On Mon, Aug 20, 2018 at 11:57:52AM +0800, jianchao.wang wrote: > Hi Ming > > On 08/20/2018 10:24 AM, Ming Lei wrote: > >> The code path is: > >> > >> elevator_release > >> -> elevator_put(e->type) > >> -> module_put(e->elevator_owner) > >> > >> In normal elevator switch path, elevator_get will hold a reference counter of the > >> elevator_owner. > >> In this patch set, the elevator_type is saved directly. To prevent the io scheduler module > >> is removed, we need to hold a reference of the module. > > Yeah, I agree that the module reference need to be held, but it need to be > > released too. > > > > My concern is that this introduced getting module reference in your patch > > isn't released. The module reference is a counter too, so the get and > > put operation should be matched. > > elevator_switch_mq > -> elevator_exit > it will put a reference count of the elevator_queue associated with the request_queue. > and the elevator_release will be invoked when the reference count of elevator_queue->kobj reaches zero. > elevator_release will put the reference count of the io scheduler module. > > the elevator_queue structure will be allocated and freed every time when we switch io scheduler. > so the elevator_release will always be invoked. > > This is the put ref corresponding to the get one in this patch. OK, got it, the added __module_get() is just like what elevator_get() does from __elevator_change(). Sorry for the noise. Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Thanks, Ming
