netdev - Re: [PATCH net-next v2 6/6] net/ncsi: Configure multi-package, multi-channel modes with failover

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Date:   Tue, 30 Oct 2018 14:05:48 +1100
From:   Samuel Mendoza-Jonas <sam@...dozajonas.com>
To:     Justin.Lee1@...l.com, netdev@...r.kernel.org
Cc:     davem@...emloft.net, linux-kernel@...r.kernel.org,
        openbmc@...ts.ozlabs.org
Subject: Re: [PATCH net-next v2 6/6] net/ncsi: Configure multi-package,
 multi-channel modes with failover

On Fri, 2018-10-26 at 21:48 +0000, Justin.Lee1@...l.com wrote:
> Hi Samuel,
> 
> There is one place that we assume the next available TX channel is under the same package.
> Please see the comment below.
> 
> Thanks,
> Justin
> 
> 
> +/* Change the active Tx channel in a multi-channel setup */
> +int ncsi_update_tx_channel(struct ncsi_dev_priv *ndp,
> > +			   struct ncsi_package *np,
> > +			   struct ncsi_channel *disable,
> > +			   struct ncsi_channel *enable)
> > +{
> > +	struct ncsi_cmd_arg nca;
> > +	struct ncsi_channel *nc;
> > +	int ret = 0;
> > +
> > +	if (!np->multi_channel)
> > +		netdev_warn(ndp->ndev.dev,
> > +			    "NCSI: Trying to update Tx channel in single-channel mode\n");
> > +	nca.ndp = ndp;
> > +	nca.package = np->id;
> 
> If the channel may be on different package, the package ID here may not be correct
> in some cases.
> 
> > +	nca.req_flags = 0;
> > +
> > +	/* Find current channel with Tx enabled */
> > +	if (!disable) {
> > +		NCSI_FOR_EACH_CHANNEL(np, nc)
> > +			if (nc->modes[NCSI_MODE_TX_ENABLE].enable)
> > +				disable = nc;
> > +	}
> > +
> > +	/* Find a suitable channel for Tx */
> > +	if (!enable) {
> > +		if (np->preferred_channel &&
> > +		    ncsi_channel_has_link(np->preferred_channel)) {
> > +			enable = np->preferred_channel;
> > +		} else {
> > +			NCSI_FOR_EACH_CHANNEL(np, nc) {
> > +				if (!(np->channel_whitelist & 0x1 << nc->id))
> > +					continue;
> > +				if (nc->state != NCSI_CHANNEL_ACTIVE)
> > +					continue;
> > +				if (ncsi_channel_has_link(nc)) {
> > +					enable = nc;
> > +					break;
> > +				}
> > +			}
> 
> When we search, we need to consider the other available channel might be on the
> package.

Good point, I've updated this to allow for enabling Tx on a different
package.

Thanks,
Sam

> 
> > +		}
> > +	}
> > +
> > +	if (disable == enable)
> > +		return -1;
> > +
> > +	if (!enable)
> > +		return -1;
> > +
> > +	if (disable) {
> > +		nca.channel = disable->id;
> > +		nca.type = NCSI_PKT_CMD_DCNT;
> > +		ret = ncsi_xmit_cmd(&nca);
> > +		if (ret)
> > +			netdev_err(ndp->ndev.dev,
> > +				   "Error %d sending DCNT\n",
> > +				   ret);
> > +	}
> 
> I remove the cable from ncsi0 and it doesn't failover to ncsi3 as ncsi0 and ncsi3 are not under
> the same package.
> 
> 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  1  3  0  0  1  1  0  1
>   2   eth2   ncsi1  000 001 0  0  1  1  1  0  0  1  0  1  1  1  0  1
>   2   eth2   ncsi2  001 000 0  0  1  1  1  0  0  1  0  1  1  1  0  1
>   2   eth2   ncsi3  001 001 1  0  1  1  1  1  0  2  1  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
> PS: Poll Status            LS: Link Status
> RU: Running                CR: Carrier OK
> NQ: Queue Stopped          HA: Hardware Arbitration