Re: [PATCH v7 0/8] devm_led_classdev_register() usage problem

From: Lee Jones
Date: Thu Mar 21 2024 - 14:11:46 EST


On Thu, 14 Mar 2024, 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 subsystem 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@xxxxxxxxxxxxxxxxx/T/
> [2] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@xxxxxxxxxxxxxxxxx/T/#mc132b9b350fa51931b4fcfe14705d9f06e91421f
> [3] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@xxxxxxxxxxxxxxxxx/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 one line
> - 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 one line
> - 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 initialization
> leds: an30259a: use devm_mutext_init for mutext initialization
> leds: powernv: add LED_RETAIN_AT_SHUTDOWN flag for leds
> - those patches 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@xxxxxxx>
>
> 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@xxxxxxxxxx>
>
> leds* patches
> remove #include <linux/devm-helpers.h> due to devm_mutex_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]
>
> v6->v7:
> locking/mutex: introduce devm_mutex_init
> fix comment at __devm_mutex_init
> move #include <linux/device.h> upper
> commit message: change devm_mutex_init -> devm_mutex_init(), add point in the end
> fix and move up tag Suggested-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> add tags (in the order received):
> Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Reviewed-by: Marek Behún <kabel@xxxxxxxxxx>
> Acked-by: Waiman Long <longman@xxxxxxxxxx>
>
> leds: powernv: use LED_RETAIN_AT_SHUTDOWN flag for leds
> remove the patch from this series to send it separately
>
> leds: mlxreg: use devm_mutex_init() for mutex initialization
> leds: an30259a: use devm_mutex_init() for mutex initialization
> commit message: change devm_mutex_init -> devm_mutex_init()
> add tag Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
>
> 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
> add tag Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
>
> [4] https://lore.kernel.org/lkml/20231204180603.470421-1-gnstark@xxxxxxxxxxxxxxxxx/T/#mf500af0eda2a9ffc95594607dbe4cb64f2e3c9a8
> [5] https://lore.kernel.org/lkml/20231204180603.470421-1-gnstark@xxxxxxxxxxxxxxxxx/T/#mc92df4fb4f7d4187fb01cc1144acfa5fb5230dd2
> [6] https://lore.kernel.org/lkml/20231204180603.470421-1-gnstark@xxxxxxxxxxxxxxxxx/T/#m300df89710c43cc2ab598baa16c68dd0a0d7d681
> [7] https://lore.kernel.org/lkml/20231204180603.470421-1-gnstark@xxxxxxxxxxxxxxxxx/T/#m8e5c65e0c6b137c91fa00bb9320ad581164d1d0b
> [8] https://lore.kernel.org/lkml/377e4437-7051-4d88-ae68-1460bcd692e1@xxxxxxxxxx/T/#m5f84a4a2f387d49678783e652b9e658e02c27450
> [9] https://lore.kernel.org/lkml/20231213223020.2713164-1-gnstark@xxxxxxxxxxxxxxxxx/T/#m19ad1fc04c560012c1e27418e3156d0c9306dd84
> [10] https://lore.kernel.org/lkml/20231213223020.2713164-1-gnstark@xxxxxxxxxxxxxxxxx/T/#m63126025f5d1bdcef69bcad50f2e58274d42e2d
> [11] https://lore.kernel.org/lkml/20240307024034.1548605-2-gnstark@xxxxxxxxxxxxxxxxx/
> [12] https://lore.kernel.org/lkml/20240307024034.1548605-3-gnstark@xxxxxxxxxxxxxxxxx/
>
> George Stark (8):
> 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 initialization
> leds: an30259a: use devm_mutex_init() for mutex initialization
>
> 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 +++++++++++++----------
> include/linux/mutex.h | 27 +++++++++++++++++++++++++++
> kernel/locking/mutex-debug.c | 11 +++++++++++
> 9 files changed, 122 insertions(+), 74 deletions(-)

Doesn't apply to v6.8.

What base was used for this?

--
Lee Jones [李琼斯]