[PATCH v2 03/11] iio: dac: ad5686: acquire lock when doing powerdown control

Rodrigo Alencar via B4 Relay
2026-04-27T11:30:11Z

Protect write access of pwr_down_mode and pwr_down_mask fields with
existing mutex lock. Each channel exposes their own attributes for
controlling powerdown modes and powerdown state. This fixes potential race
conditions as those functions perform non-atomic read-modify-write
operations to those pwr_down_* fields. This issue exists since the ad5686
driver was first introduced.

Fixes: c2f37c8dcadc ("iio: dac: New driver for AD5686R, AD5685R, AD5684R Digital to analog converters")
Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>
---
drivers/iio/dac/ad5686.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
index 24f928ea2b91..aa17ed6aee43 100644
--- a/drivers/iio/dac/ad5686.c
+++ b/drivers/iio/dac/ad5686.c
@@ -39,6 +39,8 @@ static int ad5686_set_powerdown_mode(struct iio_dev *indio_dev,
{
struct ad5686_state *st = iio_priv(indio_dev);

+ guard(mutex)(&st->lock);
+
st->pwr_down_mode &= ~(0x3 << (chan->channel * 2));
st->pwr_down_mode |= ((mode + 1) << (chan->channel * 2));

@@ -77,6 +79,8 @@ static ssize_t ad5686_write_dac_powerdown(struct iio_dev *indio_dev,
if (ret)
return ret;

+ guard(mutex)(&st->lock);
+
if (readin)
st->pwr_down_mask |= (0x3 << (chan->channel * 2));
else

--
2.43.0