Re: [PATCH net-next 07/15] net: dsa: mt7530: do not run mt7530_setup_port5() if port 5 is disabled

Dan Carpenter
2023-12-08T04:23:45Z

On Thu, Dec 07, 2023 at 08:40:15PM +0200, Vladimir Oltean wrote:
>
> We could be more pragmatic about this whole sparse false positive warning,
> and just move the "if" block which calls mt7530_setup_port5() right
> after the priv->p5_intf_sel assignments, instead of waiting to "break;"
> from the for_each_child_of_node() loop.
>
> for_each_child_of_node(dn, mac_np) {
> if (!of_device_is_compatible(mac_np,
> "mediatek,eth-mac"))
> continue;
>
> ret = of_property_read_u32(mac_np, "reg", &id);
> if (ret < 0 || id != 1)
> continue;
>
> phy_node = of_parse_phandle(mac_np, "phy-handle", 0);
> if (!phy_node)
> continue;
>
> if (phy_node->parent == priv->dev->of_node->parent) {
> ret = of_get_phy_mode(mac_np, &interface);
> if (ret && ret != -ENODEV) {
> of_node_put(mac_np);
> of_node_put(phy_node);
> return ret;
> }
> id = of_mdio_parse_addr(ds->dev, phy_node);
> if (id == 0)
> priv->p5_intf_sel = P5_INTF_SEL_PHY_P0;
> if (id == 4)
> priv->p5_intf_sel = P5_INTF_SEL_PHY_P4;
>
> if (priv->p5_intf_sel == P5_INTF_SEL_PHY_P0 || <---- here
> priv->p5_intf_sel == P5_INTF_SEL_PHY_P4)
> mt7530_setup_port5(ds, interface);

This doesn't solve the problem that Smatch doesn't know what the
original value of priv->p5_intf_sel. And also I don't like this code
because now we call mt7530_setup_port5() on every iteration after
we find the first P5_INTF_SEL_PHY_P0.

> }
> of_node_put(mac_np);
> of_node_put(phy_node);
> break;
> }

Let's not worry too much about false positives. We can just ignore
them. There is always a trade off between false positives and false
negatives. With GCC we try to get a clean run with no warnings, but
with Smatch I'm targetting the false positive ratio at "this is worth
reviewing one time."

regards,
dan carpenter