RE: [PATCH] iio: core: return ENODEV if ioctl is unknown

[Sa, Nuno]

> -----Original Message-----
> From: Alexandru Ardelean <aardelean@xxxxxxxxxxx>
> Sent: Monday, May 3, 2021 4:44 PM
> To: linux-iio@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: jic23@xxxxxxxxxx; lars@xxxxxxxxxx; Alexandru Ardelean
> <aardelean@xxxxxxxxxxx>; Linus Walleij <linus.walleij@xxxxxxxxxx>;
> Paul Cercueil <paul@xxxxxxxxxxxxxxx>; Sa, Nuno
> <Nuno.Sa@xxxxxxxxxx>
> Subject: [PATCH] iio: core: return ENODEV if ioctl is unknown
>  
> When the ioctl() mechanism was introduced in IIO core to centralize
> the
> registration of all ioctls in one place via commit 8dedcc3eee3ac ("iio:
> core: centralize ioctl() calls to the main chardev"), the return code was
> changed from ENODEV to EINVAL, when the ioctl code isn't known.
> 
> This was done by accident.
> 
> This change reverts back to the old behavior, where if the ioctl() code
> isn't known, ENODEV is returned (vs EINVAL).
> 
> This was brought into perspective by this patch:
>   https://urldefense.com/v3/__https://lore.kernel.org/linux-
> iio/20210428150815.136150-1-
> paul@xxxxxxxxxxxxxxx/__;!!A3Ni8CS0y2Y!rbiZhkgdYhOPdii_YEAgO0BlX
> UxYANj3juvQuoWtaH61DSon2xK5i_BRar5Jyw$
> 
> Fixes: 8dedcc3eee3ac ("iio: core: centralize ioctl() calls to the main
> chardev")
> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
> Cc: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> Cc: Nuno Sa <nuno.sa@xxxxxxxxxx>
> Signed-off-by: Alexandru Ardelean <aardelean@xxxxxxxxxxx>
> ---

Reviewed-by: Nuno Sá <nuno.sa@xxxxxxxxxx>

>  drivers/iio/industrialio-core.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-
> core.c
> index efb4cf91c9e4..9a3a83211a90 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -1803,7 +1803,6 @@ static long iio_ioctl(struct file *filp, unsigned
> int cmd, unsigned long arg)
>  	if (!indio_dev->info)
>  		goto out_unlock;
> 
> -	ret = -EINVAL;
>  	list_for_each_entry(h, &iio_dev_opaque->ioctl_handlers,
> entry) {
>  		ret = h->ioctl(indio_dev, filp, cmd, arg);
>  		if (ret != IIO_IOCTL_UNHANDLED)
> @@ -1811,7 +1810,7 @@ static long iio_ioctl(struct file *filp, unsigned
> int cmd, unsigned long arg)
>  	}
> 
>  	if (ret == IIO_IOCTL_UNHANDLED)
> -		ret = -EINVAL;
> +		ret = -ENODEV;
> 
>  out_unlock:
>  	mutex_unlock(&iio_dev_opaque->info_exist_lock);
> --
> 2.31.1

- Nuno Sá