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[PATCH v1 7/9] ACPI: processor: idle: Remove died codes about the verification of cstate count

Huisong Li posted 9 patches 4 months, 1 week ago
There is a newer version of this series
[PATCH v1 7/9] ACPI: processor: idle: Remove died codes about the verification of cstate count
Posted by Huisong Li 4 months, 1 week ago 
The acpi_processor_setup_cstates and acpi_processor_setup_cpuidle_cx will
be called after successfully obtaining the power information. These setup
functions have their own main role, but also verify the validity of cstate
count.

Actually, the acpi_processor_get_power_info_cst() will return failure
if the cstate count is zero and acpi_processor_get_power_info() will return
failure.

So the verification of cstate count in these functions are died code.

Signed-off-by: Huisong Li <lihuisong@huawei.com>
---
 drivers/acpi/processor_idle.c | 22 +++++++---------------
 1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 92b231f5d514..2d672afc7498 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -732,8 +732,8 @@ static int __cpuidle acpi_idle_enter_s2idle(struct cpuidle_device *dev,
 	return 0;
 }
 
-static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
-					   struct cpuidle_device *dev)
+static void acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
+					    struct cpuidle_device *dev)
 {
 	int i, count = ACPI_IDLE_STATE_START;
 	struct acpi_processor_cx *cx;
@@ -753,14 +753,9 @@ static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
 		if (count == CPUIDLE_STATE_MAX)
 			break;
 	}
-
-	if (!count)
-		return -EINVAL;
-
-	return 0;
 }
 
-static int acpi_processor_setup_cstates(struct acpi_processor *pr)
+static void acpi_processor_setup_cstates(struct acpi_processor *pr)
 {
 	int i, count;
 	struct acpi_processor_cx *cx;
@@ -822,11 +817,6 @@ static int acpi_processor_setup_cstates(struct acpi_processor *pr)
 	}
 
 	drv->state_count = count;
-
-	if (!count)
-		return -EINVAL;
-
-	return 0;
 }
 
 static inline void acpi_processor_cstate_first_run_checks(void)
@@ -1246,7 +1236,8 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
 	if (pr->flags.has_lpi)
 		return acpi_processor_setup_lpi_states(pr);
 
-	return acpi_processor_setup_cstates(pr);
+	acpi_processor_setup_cstates(pr);
+	return 0;
 }
 
 /**
@@ -1266,7 +1257,8 @@ static int acpi_processor_setup_cpuidle_dev(struct acpi_processor *pr,
 	if (pr->flags.has_lpi)
 		return 0;
 
-	return acpi_processor_setup_cpuidle_cx(pr, dev);
+	acpi_processor_setup_cpuidle_cx(pr, dev);
+	return 0;
 }
 
 static int acpi_processor_get_power_info(struct acpi_processor *pr)
-- 
2.33.0
Re: [PATCH v1 7/9] ACPI: processor: idle: Remove died codes about the verification of cstate count
Posted by Rafael J. Wysocki 3 months, 3 weeks ago 
On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@huawei.com> wrote:
>
> The acpi_processor_setup_cstates and acpi_processor_setup_cpuidle_cx will
> be called after successfully obtaining the power information. These setup
> functions have their own main role, but also verify the validity of cstate
> count.
>
> Actually, the acpi_processor_get_power_info_cst() will return failure
> if the cstate count is zero and acpi_processor_get_power_info() will return
> failure.
>
> So the verification of cstate count in these functions are died code.

It is useless overhead rather because the conditions checked cannot be true.

> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> ---
>  drivers/acpi/processor_idle.c | 22 +++++++---------------
>  1 file changed, 7 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index 92b231f5d514..2d672afc7498 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -732,8 +732,8 @@ static int __cpuidle acpi_idle_enter_s2idle(struct cpuidle_device *dev,
>         return 0;
>  }
>
> -static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
> -                                          struct cpuidle_device *dev)
> +static void acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
> +                                           struct cpuidle_device *dev)
>  {
>         int i, count = ACPI_IDLE_STATE_START;
>         struct acpi_processor_cx *cx;
> @@ -753,14 +753,9 @@ static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
>                 if (count == CPUIDLE_STATE_MAX)
>                         break;
>         }
> -
> -       if (!count)
> -               return -EINVAL;
> -
> -       return 0;
>  }
>
> -static int acpi_processor_setup_cstates(struct acpi_processor *pr)
> +static void acpi_processor_setup_cstates(struct acpi_processor *pr)
>  {
>         int i, count;
>         struct acpi_processor_cx *cx;
> @@ -822,11 +817,6 @@ static int acpi_processor_setup_cstates(struct acpi_processor *pr)
>         }
>
>         drv->state_count = count;
> -
> -       if (!count)
> -               return -EINVAL;
> -
> -       return 0;
>  }
>
>  static inline void acpi_processor_cstate_first_run_checks(void)
> @@ -1246,7 +1236,8 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
>         if (pr->flags.has_lpi)
>                 return acpi_processor_setup_lpi_states(pr);
>
> -       return acpi_processor_setup_cstates(pr);
> +       acpi_processor_setup_cstates(pr);
> +       return 0;
>  }
>
>  /**
> @@ -1266,7 +1257,8 @@ static int acpi_processor_setup_cpuidle_dev(struct acpi_processor *pr,
>         if (pr->flags.has_lpi)
>                 return 0;
>
> -       return acpi_processor_setup_cpuidle_cx(pr, dev);
> +       acpi_processor_setup_cpuidle_cx(pr, dev);
> +       return 0;
>  }
>
>  static int acpi_processor_get_power_info(struct acpi_processor *pr)
> --
> 2.33.0
>
Re: [PATCH v1 7/9] ACPI: processor: idle: Remove died codes about the verification of cstate count
Posted by lihuisong (C) 3 months, 2 weeks ago 
在 2025/10/22 3:51, Rafael J. Wysocki 写道:
> On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@huawei.com> wrote:
>> The acpi_processor_setup_cstates and acpi_processor_setup_cpuidle_cx will
>> be called after successfully obtaining the power information. These setup
>> functions have their own main role, but also verify the validity of cstate
>> count.
>>
>> Actually, the acpi_processor_get_power_info_cst() will return failure
>> if the cstate count is zero and acpi_processor_get_power_info() will return
>> failure.
>>
>> So the verification of cstate count in these functions are died code.
> It is useless overhead rather because the conditions checked cannot be true.
Yes.
This patch actually prepares for patch 8/9 and patch 9/9.
>> Signed-off-by: Huisong Li <lihuisong@huawei.com>
>> ---
>>   drivers/acpi/processor_idle.c | 22 +++++++---------------
>>   1 file changed, 7 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>> index 92b231f5d514..2d672afc7498 100644
>> --- a/drivers/acpi/processor_idle.c
>> +++ b/drivers/acpi/processor_idle.c
>> @@ -732,8 +732,8 @@ static int __cpuidle acpi_idle_enter_s2idle(struct cpuidle_device *dev,
>>          return 0;
>>   }
>>
>> -static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
>> -                                          struct cpuidle_device *dev)
>> +static void acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
>> +                                           struct cpuidle_device *dev)
>>   {
>>          int i, count = ACPI_IDLE_STATE_START;
>>          struct acpi_processor_cx *cx;
>> @@ -753,14 +753,9 @@ static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
>>                  if (count == CPUIDLE_STATE_MAX)
>>                          break;
>>          }
>> -
>> -       if (!count)
>> -               return -EINVAL;
>> -
>> -       return 0;
>>   }
>>
>> -static int acpi_processor_setup_cstates(struct acpi_processor *pr)
>> +static void acpi_processor_setup_cstates(struct acpi_processor *pr)
>>   {
>>          int i, count;
>>          struct acpi_processor_cx *cx;
>> @@ -822,11 +817,6 @@ static int acpi_processor_setup_cstates(struct acpi_processor *pr)
>>          }
>>
>>          drv->state_count = count;
>> -
>> -       if (!count)
>> -               return -EINVAL;
>> -
>> -       return 0;
>>   }
>>
>>   static inline void acpi_processor_cstate_first_run_checks(void)
>> @@ -1246,7 +1236,8 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
>>          if (pr->flags.has_lpi)
>>                  return acpi_processor_setup_lpi_states(pr);
>>
>> -       return acpi_processor_setup_cstates(pr);
>> +       acpi_processor_setup_cstates(pr);
>> +       return 0;
>>   }
>>
>>   /**
>> @@ -1266,7 +1257,8 @@ static int acpi_processor_setup_cpuidle_dev(struct acpi_processor *pr,
>>          if (pr->flags.has_lpi)
>>                  return 0;
>>
>> -       return acpi_processor_setup_cpuidle_cx(pr, dev);
>> +       acpi_processor_setup_cpuidle_cx(pr, dev);
>> +       return 0;
>>   }
>>
>>   static int acpi_processor_get_power_info(struct acpi_processor *pr)
>> --
>> 2.33.0
>>

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