[PATCH v3] iio: trigger: use put_device() in viio_trigger_alloc() error path

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

Once `device_initialize()` is called, the lifecycle of the trigger must be
managed by the kobject reference counting. Currently, if `kvasprintf()`
fails, the code manually calls kfree() and `irq_free_descs()`.

Switching to `put_device()` ensures that the device's release callback
(`iio_trig_release()`) is properly invoked. This simplifies the error
path by centralizing the cleanup logic (including `irq_free_descs()`)
inside the release handler, following the standard driver model pattern.

Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
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 | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 54416a384232..7f53e2a5a101 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -576,7 +576,7 @@ struct iio_trigger *viio_trigger_alloc(struct device *parent,
 
 	trig->name = kvasprintf(GFP_KERNEL, fmt, vargs);
 	if (trig->name == NULL)
-		goto free_descs;
+		goto free_trig;
 
 	INIT_LIST_HEAD(&trig->list);
 
@@ -594,10 +594,8 @@ struct iio_trigger *viio_trigger_alloc(struct device *parent,
 
 	return trig;
 
-free_descs:
-	irq_free_descs(trig->subirq_base, CONFIG_IIO_CONSUMERS_PER_TRIGGER);
 free_trig:
-	kfree(trig);
+	put_device(&trig->dev);
 	return NULL;
 }
 
-- 
2.43.0