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Date: Tue, 10 May 2011 13:39:13 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: masami.hiramatsu.pt@hitachi.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kprobes,x86: disable irq durinr optimized callback
Message-ID: <20110510113913.GA6779@jolsa.brq.redhat.com>
References: <1303822891-8450-1-git-send-email-jolsa@redhat.com>
 <20110510104019.GF2400@elte.hu>
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On Tue, May 10, 2011 at 12:40:19PM +0200, Ingo Molnar wrote:
> 
> * Jiri Olsa <jolsa@redhat.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

thanks,
jirka

> 
> Thanks,
> 
> 	Ingo