linux-kernel - Re: [PATCH] drm/i915: use sysfs_emit() to instead of scnprintf()

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Date:   Mon, 05 Dec 2022 12:50:53 +0200
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     ye.xingchen@....com.cn, joonas.lahtinen@...ux.intel.com
Cc:     rodrigo.vivi@...el.com, tvrtko.ursulin@...ux.intel.com,
        airlied@...il.com, daniel@...ll.ch,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/i915: use sysfs_emit() to instead of scnprintf()

On Thu, 01 Dec 2022, <ye.xingchen@....com.cn> wrote:
> From: ye xingchen <ye.xingchen@....com.cn>
>
> Replace the open-code with sysfs_emit() to simplify the code.

I was going to push this, but noticed the function has a third
scnprintf(), and the last two play together with count. It would be
confusing to have a mix of sysfs_emit() and scnprintf(). The third one
can't be blindly converted to sysfs_emit() because it writes at an
offset not aligned by PAGE_SIZE.

So I'm not taking this.

BR,
Jani.

>
> Signed-off-by: ye xingchen <ye.xingchen@....com.cn>
> ---
>  drivers/gpu/drm/i915/i915_mitigations.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_mitigations.c b/drivers/gpu/drm/i915/i915_mitigations.c
> index def7302ef7fe..2b7aaaefb3a9 100644
> --- a/drivers/gpu/drm/i915/i915_mitigations.c
> +++ b/drivers/gpu/drm/i915/i915_mitigations.c
> @@ -102,10 +102,10 @@ static int mitigations_get(char *buffer, const struct kernel_param *kp)
>  	bool enable;
>
>  	if (!local)
> -		return scnprintf(buffer, PAGE_SIZE, "%s\n", "off");
> +		return sysfs_emit(buffer, "%s\n", "off");
>
>  	if (local & BIT(BITS_PER_LONG - 1)) {
> -		count = scnprintf(buffer, PAGE_SIZE, "%s,", "auto");
> +		count = sysfs_emit(buffer, "%s,", "auto");
>  		enable = false;
>  	} else {
>  		enable = true;

-- 
Jani Nikula, Intel Open Source Graphics Center