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SubjectRe: [PATCH] arch/x86/kernel/cpu/umwait.c - remove unused variable
On Thu, Aug 08, 2019 at 10:32:38PM +0200, Thomas Gleixner wrote:
> Valdis,
>
> On Thu, 8 Aug 2019, Valdis Klētnieks wrote:
> > On Thu, 08 Aug 2019 22:04:03 +0200, Thomas Gleixner said: It isn't
> > clear that whatever is doing the device_initcall()s will be able to
> > do any reasonable recovery if we return an error, so any error
> > recovery is going to have to happen before the function returns. It
> > might make sense to do an 'if (ret) return;' before going further in
> > the function, but given the comment a few lines further down about
> > ignoring errors, it was apparently considered more important to
> > struggle through and register stuff in sysfs even if umwait was
> > broken....
>
> I missed that when going through it.
>
> The right thing to do is to have a cpu_offline callback which clears
> the umwait MSR. That covers also the failure in the cpu hotplug setup.
> Then handling an error return makes sense and keeps everything in a
> workable shape.

When cpu is offline, the MSR won't be used. We don't need to clear it, right?

Thanks.

-Fenghua

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