linux-kernel - Re: [PATCH v7 14/22] ACPI: platform_profile: Notify change events on register and unregister

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Message-ID: <46b822e9-8bfd-462e-9f2f-acddd44bba30@amd.com>
Date: Wed, 20 Nov 2024 09:37:16 -0600
From: Mario Limonciello <mario.limonciello@....com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Hans de Goede <hdegoede@...hat.com>,
 "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>, Armin Wolf <W_Armin@....de>
Subject: Re: [PATCH v7 14/22] ACPI: platform_profile: Notify change events on
 register and unregister

On 11/20/2024 09:09, Ilpo Järvinen wrote:
> On Tue, 19 Nov 2024, Mario Limonciello wrote:
> 
>> As multiple platform profile handlers may come and go, send a notification
>> to userspace each time that a platform profile handler is registered or
>> unregistered.
>>
>> Reviewed-by: Armin Wolf <W_Armin@....de>
>> Tested-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
>> Tested-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
>> Reviewed-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>> ---
>> v7:
>>   * Add Armin's tag
>> ---
>>   drivers/acpi/platform_profile.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
>> index 1530e6096cd39..de0804305b02c 100644
>> --- a/drivers/acpi/platform_profile.c
>> +++ b/drivers/acpi/platform_profile.c
>> @@ -363,6 +363,8 @@ int platform_profile_register(struct platform_profile_handler *pprof)
>>   		goto cleanup_ida;
>>   	}
>>   
>> +	sysfs_notify(acpi_kobj, NULL, "platform_profile");
>> +
>>   	cur_profile = pprof;
>>   
>>   	err = sysfs_update_group(acpi_kobj, &platform_profile_group);
> 
> Is the ordering problematic here, how long userspace has to wait for the
> update to become visible?

TBH - this feels like an artifact of the earlier patches.  I don't know 
that we really need the notify anymore since calling sysfs_update_group().

I'm tending to think drop this patch entirely.

> 
>> @@ -393,6 +395,8 @@ int platform_profile_remove(struct platform_profile_handler *pprof)
>>   	device_unregister(pprof->class_dev);
>>   	ida_free(&platform_profile_ida, id);
>>   
>> +	sysfs_notify(acpi_kobj, NULL, "platform_profile");
>> +
>>   	sysfs_update_group(acpi_kobj, &platform_profile_group);
> 
>