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References: <20240314084531.1935545-1-gnstark@salutedevices.com>
In-Reply-To: <20240314084531.1935545-1-gnstark@salutedevices.com>
From: Andy Shevchenko <andy.shevchenko@gmail.com>
Date: Thu, 14 Mar 2024 12:37:13 +0200
Message-ID: <CAHp75VdM9GkogkeffY+0rwU3r2iWeTZ8-aj901MLteUmRfcLOA@mail.gmail.com>
Subject: Re: [PATCH v6 0/9] devm_led_classdev_register() usage problem
To: George Stark <gnstark@salutedevices.com>
Cc: pavel@ucw.cz, lee@kernel.org, vadimp@nvidia.com, mpe@ellerman.id.au, 
	npiggin@gmail.com, christophe.leroy@csgroup.eu, hdegoede@redhat.com, 
	mazziesaccount@gmail.com, peterz@infradead.org, mingo@redhat.com, 
	will@kernel.org, longman@redhat.com, boqun.feng@gmail.com, 
	nikitos.tr@gmail.com, marek.behun@nic.cz, kabel@kernel.org, 
	linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linuxppc-dev@lists.ozlabs.org, kernel@salutedevices.com
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On Thu, Mar 14, 2024 at 10:46=E2=80=AFAM George Stark <gnstark@salutedevice=
s.com> wrote:
>
> This patch series fixes the problem of devm_led_classdev_register misusin=
g.
>
> The basic problem is described in [1]. Shortly when devm_led_classdev_reg=
ister()
> is used then led_classdev_unregister() called after driver's remove() cal=
lback.
> 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

subsystem

> 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 wrappe=
r
> for mutex as it's often used resource.

The leds related changes (except the last one) LGTM, hence FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
(for patches 2-8)

> [1] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@sal=
utedevices.com/T/
> [2] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@sal=
utedevices.com/T/#mc132b9b350fa51931b4fcfe14705d9f06e91421f
> [3] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@sal=
utedevices.com/T/#mdbf572a85c33f869a553caf986b6228bb65c8383

--=20
With Best Regards,
Andy Shevchenko