Re: [PATCH] acpi-cpufreq: use same acpi_cpufreq_data if policy is shared

From: Viresh Kumar
Date: Fri Jul 03 2015 - 04:47:12 EST


On 03-07-15, 16:01, Pan Xinhui wrote:
>
> cpufreq core will mark all cpus in policy->cpus as initialized
> by setting percpu cpufreq_cpu_data = policy.
> However in acpi-cpufreq, we did not set percpu acpi_cpufreq_data for
> all cpus in policy->cpus.
> That will cause a issue that when we call get_cur_freq_on_cpu for a
> cpu, it returns zero instead of a correct value.
>
> So we shared acpi_cpufreq_data for all those cpus in policy->cpus.
>
> Signed-off-by: xinhuix.pan <xinhuix.pan@xxxxxxxxx>
> ---
> drivers/cpufreq/acpi-cpufreq.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
> index 0136dfc..6c6dc97 100644
> --- a/drivers/cpufreq/acpi-cpufreq.c
> +++ b/drivers/cpufreq/acpi-cpufreq.c
> @@ -673,6 +673,7 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
> }
>
> data->acpi_data = per_cpu_ptr(acpi_perf_data, cpu);
> + cpumask_copy(policy->cpus, cpumask_of(cpu));

This is already done by cpufreq-core before calling ->init() and so
isn't required.

> per_cpu(acfreq_data, cpu) = data;
>
> if (cpu_has(c, X86_FEATURE_CONSTANT_TSC))
> @@ -712,6 +713,10 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
> }
> #endif
>
> + for_each_cpu(i, policy->cpus) {
> + per_cpu(acfreq_data, i) = data;
> + }
> +
> /* capability check */
> if (perf->state_count <= 1) {
> pr_debug("No P-States\n");
> @@ -843,7 +848,9 @@ err_free_mask:
> free_cpumask_var(data->freqdomain_cpus);
> err_free:
> kfree(data);
> - per_cpu(acfreq_data, cpu) = NULL;
> + for_each_cpu(i, policy->cpus) {
> + per_cpu(acfreq_data, i) = NULL;
> + }

The per-cpu thing is basically wrong to start with. cpufreq-policy has
a field: 'driver_data', which can be used to replace this acfreq_data.
Probably use that and things will get fixed by themselves.

--
viresh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/