Re: [PATCH v4 09/15] nvme: Implement cross-controller reset completion

[Hannes Reinecke <hare@suse.de>]

On 3/28/26 01:43, Mohamed Khalfella wrote:
> An nvme source controller that issues CCR command expects to receive an
> NVME_AER_NOTICE_CCR_COMPLETED when pending CCR succeeds or fails. Add
> sctrl->ccr_work to read NVME_LOG_CCR logpage and wakeup any thread
> waiting on CCR completion.
> 
> Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
> ---
>   drivers/nvme/host/core.c | 49 +++++++++++++++++++++++++++++++++++++++-
>   drivers/nvme/host/nvme.h |  1 +
>   2 files changed, 49 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 5603ae36444f..793f203bfc38 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1920,7 +1920,8 @@ EXPORT_SYMBOL_GPL(nvme_set_queue_count);
>   
>   #define NVME_AEN_SUPPORTED \
>   	(NVME_AEN_CFG_NS_ATTR | NVME_AEN_CFG_FW_ACT | \
> -	 NVME_AEN_CFG_ANA_CHANGE | NVME_AEN_CFG_DISC_CHANGE)
> +	 NVME_AEN_CFG_ANA_CHANGE | NVME_AEN_CFG_CCR_COMPLETE | \
> +	 NVME_AEN_CFG_DISC_CHANGE)
>   
>   static void nvme_enable_aen(struct nvme_ctrl *ctrl)
>   {
> @@ -4873,6 +4874,47 @@ static void nvme_get_fw_slot_info(struct nvme_ctrl *ctrl)
>   	kfree(log);
>   }
>   
> +static void nvme_ccr_work(struct work_struct *work)
> +{
> +	struct nvme_ctrl *ctrl = container_of(work, struct nvme_ctrl, ccr_work);
> +	struct nvme_ccr_entry *ccr;
> +	struct nvme_ccr_log_entry *entry;
> +	struct nvme_ccr_log *log;
> +	unsigned long flags;
> +	int ret, i;
> +
> +	log = kmalloc(sizeof(*log), GFP_KERNEL);
> +	if (!log)
> +		return;
> +
> +	ret = nvme_get_log(ctrl, 0, NVME_LOG_CCR, 0x01,
> +			   0x00, log, sizeof(*log), 0);
> +	if (ret)
> +		goto out;
> +
> +	spin_lock_irqsave(&ctrl->lock, flags);
> +	for (i = 0; i < le16_to_cpu(log->ne); i++) {
> +		entry = &log->entries[i];
> +		if (entry->ccrs == NVME_CCR_STATUS_IN_PROGRESS)
> +			continue;
> +
> +		list_for_each_entry(ccr, &ctrl->ccr_list, list) {
> +			struct nvme_ctrl *ictrl = ccr->ictrl;
> +
> +			if (ictrl->cntlid != le16_to_cpu(entry->icid) ||
> +			    ictrl->ciu != entry->ciu)
> +				continue;
> +
> +			/* Complete matching entry */
> +			ccr->ccrs = entry->ccrs;
> +			complete(&ccr->complete);
> +		}
> +	}
> +	spin_unlock_irqrestore(&ctrl->lock, flags);
> +out:
> +	kfree(log);
> +}
> +
>   static void nvme_fw_act_work(struct work_struct *work)
>   {
>   	struct nvme_ctrl *ctrl = container_of(work,
> @@ -4949,6 +4991,9 @@ static bool nvme_handle_aen_notice(struct nvme_ctrl *ctrl, u32 result)
>   	case NVME_AER_NOTICE_DISC_CHANGED:
>   		ctrl->aen_result = result;
>   		break;
> +	case NVME_AER_NOTICE_CCR_COMPLETED:
> +		queue_work(nvme_wq, &ctrl->ccr_work);
> +		break;
>   	default:
>   		dev_warn(ctrl->device, "async event result %08x\n", result);
>   	}
> @@ -5144,6 +5189,7 @@ void nvme_stop_ctrl(struct nvme_ctrl *ctrl)
>   	nvme_stop_failfast_work(ctrl);
>   	flush_work(&ctrl->async_event_work);
>   	cancel_work_sync(&ctrl->fw_act_work);
> +	cancel_work_sync(&ctrl->ccr_work);
>   	if (ctrl->ops->stop_ctrl)
>   		ctrl->ops->stop_ctrl(ctrl);
>   }
> @@ -5267,6 +5313,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
>   	ctrl->quirks = quirks;
>   	ctrl->numa_node = NUMA_NO_NODE;
>   	INIT_WORK(&ctrl->scan_work, nvme_scan_work);
> +	INIT_WORK(&ctrl->ccr_work, nvme_ccr_work);
>   	INIT_WORK(&ctrl->async_event_work, nvme_async_event_work);
>   	INIT_WORK(&ctrl->fw_act_work, nvme_fw_act_work);
>   	INIT_WORK(&ctrl->delete_work, nvme_delete_ctrl_work);
> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> index f2bcff9ccd25..776ee8aa5a93 100644
> --- a/drivers/nvme/host/nvme.h
> +++ b/drivers/nvme/host/nvme.h
> @@ -419,6 +419,7 @@ struct nvme_ctrl {
>   	struct nvme_effects_log *effects;
>   	struct xarray cels;
>   	struct work_struct scan_work;
> +	struct work_struct ccr_work;
>   	struct work_struct async_event_work;
>   	struct delayed_work ka_work;
>   	struct delayed_work failfast_work;

Hmm. The 'nvme_fence_ctrl' operation introduced in the previous patch
is synchronous, yet in this patch we're looking a a log page to figure
out if the cross-controller reset is complete.
Which is slightly irritating.
Wouldn't it be better to make the 'nvme_fence_ctrl' operation 
asynchronous, and then have a separate function to wait for the fence
operation to complete (which then could look at log pages etc)?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich