linux-kernel - Re: [PATCH v5 17/20] ACPI: platform_profile: Check all profile handler to calculate next

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Message-ID: <cbdc6ff5-627e-4237-a053-bbf2e77499da@amd.com>
Date: Thu, 7 Nov 2024 16:05:05 -0600
From: Mario Limonciello <mario.limonciello@....com>
To: Armin Wolf <W_Armin@....de>, Hans de Goede <hdegoede@...hat.com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: "Rafael J . Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 Maximilian Luz <luzmaximilian@...il.com>, Lee Chun-Yi <jlee@...e.com>,
 Shyam Sundar S K <Shyam-sundar.S-k@....com>,
 Corentin Chary <corentin.chary@...il.com>, "Luke D . Jones"
 <luke@...nes.dev>, Ike Panhc <ike.pan@...onical.com>,
 Henrique de Moraes Holschuh <hmh@....eng.br>,
 Alexis Belmonte <alexbelm48@...il.com>,
 Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
 Ai Chao <aichao@...inos.cn>, Gergo Koteles <soyer@....hu>,
 open list <linux-kernel@...r.kernel.org>,
 "open list:ACPI" <linux-acpi@...r.kernel.org>,
 "open list:MICROSOFT SURFACE PLATFORM PROFILE DRIVER"
 <platform-driver-x86@...r.kernel.org>,
 "open list:THINKPAD ACPI EXTRAS DRIVER"
 <ibm-acpi-devel@...ts.sourceforge.net>,
 Mark Pearson <mpearson-lenovo@...ebb.ca>,
 Matthew Schwartz <matthew.schwartz@...ux.dev>
Subject: Re: [PATCH v5 17/20] ACPI: platform_profile: Check all profile
 handler to calculate next

On 11/7/2024 02:58, Armin Wolf wrote:
> Am 07.11.24 um 07:02 schrieb Mario Limonciello:
> 
>> As multiple platform profile handlers might not all support the same
>> profile, cycling to the next profile could have a different result
>> depending on what handler are registered.
>>
>> Check what is active and supported by all handlers to decide what
>> to do.
>>
>> Tested-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>> ---
>> v5:
>>   * Adjust mutex use
>> ---
>>   drivers/acpi/platform_profile.c | 23 ++++++++++++++---------
>>   1 file changed, 14 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/ 
>> platform_profile.c
>> index 7f302ac4d3779..2c466f2d16b42 100644
>> --- a/drivers/acpi/platform_profile.c
>> +++ b/drivers/acpi/platform_profile.c
>> @@ -411,34 +411,39 @@ EXPORT_SYMBOL_GPL(platform_profile_notify);
>>
>>   int platform_profile_cycle(void)
>>   {
>> +    enum platform_profile_option next = PLATFORM_PROFILE_LAST;
>>       enum platform_profile_option profile;
>> -    enum platform_profile_option next;
>> +    unsigned long choices;
>>       int err;
>>
>>       if (!class_is_registered(&platform_profile_class))
>>           return -ENODEV;
>>
>>       scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock) {
>> -        if (!cur_profile)
>> -            return -ENODEV;
>> +        err = class_for_each_device(&platform_profile_class, NULL,
>> +                        &profile, _aggregate_profiles);
>> +        if (err)
>> +            return err;
>>
>> -        err = cur_profile->profile_get(cur_profile, &profile);
>> +        err = class_for_each_device(&platform_profile_class, NULL,
>> +                        &choices, _aggregate_choices);
>>           if (err)
>>               return err;
>>
>> -        next = find_next_bit_wrap(cur_profile->choices, 
>> PLATFORM_PROFILE_LAST,
>> +        next = find_next_bit_wrap(&choices,
>> +                      PLATFORM_PROFILE_LAST,
>>                         profile + 1);
> 
> Could it be that this would lead to be "custom" profile being selected 
> under some conditions?

Yeah, you're right.  If all drivers supported custom then this could 
happen.  I'll clear custom like this:

		choices &= ~BIT(PLATFORM_PROFILE_CUSTOM);

> Also _aggregate_profiles() expects profile to be initialized with 
> PLATFORM_PROFILE_LAST.

Will correct initialization in platform_profile_cycle() to this.

	enum platform_profile_option profile = PLATFORM_PROFILE_LAST;

But this also raises a good point.  If _aggregate_profiles() returns
custom then this should be an error because next profile is undefined.
So I'll catch that like this.
		err = class_for_each_device()
		if (err)
			return err;
		if (profile == PLATFORM_PROFILE_CUSTOM)
			return -EINVAL;
> 
> Thanks,
> Armin Wolf
> 
>>
>> -        if (WARN_ON(next == PLATFORM_PROFILE_LAST))
>> -            return -EINVAL;
>> +        err = class_for_each_device(&platform_profile_class, NULL, 
>> &next,
>> +                        _store_class_profile);
>>
>> -        err = cur_profile->profile_set(cur_profile, next);
>>           if (err)
>>               return err;
>>       }
>>
>>       sysfs_notify(acpi_kobj, NULL, "platform_profile");
>> -    return 0;
>> +
>> +    return err;
>>   }
>>   EXPORT_SYMBOL_GPL(platform_profile_cycle);
>>