On 08/20/2018 12:18 PM, Ming Lei wrote: > 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 very much for your reviewing. I will add more comment to describe the added __module_get() in the V3. Thanks Jianchao > Thanks, > Ming >
