[PATCH v3 0/3] ACPI: processor: Fix function declaration of processor_idle.c

[PATCH v3 0/3] ACPI: processor: Fix function declaration of processor_idle.c

[Huisong Li]

This serises is aimed to fix the function declaration of processor_idle.c.
And the modification idea of this series is from the link[1].

The patch fixed the warning reported by the kernel test robot in link[1]
has been applied in v2.

[1] https://lore.kernel.org/oe-kbuild-all/202508300519.tZQHY6HA-lkp@intel.com/

---
 Changelog
  v3:
   - remove the merged patch which fixed the warning in link[1]
   - add a separate patch to handle the "extern struct
     cpuidle_driver acpi_idle_driver" in processor.h.

  v2:
   - split patch v1
     https://patchwork.kernel.org/project/linux-acpi/cover/20250905081900.663869-1-lihuisong@huawei.com/

Huisong Li (3):
  ACPI: processor: Remove unused empty function definition for
    processor_idle.c
  ACPI: processor: Unify the place of function declaration of
    processor_idle.c
  ACPI: processor: Do not expose the global acpi_idle_driver variable

 drivers/acpi/processor_driver.c |  3 +--
 drivers/acpi/processor_idle.c   |  5 +++++
 include/acpi/processor.h        | 28 ++--------------------------
 3 files changed, 8 insertions(+), 28 deletions(-)

-- 
2.33.0

[PATCH v3 1/3] ACPI: processor: Remove unused empty function definition for processor_idle.c

[Huisong Li]

If CONFIG_ACPI_PROCESSOR=n and CONFIG_ACPI_PROCESSOR_IDLE=n,
we may encounter some warnings about function defined but not
used. All external functions of processor_idle.c are just used
in processor_driver.c. And if CONFIG_ACPI_PROCESSOR is selected
and CONFIG_ACPI_PROCESSOR_IDLE also be selected automatically.
So remove these empty function definitions.

Signed-off-by: Huisong Li <lihuisong@huawei.com>
---
 include/acpi/processor.h | 20 --------------------
 1 file changed, 20 deletions(-)

diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index ff864c1cee3a..2976a6d0c54f 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -425,26 +425,6 @@ int acpi_processor_power_state_has_changed(struct acpi_processor *pr);
 int acpi_processor_hotplug(struct acpi_processor *pr);
 void acpi_processor_register_idle_driver(void);
 void acpi_processor_unregister_idle_driver(void);
-#else
-static inline int acpi_processor_power_init(struct acpi_processor *pr)
-{
-	return -ENODEV;
-}
-
-static inline int acpi_processor_power_exit(struct acpi_processor *pr)
-{
-	return -ENODEV;
-}
-
-static inline int acpi_processor_power_state_has_changed(struct acpi_processor *pr)
-{
-	return -ENODEV;
-}
-
-static inline int acpi_processor_hotplug(struct acpi_processor *pr)
-{
-	return -ENODEV;
-}
 #endif /* CONFIG_ACPI_PROCESSOR_IDLE */
 
 /* in processor_thermal.c */
-- 
2.33.0

[PATCH v3 2/3] ACPI: processor: Unify the place of function declaration of processor_idle.c

[Huisong Li]

To unify the place of function declaration of processor_idle.c, move
acpi_processor_ffh_lpi_probe and acpi_processor_ffh_lpi_enter to one
place. And remove 'extern' key word in declaration by the way.

Signed-off-by: Huisong Li <lihuisong@huawei.com>
---
 include/acpi/processor.h | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 2976a6d0c54f..6ee4a69412de 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -425,6 +425,8 @@ int acpi_processor_power_state_has_changed(struct acpi_processor *pr);
 int acpi_processor_hotplug(struct acpi_processor *pr);
 void acpi_processor_register_idle_driver(void);
 void acpi_processor_unregister_idle_driver(void);
+int acpi_processor_ffh_lpi_probe(unsigned int cpu);
+int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi);
 #endif /* CONFIG_ACPI_PROCESSOR_IDLE */
 
 /* in processor_thermal.c */
@@ -447,11 +449,6 @@ static inline void acpi_thermal_cpufreq_exit(struct cpufreq_policy *policy)
 }
 #endif	/* CONFIG_CPU_FREQ */
 
-#ifdef CONFIG_ACPI_PROCESSOR_IDLE
-extern int acpi_processor_ffh_lpi_probe(unsigned int cpu);
-extern int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi);
-#endif
-
 void acpi_processor_init_invariance_cppc(void);
 
 #endif
-- 
2.33.0

[PATCH v3 3/3] ACPI: processor: Do not expose the global acpi_idle_driver variable

[Huisong Li]

Currently, processor_driver just use the global acpi_idle_driver variable
to check if the cpuidle driver is acpi_idle_driver. Actually, there is no
need to expose this global variable defined in processor_idle.c to outside.
So move the related logical to acpi_processor_power_init() and do not
expose it.

Signed-off-by: Huisong Li <lihuisong@huawei.com>
---
 drivers/acpi/processor_driver.c | 3 +--
 drivers/acpi/processor_idle.c   | 5 +++++
 include/acpi/processor.h        | 1 -
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index bc9f58a02c1d..5d824435b26b 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -166,8 +166,7 @@ static int __acpi_processor_start(struct acpi_device *device)
 	if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS))
 		dev_dbg(&device->dev, "CPPC data invalid or not present\n");
 
-	if (!cpuidle_get_driver() || cpuidle_get_driver() == &acpi_idle_driver)
-		acpi_processor_power_init(pr);
+	acpi_processor_power_init(pr);
 
 	acpi_pss_perf_init(pr);
 
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 5dacf41d7cc0..967fb13f38fa 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1404,6 +1404,11 @@ int acpi_processor_power_init(struct acpi_processor *pr)
 {
 	int retval;
 	struct cpuidle_device *dev;
+	struct cpuidle_driver *drv;
+
+	drv = cpuidle_get_driver();
+	if (drv && drv != &acpi_idle_driver)
+		return 0;
 
 	if (disabled_by_idle_boot_param())
 		return 0;
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 6ee4a69412de..bd96dde5eef5 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -417,7 +417,6 @@ static inline void acpi_processor_throttling_init(void) {}
 #endif	/* CONFIG_ACPI_CPU_FREQ_PSS */
 
 /* in processor_idle.c */
-extern struct cpuidle_driver acpi_idle_driver;
 #ifdef CONFIG_ACPI_PROCESSOR_IDLE
 int acpi_processor_power_init(struct acpi_processor *pr);
 int acpi_processor_power_exit(struct acpi_processor *pr);
-- 
2.33.0

Re: [PATCH v3 1/3] ACPI: processor: Remove unused empty function definition for processor_idle.c

[Rafael J. Wysocki]

On Thu, Sep 11, 2025 at 1:24 PM Huisong Li <lihuisong@huawei.com> wrote:
>
> If CONFIG_ACPI_PROCESSOR=n and CONFIG_ACPI_PROCESSOR_IDLE=n,
> we may encounter some warnings about function defined but not
> used. All external functions of processor_idle.c are just used
> in processor_driver.c. And if CONFIG_ACPI_PROCESSOR is selected
> and CONFIG_ACPI_PROCESSOR_IDLE also be selected automatically.
> So remove these empty function definitions.
>
> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> ---
>  include/acpi/processor.h | 20 --------------------
>  1 file changed, 20 deletions(-)
>
> diff --git a/include/acpi/processor.h b/include/acpi/processor.h
> index ff864c1cee3a..2976a6d0c54f 100644
> --- a/include/acpi/processor.h
> +++ b/include/acpi/processor.h
> @@ -425,26 +425,6 @@ int acpi_processor_power_state_has_changed(struct acpi_processor *pr);
>  int acpi_processor_hotplug(struct acpi_processor *pr);
>  void acpi_processor_register_idle_driver(void);
>  void acpi_processor_unregister_idle_driver(void);
> -#else
> -static inline int acpi_processor_power_init(struct acpi_processor *pr)
> -{
> -       return -ENODEV;
> -}
> -
> -static inline int acpi_processor_power_exit(struct acpi_processor *pr)
> -{
> -       return -ENODEV;
> -}
> -
> -static inline int acpi_processor_power_state_has_changed(struct acpi_processor *pr)
> -{
> -       return -ENODEV;
> -}
> -
> -static inline int acpi_processor_hotplug(struct acpi_processor *pr)
> -{
> -       return -ENODEV;
> -}
>  #endif /* CONFIG_ACPI_PROCESSOR_IDLE */
>
>  /* in processor_thermal.c */
> --

Applied as 6.18 material under adjusted subject and with a new
changelog, thanks!

Re: [PATCH v3 2/3] ACPI: processor: Unify the place of function declaration of processor_idle.c

[Rafael J. Wysocki]

On Thu, Sep 11, 2025 at 1:24 PM Huisong Li <lihuisong@huawei.com> wrote:
>
> To unify the place of function declaration of processor_idle.c, move
> acpi_processor_ffh_lpi_probe and acpi_processor_ffh_lpi_enter to one
> place. And remove 'extern' key word in declaration by the way.
>
> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> ---
>  include/acpi/processor.h | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/include/acpi/processor.h b/include/acpi/processor.h
> index 2976a6d0c54f..6ee4a69412de 100644
> --- a/include/acpi/processor.h
> +++ b/include/acpi/processor.h
> @@ -425,6 +425,8 @@ int acpi_processor_power_state_has_changed(struct acpi_processor *pr);
>  int acpi_processor_hotplug(struct acpi_processor *pr);
>  void acpi_processor_register_idle_driver(void);
>  void acpi_processor_unregister_idle_driver(void);
> +int acpi_processor_ffh_lpi_probe(unsigned int cpu);
> +int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi);
>  #endif /* CONFIG_ACPI_PROCESSOR_IDLE */
>
>  /* in processor_thermal.c */
> @@ -447,11 +449,6 @@ static inline void acpi_thermal_cpufreq_exit(struct cpufreq_policy *policy)
>  }
>  #endif /* CONFIG_CPU_FREQ */
>
> -#ifdef CONFIG_ACPI_PROCESSOR_IDLE
> -extern int acpi_processor_ffh_lpi_probe(unsigned int cpu);
> -extern int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi);
> -#endif
> -
>  void acpi_processor_init_invariance_cppc(void);
>
>  #endif
> --

Applied as 6.18 material under a new subject and with a new changelog, thanks!

Re: [PATCH v3 3/3] ACPI: processor: Do not expose the global acpi_idle_driver variable

[Rafael J. Wysocki]

On Thu, Sep 11, 2025 at 1:24 PM Huisong Li <lihuisong@huawei.com> wrote:
>
> Currently, processor_driver just use the global acpi_idle_driver variable
> to check if the cpuidle driver is acpi_idle_driver. Actually, there is no
> need to expose this global variable defined in processor_idle.c to outside.
> So move the related logical to acpi_processor_power_init() and do not
> expose it.

And it can also be made static, can't it?

Please do that too.

> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> ---
>  drivers/acpi/processor_driver.c | 3 +--
>  drivers/acpi/processor_idle.c   | 5 +++++
>  include/acpi/processor.h        | 1 -
>  3 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
> index bc9f58a02c1d..5d824435b26b 100644
> --- a/drivers/acpi/processor_driver.c
> +++ b/drivers/acpi/processor_driver.c
> @@ -166,8 +166,7 @@ static int __acpi_processor_start(struct acpi_device *device)
>         if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS))
>                 dev_dbg(&device->dev, "CPPC data invalid or not present\n");
>
> -       if (!cpuidle_get_driver() || cpuidle_get_driver() == &acpi_idle_driver)
> -               acpi_processor_power_init(pr);
> +       acpi_processor_power_init(pr);
>
>         acpi_pss_perf_init(pr);
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index 5dacf41d7cc0..967fb13f38fa 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -1404,6 +1404,11 @@ int acpi_processor_power_init(struct acpi_processor *pr)
>  {
>         int retval;
>         struct cpuidle_device *dev;
> +       struct cpuidle_driver *drv;
> +
> +       drv = cpuidle_get_driver();
> +       if (drv && drv != &acpi_idle_driver)
> +               return 0;
>
>         if (disabled_by_idle_boot_param())
>                 return 0;
> diff --git a/include/acpi/processor.h b/include/acpi/processor.h
> index 6ee4a69412de..bd96dde5eef5 100644
> --- a/include/acpi/processor.h
> +++ b/include/acpi/processor.h
> @@ -417,7 +417,6 @@ static inline void acpi_processor_throttling_init(void) {}
>  #endif /* CONFIG_ACPI_CPU_FREQ_PSS */
>
>  /* in processor_idle.c */
> -extern struct cpuidle_driver acpi_idle_driver;
>  #ifdef CONFIG_ACPI_PROCESSOR_IDLE
>  int acpi_processor_power_init(struct acpi_processor *pr);
>  int acpi_processor_power_exit(struct acpi_processor *pr);
> --

Re: [PATCH v3 3/3] ACPI: processor: Do not expose the global acpi_idle_driver variable

[lihuisong (C)]

在 2025/9/18 4:01, Rafael J. Wysocki 写道:
> On Thu, Sep 11, 2025 at 1:24 PM Huisong Li <lihuisong@huawei.com> wrote:
>> Currently, processor_driver just use the global acpi_idle_driver variable
>> to check if the cpuidle driver is acpi_idle_driver. Actually, there is no
>> need to expose this global variable defined in processor_idle.c to outside.
>> So move the related logical to acpi_processor_power_init() and do not
>> expose it.
> And it can also be made static, can't it?
ok, will do it in next version. Thanks.
>
> Please do that too.
>
>> Signed-off-by: Huisong Li <lihuisong@huawei.com>
>> ---
>>   drivers/acpi/processor_driver.c | 3 +--
>>   drivers/acpi/processor_idle.c   | 5 +++++
>>   include/acpi/processor.h        | 1 -
>>   3 files changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
>> index bc9f58a02c1d..5d824435b26b 100644
>> --- a/drivers/acpi/processor_driver.c
>> +++ b/drivers/acpi/processor_driver.c
>> @@ -166,8 +166,7 @@ static int __acpi_processor_start(struct acpi_device *device)
>>          if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS))
>>                  dev_dbg(&device->dev, "CPPC data invalid or not present\n");
>>
>> -       if (!cpuidle_get_driver() || cpuidle_get_driver() == &acpi_idle_driver)
>> -               acpi_processor_power_init(pr);
>> +       acpi_processor_power_init(pr);
>>
>>          acpi_pss_perf_init(pr);
>>
>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>> index 5dacf41d7cc0..967fb13f38fa 100644
>> --- a/drivers/acpi/processor_idle.c
>> +++ b/drivers/acpi/processor_idle.c
>> @@ -1404,6 +1404,11 @@ int acpi_processor_power_init(struct acpi_processor *pr)
>>   {
>>          int retval;
>>          struct cpuidle_device *dev;
>> +       struct cpuidle_driver *drv;
>> +
>> +       drv = cpuidle_get_driver();
>> +       if (drv && drv != &acpi_idle_driver)
>> +               return 0;
>>
>>          if (disabled_by_idle_boot_param())
>>                  return 0;
>> diff --git a/include/acpi/processor.h b/include/acpi/processor.h
>> index 6ee4a69412de..bd96dde5eef5 100644
>> --- a/include/acpi/processor.h
>> +++ b/include/acpi/processor.h
>> @@ -417,7 +417,6 @@ static inline void acpi_processor_throttling_init(void) {}
>>   #endif /* CONFIG_ACPI_CPU_FREQ_PSS */
>>
>>   /* in processor_idle.c */
>> -extern struct cpuidle_driver acpi_idle_driver;
>>   #ifdef CONFIG_ACPI_PROCESSOR_IDLE
>>   int acpi_processor_power_init(struct acpi_processor *pr);
>>   int acpi_processor_power_exit(struct acpi_processor *pr);
>> --

Re: [PATCH v3 3/3] ACPI: processor: Do not expose the global acpi_idle_driver variable

[Rafael J. Wysocki]

On Thu, Sep 18, 2025 at 2:23 PM lihuisong (C) <lihuisong@huawei.com> wrote:
>
>
> 在 2025/9/18 4:01, Rafael J. Wysocki 写道:
> > On Thu, Sep 11, 2025 at 1:24 PM Huisong Li <lihuisong@huawei.com> wrote:
> >> Currently, processor_driver just use the global acpi_idle_driver variable
> >> to check if the cpuidle driver is acpi_idle_driver. Actually, there is no
> >> need to expose this global variable defined in processor_idle.c to outside.
> >> So move the related logical to acpi_processor_power_init() and do not
> >> expose it.
> > And it can also be made static, can't it?
> ok, will do it in next version. Thanks.

You may as well rebase it on top of this one:

https://lore.kernel.org/linux-acpi/5044465.31r3eYUQgx@rafael.j.wysocki/

Re: [PATCH v3 3/3] ACPI: processor: Do not expose the global acpi_idle_driver variable

[lihuisong (C)]

在 2025/9/19 5:22, Rafael J. Wysocki 写道:
> On Thu, Sep 18, 2025 at 2:23 PM lihuisong (C) <lihuisong@huawei.com> wrote:
>>
>> 在 2025/9/18 4:01, Rafael J. Wysocki 写道:
>>> On Thu, Sep 11, 2025 at 1:24 PM Huisong Li <lihuisong@huawei.com> wrote:
>>>> Currently, processor_driver just use the global acpi_idle_driver variable
>>>> to check if the cpuidle driver is acpi_idle_driver. Actually, there is no
>>>> need to expose this global variable defined in processor_idle.c to outside.
>>>> So move the related logical to acpi_processor_power_init() and do not
>>>> expose it.
>>> And it can also be made static, can't it?
>> ok, will do it in next version. Thanks.
> You may as well rebase it on top of this one:
>
> https://lore.kernel.org/linux-acpi/5044465.31r3eYUQgx@rafael.j.wysocki/

Ok, will will fix it based your patch.

Thank you for the reminder.

>