Re: [PATCH v2] ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable

From: Stephen Boyd
Date: Fri Feb 13 2015 - 19:01:52 EST

On 02/13/15 15:01, Russell King - ARM Linux wrote:
> On Fri, Feb 13, 2015 at 09:44:50PM +0000, Magnus Damm wrote:
>> Also, based on the comment in mcpm_cpu_can_disable() it looks like the
>> PSCI hook may be executed once only with your change in place?
>> Hopefully PSCI is OK not being invoked for every CPU shutdown.
> This is why I've said (in the parent thread) that I'm not happy to
> apply this patch. Mark Rutland has indicated that he has MCPM cases
> where the CPUs which can be disabled changes dynamically according
> to the secure firmware requirements, and ripping out todays
> infrastructure in light of that, only to have to add it back again
> later makes no sense.

Putting it back is not hard. And the infrastructure is not currently
used for these purposes so renaming it is appropriate. I can leave it in
place if you like, i.e. make a new op for cpu_can_disable and repoint
mcpm's mcpm_cpu_disable() at it. Then when mcpm gets migrate support it
can actually implement a cpu_disable op.

> However, cleaning things up by removing unnecessary cpu_disable
> methods is a good thing to do irrespective of that.

That's fine I can split it out.

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