Re: [PATCH] drm: Use kref_put_mutex in drm_gem_object_unreference_unlocked

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Apr 07, 2015 at 03:56:07PM +0200, Maarten Lankhorst wrote:
> If kref_put_mutex returns true then the caller or the put function is responsible
> for unlocking the mutex.

This patch introduces the kref_put_mutex() usage, so this commit
message is rather confusing.

> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 1e6ae1458f7a..7a592d7e398b 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -149,14 +149,16 @@ drm_gem_object_unreference(struct drm_gem_object *obj)
>  static inline void
>  drm_gem_object_unreference_unlocked(struct drm_gem_object *obj)
>  {
> -	if (obj && !atomic_add_unless(&obj->refcount.refcount, -1, 1)) {
> -		struct drm_device *dev = obj->dev;
> +	struct drm_device *dev;
> +
> +	if (!obj)
> +		return;
>  
> -		mutex_lock(&dev->struct_mutex);
> -		if (likely(atomic_dec_and_test(&obj->refcount.refcount)))
> -			drm_gem_object_free(&obj->refcount);
> +	dev = obj->dev;
> +	if (kref_put_mutex(&obj->refcount, drm_gem_object_free, &dev->struct_mutex))
>  		mutex_unlock(&dev->struct_mutex);
> -	}
> +	else
> +		might_lock(&dev->struct_mutex);
>  }
>  
>  int drm_gem_handle_create(struct drm_file *file_priv,
> 
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-- 
Ville Syrjälä
Intel OTC
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