linux-kernel - Re: [PATCH 2/2] mfd: fsl-imx25: clean up irq settings during removal

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Date:   Thu, 14 Sep 2017 10:25:51 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Martin Kaiser <martin@...ser.cx>
Cc:     kernel@...gutronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mfd: fsl-imx25: clean up irq settings during removal

On Tue, 12 Sep 2017, Martin Kaiser wrote:

> When fsl-imx25-tsadc is compiled as a module, unloading and reloading
> the module will lead to a crash.
> 
> Add a removal function which clears the irq handler and removes the irq
> domain. With this cleanup in place, it's possible to unload and reload
> the module.

More information please.

What is it specifically that causes the crash?

Why is this code not required?  What's stopping this causing a leak?

> Signed-off-by: Martin Kaiser <martin@...ser.cx>
> ---
>  drivers/mfd/fsl-imx25-tsadc.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/mfd/fsl-imx25-tsadc.c b/drivers/mfd/fsl-imx25-tsadc.c
> index 14189ef..a6423bd 100644
> --- a/drivers/mfd/fsl-imx25-tsadc.c
> +++ b/drivers/mfd/fsl-imx25-tsadc.c
> @@ -179,6 +179,19 @@ static int mx25_tsadc_probe(struct platform_device *pdev)
>  	return devm_of_platform_populate(dev);
>  }
>  
> +static int __exit mx25_tsadc_remove(struct platform_device *pdev)
> +{
> +	struct mx25_tsadc *tsadc = platform_get_drvdata(pdev);
> +	int irq = platform_get_irq(pdev, 0);
> +
> +	if (irq) {
> +		irq_set_chained_handler_and_data(irq, NULL, NULL);
> +		irq_domain_remove(tsadc->domain);
> +	}
> +
> +	return 0;
> +}
> +
>  static const struct of_device_id mx25_tsadc_ids[] = {
>  	{ .compatible = "fsl,imx25-tsadc" },
>  	{ /* Sentinel */ }
> @@ -191,6 +204,7 @@ static struct platform_driver mx25_tsadc_driver = {
>  		.of_match_table = of_match_ptr(mx25_tsadc_ids),
>  	},
>  	.probe = mx25_tsadc_probe,
> +	.remove = __exit_p(mx25_tsadc_remove),
>  };
>  module_platform_driver(mx25_tsadc_driver);
>  

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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