Re: [PATCH v2 2/2] can: tcan4x5x: Add suspend error handling

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] irq: unbalanced IRQ wake disable on suspend error path
--

commit 35cb9abaa9dd12aabf550562b5fe36f26129d629
Author: Markus Schneider-Pargmann <msp@baylibre.com>

can: tcan4x5x: Add suspend error handling

This commit adds error handling to tcan4x5x_suspend() by checking the
return value of m_can_class_suspend(). If the suspend fails, it restores
the IRQ wake state before returning the error.

> diff --git a/drivers/net/can/m_can/tcan4x5x-core.c b/drivers/net/can/m_can/tcan4x5x-core.c
> index a5b8829aa5193..b69312413d627 100644
> --- a/drivers/net/can/m_can/tcan4x5x-core.c
> +++ b/drivers/net/can/m_can/tcan4x5x-core.c
> @@ -575,11 +575,20 @@ static int __maybe_unused tcan4x5x_suspend(struct device *dev)
>  {
>  	struct m_can_classdev *cdev = dev_get_drvdata(dev);
>  	struct spi_device *spi = to_spi_device(dev);
> +	int ret;
>  
>  	if (cdev->pm_wake_source)
>  		enable_irq_wake(spi->irq);
>  
> -	return m_can_class_suspend(dev);
> +	ret = m_can_class_suspend(dev);
> +	if (ret)
> +		goto err_disable_irq;
> +	return 0;
> +
> +err_disable_irq:
> +	if (cdev->pm_wake_source)
> +		disable_irq_wake(spi->irq);

[Severity: Low]
Will this trigger an unbalanced IRQ wake disable warning if
enable_irq_wake() fails?

The original code calls enable_irq_wake() but ignores its return value.
If the underlying IRQ controller does not support wake settings (e.g.
returning -ENXIO), wake_depth is not incremented.

If m_can_class_suspend() subsequently fails, the new error path calls
disable_irq_wake() unconditionally.  If enable_irq_wake() had previously
failed, wouldn't this underflow wake_depth and trigger a WARN from the IRQ
core?

Could we check the return value of enable_irq_wake() and only call
disable_irq_wake() if it actually succeeded?

> +	return ret;
>  }

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261016-v7-3-topic-mcan-suspend-fix-fix-v2-0-7efa2b172cce@baylibre.com?part=2