[PATCH 4.15 101/105] iio: imu: st_lsm6dsx: introduce conf_lock mutex

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lorenzo Bianconi <lorenzo.bianconi@xxxxxxxxxx>

commit 335eaedce461c9092e133ce0c6247f5a0b0baf69 upstream.

Add conf_lock mutex to prevent concurrent FIFO configuration update

Fixes: 290a6ce11d93 (iio: imu: add support to lsm6dsx driver)
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@xxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h        |    2 ++
 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c |   21 +++++++++++++--------
 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c   |    6 ++++++
 3 files changed, 21 insertions(+), 8 deletions(-)

--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
@@ -130,6 +130,7 @@ struct st_lsm6dsx_sensor {
  * @irq: Device interrupt line (I2C or SPI).
  * @lock: Mutex to protect read and write operations.
  * @fifo_lock: Mutex to prevent concurrent access to the hw FIFO.
+ * @conf_lock: Mutex to prevent concurrent FIFO configuration update.
  * @fifo_mode: FIFO operating mode supported by the device.
  * @enable_mask: Enabled sensor bitmask.
  * @sip: Total number of samples (acc/gyro) in a given pattern.
@@ -144,6 +145,7 @@ struct st_lsm6dsx_hw {
 
 	struct mutex lock;
 	struct mutex fifo_lock;
+	struct mutex conf_lock;
 
 	enum st_lsm6dsx_fifo_mode fifo_mode;
 	u8 enable_mask;
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
@@ -325,38 +325,40 @@ static int st_lsm6dsx_update_fifo(struct
 	struct st_lsm6dsx_hw *hw = sensor->hw;
 	int err;
 
+	mutex_lock(&hw->conf_lock);
+
 	if (hw->fifo_mode != ST_LSM6DSX_FIFO_BYPASS) {
 		err = st_lsm6dsx_flush_fifo(hw);
 		if (err < 0)
-			return err;
+			goto out;
 	}
 
 	if (enable) {
 		err = st_lsm6dsx_sensor_enable(sensor);
 		if (err < 0)
-			return err;
+			goto out;
 	} else {
 		err = st_lsm6dsx_sensor_disable(sensor);
 		if (err < 0)
-			return err;
+			goto out;
 	}
 
 	err = st_lsm6dsx_set_fifo_odr(sensor, enable);
 	if (err < 0)
-		return err;
+		goto out;
 
 	err = st_lsm6dsx_update_decimators(hw);
 	if (err < 0)
-		return err;
+		goto out;
 
 	err = st_lsm6dsx_update_watermark(sensor, sensor->watermark);
 	if (err < 0)
-		return err;
+		goto out;
 
 	if (hw->enable_mask) {
 		err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_CONT);
 		if (err < 0)
-			return err;
+			goto out;
 
 		/*
 		 * store enable buffer timestamp as reference to compute
@@ -365,7 +367,10 @@ static int st_lsm6dsx_update_fifo(struct
 		sensor->ts = iio_get_time_ns(iio_dev);
 	}
 
-	return 0;
+out:
+	mutex_unlock(&hw->conf_lock);
+
+	return err;
 }
 
 static irqreturn_t st_lsm6dsx_handler_irq(int irq, void *private)
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
@@ -528,7 +528,12 @@ static int st_lsm6dsx_set_watermark(stru
 	if (val < 1 || val > hw->settings->max_fifo_size)
 		return -EINVAL;
 
+	mutex_lock(&hw->conf_lock);
+
 	err = st_lsm6dsx_update_watermark(sensor, val);
+
+	mutex_unlock(&hw->conf_lock);
+
 	if (err < 0)
 		return err;
 
@@ -739,6 +744,7 @@ int st_lsm6dsx_probe(struct device *dev,
 
 	mutex_init(&hw->lock);
 	mutex_init(&hw->fifo_lock);
+	mutex_init(&hw->conf_lock);
 
 	hw->dev = dev;
 	hw->irq = irq;