Re: [PATCH net-next v7 08/16] quic: add path management

[Paolo Abeni <pabeni@redhat.com>]

On 1/15/26 4:11 PM, Xin Long wrote:
> @@ -0,0 +1,524 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/* QUIC kernel implementation
> + * (C) Copyright Red Hat Corp. 2023
> + *
> + * This file is part of the QUIC kernel implementation
> + *
> + * Initialization/cleanup for QUIC protocol support.
> + *
> + * Written or modified by:
> + *    Xin Long <lucien.xin@gmail.com>
> + */
> +
> +#include <net/udp_tunnel.h>
> +#include <linux/quic.h>
> +
> +#include "common.h"
> +#include "family.h"
> +#include "path.h"
> +
> +static int (*quic_path_rcv)(struct sock *sk, struct sk_buff *skb, u8 err);

It's unclear why an indirect call is needed here. At least some
explanation is needed in the commit message, possibly you could call
directly a static function.

> +
> +static int quic_udp_rcv(struct sock *sk, struct sk_buff *skb)
> +{
> +	memset(skb->cb, 0, sizeof(skb->cb));
> +	QUIC_SKB_CB(skb)->seqno = -1;
> +	QUIC_SKB_CB(skb)->time = quic_ktime_get_us();
> +
> +	skb_pull(skb, sizeof(struct udphdr));
> +	skb_dst_force(skb);
> +	quic_path_rcv(sk, skb, 0);
> +	return 0;

Why not:
	return quic_path_rcv(sk, skb, 0);
?

> +static struct quic_udp_sock *quic_udp_sock_create(struct sock *sk, union quic_addr *a)
> +{
> +	struct udp_tunnel_sock_cfg tuncfg = {};
> +	struct udp_port_cfg udp_conf = {};
> +	struct net *net = sock_net(sk);
> +	struct quic_uhash_head *head;
> +	struct quic_udp_sock *us;
> +	struct socket *sock;
> +
> +	us = kzalloc(sizeof(*us), GFP_KERNEL);
> +	if (!us)
> +		return NULL;
> +
> +	quic_udp_conf_init(sk, &udp_conf, a);
> +	if (udp_sock_create(net, &udp_conf, &sock)) {
> +		pr_debug("%s: failed to create udp sock\n", __func__);
> +		kfree(us);
> +		return NULL;
> +	}
> +
> +	tuncfg.encap_type = 1;
> +	tuncfg.encap_rcv = quic_udp_rcv;
> +	tuncfg.encap_err_lookup = quic_udp_err;
> +	setup_udp_tunnel_sock(net, sock, &tuncfg);
> +
> +	refcount_set(&us->refcnt, 1);
> +	us->sk = sock->sk;
> +	memcpy(&us->addr, a, sizeof(*a));
> +	us->bind_ifindex = sk->sk_bound_dev_if;
> +
> +	head = quic_udp_sock_head(net, ntohs(a->v4.sin_port));
> +	hlist_add_head(&us->node, &head->head);
> +	INIT_WORK(&us->work, quic_udp_sock_put_work);
> +
> +	return us;
> +}
> +
> +static bool quic_udp_sock_get(struct quic_udp_sock *us)
> +{
> +	return refcount_inc_not_zero(&us->refcnt);
> +}
> +
> +static void quic_udp_sock_put(struct quic_udp_sock *us)
> +{
> +	if (refcount_dec_and_test(&us->refcnt))
> +		queue_work(quic_wq, &us->work);

Why using a workqueue here? AFAICS all the caller are in process
context. Is that to break a possible deadlock due to nested mutex?
Likely a comment on the refcount/locking scheme would help.

/P