Re: [PATCH] auxdisplay: seg-led-gpio: fix work initialization race and convert to devm_add_action_or_reset()

[Surendra Singh]

Hi Andy, Chris,

Thanks for the review!

I checked the other drivers in drivers/auxdisplay/ and found that
drivers/auxdisplay/max6959.c has the exact same pattern:

1. INIT_DELAYED_WORK(&priv->work, max6959_disp_update) is called inside
   max6959_linedisp_get_map_type() (map query callback).
2. max6959_i2c_remove() calls cancel_delayed_work_sync(&priv->work)
   before linedisp_unregister(&priv->linedisp).

I can prepare a 2-patch series fixing max6959.c as well.

Furthermore, we could add devm_linedisp_register() to line-display.c
to simplify linedisp teardown across all auxdisplay drivers.

Best regards,
Surendra Singh Chouhan


On Sun, 2 Aug 2026 at 14:59, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote:
>
> On Fri, Jul 24, 2026 at 5:55 AM <kr494167@xxxxxxxxx> wrote:
> >
> > From: Surendra Singh Chouhan <kr494167@xxxxxxxxx>
> >
> > INIT_DELAYED_WORK(&priv->work, seg_led_update) was previously called inside
> > seg_led_linedisp_get_map_type(), which is invoked during/after
> > linedisp_register(). Initializing a delayed_work structure inside a map
> > query callback can re-initialize an active work item or race with
> > seg_led_linedisp_update().
> >
> > In addition, seg_led_remove() called cancel_delayed_work_sync(&priv->work)
> > before linedisp_unregister(&priv->linedisp), allowing sysfs updates to
> > reschedule work after cancel_delayed_work_sync() completed.
> >
> > Fix these by moving INIT_DELAYED_WORK() to probe() and using
> > devm_add_action_or_reset() for devm-managed cleanup. Registering
> > seg_led_unregister_linedisp after seg_led_cancel_work ensures proper LIFO
> > teardown order (sysfs interface unregistered first, followed by work
> > cancellation), allowing seg_led_remove() to be removed entirely.
>
> I think we have more drivers than this one with the same issue, no? If
> so, can we solve this once for all (the existing and possible future
> ones)?
>
> --
> With Best Regards,
> Andy Shevchenko