Re: [PATCH v2 01/10] iio: light: opt3001: move device registration to end of probe()

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 12 May 2026 12:57:21 +0200
Joshua Crofts via B4 Relay <devnull+joshua.crofts1.gmail.com@kernel.org> wrote:

> From: Joshua Crofts <joshua.crofts1@gmail.com>
> 
> Move devm_iio_device_register() to end of the opt3001_probe() function
> to prevent a race condition where userspace could interact with the
> device before the hardware IRQ was set up.
> 
> Fixes: ac663db3678a ("iio: light: opt3001: enable operation w/o IRQ")
> Reported-by: Jonathan Cameron <jic23@kernel.org>
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Closes: https://sashiko.dev/#/patchset/20260511-opt3001-cleanup-v1-0-f7879dc3455c%40gmail.com?part=7
> Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
> ---
>  drivers/iio/light/opt3001.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/light/opt3001.c b/drivers/iio/light/opt3001.c
> index 53bc455b7bad142695d9fecc6cabb934fb3ace0c..3c79e0c4ca32fedf33e318d047d6ab3f62b6c03b 100644
> --- a/drivers/iio/light/opt3001.c
> +++ b/drivers/iio/light/opt3001.c
> @@ -874,12 +874,6 @@ static int opt3001_probe(struct i2c_client *client)
>  	iio->modes = INDIO_DIRECT_MODE;
>  	iio->info = &opt3001_info;
>  
> -	ret = devm_iio_device_register(dev, iio);
> -	if (ret) {
> -		dev_err(dev, "failed to register IIO device\n");
> -		return ret;
> -	}
> -
>  	/* Make use of INT pin only if valid IRQ no. is given */
>  	if (irq > 0) {
>  		ret = request_threaded_irq(irq, NULL, opt3001_irq,
> @@ -894,6 +888,10 @@ static int opt3001_probe(struct i2c_client *client)
>  		dev_dbg(opt->dev, "enabling interrupt-less operation\n");
>  	}
>  
> +	ret = devm_iio_device_register(dev, iio);
> +	if (ret)
> +		return dev_err(dev, "failed to register IIO device\n");

Sashiko correctly points out this won't build.  I guess you were aiming for
	if (ret)
		return dev_err_probe(dev, ret, "failed to register IIO device\n");

My eyes skipped right over that whilst reading :(

The devres comment is also correct. So given this is a fix you can't do it
like this.  You'd need to move to
	ret = iio_device_register(iio);
and explicit iio_device_unregister(iio) in remove.

Then later put it back to devm when you convert the rest.

https://sashiko.dev/#/patchset/20260512-opt3001-cleanup-v2-0-8018cf3a8a0a%40gmail.com

Jonathan


> +
>  	return 0;
>  }
>  
>