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From:   Paul Cercueil <paul@crapouillou.net>
To:     Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>
Cc:     linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
        Paul Cercueil <paul@crapouillou.net>
Subject: [PATCH v2 1/2] iio: core: Forbid use of both labels and extended names
Date:   Wed, 16 Jun 2021 16:57:05 +0100
Message-Id: <20210616155706.17444-2-paul@crapouillou.net>
In-Reply-To: <20210616155706.17444-1-paul@crapouillou.net>
References: <20210616155706.17444-1-paul@crapouillou.net>
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Extended names are a problem for user-space as they make the filenames
in sysfs sometimes not parsable. They are now deprecated in favor of
labels.

This change makes sure that a device driver won't provide both labels
and extended names for its channels. It has never been the case and we
don't want it to happen.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/iio/industrialio-core.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 59efb36db2c7..81f40dab778a 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1836,6 +1836,24 @@ static int iio_check_unique_scan_index(struct iio_dev *indio_dev)
 	return 0;
 }
 
+static int iio_check_extended_name(const struct iio_dev *indio_dev)
+{
+	unsigned int i;
+
+	if (!indio_dev->info->read_label)
+		return 0;
+
+	for (i = 0; i < indio_dev->num_channels; i++) {
+		if (indio_dev->channels[i].extend_name) {
+			dev_err(&indio_dev->dev,
+				"Cannot use labels and extend_name at the same time\n");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
 static const struct iio_buffer_setup_ops noop_ring_setup_ops;
 
 int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
@@ -1860,6 +1878,10 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
 	if (ret < 0)
 		return ret;
 
+	ret = iio_check_extended_name(indio_dev);
+	if (ret < 0)
+		return ret;
+
 	iio_device_register_debugfs(indio_dev);
 
 	ret = iio_buffers_alloc_sysfs_and_mask(indio_dev);
-- 
2.30.2