linux-kernel - Re: [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB implementation

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Date:   Thu, 10 Mar 2022 15:54:58 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Hans Schultz <schultz.hans@...il.com>
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        Hans Schultz <schultz.hans+netdev@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Ido Schimmel <idosch@...dia.com>, linux-kernel@...r.kernel.org,
        bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB
 implementation

> +		if (mv88e6xxx_port_is_locked(chip, chip->ports[spid].port))
> +			err = mv88e6xxx_switchdev_handle_atu_miss_violation(chip,
> +									    chip->ports[spid].port,
> +									    &entry,
> +									    fid);

> +static int mv88e6xxx_find_vid_on_matching_fid(struct mv88e6xxx_chip *chip,
> +					      const struct mv88e6xxx_vtu_entry *entry,
> +					      void *priv)
> +{
> +	struct mv88e6xxx_fid_search_ctx *ctx = priv;
> +
> +	if (ctx->fid_search == entry->fid) {
> +		ctx->vid_found = entry->vid;
> +		return 1;
> +	}
> +	return 0;
> +}
> +
> +int mv88e6xxx_switchdev_handle_atu_miss_violation(struct mv88e6xxx_chip *chip,
> +						  int port,
> +						  struct mv88e6xxx_atu_entry *entry,
> +						  u16 fid)
> +{
> +	struct switchdev_notifier_fdb_info info = {
> +		.addr = entry->mac,
> +		.vid = 0,
> +		.added_by_user = false,
> +		.is_local = false,
> +		.offloaded = true,
> +		.locked = true,
> +	};
> +	struct mv88e6xxx_fid_search_ctx ctx;
> +	struct netlink_ext_ack *extack;
> +	struct net_device *brport;
> +	struct dsa_port *dp;
> +	int err;
> +
> +	ctx.fid_search = fid;
> +	err = mv88e6xxx_vtu_walk(chip, mv88e6xxx_find_vid_on_matching_fid, &ctx);

I could be reading this code wrong, but it looks like you assume there
is a single new entry in the ATU. But interrupts on these devices are
slow. It would be easy for two or more devices to pop into existence
at the same time. Don't you need to walk the whole ATU to find all the
new entries? Have you tried this with a traffic generating populating
the ATU with new entries at different rates, up to line rate? Do you
get notifications for them all?

    Andrew