linux-kernel - Re: [PATCH] kprobes,x86: disable irq durinr optimized callback

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Date:	Tue, 10 May 2011 13:44:18 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	masami.hiramatsu.pt@...achi.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kprobes,x86: disable irq durinr optimized callback


* Jiri Olsa <jolsa@...hat.com> wrote:

> On Tue, May 10, 2011 at 12:40:19PM +0200, Ingo Molnar wrote:
> > 
> > * Jiri Olsa <jolsa@...hat.com> wrote:
> > 
> > > +	local_irq_save(flags);
> > >  	preempt_disable();
> > >  	if (kprobe_running()) {
> > >  		kprobes_inc_nmissed_count(&op->kp);
> > > @@ -1208,6 +1210,7 @@ static void __kprobes optimized_callback(struct optimized_kprobe *op,
> > >  		__this_cpu_write(current_kprobe, NULL);
> > >  	}
> > >  	preempt_enable_no_resched();
> > > +	local_irq_restore(flags);
> > 
> > irq-disable is synonymous to preempt disable so the preempt_disable()/enable() 
> > pair looks like superfluous overhead.
> 
> yes, there's correct patch already in the list here:
> http://marc.info/?l=linux-kernel&m=130382756829695&w=2

It helps to change the subject line when you think another patch should be 
considered, to something like:

  [PATCH, v2] kprobes, x86: Disable irq during optimized callback

(also note the other changes i made to the title, 3 altogether.)

Thanks,

	Ingo
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