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

[Mohamed Khalfella <mkhalfella@purestorage.com>]

On Mon 2026-03-30 12:53:07 +0200, Hannes Reinecke wrote:
> 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)?

True nvme_fence_ctrl() is synchronous, but it runs in from ctrl->fencing_work.
What is it that you find irritating about nvme_fence_ctrl()?

> 
> 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