drm: factor out drm_close_helper() function

Will be used to plug an existing memory leak.
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114084410.15266-1-emil.l.velikov@gmail.com

drivers/gpu/drm/drm_file.c

@@ -262,6 +262,18 @@ void drm_file_free(struct drm_file *file)
 	kfree(file);
 }
 
+static void drm_close_helper(struct file *filp)
+{
+	struct drm_file *file_priv = filp->private_data;
+	struct drm_device *dev = file_priv->minor->dev;
+
+	mutex_lock(&dev->filelist_mutex);
+	list_del(&file_priv->lhead);
+	mutex_unlock(&dev->filelist_mutex);
+
+	drm_file_free(file_priv);
+}
+
 static int drm_setup(struct drm_device * dev)
 {
 	int ret;
@@ -473,11 +485,7 @@ int drm_release(struct inode *inode, struct file *filp)
 
 	DRM_DEBUG("open_count = %d\n", dev->open_count);
 
-	mutex_lock(&dev->filelist_mutex);
-	list_del(&file_priv->lhead);
-	mutex_unlock(&dev->filelist_mutex);
-
-	drm_file_free(file_priv);
+	drm_close_helper(filp);
 
 	if (!--dev->open_count) {
 		drm_lastclose(dev);