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From: George Stark <gnstark@salutedevices.com>
To: <andy.shevchenko@gmail.com>, <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>
CC: <linux-leds@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linuxppc-dev@lists.ozlabs.org>, <kernel@salutedevices.com>, George Stark
	<gnstark@salutedevices.com>
Subject: [PATCH v6 0/9] devm_led_classdev_register() usage problem
Date: Thu, 14 Mar 2024 11:45:22 +0300
Message-ID: <20240314084531.1935545-1-gnstark@salutedevices.com>
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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

Changelog:
v1->v2:
	revise patch series completely

v2->v3:
locking: add define if mutex_destroy() is not an empty function
	new patch, discussed here [8]

devm-helpers: introduce devm_mutex_init
	previous version [4]
	- revise code based on mutex_destroy define
	- update commit message
	- update devm_mutex_init()'s description

leds: aw2013: unlock mutex before destroying it
	previous version [5]
	- make this patch first in the series
	- add tags Fixes and RvB by Andy

leds: aw2013: use devm API to cleanup module's resources
	previous version [6]
	- make aw2013_chip_disable_action()'s body oneline
	- don't shadow devm_mutex_init() return code

leds: aw200xx: use devm API to cleanup module's resources
	previous version [7]
	- make aw200xx_*_action()'s bodies oneline
	- don't shadow devm_mutex_init() return code

leds: lm3532: use devm API to cleanup module's resources
leds: nic78bx: use devm API to cleanup module's resources
leds: mlxreg: use devm_mutex_init for mutex initializtion
leds: an30259a: use devm_mutext_init for mutext initialization
leds: powernv: add LED_RETAIN_AT_SHUTDOWN flag for leds
	- those pathes were planned but not sent in the series #2 due to mail server
	problem on my side. I revised them according to the comments.

v3->v4:
locking: introduce devm_mutex_init
	new patch
	- move devm_mutex_init implementation completely from devm-helpers.h to mutex.h

locking: add define if mutex_destroy() is not an empty function
	drop the patch [9]

devm-helpers: introduce devm_mutex_init
	drop the patch [10]

leds: aw2013: use devm API to cleanup module's resources
	- add tag Tested-by: Nikita Travkin <nikita@trvn.ru>

v4->v5:
leds: aw2013: unlock mutex before destroying it
	merged separately and removed from the series

locking/mutex: move mutex_destroy() definition lower
	introduce optional refactoring patch

locking/mutex: introduce devm_mutex_init
	leave only one devm_mutex_init definition
	add tag Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>

leds* patches
	remove #include <linux/devm-helpers.h> due to devm_mutext_init in mutex.h now

v5->v6:
locking/mutex: move mutex_destroy() definition lower [11]
	drop the patch due to devm_mutex_init block is big enough to be declared standalone.

locking/mutex: introduce devm_mutex_init
	redesign devm_mutex_init function to macro to keep lockdep feature working
	use typeof to redeclare mutex var in macro body (thanks to checkpatch)
	previous version [12]

[4] https://lore.kernel.org/lkml/20231204180603.470421-1-gnstark@salutedevices.com/T/#mf500af0eda2a9ffc95594607dbe4cb64f2e3c9a8
[5] https://lore.kernel.org/lkml/20231204180603.470421-1-gnstark@salutedevices.com/T/#mc92df4fb4f7d4187fb01cc1144acfa5fb5230dd2
[6] https://lore.kernel.org/lkml/20231204180603.470421-1-gnstark@salutedevices.com/T/#m300df89710c43cc2ab598baa16c68dd0a0d7d681
[7] https://lore.kernel.org/lkml/20231204180603.470421-1-gnstark@salutedevices.com/T/#m8e5c65e0c6b137c91fa00bb9320ad581164d1d0b
[8] https://lore.kernel.org/lkml/377e4437-7051-4d88-ae68-1460bcd692e1@redhat.com/T/#m5f84a4a2f387d49678783e652b9e658e02c27450
[9] https://lore.kernel.org/lkml/20231213223020.2713164-1-gnstark@salutedevices.com/T/#m19ad1fc04c560012c1e27418e3156d0c9306dd84
[10] https://lore.kernel.org/lkml/20231213223020.2713164-1-gnstark@salutedevices.com/T/#m63126025f5d1bdcef69bcad50f2e58274d42e2d
[11] https://lore.kernel.org/lkml/20240307024034.1548605-2-gnstark@salutedevices.com/
[12] https://lore.kernel.org/lkml/20240307024034.1548605-3-gnstark@salutedevices.com/

George Stark (9):
  locking/mutex: introduce devm_mutex_init
  leds: aw2013: use devm API to cleanup module's resources
  leds: aw200xx: use devm API to cleanup module's resources
  leds: lp3952: use devm API to cleanup module's resources
  leds: lm3532: use devm API to cleanup module's resources
  leds: nic78bx: use devm API to cleanup module's resources
  leds: mlxreg: use devm_mutex_init for mutex initializtion
  leds: an30259a: use devm_mutext_init for mutext initialization
  leds: powernv: use LED_RETAIN_AT_SHUTDOWN flag for leds

 drivers/leds/leds-an30259a.c | 14 ++++----------
 drivers/leds/leds-aw200xx.c  | 32 +++++++++++++++++++++-----------
 drivers/leds/leds-aw2013.c   | 25 +++++++++++++------------
 drivers/leds/leds-lm3532.c   | 29 +++++++++++++++++------------
 drivers/leds/leds-lp3952.c   | 21 +++++++++++----------
 drivers/leds/leds-mlxreg.c   | 14 +++++---------
 drivers/leds/leds-nic78bx.c  | 23 +++++++++++++----------
 drivers/leds/leds-powernv.c  | 23 ++++++++---------------
 include/linux/mutex.h        | 27 +++++++++++++++++++++++++++
 kernel/locking/mutex-debug.c | 11 +++++++++++
 10 files changed, 130 insertions(+), 89 deletions(-)

--
2.25.1