Re: [PATCH 01/51] CPU hotplug: Provide lockless versions of callback registration functions

[Gautham R Shenoy]

On Tue, Feb 11, 2014 at 09:33:56AM -0700, Toshi Kani wrote:
> 
> I agree that introducing a reader-writer semaphore allows concurrent
> executions.  Adding yet another hotplug lock is a bit unfortunate,
> though.
> 

I agree with this last part. We already have enough locks for
cpu-hotplug. Another one sounds one too many!!


> This may be a dumb question, but can't we simply do this way?
> 
>         get_online_cpus();
> 
>         for_each_online_cpu(cpu)
>                 init_cpu(cpu);
> 
>         put_online_cpus();
>
      -------- Someone chooses to hotplug a cpu here ------
      -------- But this subsystem might miss out on knowing
               about it since it hasn't registered its
               notifier yet! 

>         register_cpu_notifier(&foobar_cpu_notifier);
> 
> Thanks,
> -Toshi
> 

--
Thanks and Regards
gautham.

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