[PATCH v2] 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, correct the cleanup labels in the error path to properly unregister
the trigger before performing the triggered buffer cleanup, following the
standard LIFO (Last-In-First-Out) resource release order.

Fixes: 67e17300dc1d ("iio: potentiostat: add LMP91000 support")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
Changes in v2:
  - Fix the subject line to be more specific.
  - Use lmp91000_probe() instead of lmp91000_probe in the description.
  - Put iio_channel_get_all_cb() call on a single line.
  - Remove the unneeded blank line between iio_channel_get_all_cb() and its error check.

 drivers/iio/potentiostat/lmp91000.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/iio/potentiostat/lmp91000.c b/drivers/iio/potentiostat/lmp91000.c
index eccc2a34358f..273127063840 100644
--- a/drivers/iio/potentiostat/lmp91000.c
+++ b/drivers/iio/potentiostat/lmp91000.c
@@ -330,6 +330,16 @@ 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) {
@@ -349,18 +359,6 @@ 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);
@@ -372,12 +370,12 @@ static int lmp91000_probe(struct i2c_client *client)
 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);
 
+error_unreg_buffer:
+	iio_triggered_buffer_cleanup(indio_dev);
+
 	return ret;
 }
 
-- 
2.43.0