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

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Mon, 9 Dec 2024 12:04:11 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> 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 ?

Good catch! It has not been updated for static_call_text_reserved().
We need static_call_lock() here too.

Thanks!


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>