linux-kernel - Re: [PATCH v2 2/2] mfd: fsl-imx25: clean up irq settings during removal

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Message-ID: <1505809435.20966.7.camel@pengutronix.de>
Date:   Tue, 19 Sep 2017 10:23:55 +0200
From:   Lucas Stach <l.stach@...gutronix.de>
To:     Martin Kaiser <martin@...ser.cx>
Cc:     Lee Jones <lee.jones@...aro.org>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] mfd: fsl-imx25: clean up irq settings during
 removal

Am Dienstag, den 19.09.2017, 08:23 +0200 schrieb Martin Kaiser:
> When fsl-imx25-tsadc is compiled as a module, loading, unloading and
> reloading the module will lead to a crash.
> 
> Unable to handle kernel paging request at virtual address bf005430
> [<c004df6c>] (irq_find_matching_fwspec)
>    from [<c028d5ec>] (of_irq_get+0x58/0x74)
> [<c028d594>] (of_irq_get)
>    from [<c01ff970>] (platform_get_irq+0x48/0xc8)
> [<c01ff928>] (platform_get_irq)
>    from [<bf00e33c>] (mx25_tsadc_probe+0x220/0x2f4 [fsl_imx25_tsadc])
> 
> irq_find_matching_fwspec() loops over all registered irq domains. The
> irq domain is still registered from last time the module was loaded but
> the pointer to its operations is invalid after the module was unloaded.
> 
> 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.
> 
> Signed-off-by: Martin Kaiser <martin@...ser.cx>
> ---
> changes in v2:
>  add more details about the crash to the commit message
> 
>  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)

I don't think the __exit annotation makes sense. You can also unbind the
device by using sysfs, in which case you want to do the same IRQ
cleanup.

> +{
> +	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);
>