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Date: Mon, 1 Jul 2013 22:55:56 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com,
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        sbw@mit.edu
Subject: Re: [PATCH RFC nohz_full v2 6/7] nohz_full: Add full-system-idle
 state machine
Message-ID: <20130701205554.GQ7246@somewhere.redhat.com>
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On Mon, Jul 01, 2013 at 11:10:40AM -0700, Paul E. McKenney wrote:
> On Mon, Jul 01, 2013 at 06:35:31PM +0200, Frederic Weisbecker wrote:
> > What makes sure that we are not reading a stale value of rdtp->dynticks_idle
> > in the following scenario:
> > 
> >     CPU 0                          CPU 1
> >     
> >                                    //CPU 1 idle
> >                                    //rdtp(1)->dynticks_idle == 0
> > 
> > sysidle_check_cpu(CPU 1) {
> >     rdtp(1)->dynticks_idle == 0
> > }
> > cmpxchg(full_sysidle_state, 
> >         ...RCU_SYSIDLE_SHORT)
> >                                    rcu_irq_exit() {
> 
> rcu_irq_enter(), right?
>

Woops, I meant rcu_idle_exit(). But yeah rcu_irq_enter() as well.

Thanks.