linux-kernel - Re: [PATCH] tracing: kprobe-event: Return directly when trace kprobes is empty

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Message-ID: <20260127093401.2c2aaf18@gandalf.local.home>
Date: Tue, 27 Jan 2026 09:34:01 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: sunliming@...ux.dev
Cc: ostedt@...dmis.org, mhiramat@...nel.org, mathieu.desnoyers@...icios.com,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, sunliming
 <sunliming@...inos.cn>
Subject: Re: [PATCH] tracing: kprobe-event: Return directly when trace
 kprobes is empty

On Tue, 27 Jan 2026 10:01:37 +0800
sunliming@...ux.dev wrote:

> From: sunliming <sunliming@...inos.cn>
> 
> In enable_boot_kprobe_events(), it returns directly when trace kprobes is
> empty, thereby reducing the function's execution time. This function may
> otherwise wait for the event_mutex lock for tens of milliseconds on certain
> machines, which is unnecessary when trace kprobes is empty.
> 
> Signed-off-by: sunliming <sunliming@...inos.cn>

Reviewed-by: Steven Rostedt (Google) <rostedt@...dmis.org>

Thanks,

-- Steve

> ---
>  kernel/trace/trace_kprobe.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 9953506370a5..95f2c42603d5 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -82,6 +82,7 @@ static struct trace_kprobe *to_trace_kprobe(struct dyn_event *ev)
>  #define for_each_trace_kprobe(pos, dpos)	\
>  	for_each_dyn_event(dpos)		\
>  		if (is_trace_kprobe(dpos) && (pos = to_trace_kprobe(dpos)))
> +#define trace_kprobe_list_empty() list_empty(&dyn_event_list)
>  
>  static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
>  {
> @@ -1982,6 +1983,9 @@ static __init void enable_boot_kprobe_events(void)
>  	struct trace_kprobe *tk;
>  	struct dyn_event *pos;
>  
> +	if (trace_kprobe_list_empty())
> +		return;
> +
>  	guard(mutex)(&event_mutex);
>  	for_each_trace_kprobe(tk, pos) {
>  		list_for_each_entry(file, &tr->events, list)