linux-kernel - Re: Re: [PATCH] Input: cyapa - Fix rumtime PM imbalance on error

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Date:   Thu, 8 Apr 2021 14:29:16 +0800 (GMT+08:00)
From:   dinghao.liu@....edu.cn
To:     "Dmitry Torokhov" <dmitry.torokhov@...il.com>
Cc:     kjlu@....edu, "Fuqian Huang" <huangfq.daxian@...il.com>,
        "Benson Leung" <bleung@...omium.org>,
        "Andrzej Pietrasiewicz" <andrzej.p@...labora.com>,
        "Lee Jones" <lee.jones@...aro.org>, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Re: [PATCH] Input: cyapa - Fix rumtime PM imbalance on error

> Hi Dinghao,
> 
> On Wed, Apr 07, 2021 at 12:07:38PM +0800, Dinghao Liu wrote:
> > When mutex_lock_interruptible() fails, a pairing PM usage
> > counter decrement is needed to keep the counter balanced.
> 
> Thank you for the patch.
> 
> > 
> > Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
> > ---
> >  drivers/input/mouse/cyapa.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/input/mouse/cyapa.c b/drivers/input/mouse/cyapa.c
> > index 77cc653edca2..e411ab45a218 100644
> > --- a/drivers/input/mouse/cyapa.c
> > +++ b/drivers/input/mouse/cyapa.c
> > @@ -904,8 +904,10 @@ static ssize_t cyapa_update_rt_suspend_scanrate(struct device *dev,
> >  	pm_runtime_get_sync(dev);
> >  
> >  	error = mutex_lock_interruptible(&cyapa->state_sync_lock);
> > -	if (error)
> > +	if (error) {
> > +		pm_runtime_put_noidle(dev);
> 
> Why "noidle" and not pm_runtime_put_sync_autosuspend() like we do in
> case of normal flow?
> 

pm_runtime_put_noidle() only decrease the refcount, while 
pm_runtime_put_sync_autosuspend() will execute an extra
pm_runtime_autosuspend(). I'm not sure if the autosuspend is necessary
in this error handling path, so I only balance the counter.

Regards,
Dinghao