Re: [PATCH 3/3] nvme: allocate the keep alive request using BLK_MQ_REQ_NOWAIT

[Hannes Reinecke <hare@suse.de>]

On 3/3/21 1:53 PM, Christoph Hellwig wrote:
> To avoid an error recovery deadlock where the keep alive work is waiting
> for a request and thus can't be flushed to make progress for tearing down
> the controller.  Also print the error code returned from
> blk_mq_alloc_request to help debugging any future issues in this code.
> 
> Based on an earlier patch from Hannes Reinecke <hare@suse.de>.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/nvme/host/core.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index bdeb3feae61899..8a4a9fe96cdf83 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1241,10 +1241,10 @@ static void nvme_keep_alive_work(struct work_struct *work)
>   	}
>   
>   	rq = nvme_alloc_request(ctrl->admin_q, &ctrl->ka_cmd,
> -				BLK_MQ_REQ_RESERVED);
> +				BLK_MQ_REQ_RESERVED | BLK_MQ_REQ_NOWAIT);
>   	if (IS_ERR(rq)) {
>   		/* allocation failure, reset the controller */
> -		dev_err(ctrl->device, "keep-alive failed\n");
> +		dev_err(ctrl->device, "keep-alive failed: %ld\n", PTR_ERR(rq));
>   		nvme_reset_ctrl(ctrl);
>   		return;
>   	}
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer

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