Re: [net-next,v3,08/15] net: ftgmac100: Move NCSI probe code into a helper

[Jakub Kicinski <kuba@kernel.org>]

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---
net: ftgmac100: Move NCSI probe code into a helper

This commit refactors ftgmac100_probe() by extracting NCSI-specific probe
code into a new helper function ftgmac100_probe_ncsi(). The commit message
states "No functional change intended."

> diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
> index e511d6d5f7c2..9d8256d4d368 100644
> --- a/drivers/net/ethernet/faraday/ftgmac100.c
> +++ b/drivers/net/ethernet/faraday/ftgmac100.c
> @@ -1839,6 +1839,39 @@ static bool ftgmac100_has_child_node(struct device_node *np, const char *name)
> 	return ret;
>  }
>
> +static int ftgmac100_probe_ncsi(struct net_device *netdev,
> +				struct ftgmac100 *priv,
> +				struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct phy_device *phydev;
> +	int err;
> +
> +	if (!IS_ENABLED(CONFIG_NET_NCSI)) {
> +		dev_err(&pdev->dev, "NCSI stack not enabled\n");
> +		return -EINVAL;
> +	}
> +
> +	dev_info(&pdev->dev, "Using NCSI interface\n");
> +	priv->use_ncsi = true;
> +	priv->ndev = ncsi_register_dev(netdev, ftgmac100_ncsi_handler);
> +	if (!priv->ndev)
> +		return -EINVAL;
> +
> +	phydev = fixed_phy_register(&ncsi_phy_status, np);
> +	if (IS_ERR(phydev)) {
> +		dev_err(&pdev->dev, "failed to register fixed PHY device\n");
> +		return PTR_ERR(phydev);

If fixed_phy_register() fails here, doesn't priv->ndev leak? The NCSI device
was registered via ncsi_register_dev() above, but this error path returns
without calling ncsi_unregister_dev().

> +	}
> +	err = phy_connect_direct(netdev, phydev, ftgmac100_adjust_link,
> +				 PHY_INTERFACE_MODE_RMII);
> +	if (err) {
> +		dev_err(&pdev->dev, "Connecting PHY failed\n");
> +		fixed_phy_unregister(phydev);
> +	}
> +	return err;

Similarly, if phy_connect_direct() fails, fixed_phy_unregister() is called
but ncsi_unregister_dev(priv->ndev) is not.

[ ... ]

> @@ -1928,32 +1960,9 @@ static int ftgmac100_probe(struct platform_device *pdev)
>  	}
>
>  	if (np && of_get_property(np, "use-ncsi", NULL)) {
> -		if (!IS_ENABLED(CONFIG_NET_NCSI)) {
> -			dev_err(&pdev->dev, "NCSI stack not enabled\n");
> -			err = -EINVAL;
> -			goto err_phy_connect;

[ ... ]

> -		phydev = fixed_phy_register(&ncsi_phy_status, np);
> -		if (IS_ERR(phydev)) {
> -			dev_err(&pdev->dev, "failed to register fixed PHY device\n");
> -			err = PTR_ERR(phydev);
> -			goto err_phy_connect;

The old code jumped to err_phy_connect on failure, which falls through to
err_ncsi_dev where ncsi_unregister_dev(priv->ndev) is called.

> +		err = ftgmac100_probe_ncsi(netdev, priv, pdev);
> +		if (err)
> +			goto err_setup_mdio;

The new code jumps to err_setup_mdio, which skips the err_ncsi_dev label
entirely. Combined with the helper not cleaning up priv->ndev on its error
paths, this appears to be a behavioral change from the original code.
-- 
pw-bot: cr