[PATCH] backlight: lm3630a: Cancel delayed work before destroying workqueue

[PATCH] backlight: lm3630a: Cancel delayed work before destroying workqueue

[Myeonghun Pak]

The interrupt handler queues delayed work to read the interrupt status.
After free_irq() stops the producer, this work can still be waiting on its
timer. destroy_workqueue() cannot drain delayed work that has not yet been
queued by its timer, so the timer can outlive both the workqueue and the
devm-allocated chip containing the work.

Cancel the delayed work synchronously after freeing the IRQ and before
destroying the workqueue. This also waits for any running status read to
finish before the chip's resources are released.

This issue was identified during our ongoing static-analysis research
while reviewing kernel code.

Fixes: 0c2a665a648e ("backlight: add Backlight driver for lm3630 chip")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
---
 drivers/video/backlight/lm3630a_bl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index 8f49e59ce374..8ef8163c7fef 100644
--- a/drivers/video/backlight/lm3630a_bl.c
+++ b/drivers/video/backlight/lm3630a_bl.c
@@ -591,6 +591,7 @@ static void lm3630a_remove(struct i2c_client *client)
 
 	if (pchip->irq) {
 		free_irq(pchip->irq, pchip);
+		cancel_delayed_work_sync(&pchip->work);
 		destroy_workqueue(pchip->irqthread);
 	}
 }
-- 
2.53.0

Re: [PATCH] backlight: lm3630a: Cancel delayed work before destroying workqueue

[Daniel Thompson]

On Fri, Oct 02, 2026 at 11:04:39PM -0400, Myeonghun Pak wrote:
> The interrupt handler queues delayed work to read the interrupt status.
> After free_irq() stops the producer, this work can still be waiting on its
> timer. destroy_workqueue() cannot drain delayed work that has not yet been
> queued by its timer, so the timer can outlive both the workqueue and the
> devm-allocated chip containing the work.
>
> Cancel the delayed work synchronously after freeing the IRQ and before
> destroying the workqueue. This also waits for any running status read to
> finish before the chip's resources are released.
>
> This issue was identified during our ongoing static-analysis research
> while reviewing kernel code.
>
> Fixes: 0c2a665a648e ("backlight: add Backlight driver for lm3630 chip")
> Cc: stable@vger.kernel.org
> Assisted-by: LLM
> Co-developed-by: Ijae Kim <ae878000@gmail.com>
> Signed-off-by: Ijae Kim <ae878000@gmail.com>
> Signed-off-by: Myeonghun Pak <mhun512@gmail.com>

Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>


Daniel.