iio:magn: preenable/postenable/predisable fixup for ST magn buffer

This patch is trying to cleanup for good the buffers operation functions.
Let's rename the goto label using operation to perform and not
where it fails.

Not stable material as not fixing a 'bug' but rather bringing the
driver in line with general 'patterns' to allow a subsystem wide
cleanup.
Signed-off-by: Denis Ciocca <denis.ciocca@st.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/magnetometer/st_magn_buffer.c

@@ -31,40 +31,42 @@ int st_magn_trig_set_state(struct iio_trigger *trig, bool state)
 
 static int st_magn_buffer_postenable(struct iio_dev *indio_dev)
 {
-	int err;
 	struct st_sensor_data *mdata = iio_priv(indio_dev);
+	int err;
 
 	mdata->buffer_data = kmalloc(indio_dev->scan_bytes,
 				     GFP_DMA | GFP_KERNEL);
-	if (mdata->buffer_data == NULL) {
-		err = -ENOMEM;
-		goto allocate_memory_error;
-	}
+	if (!mdata->buffer_data)
+		return -ENOMEM;
 
 	err = iio_triggered_buffer_postenable(indio_dev);
 	if (err < 0)
-		goto st_magn_buffer_postenable_error;
+		goto st_magn_free_buffer;
+
+	err = st_sensors_set_enable(indio_dev, true);
+	if (err < 0)
+		goto st_magn_buffer_predisable;
 
-	return st_sensors_set_enable(indio_dev, true);
+	return 0;
 
-st_magn_buffer_postenable_error:
+st_magn_buffer_predisable:
+	iio_triggered_buffer_predisable(indio_dev);
+st_magn_free_buffer:
 	kfree(mdata->buffer_data);
-allocate_memory_error:
 	return err;
 }
 
 static int st_magn_buffer_predisable(struct iio_dev *indio_dev)
 {
-	int err;
 	struct st_sensor_data *mdata = iio_priv(indio_dev);
+	int err, err2;
 
 	err = st_sensors_set_enable(indio_dev, false);
-	if (err < 0)
-		goto st_magn_buffer_predisable_error;
 
-	err = iio_triggered_buffer_predisable(indio_dev);
+	err2 = iio_triggered_buffer_predisable(indio_dev);
+	if (!err)
+		err = err2;
 
-st_magn_buffer_predisable_error:
 	kfree(mdata->buffer_data);
 	return err;
 }