iio: trigger: Fix reference counting

commit a827a4984664308f13599a0b26c77018176d0c7c upstream.

In viio_trigger_alloc() device_initialize() is used to set the initial
reference count of the trigger to 1. Then another get_device() is called on
trigger. This sets the reference count to 2 before the trigger is returned.

iio_trigger_free(), which is the matching API to viio_trigger_alloc(),
calls put_device() which decreases the reference count by 1. But the second
reference count acquired in viio_trigger_alloc() is never dropped.

As a result the iio_trigger_release() function is never called and the
memory associated with the trigger is never freed.

Since there is no reason for the trigger to start its lifetime with two
reference counts just remove the extra get_device() in
viio_trigger_alloc().

Fixes: 5f9c035cae18 ("staging:iio:triggers. Add a reference get to the core for triggers.")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20211024092700.6844-2-lars@metafoo.de
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index b23caa2f2aa1fd30327ee5f5c1ed1251e6b3768a..93990ff1dfe39e5a760e9b8c82099f4af8f5a282 100644 (file)
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -556,7 +556,6 @@ struct iio_trigger *viio_trigger_alloc(struct device *parent,
                irq_modify_status(trig->subirq_base + i,
                                  IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);
        }
-       get_device(&trig->dev);
 
        return trig;