Re: drivers/acpi/processor_thermal.c: avoid cpufreq_get_policy()

[Manfred Spraul]

Hi Rafael,

On 12/30/21 17:23, Rafael J. Wysocki wrote:
> On Wed, Dec 22, 2021 at 8:14 PM Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> wrote:
> > cpu_has_cpufreq() stores a 'struct cpufreq_policy' on the stack.
> > Unfortunately, with debugging options enabled, the structure can be
> > larger than 1024 bytes, which causes a compiler warning/error.
> >
> > (actually observed: 1184 bytes).
> >
> > Therefore: Switch to cpufreq_cpu_get().
> >
> > Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
> >
> > ---
> >   drivers/acpi/processor_thermal.c | 15 ++++++++++++---
> >   1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/acpi/processor_thermal.c b/drivers/acpi/processor_thermal.c
> > index a3d34e3f9f94..74210d63f62c 100644
> > --- a/drivers/acpi/processor_thermal.c
> > +++ b/drivers/acpi/processor_thermal.c
> > @@ -53,10 +53,19 @@ static int phys_package_first_cpu(int cpu)
> >
> >   static int cpu_has_cpufreq(unsigned int cpu)
> >   {
> > -       struct cpufreq_policy policy;
> > -       if (!acpi_processor_cpufreq_init || cpufreq_get_policy(&policy, cpu))
> > +       struct cpufreq_policy *policy;
> > +       int retval;
> Why is this needed?
You are right, this can be simplified. Updated patch is attached.
> > +
> > +       if (!acpi_processor_cpufreq_init)
> >                  return 0;
> > -       return 1;
> > +
> > +       retval = 0;
> > +       policy = cpufreq_cpu_get(cpu);
> > +       if (policy) {
> > +               cpufreq_cpu_put(policy);
> return 1;
>
> > +               retval = 1;
> > +       }
> > +       return retval;
> return 0;
>
> >   }
> >
> >   static int cpufreq_get_max_state(unsigned int cpu)
> > --
> > 2.33.1
From b6a988751d93692026b62531f0b55a7fe69b1092 Mon Sep 17 00:00:00 2001
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Date: Wed, 22 Dec 2021 15:09:31 +0100
Subject: [PATCH] drivers/acpi/processor_thermal.c: avoid cpufreq_get_policy()

cpu_has_cpufreq() stores a 'struct cpufreq_policy' on the stack.
Unfortunately, with debugging options enabled, the structure can be
larger than 1024 bytes, which causes a compiler warning/error.

(actually observed: 1184 bytes).

Therefore: Switch to cpufreq_cpu_get().

Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
---
 drivers/acpi/processor_thermal.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/processor_thermal.c b/drivers/acpi/processor_thermal.c
index a3d34e3f9f94..d8b2dfcd59b5 100644
--- a/drivers/acpi/processor_thermal.c
+++ b/drivers/acpi/processor_thermal.c
@@ -53,10 +53,17 @@ static int phys_package_first_cpu(int cpu)
 
 static int cpu_has_cpufreq(unsigned int cpu)
 {
-	struct cpufreq_policy policy;
-	if (!acpi_processor_cpufreq_init || cpufreq_get_policy(&policy, cpu))
+	struct cpufreq_policy *policy;
+
+	if (!acpi_processor_cpufreq_init)
 		return 0;
-	return 1;
+
+	policy = cpufreq_cpu_get(cpu);
+	if (policy) {
+		cpufreq_cpu_put(policy);
+		return 1;
+	}
+	return 0;
 }
 
 static int cpufreq_get_max_state(unsigned int cpu)
-- 
2.33.1