Re: [RFC PATCH net-next 2/3] net: hsr: add DSA offloading support

[Vladimir Oltean <olteanv@gmail.com>]

On Fri, Jan 22, 2021 at 09:59:47AM -0600, George McCollister wrote:
> diff --git a/net/dsa/slave.c b/net/dsa/slave.c
> index f2fb433f3828..fc7e3ff11c5c 100644
> --- a/net/dsa/slave.c
> +++ b/net/dsa/slave.c
> @@ -1924,6 +1924,19 @@ static int dsa_slave_changeupper(struct net_device *dev,
>  			dsa_port_lag_leave(dp, info->upper_dev);
>  			err = NOTIFY_OK;
>  		}
> +	} else if (netif_is_hsr_master(info->upper_dev)) {
> +		if (info->linking) {
> +			err = dsa_port_hsr_join(dp, info->upper_dev);
> +			if (err == -EOPNOTSUPP) {
> +				NL_SET_ERR_MSG_MOD(info->info.extack,
> +						   "Offloading not supported");
> +				err = 0;
> +			}
> +			err = notifier_from_errno(err);
> +		} else {
> +			dsa_port_hsr_leave(dp, info->upper_dev);
> +			err = NOTIFY_OK;
> +		}
>  	}

How is the RedBox use case handled with the Linux hsr driver (i.e. a
HSR-unaware SAN endpoint attached to a HSR ring)? I would expect
something like this:

                   +---------+
                   |         |
                   |   SAN   |
                   |         |
                   +---------+
                        |
                        |
                        |
 +-----------------+---------+------------------+
 |                 |         |                  |
 |  Your           |   swp0  |                  |
 |  board          |         |                  |
 |                 +---------+                  |
 |                    |   ^                     |
 |                    |   |                     |
 |                    |   | br0                 |
 |                    |   |                     |
 |                    v   |                     |
 |       +-----------------------------+        |
 |       |                             |        |
 |       |             hsr0            |        |
 |       |                             |        |
 |       +---------+---------+---------+        |
 |       |         |         |         |        |
 |       |   swp1  |  DAN-H  |  swp2   |        |
 |       |         |         |         |        |
 +-------+---------+---------+---------+--------+
            |   ^               |   ^
    to/from |   |               |   | to/from
     ring   |   |               |   |  ring
            v   |               v   |

Therefore, aren't you interested in offloading this setup as well?
I.e. the case where the hsr0 interface joins a bridge that also
contains other DSA switch ports. This would be similar to the LAG
offload recently added by Tobias.