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

[Alexandru Ardelean]

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://lore.kernel.org/linux-iio/20210428150815.136150-1-paul@xxxxxxxxxxxxxxx/

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>
---
 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