On Fri, Apr 10, 2020 at 09:42:04AM +0100, Lukasz Luba wrote: > Add support for other devices that CPUs. The registration function > does not require a valid cpumask pointer and is ready to handle new > devices. Some of the internal structures has been reorganized in order to > keep consistent view (like removing per_cpu pd pointers). To track usage > of the Energy Model structures, they are protected with kref. Why not add the energy model structure in the struct device directly? For instance for the em_cpu_get() function, the cpu id allows to retrieve the cpu device and then from there, the energy model instead of browsing another list. The em_device life cycle will be tied to the struct device. Then when the struct device and the em_device are connected, add the debugfs with a struct device list for those which are energy aware, so you end up with a structure: struct em_device { struct device *dev; struct list_head em_dev_list; }; (a global single dentry for debugfs to do a recursive delete is enough). Locks when inspecting and add/removal called from the struct device release function. So no need of an extra refcounting. Does it make sense?