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From: "Aguirre, Sergio" <saaguirre@ti.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Huang Ying <ying.huang@intel.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Ingo Molnar <mingo@elte.hu>, Kyle McMartin <kyle@mcmartin.ca>
Subject: RE: [RFC][PATCH] irq_work: Don't ignore possible cmpxchg failure
Date: Tue, 16 Nov 2010 10:57:02 -0600	[thread overview]
Message-ID: <A24693684029E5489D1D202277BE89447382A55A@dlee02.ent.ti.com> (raw)
In-Reply-To: <1289925901.2109.629.camel@laptop>

Hi Peter,

> -----Original Message-----
> From: Peter Zijlstra [mailto:a.p.zijlstra@chello.nl]
> Sent: Tuesday, November 16, 2010 10:45 AM
> To: Aguirre, Sergio
> Cc: LKML; Huang Ying; Martin Schwidefsky; Ingo Molnar; Kyle McMartin
> Subject: Re: [RFC][PATCH] irq_work: Don't ignore possible cmpxchg failure
> 
> On Tue, 2010-11-16 at 10:32 -0600, Sergio Aguirre wrote:
> > Although is very unlikely, it's better to make sure we're not
> > letting this happen.
> >
> > This solves this compilation warning:
> >
> > kernel/irq_work.c: In function 'irq_work_run':
> > kernel/irq_work.c:148: warning: value computed is not used
> >
> 
> > @@ -145,7 +145,10 @@ void irq_work_run(void)
> >  		 * Clear the BUSY bit and return to the free state if
> >  		 * no-one else claimed it meanwhile.
> >  		 */
> > -		cmpxchg(&entry->next, next_flags(NULL, IRQ_WORK_BUSY), NULL);
> > +		xchgres = cmpxchg(&entry->next,
> > +				  next_flags(NULL, IRQ_WORK_BUSY),
> > +				  NULL);
> > +		BUG_ON(unlikely(xchgres != next_flags(NULL, IRQ_WORK_BUSY)));
> 
> simply adding (void) in front would be much easier.

But isn't that still leaving the remote possibility of a hidden cmpxchg
Failure open?

Regards,
Sergio

  reply	other threads:[~2010-11-16 16:57 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-16 16:32 [RFC][PATCH] irq_work: Don't ignore possible cmpxchg failure Sergio Aguirre
2010-11-16 16:45 ` Peter Zijlstra
2010-11-16 16:57   ` Aguirre, Sergio [this message]
2010-11-16 17:08     ` Peter Zijlstra
2010-11-16 17:11       ` Aguirre, Sergio

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