Re: S3 resume issue in cpufreq -> get_cpu_idle_time->vcpu_runstate_get

[Juergen Gross <jgross@xxxxxxxx>]

On 18.08.21 08:41, Jan Beulich wrote:
> On 18.08.2021 08:24, Juergen Gross wrote:
> > Could you please try the attached patch?
> Seeing the patch, two questions:
>
> 1) Can idle_vcpu[cpu] ever be NULL when cpu_online(cpu) returned true?
No.

> 2) Seeing get_sched_res()'es access to per-CPU data, would it make sense
> to move the cpu_online() check into there? While I guess the majority of
> users are guaranteed to invoke it for online CPUs, I wonder if there
> aren't any further uses on the CPU bringup / teardown code paths.
As get_sched_res() is private to the scheduler sources, this would imply
a scheduler function being used for an offline cpu, which is rather
unlikely. Especially as get_cpu_idle_time() is the only official
scheduler function taking a physical cpu number as parameter. All other
functions only work with vcpus, and this would require to wake, pause,
... an idle vcpu of an offline cpu to hit the problem.


Juergen

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