In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: fix pci device refcount leak
As comment of pci_get_domain_bus_and_slot() says, it returns a pci device with refcount increment, when finish using it, the caller must decrement the reference count by calling pci_dev_put().
So before returning from amdgpu_device_resume|suspend_display_audio(), pci_dev_put() is called to avoid refcount leak.