Re: [patch] cpufreq: ondemand: Use cpumask_var_t for on-stack cpu mask

From: Viresh Kumar
Date: Mon Jul 25 2022 - 06:31:01 EST


On 22-07-22, 10:50, Zhao Liu wrote:
> A cpumask structure on the stack can cause a warning with
> CONFIG_NR_CPUS=8192 (e.g. Ubuntu 22.04 uses this):
>
> drivers/cpufreq/cpufreq_ondemand.c: In function 'od_set_powersave_bias':
> drivers/cpufreq/cpufreq_ondemand.c:449:1: warning: the frame size of
> 1032 bytes is larger than 1024 bytes [-Wframe-larger-than=]
> 449 | }
> | ^
>
> CONFIG_CPUMASK_OFFSTACK=y is enabled by default for most distros, and
> hence we can work around the warning by using cpumask_var_t.
>
> Signed-off-by: Zhao Liu <zhao1.liu@xxxxxxxxxxxxxxx>
> ---
> drivers/cpufreq/cpufreq_ondemand.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
> index e8fbf970ff07..c52d19d67557 100644
> --- a/drivers/cpufreq/cpufreq_ondemand.c
> +++ b/drivers/cpufreq/cpufreq_ondemand.c
> @@ -416,10 +416,13 @@ static struct dbs_governor od_dbs_gov = {
> static void od_set_powersave_bias(unsigned int powersave_bias)
> {
> unsigned int cpu;
> - cpumask_t done;
> + cpumask_var_t done;
> +
> + if (!alloc_cpumask_var(&done, GFP_KERNEL))
> + return;
>
> default_powersave_bias = powersave_bias;
> - cpumask_clear(&done);
> + cpumask_clear(done);
>
> cpus_read_lock();
> for_each_online_cpu(cpu) {
> @@ -428,7 +431,7 @@ static void od_set_powersave_bias(unsigned int powersave_bias)
> struct dbs_data *dbs_data;
> struct od_dbs_tuners *od_tuners;
>
> - if (cpumask_test_cpu(cpu, &done))
> + if (cpumask_test_cpu(cpu, done))
> continue;
>
> policy = cpufreq_cpu_get_raw(cpu);
> @@ -439,13 +442,15 @@ static void od_set_powersave_bias(unsigned int powersave_bias)
> if (!policy_dbs)
> continue;
>
> - cpumask_or(&done, &done, policy->cpus);
> + cpumask_or(done, done, policy->cpus);
>
> dbs_data = policy_dbs->dbs_data;
> od_tuners = dbs_data->tuners;
> od_tuners->powersave_bias = default_powersave_bias;
> }
> cpus_read_unlock();
> +
> + free_cpumask_var(done);
> }
>
> void od_register_powersave_bias_handler(unsigned int (*f)

Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>

--
viresh