2022-07-22 03:18:13

by Zhao Liu

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

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 <[email protected]>
---
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)
--
2.34.1

2022-07-25 10:38:30

by Viresh Kumar

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

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 <[email protected]>
> ---
> 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 <[email protected]>

--
viresh

2022-07-25 18:46:26

by Rafael J. Wysocki

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

On Mon, Jul 25, 2022 at 12:30 PM Viresh Kumar <[email protected]> wrote:
>
> 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 <[email protected]>
> > ---
> > 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 <[email protected]>

Applied as 5.20 material, thanks!