[Patch v3] iio: potentiostat: lmp91000: fix probe order and cleanup paths

[Salah Triki <salah.triki@gmail.com>]

Fix the initialization order in lmp91000_probe() where the immutable
trigger is set before data->cb_buffer is initialized, which would cause a
NULL pointer dereference.

Also, reorder the cleanup labels and ensure all error paths properly unwind
resources using gotos instead of direct returns, following the standard
LIFO resource release order.

Fixes: 67e17300dc1d ("iio: potentiostat: add LMP91000 support")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
 drivers/iio/potentiostat/lmp91000.c | 34 ++++++++++++++---------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/drivers/iio/potentiostat/lmp91000.c b/drivers/iio/potentiostat/lmp91000.c
index eccc2a34358f..30b40b3a97d9 100644
--- a/drivers/iio/potentiostat/lmp91000.c
+++ b/drivers/iio/potentiostat/lmp91000.c
@@ -330,17 +330,27 @@ static int lmp91000_probe(struct i2c_client *client)
 	if (ret)
 		return ret;
 
+	data->cb_buffer = iio_channel_get_all_cb(dev, &lmp91000_buffer_cb, indio_dev);
+	if (IS_ERR(data->cb_buffer)) {
+		if (PTR_ERR(data->cb_buffer) == -ENODEV)
+			ret = -EPROBE_DEFER;
+		else
+			ret = PTR_ERR(data->cb_buffer);
+
+		goto error_unreg_buffer;
+	}
+
 	ret = iio_trigger_set_immutable(iio_channel_cb_get_iio_dev(data->cb_buffer),
 					data->trig);
 	if (ret) {
 		dev_err(dev, "cannot set immutable trigger.\n");
-		return ret;
+		goto error_unreg_cb_buffer;
 	}
 
 	ret = iio_trigger_register(data->trig);
 	if (ret) {
 		dev_err(dev, "cannot register iio trigger.\n");
-		return ret;
+		goto error_unreg_cb_buffer;
 	}
 
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
@@ -349,35 +359,23 @@ static int lmp91000_probe(struct i2c_client *client)
 	if (ret)
 		goto error_unreg_trigger;
 
-	data->cb_buffer = iio_channel_get_all_cb(dev, &lmp91000_buffer_cb,
-						 indio_dev);
-
-	if (IS_ERR(data->cb_buffer)) {
-		if (PTR_ERR(data->cb_buffer) == -ENODEV)
-			ret = -EPROBE_DEFER;
-		else
-			ret = PTR_ERR(data->cb_buffer);
-
-		goto error_unreg_buffer;
-	}
-
 	data->adc_chan = iio_channel_cb_get_channels(data->cb_buffer);
 
 	ret = iio_device_register(indio_dev);
 	if (ret)
-		goto error_unreg_cb_buffer;
+		goto error_unreg_trigger;
 
 	return 0;
 
+error_unreg_trigger:
+	iio_trigger_unregister(data->trig);
+
 error_unreg_cb_buffer:
 	iio_channel_release_all_cb(data->cb_buffer);
 
 error_unreg_buffer:
 	iio_triggered_buffer_cleanup(indio_dev);
 
-error_unreg_trigger:
-	iio_trigger_unregister(data->trig);
-
 	return ret;
 }
 
-- 
2.43.0