Re: [PATCH net-next] net: reject a netdev that implements only one hwtstamp NDO

[Jakub Kicinski <kuba@kernel.org>]

On Tue, 29 Sep 2026 23:32:32 +0200 Nicolai Buchwitz wrote:
> @@ -11447,6 +11447,13 @@ int register_netdevice(struct net_device *dev)
>  		goto err_uninit;
>  	}
>  
> +	if (!dev->netdev_ops->ndo_hwtstamp_get !=
> +	    !dev->netdev_ops->ndo_hwtstamp_set) {
> +		netdev_WARN(dev, "driver implements only one hwtstamp NDO\n");
> +		ret = -EINVAL;
> +		goto err_uninit;
> +	}
> +
>  	if (netdev_need_ops_lock(dev) &&
>  	    dev->netdev_ops->ndo_set_rx_mode &&
>  	    !dev->netdev_ops->ndo_set_rx_mode_async)

Third such check added here.. we should probably factor all three
out of register_netdevice(). Hardest part is probably naming the
new helper. netdev_check_ops() ? We already have ethtool_check_ops()
We can't move it earlier because some drivers set features form
ndo_init And while you move it you can also make the warning
about not using _async return an error. It was "soft" to avoid
bricking people's systems on boot, but it's been there since v7.1
people will have enough time to spot offenders by v7.4
-- 
pw-bot: cr