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

[Liu, Chuansheng]

> -----Original Message-----
> From: Peter Zijlstra [mailto:peterz@xxxxxxxxxxxxx]
> Sent: Wednesday, March 14, 2012 5:43 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 Wed, 2012-03-14 at 06:27 +0000, Liu, Chuansheng wrote:
> > On the unplug case, after set the CPU to !active, we do not need IPI
> > handling for the corresponding CPU before it is set to offline. I did
> > not find any impact that limiting the smp_call_function just after CPU
> > is active.
> 
> Have a look at Alpha, it's flush_tlb_mm() can use smp_call_function(), in
> the !active,online case you very much still need to tlb flush that cpu.
> 
> The fact that it works on a limited use case on x86 doesn't say anything much
> at all.
Thanks your pointing out, do you have any other perfect solution for this issue?
As for the stress test result, advancing the setting active before setting online broken
something either.
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