Re: [PATCH -next] pwm: img: Fix PM reference leak in img_pwm_enable()

[Samuel Zou]

Hi Uwe,

Sorry for the delayed reply.
Thanks for all the review,.
To keep the consistency, it's better to clean this up accordingly, and I 
will send a new patch soon.

On 2021/6/29 1:01, Uwe Kleine-König wrote:
> Hello Zou,
> On Mon, Jun 28, 2021 at 08:38:39AM +0200, Uwe Kleine-König wrote:
> > On Fri, Jun 25, 2021 at 07:45:14PM +0200, Rafael J. Wysocki wrote:
> > > On Wed, May 12, 2021 at 6:52 AM Uwe Kleine-König
> > > <u.kleine-koenig@xxxxxxxxxxxxxx> wrote:
> > > > On Wed, May 12, 2021 at 11:57:17AM +0800, Zou Wei wrote:
> > > > > pm_runtime_get_sync will increment pm usage counter even it failed.
> > > > > Forgetting to putting operation will result in reference leak here.
> > > > > Fix it by replacing it with pm_runtime_resume_and_get to keep usage
> > > > > counter balanced.
> > > > >
> > > > > Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> > > > > Signed-off-by: Zou Wei <zou_wei@xxxxxxxxxx>
> > > > > ---
> > > > >   drivers/pwm/pwm-img.c | 2 +-
> > > > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/pwm/pwm-img.c b/drivers/pwm/pwm-img.c
> > > > > index cc37054..11b16ec 100644
> > > > > --- a/drivers/pwm/pwm-img.c
> > > > > +++ b/drivers/pwm/pwm-img.c
> > > > > @@ -156,7 +156,7 @@ static int img_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> > > > >        struct img_pwm_chip *pwm_chip = to_img_pwm_chip(chip);
> > > > >        int ret;
> > > > >
> > > > > -     ret = pm_runtime_get_sync(chip->dev);
> > > > > +     ret = pm_runtime_resume_and_get(chip->dev);
> > > > >        if (ret < 0)
> > > > >                return ret;
> > > >
> > > > This patch looks right with my limited understanding of pm_runtime. A
> > > > similar issue in this driver was fixed in commit
> > > >
> > > >          ca162ce98110 ("pwm: img: Call pm_runtime_put() in pm_runtime_get_sync() failed case")
> > > >
> > > > where (even though the commit log talks about pm_runtime_put()) a call
> > > > to pm_runtime_put_autosuspend() was added in the error path.
> > > >
> > > > I added the PM guys to Cc, maybe they can advise about the right thing
> > > > to do here. Does it make sense to use the same idiom in both
> > > > img_pwm_enable() and img_pwm_config()?
> > >
> > > I think so.
> > >
> > > And calling pm_runtime_put_autosuspend() in the img_pwm_enable() error
> > > path would work too.
> >
> > Do you care to clean this up accordingly and send a new patch?
>
> Note that Thierry applied your initial patch regardless of the
> inconsistency. Still I'd like to see this done in a consistent way. Do
> you care to follow up with a patch that unifies the behaviour?
>
> Best regards
> Uwe