Re: [PATCH net-next 5/6] net/ncsi: Reset channel state in ncsi_start_dev()

[Samuel Mendoza-Jonas]

On Tue, 2018-10-30 at 21:26 +0000, Justin.Lee1@xxxxxxxx wrote:
> > +int ncsi_reset_dev(struct ncsi_dev *nd)
> > +{
> > +	struct ncsi_dev_priv *ndp = TO_NCSI_DEV_PRIV(nd);
> > +	struct ncsi_channel *nc, *active;
> > +	struct ncsi_package *np;
> > +	unsigned long flags;
> > +	bool enabled;
> > +	int state;
> > +
> > +	active = NULL;
> > +	NCSI_FOR_EACH_PACKAGE(ndp, np) {
> > +		NCSI_FOR_EACH_CHANNEL(np, nc) {
> > +			spin_lock_irqsave(&nc->lock, flags);
> > +			enabled = nc->monitor.enabled;
> > +			state = nc->state;
> > +			spin_unlock_irqrestore(&nc->lock, flags);
> > +
> > +			if (enabled)
> > +				ncsi_stop_channel_monitor(nc);
> > +			if (state == NCSI_CHANNEL_ACTIVE) {
> > +				active = nc;
> > +				break;
> 
> Is the original intention to process the channel one by one?
> If it is the case, there are two loops and we might need to use
> "goto found" instead.

Yes we'll need to break out of the package loop here as well.

> 
> > +			}
> > +		}
> > +	}
> > +
> 
> found: ?
> 
> > +	if (!active) {
> > +		/* Done */
> > +		spin_lock_irqsave(&ndp->lock, flags);
> > +		ndp->flags &= ~NCSI_DEV_RESET;
> > +		spin_unlock_irqrestore(&ndp->lock, flags);
> > +		return ncsi_choose_active_channel(ndp);
> > +	}
> > +
> > +	spin_lock_irqsave(&ndp->lock, flags);
> > +	ndp->flags |= NCSI_DEV_RESET;
> > +	ndp->active_channel = active;
> > +	ndp->active_package = active->package;
> > +	spin_unlock_irqrestore(&ndp->lock, flags);
> > +
> > +	nd->state = ncsi_dev_state_suspend;
> > +	schedule_work(&ndp->work);
> > +	return 0;
> > +}
> 
> Also similar issue in ncsi_choose_active_channel() function below.
> 
> > @@ -916,32 +1045,49 @@ static int ncsi_choose_active_channel(struct ncsi_dev_priv *ndp)
> >  
> >  			ncm = &nc->modes[NCSI_MODE_LINK];
> >  			if (ncm->data[2] & 0x1) {
> > -				spin_unlock_irqrestore(&nc->lock, flags);
> >  				found = nc;
> > -				goto out;
> > +				with_link = true;
> >  			}
> >  
> > -			spin_unlock_irqrestore(&nc->lock, flags);
> > +			/* If multi_channel is enabled configure all valid
> > +			 * channels whether or not they currently have link
> > +			 * so they will have AENs enabled.
> > +			 */
> > +			if (with_link || np->multi_channel) {
> 
> I notice that there is a case that we will misconfigure the interface.
> For example below, multi-channel is not enable for package 1.
> But we enable the channel for ncsi2 below (package 1 channel 0) as that interface is the first
> channel for that package with link.

I don't think I see the issue here; multi-channel is not set on package
1, but both channels are in the channel whitelist. Channel 0 is
configured since it's the first found on package 1, and channel 1 is not
since channel 0 is already found. Are you expecting something different?
 
> 
> cat /sys/kernel/debug/ncsi_protocol/ncsi_device_
> IFIDX IFNAME NAME   PID CID RX TX MP MC WP WC PC CS PS LS RU CR NQ HA
> =====================================================================
>   2   eth2   ncsi0  000 000 1  1  1  1  1  1  0  2  1  1  1  1  0  1
>   2   eth2   ncsi1  000 001 1  0  1  1  1  1  0  2  1  1  1  1  0  1
>   2   eth2   ncsi2  001 000 1  0  1  0  1  1  0  2  1  1  1  1  0  1
>   2   eth2   ncsi3  001 001 0  0  1  0  1  1  0  1  0  1  1  1  0  1
> =====================================================================
> MP: Multi-mode Package     WP: Whitelist Package
> MC: Multi-mode Channel     WC: Whitelist Channel
> PC: Primary Channel        CS: Channel State IA/A/IV 1/2/3
> PS: Poll Status            LS: Link Status
> RU: Running                CR: Carrier OK
> NQ: Queue Stopped          HA: Hardware Arbitration
> 
> I temporally change to the following to avoid that.
> 			if ((with_link &&
> 			     !np->multi_channel &&
> 			     list_empty(&ndp->channel_queue)) || np->multi_channel) {
> 
> > +				spin_lock_irqsave(&ndp->lock, flags);
> > +				list_add_tail_rcu(&nc->link,
> > +						  &ndp->channel_queue);
> > +				spin_unlock_irqrestore(&ndp->lock, flags);
> > +
> > +				netdev_dbg(ndp->ndev.dev,
> > +					   "NCSI: Channel %u added to queue (link %s)\n",
> > +					   nc->id,
> > +					   ncm->data[2] & 0x1 ? "up" : "down");
> > +			}
> > +
> > +			spin_unlock_irqrestore(&nc->lock, cflags);
> > +
> > +			if (with_link && !np->multi_channel)
> > +				break;
> 
> Similar issue here. As we are using break, so each package will configure one active TX.
> 

I believe this is handled properly in ncsi_channel_is_tx() in the most
recent revision.

> >  		}
> > +		if (with_link && !ndp->multi_package)
> > +			break;
> >  	}
> >  
> > -	if (!found) {
> > +	if (list_empty(&ndp->channel_queue) && found) {
> > +		netdev_info(ndp->ndev.dev,
> > +			    "NCSI: No channel with link found, configuring channel %u\n",
> > +			    found->id);
> > +		spin_lock_irqsave(&ndp->lock, flags);
> > +		list_add_tail_rcu(&found->link, &ndp->channel_queue);
> > +		spin_unlock_irqrestore(&ndp->lock, flags);
> > +	} else if (!found) {
> >  		netdev_warn(ndp->ndev.dev,
> > -			    "NCSI: No channel found with link\n");
> > +			    "NCSI: No channel found to configure!\n");
> >  		ncsi_report_link(ndp, true);
> >  		return -ENODEV;
> >  	}
> 
> Also, for deselect package handler function, do we want to set to inactive here?
> If we just change the state, the cached data still keeps the old value. If the new 
> ncsi_reset_dev() function is handling one by one, can we skip this part?

Technically yes we could skip the state change here since
ncsi_reset_dev() will have already done it. However if we send a DP
command via some other means then it is probably best to ensure we treat
all channels on that package as inactive.

> 
> static int ncsi_rsp_handler_dp(struct ncsi_request *nr)
> {
> 	struct ncsi_rsp_pkt *rsp;
> 	struct ncsi_dev_priv *ndp = nr->ndp;
> 	struct ncsi_package *np;
> 	struct ncsi_channel *nc;
> 	unsigned long flags;
> 
> 	/* Find the package */
> 	rsp = (struct ncsi_rsp_pkt *)skb_network_header(nr->rsp);
> 	ncsi_find_package_and_channel(ndp, rsp->rsp.common.channel,
> 				      &np, NULL);
> 	if (!np)
> 		return -ENODEV;
> 
> 	/* Change state of all channels attached to the package */
> 	NCSI_FOR_EACH_CHANNEL(np, nc) {
> 		spin_lock_irqsave(&nc->lock, flags);
> 		nc->state = NCSI_CHANNEL_INACTIVE;
> 
> 		spin_unlock_irqrestore(&nc->lock, flags);
> 	}
> 
> 	return 0;
> }
> 
>