From: =?UTF-8?q?Nuno=20S=C3=A1?= <nuno.sa@analog.com>
Date: Thu, 16 Feb 2023 11:14:50 +0100
Subject: [PATCH] iio: buffer: correctly return bytes written in output buffers
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References: bsc#1012628
Patch-mainline: 6.2.11
Git-commit: b5184a26a28fac1d708b0bfeeb958a9260c2924c

commit b5184a26a28fac1d708b0bfeeb958a9260c2924c upstream.

If for some reason 'rb->access->write()' does not write the full
requested data and the O_NONBLOCK is set, we would return 'n' to
userspace which is not really truth. Hence, let's return the number of
bytes we effectively wrote.

Fixes: 9eeee3b0bf190 ("iio: Add output buffer support")
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/20230216101452.591805-2-nuno.sa@analog.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/iio/industrialio-buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 80c78bd6..6340d8e1 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -220,7 +220,7 @@ static ssize_t iio_buffer_write(struct file *filp, const char __user *buf,
 	} while (ret == 0);
 	remove_wait_queue(&rb->pollq, &wait);
 
-	return ret < 0 ? ret : n;
+	return ret < 0 ? ret : written;
 }
 
 /**
-- 
2.35.3