[PATCH 2/2] iio: viio_trigger_alloc(): Correctly free trigger on error

[Lars-Peter Clausen <lars@metafoo.de>]

Once device_initialize() has been called on a struct device the device must
be freed by decreasing the reference count rather than directly freeing the
underlying memory.

This is so that any additional state and resources associated with the
device get properly freed.

In this particular case there are no additional resources associated with
the device and no additional reference count. So there is no resource leak
or use-after-free by freeing the struct device directly

But in order to follow best practices and avoid accidental future breakage
use put_device() instead of kfree() to free the device when an error
occurs.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/iio/industrialio-trigger.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 93990ff1dfe3..d566e8d4a14b 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -480,7 +480,7 @@ static void iio_trig_release(struct device *device)
 	struct iio_trigger *trig = to_iio_trigger(device);
 	int i;
 
-	if (trig->subirq_base) {
+	if (trig->subirq_base > 0) {
 		for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
 			irq_modify_status(trig->subirq_base + i,
 					  IRQ_NOAUTOEN,
@@ -541,11 +541,11 @@ struct iio_trigger *viio_trigger_alloc(struct device *parent,
 					    CONFIG_IIO_CONSUMERS_PER_TRIGGER,
 					    0);
 	if (trig->subirq_base < 0)
-		goto free_trig;
+		goto err_put_trig;
 
 	trig->name = kvasprintf(GFP_KERNEL, fmt, vargs);
 	if (trig->name == NULL)
-		goto free_descs;
+		goto err_put_trig;
 
 	trig->subirq_chip.name = trig->name;
 	trig->subirq_chip.irq_mask = &iio_trig_subirqmask;
@@ -559,10 +559,8 @@ 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);
+err_put_trig:
+	put_device(&trig->dev);
 	return NULL;
 }
 
-- 
2.20.1