linux-kernel - Re: [PATCH] drm/msm: Use div64_ul instead of do

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Date:   Tue, 21 Jun 2022 10:29:07 -0700
From:   Abhinav Kumar <quic_abhinavk@...cinc.com>
To:     Wan Jiabing <wanjiabing@...o.com>, Rob Clark <robdclark@...il.com>,
        "Sean Paul" <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/msm: Use div64_ul instead of do_div



On 4/26/2022 6:21 AM, Wan Jiabing wrote:
> Fix following coccicheck warning:
> drivers/gpu/drm/msm/msm_gpu_devfreq.c:72:1-7: WARNING: do_div() does a 64-by-32 division, please consider using div64_ul instead.
> 
> Use div64_ul instead of do_div to avoid a possible truncation.
> 
> Signed-off-by: Wan Jiabing <wanjiabing@...o.com>
Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> ---
>   drivers/gpu/drm/msm/msm_gpu_devfreq.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> index d2539ca78c29..c2ea978c8921 100644
> --- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> +++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> @@ -69,7 +69,7 @@ static void get_raw_dev_status(struct msm_gpu *gpu,
>   	df->time = time;
>   
>   	busy_time *= USEC_PER_SEC;
> -	do_div(busy_time, sample_rate);
> +	busy_time = div64_ul(busy_time, sample_rate);
>   	if (WARN_ON(busy_time > ~0LU))
>   		busy_time = ~0LU;
>