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

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Message-ID: <da38cf78-bd18-49ee-a25d-c4b446cfa2fa@huawei.com>
Date: Thu, 23 Oct 2025 18:19:42 +0800
From: "lihuisong (C)" <lihuisong@...wei.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
CC: <lenb@...nel.org>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <Sudeep.Holla@....com>,
	<linuxarm@...wei.com>, <jonathan.cameron@...wei.com>,
	<zhanjie9@...ilicon.com>, <zhenglifeng1@...wei.com>, <yubowen8@...wei.com>
Subject: Re: [PATCH v1 7/9] ACPI: processor: idle: Remove died codes about the
 verification of cstate count


在 2025/10/22 3:51, Rafael J. Wysocki 写道:
> On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@...wei.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@...wei.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
>>