Re: [PATCH 2/5] kprobes: Use guard() for external locks

Peter Zijlstra
2024-12-09T11:04:22Z

On Mon, Dec 09, 2024 at 11:41:26AM +0900, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> Use guard() for text_mutex, cpu_read_lock, and jump_label_lock in
> the kprobes.

> @@ -853,29 +850,24 @@ static void try_to_optimize_kprobe(struct kprobe *p)
> return;
>
> /* For preparing optimization, jump_label_text_reserved() is called. */
> - cpus_read_lock();
> - jump_label_lock();
> - mutex_lock(&text_mutex);
> + guard(cpus_read_lock)();
> + guard(jump_label_lock)();
> + guard(mutex)(&text_mutex);
>

> @@ -1294,62 +1280,55 @@ static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
> int ret = 0;
> struct kprobe *ap = orig_p;
>
> - cpus_read_lock();
> -
> - /* For preparing optimization, jump_label_text_reserved() is called */
> - jump_label_lock();
> - mutex_lock(&text_mutex);

Why does kprobe need jump_label_lock and how does it then not also need
static_call_lock ?