Re: [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...