linux-kernel - Re: [PATCH v1 3/9] ACPI: processor: idle: Return failure when get lpi_state->arch

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Message-ID: <5caae4ef-e259-47cc-b0b7-f383dce4a334@huawei.com>
Date: Thu, 23 Oct 2025 17:59:49 +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 3/9] ACPI: processor: idle: Return failure when get
 lpi_state->arch_flags failed


在 2025/10/22 3:36, Rafael J. Wysocki 写道:
> On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@...wei.com> wrote:
>> The architecture specific context loss flags is important for ARM.
>> And this flag is used to control the execution of different code
>> flows in acpi_processor_ffh_lpi_enter().
>>
>> So it is better to return failure when get lpi_state->arch_flags
>> failed.
> A failure means no idle states at all.
Actually, I didn't know why driver should continue to do cpu idle 
scaling if the idle state doesn't meet the developer's expectations.🙂
> Wouldn't it be better to skip the state with invalid arch flags?
This arch flags is important.  And acpi_processor_ffh_lpi_enter will use it.
There is no other place to verify its validity. so here do it.
This check is just to prevent potential issues in cpuidle scaling later.
>
>> Fixes: a36a7fecfe60 ("ACPI / processor_idle: Add support for Low Power Idle(LPI) states")
>> Signed-off-by: Huisong Li <lihuisong@...wei.com>
>> ---
>>   drivers/acpi/processor_idle.c | 7 +++++--
>>   1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>> index 681587f2614b..f36f9514b6c7 100644
>> --- a/drivers/acpi/processor_idle.c
>> +++ b/drivers/acpi/processor_idle.c
>> @@ -984,8 +984,11 @@ static int acpi_processor_evaluate_lpi(acpi_handle handle,
>>                  if (obj_get_integer(pkg_elem + 2, &lpi_state->flags))
>>                          lpi_state->flags = 0;
>>
>> -               if (obj_get_integer(pkg_elem + 3, &lpi_state->arch_flags))
>> -                       lpi_state->arch_flags = 0;
>> +               if (obj_get_integer(pkg_elem + 3, &lpi_state->arch_flags)) {
>> +                       pr_err("Get architecture specific context loss flags failed.\n");
>> +                       ret = -EINVAL;
>> +                       goto end;
>> +               }
>>
>>                  if (obj_get_integer(pkg_elem + 4, &lpi_state->res_cnt_freq))
>>                          lpi_state->res_cnt_freq = 1;
>> --
>> 2.33.0
>>