iio: chemical: scd30: Use guard(mutex) to allow early returns

Auto cleanup based release of the lock allows for simpler code flow in a
few functions with large multiplexing style switch statements and no
common operations following the switch.

Suggested-by: David Lechner <dlechner@baylibre.com>
Cc: Tomasz Duszynski <tomasz.duszynski@octakon.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250209180624.701140-3-jic23@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30_core.c
index d613c54cb28d9c50f54a0444f2a49b7f9e8dafd1..23ba46f7ca32062604e5ab1e65df205f47d93c36 100644 (file)
--- a/drivers/iio/chemical/scd30_core.c
+++ b/drivers/iio/chemical/scd30_core.c
@@ -5,6 +5,7 @@
  * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
  */
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/completion.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -198,112 +199,104 @@ static int scd30_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const
                          int *val, int *val2, long mask)
 {
        struct scd30_state *state = iio_priv(indio_dev);
-       int ret = -EINVAL;
+       int ret;
        u16 tmp;
 
-       mutex_lock(&state->lock);
+       guard(mutex)(&state->lock);
        switch (mask) {
        case IIO_CHAN_INFO_RAW:
        case IIO_CHAN_INFO_PROCESSED:
                if (chan->output) {
                        *val = state->pressure_comp;
-                       ret = IIO_VAL_INT;
-                       break;
+                       return IIO_VAL_INT;
                }
 
                ret = iio_device_claim_direct_mode(indio_dev);
                if (ret)
-                       break;
+                       return ret;
 
                ret = scd30_read(state);
                if (ret) {
                        iio_device_release_direct_mode(indio_dev);
-                       break;
+                       return ret;
                }
 
                *val = state->meas[chan->address];
                iio_device_release_direct_mode(indio_dev);
-               ret = IIO_VAL_INT;
-               break;
+               return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = 0;
                *val2 = 1;
-               ret = IIO_VAL_INT_PLUS_MICRO;
-               break;
+               return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_SAMP_FREQ:
                ret = scd30_command_read(state, CMD_MEAS_INTERVAL, &tmp);
                if (ret)
-                       break;
+                       return ret;
 
                *val = 0;
                *val2 = 1000000000 / tmp;
-               ret = IIO_VAL_INT_PLUS_NANO;
-               break;
+               return IIO_VAL_INT_PLUS_NANO;
        case IIO_CHAN_INFO_CALIBBIAS:
                ret = scd30_command_read(state, CMD_TEMP_OFFSET, &tmp);
                if (ret)
-                       break;
+                       return ret;
 
                *val = tmp;
-               ret = IIO_VAL_INT;
-               break;
+               return IIO_VAL_INT;
+       default:
+               return -EINVAL;
        }
-       mutex_unlock(&state->lock);
-
-       return ret;
 }
 
 static int scd30_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
                           int val, int val2, long mask)
 {
        struct scd30_state *state = iio_priv(indio_dev);
-       int ret = -EINVAL;
+       int ret;
 
-       mutex_lock(&state->lock);
+       guard(mutex)(&state->lock);
        switch (mask) {
        case IIO_CHAN_INFO_SAMP_FREQ:
                if (val)
-                       break;
+                       return -EINVAL;
 
                val = 1000000000 / val2;
                if (val < SCD30_MEAS_INTERVAL_MIN_S || val > SCD30_MEAS_INTERVAL_MAX_S)
-                       break;
+                       return -EINVAL;
 
                ret = scd30_command_write(state, CMD_MEAS_INTERVAL, val);
                if (ret)
-                       break;
+                       return ret;
 
                state->meas_interval = val;
-               break;
+               return 0;
        case IIO_CHAN_INFO_RAW:
                switch (chan->type) {
                case IIO_PRESSURE:
                        if (val < SCD30_PRESSURE_COMP_MIN_MBAR ||
                            val > SCD30_PRESSURE_COMP_MAX_MBAR)
-                               break;
+                               return -EINVAL;
 
                        ret = scd30_command_write(state, CMD_START_MEAS, val);
                        if (ret)
-                               break;
+                               return ret;
 
                        state->pressure_comp = val;
-                       break;
+                       return 0;
                default:
-                       break;
+                       return -EINVAL;
                }
-               break;
        case IIO_CHAN_INFO_CALIBBIAS:
                if (val < 0 || val > SCD30_TEMP_OFFSET_MAX)
-                       break;
+                       return -EINVAL;
                /*
                 * Manufacturer does not explicitly specify min/max sensible
                 * values hence check is omitted for simplicity.
                 */
-               ret = scd30_command_write(state, CMD_TEMP_OFFSET / 10, val);
+               return scd30_command_write(state, CMD_TEMP_OFFSET / 10, val);
+       default:
+               return -EINVAL;
        }
-       mutex_unlock(&state->lock);
-
-       return ret;
 }
 
 static int scd30_write_raw_get_fmt(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,