Re: [PATCH V2] cpufreq: Call transition notifier only once for each policy

[Viresh Kumar]

On 18-03-19, 12:49, Rafael J. Wysocki wrote:
> To summarize, I think that it would be sufficient to do this just for
> policy->cpu and, as Peter said, warn once if there are more CPUs in
> the policy or policy->cpu is not the CPU running this code.  And mark
> the TSC as unstable in both of these cases.

How about this ?

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 3fae23834069..4d3681cfb6e0 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -958,10 +958,13 @@ 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 policy has more than CPU");
+
        lpj = &boot_cpu_data.loops_per_jiffy;
 #ifdef CONFIG_SMP
        if (!(freq->flags & CPUFREQ_CONST_LOOPS))
-               lpj = &cpu_data(freq->cpu).loops_per_jiffy;
+               lpj = &cpu_data(freq->policy->cpu).loops_per_jiffy;
 #endif
 
        if (!ref_freq) {
@@ -977,7 +980,7 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
                if (!(freq->flags & CPUFREQ_CONST_LOOPS))
                        mark_tsc_unstable("cpufreq changes");
 
-               set_cyc2ns_scale(tsc_khz, freq->cpu, rdtsc());
+               set_cyc2ns_scale(tsc_khz, freq->policy->cpu, rdtsc());
        }
 
        return 0;