Re: [Xen-devel] [PATCH v2 1/6] xen/sched: call cpu_disable_scheduler() via cpu notifier

[Dario Faggioli <dfaggioli@xxxxxxxx>]

On Thu, 2019-03-28 at 13:06 +0100, Juergen Gross wrote:
> cpu_disable_scheduler() is being called from __cpu_disable() today.
> There is no need to execute it on the cpu just being disabled, so use
> the CPU_DEAD case of the cpu notifier chain. Moving the call out of
> stop_machine() context is fine, as we just need to hold the domain
> RCU
> lock and need the scheduler percpu data to be still allocated.
> 
> Add another hook for CPU_DOWN_PREPARE to bail out early in case
> cpu_disable_scheduler() would fail. This will avoid crashes in rare
> cases for cpu hotplug or suspend.
> 
> While at it remove a superfluous smp_mb() in the ARM __cpu_disable()
> incarnation.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> V2:
> - add CPU_DOWN_PREPARE hook
> - BUG() in case of cpu_disable_scheduler() failing in CPU_DEAD
>   (Jan Beulich)
> - modify ARM __cpu_disable(), too (Andrew Cooper)
> ---
>
Reviewed-by: Dario Faggioli <dfaggioli@xxxxxxxx>

Regards,
Dario
-- 
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
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