Thread (32 messages) 32 messages, 5 authors, 2024-02-23

Re: [PATCH v4 00/10] devm_led_classdev_register() usage problem

From: Andy Shevchenko <hidden>
Date: 2024-02-09 17:18:07
Also in: linux-leds, lkml

On Thu, Dec 14, 2023 at 08:36:04PM +0300, 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/ (local)
[2] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@salutedevices.com/T/#mc132b9b350fa51931b4fcfe14705d9f06e91421f (local)
[3] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@salutedevices.com/T/#mdbf572a85c33f869a553caf986b6228bb65c8383 (local)
Are you going to send an updated version with the amended second patch?

-- 
With Best Regards,
Andy Shevchenko

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