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From: Ingo Molnar <mingo@elte.hu>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] markers: bit-field is not thread-safe nor smp-safe
Date: Fri, 10 Oct 2008 09:35:21 +0200	[thread overview]
Message-ID: <20081010073520.GC16016@elte.hu> (raw)
In-Reply-To: <20081010073136.GC23247@Krystal>


* Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:

> * Lai Jiangshan (laijs@cn.fujitsu.com) wrote:
> > 
> > bit-field is not thread-safe nor smp-safe.
> > 
> > struct marker_entry.rcu_pending is not protected by any lock
> > in rcu-callback free_old_closure().
> > so we must turn it into a safe type.
> > 
> 
> 
> hrm, yes, you are right. I first test for 
> 
>         if (entry->rcu_pending)
>            rcu_barrier_sched();
> 
> To check if I must execute the rcu callback, and _this_ races against
> the entry->rcu_pending = 0; within the callback.
> 
> Your fix is therefore needed.
> 
> Thanks !
> 
> Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

applied to tip/tracing/markers, thanks guys!

	Ingo

  reply	other threads:[~2008-10-10  7:35 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-10  6:43 [PATCH] markers: bit-field is not thread-safe nor smp-safe Lai Jiangshan
2008-10-10  7:31 ` Mathieu Desnoyers
2008-10-10  7:35   ` Ingo Molnar [this message]
  -- strict thread matches above, loose matches on Subject: below --
2008-10-10  3:06 Lai Jiangshan
2008-10-10  4:26 ` KOSAKI Motohiro
2008-10-10  5:30   ` Lai Jiangshan
2008-10-10  5:42 ` Mathieu Desnoyers

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