Thread (32 messages) 32 messages, 5 authors, 2024-02-23

Re: [DMARC error][SPF error] Re: [PATCH v4 00/10] devm_led_classdev_register() usage problem

From: Andy Shevchenko <hidden>
Date: 2024-02-12 09:54:28
Also in: linux-leds, lkml

On Mon, Feb 12, 2024 at 1:52 AM George Stark [off-list ref] 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:
quoted
On Thu, Dec 21, 2023 at 03:11:11PM +0000, Lee Jones wrote:
quoted
On Thu, 14 Dec 2023, George Stark wrote:
quoted
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/ (local)
[2] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@salutedevices.com/T/#mc132b9b350fa51931b4fcfe14705d9f06e91421f (local)
[3] https://lore.kernel.org/lkml/8704539b-ed3b-44e6-aa82-586e2f895e2b@salutedevices.com/T/#mdbf572a85c33f869a553caf986b6228bb65c8383 (local)
...
quoted
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.
-- 
With Best Regards,
Andy Shevchenko
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