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Date: Wed, 30 Mar 2011 17:52:38 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Olsa <jolsa@redhat.com>, Paul Mackerras <paulus@samba.org>,
        Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH,RFC] perf: panic due to inclied cpu context task_ctx
	value
Message-ID: <20110330155238.GA5455@redhat.com>
References: <20110326170922.GA20329@redhat.com> <20110326173545.GA22919@redhat.com> <1301164168.2250.370.camel@laptop> <20110328133033.GA8254@redhat.com> <1301324275.4859.25.camel@twins> <1301327368.4859.28.camel@twins> <20110328165648.GA9304@redhat.com> <20110330130951.GA2124@jolsa.brq.redhat.com> <20110330153228.GA1787@redhat.com> <1301499652.4859.193.camel@twins>
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On 03/30, Peter Zijlstra wrote:
>
> On Wed, 2011-03-30 at 17:32 +0200, Oleg Nesterov wrote:
> > > +#ifdef HAVE_JUMP_LABEL
> > > +static inline
> > > +void perf_sched_events_inc(void)
> > > +{
> > > +     jump_label_inc(&perf_sched_events_out);
> > > +     smp_mb__after_atomic_inc();
> > > +     jump_label_inc(&perf_sched_events_in);
> > > +}
> >
> > probably smp_mb__after_atomic_inc() needs a comment...
>
> You don't need it, jump_label_inc() uses atomic_add_return() which
> implies a full mb.

Yes, but only if HAVE_JUMP_LABEL.

Oleg.