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Subject: Re: [PATCH v2 4/5] nvme-fc: Wait with a timeout for queue to freeze
To:     Daniel Wagner <dwagner@suse.de>, linux-nvme@lists.infradead.org
Cc:     linux-kernel@vger.kernel.org,
        James Smart <james.smart@broadcom.com>,
        Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
        Ming Lei <ming.lei@redhat.com>,
        Sagi Grimberg <sagi@grimberg.me>,
        James Smart <jsmart2021@gmail.com>
References: <20210708092755.15660-1-dwagner@suse.de>
 <20210708092755.15660-5-dwagner@suse.de>
From:   Hannes Reinecke <hare@suse.de>
Message-ID: <bf265380-6164-2462-ff30-6144e9f9b2ea@suse.de>
Date:   Thu, 8 Jul 2021 12:12:21 +0200
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On 7/8/21 11:27 AM, Daniel Wagner wrote:
> Do not wait indifinitly for all queues to freeze. Instead use a
> timeout and abort the operation if we get stuck.
> 
> Reviewed-by: James Smart <jsmart2021@gmail.com>
> Signed-off-by: Daniel Wagner <dwagner@suse.de>
> ---
>   drivers/nvme/host/fc.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
> index d0eb81387d4e..8e1fc3796735 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -2956,7 +2956,14 @@ nvme_fc_recreate_io_queues(struct nvme_fc_ctrl *ctrl)
>   		dev_info(ctrl->ctrl.device,
>   			"reconnect: revising io queue count from %d to %d\n",
>   			prior_ioq_cnt, nr_io_queues);
> -		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 to
> +			 * be stuck.  Fail the controller initialization just
> +			 * to be safe.
> +			 */
> +			return -ENODEV;

For controller reset we're using '-ENOTCONN'; maybe it's worthwhile to 
use the same error code here.
But that's just a minor detail.

> +		}
>   		blk_mq_update_nr_hw_queues(&ctrl->tag_set, nr_io_queues);
>   		nvme_unfreeze(&ctrl->ctrl);
>   	}
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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