linux-kernel - Re: [DMARC error][SPF error] Re: [PATCH v4 00/10] devm_led_classdev

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Message-ID: <d844862e-1d1c-4c9a-b7fe-e0ac44f4126e@salutedevices.com>
Date: Mon, 12 Feb 2024 02:52:06 +0300
From: George Stark <gnstark@...utedevices.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
CC: <pavel@....cz>, <vadimp@...dia.com>, <mpe@...erman.id.au>,
	<npiggin@...il.com>, <christophe.leroy@...roup.eu>, <hdegoede@...hat.com>,
	<mazziesaccount@...il.com>, <peterz@...radead.org>, <mingo@...hat.com>,
	<will@...nel.org>, <longman@...hat.com>, <boqun.feng@...il.com>,
	<nikitos.tr@...il.com>, <linux-leds@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linuxppc-dev@...ts.ozlabs.org>, Lee Jones
	<lee@...nel.org>, <kernel@...utedevices.com>
Subject: Re: [DMARC error][SPF error] Re: [PATCH v4 00/10]
 devm_led_classdev_register() usage problem

Hello Andy.


I haven't lose hope for the devm_mutex thing and keep pinging those guys 
from time to time.

Sure I can single out the fix-only patch I'll do it tomorrow.


On 2/9/24 20:11, Andy Shevchenko wrote:
> On Thu, Dec 21, 2023 at 03:11:11PM +0000, Lee Jones wrote:
>> On Thu, 14 Dec 2023, George Stark wrote:
>>
>>> This patch series fixes the problem of devm_led_classdev_register misusing.
>>>
>>> The basic problem is described in [1]. Shortly when devm_led_classdev_register()
>>> is used then led_classdev_unregister() called after driver's remove() callback.
>>> led_classdev_unregister() calls driver's brightness_set callback and that callback
>>> may use resources which were destroyed already in driver's remove().
>>>
>>> After discussion with maintainers [2] [3] we decided:
>>> 1) don't touch led subsytem core code and don't remove led_set_brightness() from it
>>> but fix drivers
>>> 2) don't use devm_led_classdev_unregister
>>>
>>> So the solution is to use devm wrappers for all resources
>>> driver's brightness_set() depends on. And introduce dedicated devm wrapper
>>> for mutex as it's often used resource.
>>>
>>> [1] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@salutedevices.com/T/
>>> [2] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@salutedevices.com/T/#mc132b9b350fa51931b4fcfe14705d9f06e91421f
>>> [3] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@salutedevices.com/T/#mdbf572a85c33f869a553caf986b6228bb65c8383
> 
> ...
> 
>> FYI: I'll conduct my review once the locking side is settled.
> 
> To reduce burden can you apply the first one? It's a fix.
> 

-- 
Best regards
George