Re: [PATCH v2] perf/ftrace: Fix WARNING in __unregister_ftrace_function

[Steven Rostedt]

On Wed, 13 May 2026 16:19:16 -0400
Rik van Riel <riel@xxxxxxxxxxx> wrote:

> diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
> index a6bb7577e8c5..58e1b427b576 100644
> --- a/kernel/trace/trace_event_perf.c
> +++ b/kernel/trace/trace_event_perf.c
> @@ -497,7 +497,11 @@ static int perf_ftrace_function_register(struct perf_event *event)
>  static int perf_ftrace_function_unregister(struct perf_event *event)
>  {
>  	struct ftrace_ops *ops = &event->ftrace_ops;
> -	int ret = unregister_ftrace_function(ops);
> +	int ret = 0;
> +

Because this is different than unregister_ftrace_function() where it will
not fail if the ops is not registered, it deserves a comment. Something
like:

	/*
	 * Perf will call this unconditionally even if the ops is not
	 * enabled. The unregister_ftrace_function() will warn if called
	 * when not enabled. Just bypass the unregistering if ops isn't
	 * enabled here.
	 */

Thanks,

-- Steve


> +	if (ops->flags & FTRACE_OPS_FL_ENABLED)
> +		ret = unregister_ftrace_function(ops);
> +
>  	ftrace_free_filter(ops);
>  	return ret;
>  }