Re: [PATCH V2 3/3] nvme-rdma: fix potential unbalanced freeze & unfreeze

[Yi Zhang <yi.zhang@redhat.com>]

Verified it with the nvme/rdma scenario, Thanks Ming
Tested-by: Yi Zhang <yi.zhang@redhat.com>

On Tue, Jul 11, 2023 at 5:41 PM Ming Lei <ming.lei@redhat.com> wrote:
>
> Move start_freeze into nvme_rdma_configure_io_queues(), and there is
> at least two benefits:
>
> 1) fix unbalanced freeze and unfreeze, since re-connection work may
> fail or be broken by removal
>
> 2) IO during error recovery can be failfast quickly because nvme fabrics
> unquiesces queues after teardown.
>
> One side-effect is that !mpath request may timeout during connecting
> because of queue topo change, but that looks not one big deal:
>
> 1) same problem exists with current code base
>
> 2) compared with !mpath, mpath use case is dominant
>
> Fixes: 9f98772ba307 ("nvme-rdma: fix controller reset hang during traffic")
> Cc: stable@vger.kernel.org
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>  drivers/nvme/host/rdma.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index d433b2ec07a6..337a624a537c 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -883,6 +883,7 @@ static int nvme_rdma_configure_io_queues(struct nvme_rdma_ctrl *ctrl, bool new)
>                 goto out_cleanup_tagset;
>
>         if (!new) {
> +               nvme_start_freeze(&ctrl->ctrl);
>                 nvme_unquiesce_io_queues(&ctrl->ctrl);
>                 if (!nvme_wait_freeze_timeout(&ctrl->ctrl, NVME_IO_TIMEOUT)) {
>                         /*
> @@ -891,6 +892,7 @@ static int nvme_rdma_configure_io_queues(struct nvme_rdma_ctrl *ctrl, bool new)
>                          * to be safe.
>                          */
>                         ret = -ENODEV;
> +                       nvme_unfreeze(&ctrl->ctrl);
>                         goto out_wait_freeze_timed_out;
>                 }
>                 blk_mq_update_nr_hw_queues(ctrl->ctrl.tagset,
> @@ -940,7 +942,6 @@ static void nvme_rdma_teardown_io_queues(struct nvme_rdma_ctrl *ctrl,
>                 bool remove)
>  {
>         if (ctrl->ctrl.queue_count > 1) {
> -               nvme_start_freeze(&ctrl->ctrl);
>                 nvme_quiesce_io_queues(&ctrl->ctrl);
>                 nvme_sync_io_queues(&ctrl->ctrl);
>                 nvme_rdma_stop_io_queues(ctrl);
> --
> 2.40.1
>


-- 
Best Regards,
  Yi Zhang