[PATCH] iio: imu: st_lsm6dsx: fix possible lockup during FIFO read

[Silvano Seva <s.seva@4sigma.it>]

Prevent st_lsm6dsx_read_fifo and st_lsm6dsx_read_tagged_fifo functions
from falling in an infinite loop in case pattern_len is equal to zero and
the device FIFO is not empty.

Signed-off-by: Silvano Seva <s.seva@4sigma.it>
---
 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
index 0a7cd8c1aa33..7f343614f8a5 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
@@ -395,12 +395,17 @@ int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
 	fifo_len = (le16_to_cpu(fifo_status) & fifo_diff_mask) *
 		   ST_LSM6DSX_CHAN_SIZE;
 	fifo_len = (fifo_len / pattern_len) * pattern_len;
+	if (!fifo_len)
+		return 0;
 
 	acc_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
 	gyro_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_GYRO]);
 	if (hw->iio_devs[ST_LSM6DSX_ID_EXT0])
 		ext_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_EXT0]);
 
+	if (!pattern_len)
+		pattern_len = ST_LSM6DSX_SAMPLE_SIZE;
+
 	for (read_len = 0; read_len < fifo_len; read_len += pattern_len) {
 		err = st_lsm6dsx_read_block(hw, ST_LSM6DSX_REG_FIFO_OUTL_ADDR,
 					    hw->buff, pattern_len,
@@ -623,6 +628,9 @@ int st_lsm6dsx_read_tagged_fifo(struct st_lsm6dsx_hw *hw)
 	if (!fifo_len)
 		return 0;
 
+	if (!pattern_len)
+		pattern_len = ST_LSM6DSX_TAGGED_SAMPLE_SIZE;
+
 	for (read_len = 0; read_len < fifo_len; read_len += pattern_len) {
 		err = st_lsm6dsx_read_block(hw,
 					    ST_LSM6DSX_REG_FIFO_OUT_TAG_ADDR,
-- 
2.48.1