linux-kernel - Re: [PATCH 4/4] PM / devfreq: Check governor before using governor->name

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Message-ID: <CAGTfZH0jQ7j7_u=tMpe32n8RzG5sZk7ze5vOAnkbh5mxmba_EA@mail.gmail.com>
Date: Wed, 14 May 2025 02:43:53 +0900
From: Chanwoo Choi <chanwoo@...nel.org>
To: Lifeng Zheng <zhenglifeng1@...wei.com>
Cc: myungjoo.ham@...sung.com, kyungmin.park@...sung.com, cw00.choi@...sung.com, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, linuxarm@...wei.com, 
	jonathan.cameron@...wei.com, zhanjie9@...ilicon.com, lihuisong@...wei.com, 
	yubowen8@...wei.com, cenxinghai@...artners.com
Subject: Re: [PATCH 4/4] PM / devfreq: Check governor before using governor->name

Hi,

Applied it. Thanks.

On Mon, Apr 21, 2025 at 12:01 PM Lifeng Zheng <zhenglifeng1@...wei.com> wrote:
>
> Commit 96ffcdf239de ("PM / devfreq: Remove redundant governor_name from
> struct devfreq") removes governor_name and uses governor->name to replace
> it. But devfreq->governor may be NULL and directly using
> devfreq->governor->name may cause null pointer exception. Move the check of
> governor to before using governor->name.
>
> Fixes: 96ffcdf239de ("PM / devfreq: Remove redundant governor_name from struct devfreq")
> Signed-off-by: Lifeng Zheng <zhenglifeng1@...wei.com>
> ---
>  drivers/devfreq/devfreq.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 18e3f7e063a4..46f3a8053197 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -1376,15 +1376,11 @@ int devfreq_remove_governor(struct devfreq_governor *governor)
>                 int ret;
>                 struct device *dev = devfreq->dev.parent;
>
> +               if (!devfreq->governor)
> +                       continue;
> +
>                 if (!strncmp(devfreq->governor->name, governor->name,
>                              DEVFREQ_NAME_LEN)) {
> -                       /* we should have a devfreq governor! */
> -                       if (!devfreq->governor) {
> -                               dev_warn(dev, "%s: Governor %s NOT present\n",
> -                                        __func__, governor->name);
> -                               continue;
> -                               /* Fall through */
> -                       }
>                         ret = devfreq->governor->event_handler(devfreq,
>                                                 DEVFREQ_GOV_STOP, NULL);
>                         if (ret) {
> --
> 2.33.0
>
>


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics