linux-kernel - [PATCH] iio: core: return -EINVAL when no ioctl handler has been run

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Message-ID: <20201117095154.7189-1-alexandru.ardelean@analog.com>
Date:   Tue, 17 Nov 2020 11:51:54 +0200
From:   Alexandru Ardelean <alexandru.ardelean@...log.com>
To:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <jic23@...nel.org>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>
Subject: [PATCH] iio: core: return -EINVAL when no ioctl handler has been run

It seems that when this was tested the happy case was more tested. A few of
the userspace apps rely on this returning negative error codes in case an
ioctl() is not available.

When running multiple ioctl() handlers or when calling an ioctl() that
doesn't exist, IIO_IOCTL_UNHANDLED is returned. In that case -EINVAL should
be returned.

Fixes: 8dedcc3eee3a ("iio: core: centralize ioctl() calls to the main chardev")
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
---

Apologies for not noticing this earlier.
This came up when trying to write more IIO buffer code.

>From my side either is fine: whether it be applied as a fix or whether
it's squashed into the original patch.

 drivers/iio/industrialio-core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index e53c771d66eb..419d6f8acc13 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1743,6 +1743,9 @@ static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 			break;
 	}
 
+	if (ret == IIO_IOCTL_UNHANDLED)
+		ret = -EINVAL;
+
 out_unlock:
 	mutex_unlock(&indio_dev->info_exist_lock);
 
-- 
2.17.1