Re: [PATCH v5 10/16] nvme-tcp: Use CCR to recover controller that hits an error

On 7/12/26 4:23 AM, Mohamed Khalfella wrote:
> An alive nvme controller that hits an error now will move to FENCING
> state instead of RESETTING state. ctrl->fencing_work attempts CCR to
> terminate inflight IOs. Regardless of the success or failure of CCR
> operation the controller is transitioned to RESETTING state to continue
> error recovery process.
> 
> Signed-off-by: Mohamed Khalfella <[email protected]>
> ---
>   drivers/nvme/host/tcp.c | 30 +++++++++++++++++++++++++++++-
>   1 file changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index ba5c7b3e2a7c..a1711dd1d3c2 100644
> --- a/drivers/nvme/host/tcp.c
> +++ b/drivers/nvme/host/tcp.c
> @@ -161,6 +161,7 @@ struct nvme_tcp_ctrl {
>   	struct sockaddr_storage src_addr;
>   	struct nvme_ctrl	ctrl;
>   
> +	struct work_struct	fencing_work;
>   	struct work_struct	err_work;
>   	struct delayed_work	connect_work;
>   	struct nvme_tcp_request async_req;
> @@ -605,6 +606,12 @@ static void nvme_tcp_init_recv_ctx(struct nvme_tcp_queue *queue)
>   
>   static void nvme_tcp_error_recovery(struct nvme_ctrl *ctrl)
>   {
> +	if (nvme_change_ctrl_state(ctrl, NVME_CTRL_FENCING)) {
> +		dev_warn(ctrl->device, "starting controller fencing\n");
> +		queue_work(nvme_wq, &to_tcp_ctrl(ctrl)->fencing_work);
> +		return;
> +	}
> +
>   	if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
>   		return;
>   
> @@ -2494,12 +2501,29 @@ static void nvme_tcp_reconnect_ctrl_work(struct work_struct *work)
>   	nvme_tcp_reconnect_or_remove(ctrl, ret);
>   }
>   
> +static void nvme_tcp_fencing_work(struct work_struct *work)
> +{
> +	struct nvme_tcp_ctrl *tcp_ctrl = container_of(work,
> +			struct nvme_tcp_ctrl, fencing_work);
> +	struct nvme_ctrl *ctrl = &tcp_ctrl->ctrl;
> +	unsigned long rem;
> +
> +	rem = nvme_fence_ctrl(ctrl);
> +	if (rem)
> +		dev_info(ctrl->device, "CCR failed, starting error recovery\n");
> +
> +	nvme_change_ctrl_state(ctrl, NVME_CTRL_FENCED);

This needs to be before nvme_fence_ctrl(). Otherwise the state is 
meaningless are we're moving to RESETTING directly afterwards.

> +	if (nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
> +		queue_work(nvme_reset_wq, &tcp_ctrl->err_work);
> +}
> +
>   static void nvme_tcp_error_recovery_work(struct work_struct *work)
>   {
>   	struct nvme_tcp_ctrl *tcp_ctrl = container_of(work,
>   				struct nvme_tcp_ctrl, err_work);
>   	struct nvme_ctrl *ctrl = &tcp_ctrl->ctrl;
>   
> +	flush_work(&to_tcp_ctrl(ctrl)->fencing_work);

Not so happy with this one here.
_If_ fencing is still running we really should not be entering here.
And If fencing is not running we won't need to call it.
I'd prefer some sort of WARN_ON() here if fencing is still running.

>   	if (nvme_tcp_key_revoke_needed(ctrl))
>   		nvme_auth_revoke_tls_key(ctrl);
>   	nvme_stop_keep_alive(ctrl);
> @@ -2542,6 +2566,7 @@ static void nvme_reset_ctrl_work(struct work_struct *work)
>   		container_of(work, struct nvme_ctrl, reset_work);
>   	int ret;
>   
> +	flush_work(&to_tcp_ctrl(ctrl)->fencing_work);

Same here.

>   	if (nvme_tcp_key_revoke_needed(ctrl))
>   		nvme_auth_revoke_tls_key(ctrl);
>   	nvme_stop_ctrl(ctrl);
> @@ -2667,13 +2692,15 @@ static enum blk_eh_timer_return nvme_tcp_timeout(struct request *rq)
>   	struct nvme_tcp_cmd_pdu *pdu = nvme_tcp_req_cmd_pdu(req);
>   	struct nvme_command *cmd = &pdu->cmd;
>   	int qid = nvme_tcp_queue_id(req->queue);
> +	enum nvme_ctrl_state state;
>   
>   	dev_warn(ctrl->device,
>   		 "I/O tag %d (%04x) type %d opcode %#x (%s) QID %d timeout\n",
>   		 rq->tag, nvme_cid(rq), pdu->hdr.type, cmd->common.opcode,
>   		 nvme_fabrics_opcode_str(qid, cmd), qid);
>   
> -	if (nvme_ctrl_state(ctrl) != NVME_CTRL_LIVE) {
> +	state = nvme_ctrl_state(ctrl);
> +	if (state != NVME_CTRL_LIVE && state != NVME_CTRL_FENCING) {
>   		/*
>   		 * If we are resetting, connecting or deleting we should
>   		 * complete immediately because we may block controller
> @@ -2928,6 +2955,7 @@ static struct nvme_tcp_ctrl *nvme_tcp_alloc_ctrl(struct device *dev,
>   
>   	INIT_DELAYED_WORK(&ctrl->connect_work,
>   			nvme_tcp_reconnect_ctrl_work);
> +	INIT_WORK(&ctrl->fencing_work, nvme_tcp_fencing_work);
>   	INIT_WORK(&ctrl->err_work, nvme_tcp_error_recovery_work);
>   	INIT_WORK(&ctrl->ctrl.reset_work, nvme_reset_ctrl_work);
>   

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
[email protected]                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
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