[PATCH v2 00/10] devm_led_classdev_register() usage problem

George Stark gnstark at salutedevices.com
Tue Dec 5 05:05:53 AEDT 2023

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

George Stark (10):
  devm-helpers: introduce devm_mutex_init
  leds: aw2013: unlock mutex before destroying it
  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: add LED_RETAIN_AT_SHUTDOWN flag for leds

 drivers/leds/leds-an30259a.c | 14 ++++----------
 drivers/leds/leds-aw200xx.c  | 36 +++++++++++++++++++++++++-----------
 drivers/leds/leds-aw2013.c   | 28 ++++++++++++++++------------
 drivers/leds/leds-lm3532.c   | 29 +++++++++++++++++------------
 drivers/leds/leds-lp3952.c   | 21 +++++++++++----------
 drivers/leds/leds-mlxreg.c   | 15 ++++-----------
 drivers/leds/leds-nic78bx.c  | 25 +++++++++++++------------
 drivers/leds/leds-powernv.c  | 23 ++++++++---------------
 include/linux/devm-helpers.h | 18 ++++++++++++++++++
 9 files changed, 116 insertions(+), 93 deletions(-)


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