Re: Subject: [PATCH] kobject: fix the race between kobject_del and get_device_parent

[Tejun Heo <tj@kernel.org>]

Hello,

Sorry about the delay.

On Wed, Oct 22, 2014 at 04:07:44PM +0800, Weng Meiling wrote:
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 28b808c..645eacf 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -724,12 +724,12 @@ class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
>  	return &dir->kobj;
>  }
> 
> +static DEFINE_MUTEX(gdp_mutex);
> 
>  static struct kobject *get_device_parent(struct device *dev,
>  					 struct device *parent)
>  {
>  	if (dev->class) {
> -		static DEFINE_MUTEX(gdp_mutex);
>  		struct kobject *kobj = NULL;
>  		struct kobject *parent_kobj;
>  		struct kobject *k;
> @@ -793,7 +793,9 @@ static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
>  	    glue_dir->kset != &dev->class->p->glue_dirs)
>  		return;
> 
> +	mutex_lock(&gdp_mutex);
>  	kobject_put(glue_dir);
> +	mutex_unlock(&gdp_mutex);

So, yeah, this looks like a correct approach; however, do we even need
to clear the glue directories?  What's the downside of just keeping
them around once created?

Thanks.

-- 
tejun