Re: [PATCH V3] cpufreq: Call transition notifier only once for each policy

[Viresh Kumar]

On 21-03-19, 16:49, Thomas Gleixner wrote:
> On Wed, 20 Mar 2019, Viresh Kumar wrote:
> >
> > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> > index 3fae23834069..b2fe665878f7 100644
> > --- a/arch/x86/kernel/tsc.c
> > +++ b/arch/x86/kernel/tsc.c
> > @@ -958,10 +958,15 @@ static int time_cpufreq_notifier(struct 
> > notifier_block *nb, unsigned long val,
> >     struct cpufreq_freqs *freq = data;
> >     unsigned long *lpj;
> >  
> > +   if (WARN_ON_ONCE(cpumask_weight(freq->policy->related_cpus) != 1)) {
> > +           mark_tsc_unstable("cpufreq changes: related CPUs affected");
> > +           return 0;
> > +   }
> 
> You might add a check which ensures that policy->cpu == smp_processor_id()
> because if this is not the case ....

How about something like this ?

        if (WARN_ON_ONCE(cpumask_weight(freq->policy->related_cpus) != 1 ||
                         freq->policy->cpu != smp_processor_id())) {
                mark_tsc_unstable("cpufreq changes: related CPUs affected");
                return 0;
        }


Thanks for your feedback.

-- 
viresh