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Date: Tue, 17 Aug 2010 20:48:39 +0800
From: Yong Zhang <yong.zhang0@gmail.com>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>, Don Zickus <dzickus@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fix BUG using smp_processor_id() in touch_nmi_watchdog
 and touch_softlockup_watchdog
Message-ID: <20100817124839.GA2838@zhy>
Reply-To: Yong Zhang <yong.zhang0@gmail.com>
References: <20100816133452.GS4879@redhat.com>
 <1281966418.1926.1421.camel@laptop>
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 <AANLkTik-4S_=L5FLhMfommf5Umd0xO+h4QP9uoxwrgFE@mail.gmail.com>
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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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