addr_range - Represents an address region of [@start, @end).
> --
> 2.31.0