linux-kernel - Re: [PATCH V2] thermal: Fix locking in cooling device sysfs update cur

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Date:   Thu, 03 Jan 2019 10:51:22 +0800
From:   Zhang Rui <rui.zhang@...el.com>
To:     Thara Gopinath <thara.gopinath@...aro.org>, edubezval@...il.com,
        daniel.lezcano@...aro.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] thermal: Fix locking in cooling device sysfs update
 cur_state

On 三, 2019-01-02 at 21:29 -0500, Thara Gopinath wrote:
> On 11/27/2018 05:43 PM, Thara Gopinath wrote:
> > 
> > Sysfs interface to update cooling device cur_state does not
> > currently holding cooling device lock sometimes leading to
> > stale values in cur_state if getting updated simultanelously
> > from user space and thermal framework. Adding the proper locking
> > code fixes this issue.
> > 
> > Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
> > ---
> > 
> > V1->V2: Rearranged the code as per Daniel's  review comment 
> Hi Eduardo, Daniel
> 
> Any comments on this ?
> 
it's already in my tree, and will be included in my pull request which
will be sent out soon.

thanks,
rui

> Regards
> Thara
> 
> > 
> > 
> >  drivers/thermal/thermal_sysfs.c | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/thermal/thermal_sysfs.c
> > b/drivers/thermal/thermal_sysfs.c
> > index 2241cea..aa99edb 100644
> > --- a/drivers/thermal/thermal_sysfs.c
> > +++ b/drivers/thermal/thermal_sysfs.c
> > @@ -712,11 +712,14 @@ cur_state_store(struct device *dev, struct
> > device_attribute *attr,
> >  	if ((long)state < 0)
> >  		return -EINVAL;
> >  
> > +	mutex_lock(&cdev->lock);
> > +
> >  	result = cdev->ops->set_cur_state(cdev, state);
> > -	if (result)
> > -		return result;
> > -	thermal_cooling_device_stats_update(cdev, state);
> > -	return count;
> > +	if (!result)
> > +		thermal_cooling_device_stats_update(cdev, state);
> > +
> > +	mutex_unlock(&cdev->lock);
> > +	return result ? result : count;
> >  }
> >  
> >  static struct device_attribute
> > 
> 
>