linux-kernel - RE: [PATCH net-next v2 6/6] net/ncsi: Configure multi-package, multi-channel modes with failover

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Date:   Fri, 26 Oct 2018 21:48:58 +0000
From:   <Justin.Lee1@...l.com>
To:     <sam@...dozajonas.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

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.

> +		}
> +	}
> +
> +	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