linux-kernel - Re: [PATCH] iio: max5481: use devres for iio device registration

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Date:   Sun, 18 Aug 2019 18:18:53 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Martin Kaiser <martin@...ser.cx>
Cc:     Hartmut Knaack <knaack.h@....de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Lars-Peter Clausen <lars@...afoo.de>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: max5481: use devres for iio device registration

On Wed, 14 Aug 2019 11:21:44 +0200
Martin Kaiser <martin@...ser.cx> wrote:

> Replace iio_device_register with the devres variant and drop the
> explicit function call to unregister the iio device.
> 
> Signed-off-by: Martin Kaiser <martin@...ser.cx>
This changes the order of removal compared to probe as now we don't remove
the userspace interface before storing to non volatile memory.

Admittedly it's a pretty unlikely race to hit but I don't want to set
a precedent of judging just how unlikely a race is.

I'm also not keen to use dev_add_action_or_reset for this one as the
action in remove is not balanced to one in probe - I want to see it
clearly laid out in code, as it currently is.

So a no on this sort of change in this particular driver.

Thanks,

Jonathan

> ---
>  drivers/iio/potentiometer/max5481.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/potentiometer/max5481.c b/drivers/iio/potentiometer/max5481.c
> index 732375b6d131..40b7212e68dc 100644
> --- a/drivers/iio/potentiometer/max5481.c
> +++ b/drivers/iio/potentiometer/max5481.c
> @@ -162,7 +162,7 @@ static int max5481_probe(struct spi_device *spi)
>  	if (ret < 0)
>  		return ret;
>  
> -	return iio_device_register(indio_dev);
> +	return devm_iio_device_register(&spi->dev, indio_dev);
>  }
>  
>  static int max5481_remove(struct spi_device *spi)
> @@ -170,8 +170,6 @@ static int max5481_remove(struct spi_device *spi)
>  	struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
>  	struct max5481_data *data = iio_priv(indio_dev);
>  
> -	iio_device_unregister(indio_dev);
> -
>  	/* save wiper reg to NV reg */
>  	return max5481_write_cmd(data, MAX5481_COPY_AB_TO_NV, 0);
>  }