The pp_debugfs_dir is already initialized by the module init function. If it doesn't exist here, I think we should just return instead of trying again. It's also worth noting, though it is probably no harm, the code here does not check debugfs_initialized().
+static int __init tool_init(void)This should be pp_init() not tool_init().
Yup, this is just sloppy copying on my part. I copied from two different places. I'll fix these oversights.
Thanks, Logan