RE: [PATCH] Fix the race between smp_call_function and CPU booting

From: Liu, Chuansheng
Date: Tue Mar 13 2012 - 02:46:16 EST




> -----Original Message-----
> From: Peter Zijlstra [mailto:peterz@xxxxxxxxxxxxx]
> Sent: Monday, March 12, 2012 5:58 PM
> To: Liu, Chuansheng
> Cc: linux-kernel@xxxxxxxxxxxxxxx; Yanmin Zhang; tglx@xxxxxxxxxxxxx
> Subject: Re: [PATCH] Fix the race between smp_call_function and CPU booting
>
> On Mon, 2012-03-12 at 09:27 +0000, Liu, Chuansheng wrote:
> > The solution is just to send smp call to active cpus instead of online
> > cpus.
>
> BTW, that solution is broken because !active cpus can still be online and
> actually running stuff, so sending IPIs to them is perfectly fine and actually
> required.
>
Based on current code base, the IPI can be handled only after the cpu is active, before CPU is active,
Any sending IPI is meanless.
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