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From:   SeongJae Park <sj@kernel.org>
To:     Xin Hao <xhao@linux.alibaba.com>
Cc:     sj@kernel.org, akpm@linux-foundation.org, damon@lists.linux.dev,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 1/2] mm/damon/sysfs: remove unnecessary variables
Date:   Mon, 19 Sep 2022 17:03:05 +0000
Message-Id: <20220919170305.61335-1-sj@kernel.org>
In-Reply-To: <20220919151201.66696-1-xhao@linux.alibaba.com>
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On Mon, 19 Sep 2022 23:12:00 +0800 Xin Hao <xhao@linux.alibaba.com> wrote:

> Just do a little change here, the 'err' variable really no need to stay
> here.
> 
> Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
> ---
>  mm/damon/sysfs.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
> index 0cca1909bf67..b852a75b9f39 100644
> --- a/mm/damon/sysfs.c
> +++ b/mm/damon/sysfs.c
> @@ -1109,9 +1109,8 @@ static ssize_t start_store(struct kobject *kobj, struct kobj_attribute *attr,
>  {
>  	struct damon_sysfs_region *region = container_of(kobj,
>  			struct damon_sysfs_region, kobj);
> -	int err = kstrtoul(buf, 0, &region->start);
> 
> -	if (err)
> +	if (kstrtoul(buf, 0, &region->start))
>  		return -EINVAL;

Good finding.  But, I'd like to let the user know why it really fails by giving
them the error code that returned by 'kstrtoul()' here.  Let's keep the 'err'
but return 'err' here.

>  	return count;
>  }
> @@ -1130,9 +1129,8 @@ static ssize_t end_store(struct kobject *kobj, struct kobj_attribute *attr,
>  {
>  	struct damon_sysfs_region *region = container_of(kobj,
>  			struct damon_sysfs_region, kobj);
> -	int err = kstrtoul(buf, 0, &region->end);
> 
> -	if (err)
> +	if (kstrtoul(buf, 0, &region->end))
>  		return -EINVAL;

ditto.

>  	return count;
>  }
> --
> 2.31.0


Thanks,
SJ