From 5237c3175cae5ab05f18878cec3301a04403859e Mon Sep 17 00:00:00 2001 From: Rodrigo Alencar Date: Tue, 5 May 2026 13:35:04 +0100 Subject: [PATCH] iio: dac: ad5686: acquire lock when doing powerdown control Protect 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 the write 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 Cc: Signed-off-by: Jonathan Cameron --- drivers/iio/dac/ad5686.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c index 27878a6318ff..2e443fcfeb39 100644 --- a/drivers/iio/dac/ad5686.c +++ b/drivers/iio/dac/ad5686.c @@ -30,6 +30,8 @@ static int ad5686_get_powerdown_mode(struct iio_dev *indio_dev, { struct ad5686_state *st = iio_priv(indio_dev); + guard(mutex)(&st->lock); + return ((st->pwr_down_mode >> (chan->channel * 2)) & 0x3) - 1; } @@ -39,6 +41,8 @@ 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)); @@ -57,6 +61,8 @@ static ssize_t ad5686_read_dac_powerdown(struct iio_dev *indio_dev, { struct ad5686_state *st = iio_priv(indio_dev); + guard(mutex)(&st->lock); + return sysfs_emit(buf, "%d\n", !!(st->pwr_down_mask & (0x3 << (chan->channel * 2)))); } @@ -77,6 +83,8 @@ 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