Messages in this thread | | | Subject | Re: [PATCH V2 1/2] blk-mq: init hctx sched after update ctx and hctx mapping | From | "jianchao.wang" <> | Date | Mon, 20 Aug 2018 11:57:52 +0800 |
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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.
Thanks Jianchao
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