From: Gautham R Shenoy <ego@in.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
mathieu.desnoyers@polymtl.ca, mingo@elte.hu, hch@infradead.org,
mmlnx@us.ibm.com, dipankar@in.ibm.com, dsmith@redhat.com,
rostedt@goodmis.org, adrian.bunk@movial.fi,
a.p.zijlstra@chello.nl, niv@us.ibm.com, dvhltc@us.ibm.com,
rusty@au1.ibm.com, jkenisto@linux.vnet.ibm.com, oleg@tv-sign.ru
Subject: Re: [PATCH,RFC] Add call_rcu_sched()
Date: Tue, 8 Apr 2008 14:26:37 +0530 [thread overview]
Message-ID: <20080408085637.GA30496@in.ibm.com> (raw)
In-Reply-To: <20080408013936.b84ae895.akpm@linux-foundation.org>
On Tue, Apr 08, 2008 at 01:39:36AM -0700, Andrew Morton wrote:
> On Tue, 8 Apr 2008 13:40:48 +0530 Gautham R Shenoy <ego@in.ibm.com> wrote:
>
> > > > + rdp = RCU_DATA_CPU(cpu);
> > <-- here ------\
> > > > + spin_lock_irqsave(&rdp->lock, flags); |
> > > > + |
> > > > + /* |
> > > > + * We are running on this CPU irq-disabled, so no |
> > > > + * CPU can go offline until we re-enable irqs. |
> > > |
> > > but, but, but. The cpu at `cpu' could have gone offline just before we |
> > > disabled local interrupts. |
> > |
> > In that case the CPU_DEAD callback should have migrated the rcu-lists to |
> > a cpu which is online. |
> |
> But local variable rdp might be pointing at the now-offlined CPU's data? -------/
Right. But then rdp wouldn't contain anything useful at this point.
So, we may only end up taking the rdp->lock, observe that there's nothing to do,
and move on.
Is there something else that I am missing?
--
Thanks and Regards
gautham
next prev parent reply other threads:[~2008-04-08 8:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-21 14:36 [PATCH,RFC] Add call_rcu_sched() Paul E. McKenney
2008-03-21 22:40 ` Paul E. McKenney
2008-03-24 5:06 ` Mathieu Desnoyers
2008-03-24 5:46 ` Paul E. McKenney
2008-03-24 13:59 ` Mathieu Desnoyers
2008-03-25 12:53 ` [PATCH,RFC] Initialize call_rcu_sched sooner Mathieu Desnoyers
2008-03-25 18:49 ` Paul E. McKenney
2008-04-06 21:37 ` [PATCH,RFC] Add call_rcu_sched() Paul E. McKenney
2008-04-08 7:34 ` Andrew Morton
2008-04-08 8:10 ` Gautham R Shenoy
2008-04-08 8:39 ` Andrew Morton
2008-04-08 8:56 ` Gautham R Shenoy [this message]
2008-04-08 9:07 ` Andrew Morton
2008-04-08 17:17 ` Paul E. McKenney
2008-04-08 16:59 ` Paul E. McKenney
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