[PATCH 3/8] nvme-loop: quiesce admin_q instead of stopping hw queues

[Sagi Grimberg]

>> diff --git a/drivers/nvme/target/loop.c b/drivers/nvme/target/loop.c
>> index 3d51341e62ee..891002ee005f 100644
>> --- a/drivers/nvme/target/loop.c
>> +++ b/drivers/nvme/target/loop.c
>> @@ -434,7 +434,7 @@ static void nvme_loop_shutdown_ctrl(struct nvme_loop_ctrl *ctrl)
>>   	if (ctrl->ctrl.state == NVME_CTRL_LIVE)
>>   		nvme_shutdown_ctrl(&ctrl->ctrl);
>>   
>> -	blk_mq_stop_hw_queues(ctrl->ctrl.admin_q);
>> +	blk_mq_quiesce_queue(ctrl->ctrl.admin_q);
>>   	blk_mq_tagset_busy_iter(&ctrl->admin_tag_set,
>>   				nvme_cancel_request, &ctrl->ctrl);
>>   	nvme_loop_destroy_admin_queue(ctrl);
> 
> Is the queue killed before calling nvme_loop_destroy_admin_queue()?

No, its not.

> If not, simply quiescing and not unquiescing will hang in
> blk_cleanup_queue().

Why should it? blk_cleanup_queue does not hang, even under IO load...

> So I suggest to put blk_mq_unquiesce_queue() after blk_mq_tagset_busy_iter().

I can do that, but I don't understand why...