Subject: Re: [PATCH v21 04/20] net/tls,core: export get_netdev_for_sock

From: Jakub Kicinski <[email-masked]>
Date: Thu, 14 Dec 2023 18:11:28 -0800

On Thu, 14 Dec 2023 13:26:07 +0000 Aurelien Aptel wrote:
> -struct net_device *netdev_sk_get_lowest_dev(struct net_device *dev,
> -					    struct sock *sk)
> +struct net_device *get_netdev_for_sock(struct sock *sk)
>  {
> -	struct net_device *lower;
> +	struct dst_entry *dst = sk_dst_get(sk);
> +	struct net_device *dev, *lower;
>  
> -	lower = netdev_sk_get_lower_dev(dev, sk);
> -	while (lower) {
> +	if (unlikely(!dst))
> +		return NULL;
> +	dev = dst->dev;
> +	while ((lower = netdev_sk_get_lower_dev(dev, sk)))
>  		dev = lower;
> -		lower = netdev_sk_get_lower_dev(dev, sk);
> -	}
> -
> +	dev_hold(dev);
> +	dst_release(dst);
>  	return dev;
>  }
> -EXPORT_SYMBOL(netdev_sk_get_lowest_dev);
> +EXPORT_SYMBOL_GPL(get_netdev_for_sock);

Since the use of this helper is now spreading we should
switch it to netdev_hold and have the caller pass in a
netdevice_tracker.