Re: [PATCH v2 8/8] nvme-rdma: fix reset hang if controller died in the middle of a reset

[Christoph Hellwig <hch@lst.de>]

On Thu, Aug 06, 2020 at 12:11:27PM -0700, Sagi Grimberg wrote:
> If the controller becomes unresponsive in the middle of a reset, we
> will hang because we are waiting for the freeze to complete, but that
> cannot happen since we have commands that are inflight holding the
> q_usage_counter, and we can't blindly fail requests that times out.
> 
> So give a timeout and if we cannot wait for queue freeze before
> unfreezing, fail and have the error handling take care how to
> proceed (either schedule a reconnect of remove the controller).
> 
> Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
> ---
>  drivers/nvme/host/rdma.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index 30b401fcc06a..4ca53b864636 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -976,7 +976,13 @@ static int nvme_rdma_configure_io_queues(struct nvme_rdma_ctrl *ctrl, bool new)
>  
>  	if (!new) {
>  		nvme_start_queues(&ctrl->ctrl);
> -		nvme_wait_freeze(&ctrl->ctrl);
> +		if (!nvme_wait_freeze_timeout(&ctrl->ctrl, NVME_IO_TIMEOUT)) {
> +			/* if we timed out waiting for freeze we are
> +			 * likely stuck, fail just to be safe
> +			 */

			/*
			 * If we timed out waiting for freeze we are likely to
			 * be stuck.  Fail the controller initialization just
			 * to be safe.
			 */

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