[PATCH V2] iio:accel:kxsd9 fix missing mutex unlock

[Jonathan Cameron <jic23@kernel.org>]

From: Frank Zago <frank@zago.net>

This will leave a lock held after reading from the device, preventing
any further reads.

Signed-off-by: Frank Zago <frank@zago.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
---

This is Frank's original patch.  As Lars-Peter pointed out, I really didn't
think my way through my shortened (and incorrect version).

Oops!

Frank, just to check, are you fine signing off on this?

 drivers/iio/accel/kxsd9.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/accel/kxsd9.c b/drivers/iio/accel/kxsd9.c
index d72118d1189c..98ba761cbb9c 100644
--- a/drivers/iio/accel/kxsd9.c
+++ b/drivers/iio/accel/kxsd9.c
@@ -112,9 +112,10 @@ static int kxsd9_read(struct iio_dev *indio_dev, u8 address)
 	mutex_lock(&st->buf_lock);
 	st->tx[0] = KXSD9_READ(address);
 	ret = spi_sync_transfer(st->us, xfers, ARRAY_SIZE(xfers));
-	if (ret)
-		return ret;
-	return (((u16)(st->rx[0])) << 8) | (st->rx[1] & 0xF0);
+	if (!ret)
+		ret = (((u16)(st->rx[0])) << 8) | (st->rx[1] & 0xF0);
+	mutex_unlock(&st->buf_lock);
+	return ret;
 }
 
 static IIO_CONST_ATTR(accel_scale_available,
-- 
1.8.4.2