[PATCH AUTOSEL 5.4 02/34] iio: st_sensors: Add a local lock for protecting odr

Sasha Levin
2022-06-07T19:53:32Z

From: Miquel Raynal <miquel.raynal@bootlin.com>

[ Upstream commit 474010127e2505fc463236470908e1ff5ddb3578 ]

Right now the (framework) mlock lock is (ab)used for multiple purposes:
1- protecting concurrent accesses over the odr local cache
2- avoid changing samplig frequency whilst buffer is running

Let's start by handling situation #1 with a local lock.

Suggested-by: Jonathan Cameron <jic23@kernel.org>
Cc: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20220207143840.707510-7-miquel.raynal@bootlin.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../iio/common/st_sensors/st_sensors_core.c | 24 ++++++++++++++-----
include/linux/iio/common/st_sensors.h | 3 +++
2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/common/st_sensors/st_sensors_core.c b/drivers/iio/common/st_sensors/st_sensors_core.c
index 364683783ae5..c25b0bc89b0c 100644
--- a/drivers/iio/common/st_sensors/st_sensors_core.c
+++ b/drivers/iio/common/st_sensors/st_sensors_core.c
@@ -76,16 +76,18 @@ static int st_sensors_match_odr(struct st_sensor_settings *sensor_settings,

int st_sensors_set_odr(struct iio_dev *indio_dev, unsigned int odr)
{
- int err;
+ int err = 0;
struct st_sensor_odr_avl odr_out = {0, 0};
struct st_sensor_data *sdata = iio_priv(indio_dev);

+ mutex_lock(&sdata->odr_lock);
+
if (!sdata->sensor_settings->odr.mask)
- return 0;
+ goto unlock_mutex;

err = st_sensors_match_odr(sdata->sensor_settings, odr, &odr_out);
if (err < 0)
- goto st_sensors_match_odr_error;
+ goto unlock_mutex;

if ((sdata->sensor_settings->odr.addr ==
sdata->sensor_settings->pw.addr) &&
@@ -108,7 +110,9 @@ int st_sensors_set_odr(struct iio_dev *indio_dev, unsigned int odr)
if (err >= 0)
sdata->odr = odr_out.hz;

-st_sensors_match_odr_error:
+unlock_mutex:
+ mutex_unlock(&sdata->odr_lock);
+
return err;
}
EXPORT_SYMBOL(st_sensors_set_odr);
@@ -384,6 +388,8 @@ int st_sensors_init_sensor(struct iio_dev *indio_dev,
struct st_sensors_platform_data *of_pdata;
int err = 0;

+ mutex_init(&sdata->odr_lock);
+
/* If OF/DT pdata exists, it will take precedence of anything else */
of_pdata = st_sensors_of_probe(indio_dev->dev.parent, pdata);
if (of_pdata)
@@ -575,18 +581,24 @@ int st_sensors_read_info_raw(struct iio_dev *indio_dev,
err = -EBUSY;
goto out;
} else {
+ mutex_lock(&sdata->odr_lock);
err = st_sensors_set_enable(indio_dev, true);
- if (err < 0)
+ if (err < 0) {
+ mutex_unlock(&sdata->odr_lock);
goto out;
+ }

msleep((sdata->sensor_settings->bootime * 1000) / sdata->odr);
err = st_sensors_read_axis_data(indio_dev, ch, val);
- if (err < 0)
+ if (err < 0) {
+ mutex_unlock(&sdata->odr_lock);
goto out;
+ }

*val = *val >> ch->scan_type.shift;

err = st_sensors_set_enable(indio_dev, false);
+ mutex_unlock(&sdata->odr_lock);
}
out:
mutex_unlock(&indio_dev->mlock);
diff --git a/include/linux/iio/common/st_sensors.h b/include/linux/iio/common/st_sensors.h
index 686be532f4cb..7816bf070f83 100644
--- a/include/linux/iio/common/st_sensors.h
+++ b/include/linux/iio/common/st_sensors.h
@@ -228,6 +228,7 @@ struct st_sensor_settings {
* @hw_irq_trigger: if we're using the hardware interrupt on the sensor.
* @hw_timestamp: Latest timestamp from the interrupt handler, when in use.
* @buffer_data: Data used by buffer part.
+ * @odr_lock: Local lock for preventing concurrent ODR accesses/changes
*/
struct st_sensor_data {
struct device *dev;
@@ -253,6 +254,8 @@ struct st_sensor_data {
s64 hw_timestamp;

char buffer_data[ST_SENSORS_MAX_BUFFER_SIZE] ____cacheline_aligned;
+
+ struct mutex odr_lock;
};

#ifdef CONFIG_IIO_BUFFER
--
2.35.1