[PATCH 3/3] iio: frequency: ad9834: add mutex_lock() when reading st->control

[Joshua Crofts <joshua.crofts1@gmail.com>]

Add mutex_lock() and mutex_unlock() when reading st->control to
prevent data races as st->control is actively modified by
sysfs _write and _store functions.

Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
---
 drivers/staging/iio/frequency/ad9834.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
index 9499e05a73..33570474c4 100644
--- a/drivers/staging/iio/frequency/ad9834.c
+++ b/drivers/staging/iio/frequency/ad9834.c
@@ -283,12 +283,14 @@ ssize_t ad9834_show_out0_wavetype_available(struct device *dev,
 	struct ad9834_state *st = iio_priv(indio_dev);
 	char *str;
 
+	mutex_lock(&st->lock);
 	if (st->devid == ID_AD9833 || st->devid == ID_AD9837)
 		str = "sine triangle square";
 	else if (st->control & AD9834_OPBITEN)
 		str = "sine";
 	else
 		str = "sine triangle";
+	mutex_unlock(&st->lock);
 
 	return sysfs_emit(buf, "%s\n", str);
 }
@@ -305,10 +307,12 @@ ssize_t ad9834_show_out1_wavetype_available(struct device *dev,
 	struct ad9834_state *st = iio_priv(indio_dev);
 	char *str;
 
+	mutex_lock(&st->lock);
 	if (st->control & AD9834_MODE)
 		str = "";
 	else
 		str = "square";
+	mutex_unlock(&st->lock);
 
 	return sysfs_emit(buf, "%s\n", str);
 }
-- 
2.47.3