linux-kernel - [PATCH v3 00/11] devm_led_classdev

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Date:   Thu, 14 Dec 2023 01:30:09 +0300
From:   George Stark <gnstark@...utedevices.com>
To:     <andy.shevchenko@...il.com>, <pavel@....cz>, <lee@...nel.org>,
        <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>
CC:     <linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linuxppc-dev@...ts.ozlabs.org>, <kernel@...utedevices.com>,
        George Stark <gnstark@...utedevices.com>
Subject: [PATCH v3 00/11] devm_led_classdev_register() usage problem

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.

[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

George Stark (11):
  leds: aw2013: unlock mutex before destroying it
  locking: add define if mutex_destroy() is not an empty function
  devm-helpers: 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 | 15 +++++----------
 drivers/leds/leds-aw200xx.c  | 33 ++++++++++++++++++++++-----------
 drivers/leds/leds-aw2013.c   | 27 +++++++++++++++------------
 drivers/leds/leds-lm3532.c   | 30 ++++++++++++++++++------------
 drivers/leds/leds-lp3952.c   | 21 +++++++++++----------
 drivers/leds/leds-mlxreg.c   | 17 ++++++-----------
 drivers/leds/leds-nic78bx.c  | 25 +++++++++++++------------
 drivers/leds/leds-powernv.c  | 23 ++++++++---------------
 include/linux/devm-helpers.h | 27 +++++++++++++++++++++++++++
 include/linux/mutex.h        |  3 +++
 10 files changed, 128 insertions(+), 93 deletions(-)

-- 
2.25.1