[PATCH v4] iio: core: Clean up device correctly on viio_trigger_alloc() failure

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

Once we called device_initialize() we have to call put_device()
on it. Refactor the code to make it in the right order.

Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
Changes in v4:
- Move device_initialize() after all potential failure points (kvasprintf and 
  irq_alloc_descs) to avoid premature lifecycle management via kobject.
- Revert the use of put_device() in the error path and use kfree() instead, 
  as the device is not yet initialized.
- Align the implementation with the pattern used in iio_device_alloc(), 
  as suggested by Nuno Sá.

Changes in v3:
- Rewrite commit message to focus on standard design patterns.
- Remove the "Fixes" tag as the change is a cleanup/robustness improvement.
- Simplify the description of the fix as requested by the maintainer.
- Change title to better reflect the change (not a use-after-free).

Changes in v2:
- Remove the manual call to irq_free_descs() in the error path to avoid
  a double free, as this is already handled by iio_trig_release().
- Clarify the error path and the potential for memory corruption in
  the commit description.
- Remove the blank line in the tag block to comply with kernel script
  requirements.

 drivers/iio/industrialio-trigger.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 54416a384232..c995311bf699 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -561,10 +561,6 @@ struct iio_trigger *viio_trigger_alloc(struct device *parent,
 	if (!trig)
 		return NULL;
 
-	trig->dev.parent = parent;
-	trig->dev.type = &iio_trig_type;
-	trig->dev.bus = &iio_bus_type;
-	device_initialize(&trig->dev);
 	INIT_WORK(&trig->reenable_work, iio_reenable_work_fn);
 
 	mutex_init(&trig->pool_lock);
@@ -592,6 +588,11 @@ struct iio_trigger *viio_trigger_alloc(struct device *parent,
 				  IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);
 	}
 
+	trig->dev.parent = parent;
+	trig->dev.type = &iio_trig_type;
+	trig->dev.bus = &iio_bus_type;
+	device_initialize(&trig->dev);
+
 	return trig;
 
 free_descs:
-- 
2.43.0