netdev - Re: [RFC PATCH 2/3] net: sparx5: Add Sparx5 switchdev driver

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Date:   Fri, 27 Nov 2020 18:15:06 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Steen Hegelund <steen.hegelund@...rochip.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Lars Povlsen <lars.povlsen@...rochip.com>,
        Bjarni Jonasson <bjarni.jonasson@...rochip.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Microsemi List <microsemi@...ts.bootlin.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/3] net: sparx5: Add Sparx5 switchdev driver

This is a very large driver, which is going to make it slow to review.

> +static int sparx5_probe_port(struct sparx5 *sparx5,
> +			     struct device_node *portnp,
> +			     struct phy *serdes,
> +			     u32 portno,
> +			     struct sparx5_port_config *conf)
> +{
> +	phy_interface_t phy_mode = conf->phy_mode;
> +	struct sparx5_port *spx5_port;
> +	struct net_device *ndev;
> +	struct phylink *phylink;
> +	int err;
> +
> +	err = sparx5_create_targets(sparx5);
> +	if (err)
> +		return err;
> +	ndev = sparx5_create_netdev(sparx5, portno);
> +	if (IS_ERR(ndev)) {
> +		dev_err(sparx5->dev, "Could not create net device: %02u\n", portno);
> +		return PTR_ERR(ndev);
> +	}
> +	spx5_port = netdev_priv(ndev);
> +	spx5_port->of_node = portnp;
> +	spx5_port->serdes = serdes;
> +	spx5_port->pvid = NULL_VID;
> +	spx5_port->signd_internal = true;
> +	spx5_port->signd_active_high = true;
> +	spx5_port->signd_enable = true;
> +	spx5_port->flow_control = false;
> +	spx5_port->max_vlan_tags = SPX5_PORT_MAX_TAGS_NONE;
> +	spx5_port->vlan_type = SPX5_VLAN_PORT_TYPE_UNAWARE;
> +	spx5_port->custom_etype = 0x8880; /* Vitesse */
> +	conf->portmode = conf->phy_mode;
> +	spx5_port->conf.speed = SPEED_UNKNOWN;
> +	spx5_port->conf.power_down = true;
> +	sparx5->ports[portno] = spx5_port;


> +struct net_device *sparx5_create_netdev(struct sparx5 *sparx5, u32 portno)
> +{
> +	struct net_device *ndev;
> +	struct sparx5_port *spx5_port;
> +	int err;
> +
> +	ndev = devm_alloc_etherdev(sparx5->dev, sizeof(struct sparx5_port));
> +	if (!ndev)
> +		return ERR_PTR(-ENOMEM);
> +

...

> +	err = register_netdev(ndev);
> +	if (err) {
> +		dev_err(sparx5->dev, "netdev registration failed\n");
> +		return ERR_PTR(err);
> +	}

This is one of the classic bugs in network drivers. As soon as you
call register_netdev() the interface is live. The network stack can
start using it. But you have not finished initialzing spx5_port. So
bad things are going to happen.

    Andrew