Re: [PATCH v2 7/9] Input: cap11xx - refactor code for better CAP1114 support.

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] The input device is registered and exposed to userspace before its threaded IRQ handler is requested, creating a race window where events could be lost or unhandled.
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commit d2a53f68ed5e5f2311cb5dfaea4bd95be2449ab4
Author: Jun Yan <jerrysteve1101@gmail.com>

Input: cap11xx - refactor code for better CAP1114 support.

Extend cap11xx_hw_model structure to support CAP1114 with
different register offsets and hardware characteristics.

> diff --git a/drivers/input/keyboard/cap11xx.c b/drivers/input/keyboard/cap11xx.c
> index 75746a8a22332..d45bb231d7a1f 100644
> --- a/drivers/input/keyboard/cap11xx.c
> +++ b/drivers/input/keyboard/cap11xx.c
[ ... ]
> @@ -554,41 +564,64 @@ static int cap11xx_i2c_probe(struct i2c_client *i2c_client)
>  }

[Severity: High]
This isn't a bug introduced by this patch, but looking at cap11xx_i2c_probe(),
the input device is registered and exposed to userspace before its threaded
IRQ handler is requested:

	error = input_register_device(priv->idev);
	if (error)
		return error;

	error = devm_request_threaded_irq(dev, i2c_client->irq,
					  NULL, cap11xx_thread_func,
					  IRQF_ONESHOT, dev_name(dev), priv);

Since input_register_device() makes the device visible to userspace, processes
like udev can immediately open the device. This invokes cap11xx_input_open()
and wakes the hardware from deep sleep.

If a hardware interrupt occurs before devm_request_threaded_irq() registers
the handler, could this unhandled interrupt cause an interrupt storm? The
kernel might then disable the IRQ line ('nobody cared'), rendering the touch
controller permanently inoperable until the module is reloaded or the system
reboots.

Should the IRQ handler be requested before the device is registered?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260612072237.1177304-1-jerrysteve1101@gmail.com?part=7