iio: chemical: scd30: Replace manual locking with RAII locking

scd30_core.c currently uses manual mutex_lock() and mutex_unlock()
calls. Replace them with the newer guard(mutex)() for cleaner RAII
patterns and to improve maintainability.

Add new helper function scd30_trigger_handler_helper() containing
the critical section for scd30_trigger_handler().

In addition, small refactor to replace "?:" operator with regular
if/else returns.

Signed-off-by: Maxwell Doose <m32285159@gmail.com>
Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30_core.c
index 11d6bc1b63e670292857d4741dec266227105e25..4e99b29f451881bb8b8768bf2a0aa1b847acbfd2 100644 (file)
--- a/drivers/iio/chemical/scd30_core.c
+++ b/drivers/iio/chemical/scd30_core.c
@@ -368,11 +368,13 @@ static ssize_t calibration_auto_enable_show(struct device *dev, struct device_at
        int ret;
        u16 val;
 
-       mutex_lock(&state->lock);
+       guard(mutex)(&state->lock);
+
        ret = scd30_command_read(state, CMD_ASC, &val);
-       mutex_unlock(&state->lock);
+       if (ret)
+               return ret;
 
-       return ret ?: sysfs_emit(buf, "%d\n", val);
+       return sysfs_emit(buf, "%d\n", val);
 }
 
 static ssize_t calibration_auto_enable_store(struct device *dev, struct device_attribute *attr,
@@ -387,11 +389,13 @@ static ssize_t calibration_auto_enable_store(struct device *dev, struct device_a
        if (ret)
                return ret;
 
-       mutex_lock(&state->lock);
+       guard(mutex)(&state->lock);
+
        ret = scd30_command_write(state, CMD_ASC, val);
-       mutex_unlock(&state->lock);
+       if (ret)
+               return ret;
 
-       return ret ?: len;
+       return len;
 }
 
 static ssize_t calibration_forced_value_show(struct device *dev, struct device_attribute *attr,
@@ -402,11 +406,13 @@ static ssize_t calibration_forced_value_show(struct device *dev, struct device_a
        int ret;
        u16 val;
 
-       mutex_lock(&state->lock);
+       guard(mutex)(&state->lock);
+
        ret = scd30_command_read(state, CMD_FRC, &val);
-       mutex_unlock(&state->lock);
+       if (ret)
+               return ret;
 
-       return ret ?: sysfs_emit(buf, "%d\n", val);
+       return sysfs_emit(buf, "%d\n", val);
 }
 
 static ssize_t calibration_forced_value_store(struct device *dev, struct device_attribute *attr,
@@ -424,11 +430,13 @@ static ssize_t calibration_forced_value_store(struct device *dev, struct device_
        if (val < SCD30_FRC_MIN_PPM || val > SCD30_FRC_MAX_PPM)
                return -EINVAL;
 
-       mutex_lock(&state->lock);
+       guard(mutex)(&state->lock);
+
        ret = scd30_command_write(state, CMD_FRC, val);
-       mutex_unlock(&state->lock);
+       if (ret)
+               return ret;
 
-       return ret ?: len;
+       return len;
 }
 
 static IIO_DEVICE_ATTR_RO(sampling_frequency_available, 0);
@@ -579,24 +587,34 @@ out:
        return IRQ_HANDLED;
 }
 
+static int scd30_trigger_handler_helper(struct iio_dev *indio_dev, int *scan_data,
+                                       size_t scan_data_size)
+{
+       struct scd30_state *state = iio_priv(indio_dev);
+       int ret;
+
+       guard(mutex)(&state->lock);
+
+       if (!iio_trigger_using_own(indio_dev))
+               ret = scd30_read_poll(state);
+       else
+               ret = scd30_read_meas(state);
+       memcpy(scan_data, state->meas, scan_data_size);
+
+       return ret;
+}
+
 static irqreturn_t scd30_trigger_handler(int irq, void *p)
 {
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
-       struct scd30_state *state = iio_priv(indio_dev);
        struct {
                int data[SCD30_MEAS_COUNT];
                aligned_s64 ts;
        } scan = { };
        int ret;
 
-       mutex_lock(&state->lock);
-       if (!iio_trigger_using_own(indio_dev))
-               ret = scd30_read_poll(state);
-       else
-               ret = scd30_read_meas(state);
-       memcpy(scan.data, state->meas, sizeof(state->meas));
-       mutex_unlock(&state->lock);
+       ret = scd30_trigger_handler_helper(indio_dev, scan.data, sizeof(scan.data));
        if (ret)
                goto out;