linux-kernel - Re: [PATCH net-next v11 08/23] ovpn: implement basic TX path (UDP)

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Message-ID: <ZyJpcbHJI5MqZHVB@hog>
Date: Wed, 30 Oct 2024 18:14:25 +0100
From: Sabrina Dubroca <sd@...asysnail.net>
To: Antonio Quartulli <antonio@...nvpn.net>
Cc: Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Donald Hunter <donald.hunter@...il.com>,
	Shuah Khan <shuah@...nel.org>, ryazanov.s.a@...il.com,
	Andrew Lunn <andrew@...n.ch>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next v11 08/23] ovpn: implement basic TX path (UDP)

2024-10-29, 11:47:21 +0100, Antonio Quartulli wrote:
> +static void ovpn_send(struct ovpn_struct *ovpn, struct sk_buff *skb,
> +		      struct ovpn_peer *peer)
> +{
> +	struct sk_buff *curr, *next;
> +
> +	if (likely(!peer))
> +		/* retrieve peer serving the destination IP of this packet */
> +		peer = ovpn_peer_get_by_dst(ovpn, skb);
> +	if (unlikely(!peer)) {
> +		net_dbg_ratelimited("%s: no peer to send data to\n",
> +				    ovpn->dev->name);
> +		dev_core_stats_tx_dropped_inc(ovpn->dev);
> +		goto drop;
> +	}
> +
> +	/* this might be a GSO-segmented skb list: process each skb
> +	 * independently
> +	 */
> +	skb_list_walk_safe(skb, curr, next)

nit (if you end up reposting): there should probably be some braces
around the (multi-line) loop body.

> +		if (unlikely(!ovpn_encrypt_one(peer, curr))) {
> +			dev_core_stats_tx_dropped_inc(ovpn->dev);
> +			kfree_skb(curr);
> +		}

> +void ovpn_udp_send_skb(struct ovpn_struct *ovpn, struct ovpn_peer *peer,
> +		       struct sk_buff *skb)
> +{
[...]
> +	/* crypto layer -> transport (UDP) */
> +	pkt_len = skb->len;
> +	ret = ovpn_udp_output(ovpn, bind, &peer->dst_cache, sock->sk, skb);
> +
> +out_unlock:
> +	rcu_read_unlock();
> +out:
> +	if (unlikely(ret < 0)) {
> +		dev_core_stats_tx_dropped_inc(ovpn->dev);
> +		kfree_skb(skb);
> +		return;
> +	}
> +
> +	dev_sw_netstats_tx_add(ovpn->dev, 1, pkt_len);

If I'm following things correctly, that's already been counted:

ovpn_udp_output -> ovpn_udp4_output -> udp_tunnel_xmit_skb
                                    -> iptunnel_xmit
                                    -> iptunnel_xmit_stats

which does (on success) the same thing as dev_sw_netstats_tx_add. On
failure it increments a different tx_dropped counter than what
dev_core_stats_tx_dropped_inc, but they should get summed in the end.

> +}

-- 
Sabrina