iio: st_sensors: Add a local lock for protecting odr

[ 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>

diff --git a/drivers/iio/common/st_sensors/st_sensors_core.c b/drivers/iio/common/st_sensors/st_sensors_core.c
index 0bbb090..aff9815 100644 (file)
--- a/drivers/iio/common/st_sensors/st_sensors_core.c
+++ b/drivers/iio/common/st_sensors/st_sensors_core.c
@@ -71,16 +71,18 @@ st_sensors_match_odr_error:
 
 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) &&
@@ -103,7 +105,9 @@ 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);
@@ -365,6 +369,8 @@ 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_dev_probe(indio_dev->dev.parent, pdata);
        if (IS_ERR(of_pdata))
@@ -558,18 +564,24 @@ 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 8bdbaf3..69f4a1f 100644 (file)
--- a/include/linux/iio/common/st_sensors.h
+++ b/include/linux/iio/common/st_sensors.h
@@ -238,6 +238,7 @@ 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;
@@ -263,6 +264,8 @@ 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