FAILED: patch "[PATCH] iio: trigger: Fix reference counting" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a827a4984664308f13599a0b26c77018176d0c7c Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <[email protected]>
Date: Sun, 24 Oct 2021 11:27:00 +0200
Subject: [PATCH] iio: trigger: Fix reference counting
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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().

index b23caa2f2aa1..93990ff1dfe3 100644
@@ -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;