Hi Ming On 4/1/19 10:52 AM, Ming Lei wrote: >> percpu_ref_tryget_live() fails if a per-cpu counter is in the "dead" state. >> percpu_ref_kill() changes the state of a per-cpu counter to the "dead" >> state. blk_freeze_queue_start() calls percpu_ref_kill(). blk_cleanup_queue() >> already calls blk_set_queue_dying() and that last function calls >> blk_freeze_queue_start(). So I think that what you wrote is not correct and >> that inserting a percpu_ref_tryget_live()/percpu_ref_put() pair in >> blk_mq_run_hw_queues() or blk_mq_run_hw_queue() would make a difference and >> also that moving the percpu_ref_exit() call into blk_release_queue() makes >> sense. > If percpu_ref_exit() is moved to blk_release_queue(), we still need to > move freeing of hw queue's resource into blk_release_queue() like what > the patchset is doing. > > Then we don't need to get/put q_usage_counter in blk_mq_run_hw_queues() any more, > do we? IMO, if we could get a way to prevent any attempt to run queue, it would be better and clearer. Thanks Jianchao
