linux-kernel - Re: [PATCH] fix BUG using smp_processor_id() in touch_nmi_watchdog and touch_softlockup

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Message-ID: <20100817124839.GA2838@zhy>
Date:	Tue, 17 Aug 2010 20:48:39 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Don Zickus <dzickus@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fix BUG using smp_processor_id() in touch_nmi_watchdog
 and touch_softlockup_watchdog

On Tue, Aug 17, 2010 at 01:28:19PM +0300, Sergey Senozhatsky wrote:
> > So preempt_disable() is redundant here.
> >
> 
> Shouldn't we be for sure not preepmtible when calling __raw_get_cpu_var?

IMHO, it's the caller's responsibility.

> 
> preempt_disable is reduntant here because current_thread_info()->cpu is 
> atomic and we just don't want preempt_(enable|disable) overhead?

Yep.

Thanks,
Yong
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