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c129903057
Linux kernel commit 8bd76b3d3f3a ("gpio: sim: lock up configfs that an
instantiated device depends on") has uncovered an issue in libgpiosim:
we use reference counting for all objects (to make RAII easier for
bindings) but, with the above change, if the user doesn't explicitly
disable the device before dropping the last reference to a bank object,
the parent device will never get correctly cleaned up.
This is because we remove the hog and line directories in bank's
release() callback unconditionally. With the directories being locked
now, this fails if device is active and then when we eventually call the
device object's release(), we'll end up stuck with leftover bank
directories and never actually clean-up correctly.
Extend the gpiosim device with a list of deferred banks. When releasing
a bank on an active device, defer any actual cleanup until the time the
device gets deactivated which may be triggered by the user explictly or
will happen automatically when the last reference to the device object is
dropped. For inactive devices, there's no functional change.
Link: https://lore.kernel.org/r/20250214102648.71382-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>