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From: Andy Shevchenko <andy.shevchenko@gmail.com>
Date: Mon, 12 Feb 2024 11:53:49 +0200
Message-ID: <CAHp75VfQd9e4fLAYkYrMajnJfPQqno6s_aiTarErPiqP-Z6ydg@mail.gmail.com>
Subject: Re: [DMARC error][SPF error] Re: [PATCH v4 00/10] devm_led_classdev_register()
 usage problem
To: George Stark <gnstark@salutedevices.com>
Cc: pavel@ucw.cz, 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, linux-leds@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, 
	Lee Jones <lee@kernel.org>, kernel@salutedevices.com
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On Mon, Feb 12, 2024 at 1:52=E2=80=AFAM George Stark <gnstark@salutedevices=
com> wrote:
> I haven't lose hope for the devm_mutex thing and keep pinging those guys
> from time to time.

I don't understand. According to v4 thread Christophe proposed on how
the patch should look like. What you need is to incorporate an updated
version into your series. Am I wrong?

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

I believe it can be handled without issuing it separately. `b4` tool
is capable of selective choices. It was rather Q to Lee if he can/want
to apply it right away.

> 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 mis=
using.
> >>>
> >>> 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_bright=
ness() 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 wr=
apper
> >>> 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.

--=20
With Best Regards,
Andy Shevchenko