Re: [PATCH 1/2] Input: tca8418_keypad - Add devm cleanup to disable interrupts on unload

[Zhian Liang]

Hi Dmitry,

The INT output is "active-low interrupt output, open drain structure" (Datasheet §5, pin
table). With the handler gone but hardware still enabled, a key press pulls INT low with nobody to service it.
And the driver requests the IRQ with IRQF_SHARED,

	error = devm_request_threaded_irq(dev, client->irq,
					  NULL, tca8418_irq_handler,
					  IRQF_SHARED | IRQF_ONESHOT,
					  client->name, keypad_data);
	if (error) {
		dev_err(dev, "Unable to claim irq %d; error %d\n",
			client->irq, error);
		return error;
	}

this stuck interrupt is seen by every other device sharing the line, and may trigger "nobody cared" IRQ storms or, in the worst case, cause the kernel to disable the shared IRQ line entirely, breaking unrelated devices.

The same leak happens on driver unbind (I think it's a rare case though).

--
Zhian