Re: [PATCH] mfd: wcd934x: Unroll regmap and irqchip on removal

[Lee Jones <lee@kernel.org>]

On Mon, 09 Mar 2026, Bjorn Andersson wrote:

> When the slimbus-up event is handled a new regmap is created, an IRQ
> chip is registered on this regmap and then the MFD devices are added.
> 
> But the regmap is left dangling if either any of those operations are
> failing or if the slimbus-down event ever comes. Which manifest itself
> as an error print from debugfs once the next slimbus-up event happens.
> 
> Likewise, if for some reason a slimbus-down event would be followed by
> a slimbus-up event without the MFD being torn down by the slimbus
> controller inbetween, we're going to have a dangling irq_chip.
> 
> Add cleanup of the registered resources on failure and on removal.
> 
> Fixes: 6ac7e4d7ad70 ("mfd: wcd934x: Add support to wcd9340/wcd9341 codec")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>
> ---
>  drivers/mfd/wcd934x.c | 49 ++++++++++++++++++++++++++++++++++++++-----------
>  1 file changed, 38 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/mfd/wcd934x.c b/drivers/mfd/wcd934x.c
> index 3c3080e8c8cf7ecaaa62e255c7e01a850e65e9ad..b03cc91cc3a6a114a34efdb278420ae3dfa016eb 100644
> --- a/drivers/mfd/wcd934x.c
> +++ b/drivers/mfd/wcd934x.c
> @@ -170,29 +170,56 @@ static int wcd934x_slim_status_up(struct slim_device *sdev)
>  	ret = wcd934x_bring_up(ddata);
>  	if (ret) {
>  		dev_err(dev, "Failed to bring up WCD934X: err = %d\n", ret);
> -		return ret;
> +		goto err_regmap_exit;
>  	}
>  
> -	ret = devm_regmap_add_irq_chip(dev, ddata->regmap, ddata->irq,
> -				       IRQF_TRIGGER_HIGH, 0,
> -				       &wcd934x_regmap_irq_chip,
> -				       &ddata->irq_data);
> +	ret = regmap_add_irq_chip(ddata->regmap, ddata->irq,
> +				  IRQF_TRIGGER_HIGH, 0,
> +				  &wcd934x_regmap_irq_chip,
> +				  &ddata->irq_data);
>  	if (ret) {
>  		dev_err(dev, "Failed to add IRQ chip: err = %d\n", ret);
> -		return ret;
> +		goto err_regmap_exit;
>  	}
>  
>  	ret = mfd_add_devices(dev, PLATFORM_DEVID_AUTO, wcd934x_devices,
>  			      ARRAY_SIZE(wcd934x_devices), NULL, 0, NULL);
>  	if (ret) {
> -		dev_err(dev, "Failed to add child devices: err = %d\n",
> -			ret);
> -		return ret;
> +		dev_err(dev, "Failed to add child devices: err = %d\n", ret);
> +		goto err_del_irq_chip;
>  	}
>  
> +	return 0;
> +
> +err_del_irq_chip:
> +	regmap_del_irq_chip(ddata->irq, ddata->irq_data);
> +	ddata->irq_data = NULL;
> +err_regmap_exit:
> +	regmap_exit(ddata->regmap);
> +	ddata->regmap = NULL;
>  	return ret;
>  }
>  
> +static void wcd934x_slim_status_down(struct slim_device *sdev)
> +{
> +	struct device *dev = &sdev->dev;
> +	struct wcd934x_ddata *ddata;
> +
> +	ddata = dev_get_drvdata(dev);

Is this guaranteed to be populated?

If this fails for any reason, we'll nul-ptr-deref below.

> +	mfd_remove_devices(&sdev->dev);
> +
> +	if (ddata->irq_data) {
> +		regmap_del_irq_chip(ddata->irq, ddata->irq_data);
> +		ddata->irq_data = NULL;
> +	}
> +
> +	if (ddata->regmap) {
> +		regmap_exit(ddata->regmap);
> +		ddata->regmap = NULL;
> +	}
> +}

[...]

-- 
Lee Jones [李琼斯]