From: Xin Long <lucien.xin@gmail.com>
To: Paolo Abeni <pabeni@redhat.com>
Cc: network dev <netdev@vger.kernel.org>,
quic@lists.linux.dev, davem@davemloft.net, kuba@kernel.org,
Eric Dumazet <edumazet@google.com>,
Simon Horman <horms@kernel.org>,
Stefan Metzmacher <metze@samba.org>,
Moritz Buhl <mbuhl@openbsd.org>,
Tyler Fanelli <tfanelli@redhat.com>,
Pengtao He <hepengtao@xiaomi.com>,
Thomas Dreibholz <dreibh@simula.no>,
linux-cifs@vger.kernel.org, Steve French <smfrench@gmail.com>,
Namjae Jeon <linkinjeon@kernel.org>,
Paulo Alcantara <pc@manguebit.com>, Tom Talpey <tom@talpey.com>,
kernel-tls-handshake@lists.linux.dev,
Chuck Lever <chuck.lever@oracle.com>,
Jeff Layton <jlayton@kernel.org>,
Steve Dickson <steved@redhat.com>,
Hannes Reinecke <hare@suse.de>,
Alexander Aring <aahringo@redhat.com>,
David Howells <dhowells@redhat.com>,
Matthieu Baerts <matttbe@kernel.org>,
John Ericson <mail@johnericson.me>,
Cong Wang <xiyou.wangcong@gmail.com>,
"D . Wythe" <alibuda@linux.alibaba.com>,
Jason Baron <jbaron@akamai.com>,
illiliti <illiliti@protonmail.com>,
Sabrina Dubroca <sd@queasysnail.net>,
Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
Daniel Stenberg <daniel@haxx.se>,
Andy Gospodarek <andrew.gospodarek@broadcom.com>
Subject: Re: [PATCH net-next v8 08/15] quic: add path management
Date: Thu, 29 Jan 2026 15:46:17 -0500 [thread overview]
Message-ID: <CADvbK_f3v+0hXyBHiZeR0uFEn+rvq_wT=QDv8G-e8qvB-e-3rQ@mail.gmail.com> (raw)
In-Reply-To: <a7b64f16-5ca9-4344-b7e8-c0d4508e43cc@redhat.com>
On Thu, Jan 29, 2026 at 11:20 AM Paolo Abeni <pabeni@redhat.com> wrote:
>
> On 1/26/26 3:51 PM, Xin Long wrote:
> > This patch introduces 'quic_path_group' for managing paths, represented
> > by 'struct quic_path'. A connection may use two paths simultaneously
> > for connection migration.
> >
> > Each path is associated with a UDP tunnel socket (sk), and a single
> > UDP tunnel socket can be related to multiple paths from different sockets.
> > These UDP tunnel sockets are wrapped in 'quic_udp_sock' structures and
> > stored in a hash table.
> >
> > It includes mechanisms to bind and unbind paths, detect alternative paths
> > for migration, and swap paths to support seamless transition between
> > networks.
> >
> > - quic_path_bind(): Bind a path to a port and associate it with a UDP sk.
> >
> > - quic_path_unbind(): Unbind a path from a port and disassociate it from a
> > UDP sk.
> >
> > - quic_path_swap(): Swap two paths to facilitate connection migration.
> >
> > - quic_path_detect_alt(): Determine if a packet is using an alternative
> > path, used for connection migration.
> >
> > It also integrates basic support for Packetization Layer Path MTU
> > Discovery (PLPMTUD), using PING frames and ICMP feedback to adjust path
> > MTU and handle probe confirmation or resets during routing changes.
> >
> > - quic_path_pl_recv(): state transition and pmtu update after the probe
> > packet is acked.
> >
> > - quic_path_pl_toobig(): state transition and pmtu update after
> > receiving a toobig or needfrag icmp packet.
> >
> > - quic_path_pl_send(): state transition and pmtu update after sending a
> > probe packet.
> >
> > - quic_path_pl_reset(): restart the probing when path routing changes.
> >
> > - quic_path_pl_confirm(): check if probe packet gets acked.
> >
> > Signed-off-by: Tyler Fanelli <tfanelli@redhat.com>
> > Signed-off-by: Xin Long <lucien.xin@gmail.com>
> > ---
> > v3:
> > - Fix annotation in quic_udp_sock_lookup() (noted by Paolo).
> > - Use inet_sk_get_local_port_range() instead of
> > inet_get_local_port_range() (suggested by Paolo).
> > - Adjust global UDP tunnel socket hashtable operations for the new
> > hashtable type.
> > - Delete quic_workqueue; use system_wq for UDP tunnel socket destroy.
> > v4:
> > - Cache UDP tunnel socket pointer and its source address in struct
> > quic_path for RCU-protected lookup/access.
> > - Return -EAGAIN instead of -EINVAL in quic_path_bind() when UDP
> > socket is being released in workqueue.
> > - Move udp_tunnel_sock_release() out of the mutex_lock to avoid a
> > warning of lockdep in quic_udp_sock_put_work().
> > - Introduce quic_wq for UDP socket release work, so all pending works
> > can be flushed before destroying the hashtable in quic_exit().
> > v5:
> > - Rename quic_path_free() to quic_path_unbind() (suggested by Paolo).
> > - Remove the 'serv' member from struct quic_path_group, since
> > quic_is_serv() defined in a previous patch now uses
> > sk->sk_max_ack_backlog for server-side detection.
> > - Use quic_ktime_get_us() to set skb_cb->time, as RTT is measured
> > in microseconds and jiffies_to_usecs() is not accurate enough.
> > v6:
> > - Do not reset transport_header for QUIC in quic_udp_rcv(), allowing
> > removal of udph_offset and enabling access to the UDP header via
> > udp_hdr(); Pull skb->data in quic_udp_rcv() to allow access to the
> > QUIC header via skb->data.
> > v7:
> > - Pass udp sk to quic_path_rcv() and move the call to skb_linearize()
> > and skb_set_owner_sk_safe() to .quic_path_rcv().
> > - Delete the call to skb_linearize() and skb_set_owner_sk_safe() from
> > quic_udp_err(), as it should not change skb in .encap_err_lookup()
> > (noted by AI review).
> > v8:
> > - Remove indirect quic_path_rcv and late call quic_packet_rcv()
> > directly via extern (noted by Paolo).
> > - Add a comment in quic_udp_rcv() clarifying it must return 0.
> > - Add a comment in quic_udp_sock_put() clarifying the UDP socket
> > may be freed in atomic RX context during connection migration.
> > - Reorder some quic_path_group members to reduce struct size.
> > ---
> > net/quic/Makefile | 2 +-
> > net/quic/path.c | 520 ++++++++++++++++++++++++++++++++++++++++++++
> > net/quic/path.h | 170 +++++++++++++++
> > net/quic/protocol.c | 11 +
> > net/quic/socket.c | 3 +
> > net/quic/socket.h | 7 +
> > 6 files changed, 712 insertions(+), 1 deletion(-)
> > create mode 100644 net/quic/path.c
> > create mode 100644 net/quic/path.h
> >
> > diff --git a/net/quic/Makefile b/net/quic/Makefile
> > index eee7501588d3..1565fb5cef9d 100644
> > --- a/net/quic/Makefile
> > +++ b/net/quic/Makefile
> > @@ -5,4 +5,4 @@
> >
> > obj-$(CONFIG_IP_QUIC) += quic.o
> >
> > -quic-y := common.o family.o protocol.o socket.o stream.o connid.o
> > +quic-y := common.o family.o protocol.o socket.o stream.o connid.o path.o
> > diff --git a/net/quic/path.c b/net/quic/path.c
> > new file mode 100644
> > index 000000000000..9556607a009e
> > --- /dev/null
> > +++ b/net/quic/path.c
> > @@ -0,0 +1,520 @@
> > +// 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_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);
> > + kfree_skb(skb);
> > + return 0; /* .encap_rcv must return 0 if skb was either consumed or dropped. */
> > +}
> > +
> > +static int quic_udp_err(struct sock *sk, struct sk_buff *skb)
> > +{
> > + return 0;
> > +}
> > +
> > +static void quic_udp_sock_put_work(struct work_struct *work)
> > +{
> > + struct quic_udp_sock *us = container_of(work, struct quic_udp_sock, work);
> > + struct quic_uhash_head *head;
> > + struct sock *sk = us->sk;
> > +
> > + /* Hold the sock to safely access it in quic_udp_sock_lookup() even after
> > + * udp_tunnel_sock_release(). The release must occur before __hlist_del()
> > + * so a new UDP tunnel socket can be created for the same address and port
> > + * if quic_udp_sock_lookup() fails to find one.
> > + *
> > + * Note: udp_tunnel_sock_release() cannot be called under the mutex due to
> > + * some lockdep warnings.
> > + */
> > + sock_hold(sk);
> > + udp_tunnel_sock_release(sk->sk_socket);
> > +
> > + head = quic_udp_sock_head(sock_net(sk), ntohs(us->addr.v4.sin_port));
> > + mutex_lock(&head->lock);
> > + __hlist_del(&us->node);
> > + mutex_unlock(&head->lock);
> > +
> > + sock_put(sk);
> > + kfree(us);
> > +}
> > +
> > +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);
>
> Possibly you need to adjust UDP_MAX_TUNNEL_TYPES in udp_offload.c. You
> could check running a kernel with QUIC enabled and geneve, vxlan, FOU
> and xfrm disabled.
It does not currently implement gro_receive, so there is no need to touch
UDP_MAX_TUNNEL_TYPES. Adding .gro_receive support for QUIC can be
considered as a future enhancement.
>
> > +
> > + 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);
>
> Is unclear to me if quick udp socket lookup be done locklessy with
> future series?
>
No, quic udp socket lookup will not be done locklessy.
As this is not on the DATA path, I didn't intend to use RCU things on it.
next prev parent reply other threads:[~2026-01-29 20:46 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-26 14:50 [PATCH net-next v8 00/15] net: introduce QUIC infrastructure and core subcomponents Xin Long
2026-01-26 14:50 ` [PATCH net-next v8 01/15] net: define IPPROTO_QUIC and SOL_QUIC constants Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 02/15] net: build socket infrastructure for QUIC protocol Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 03/15] quic: provide common utilities and data structures Xin Long
2026-01-29 16:26 ` Paolo Abeni
2026-01-29 19:40 ` Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 04/15] quic: provide family ops for address and protocol Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 05/15] quic: provide quic.h header files for kernel and userspace Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 06/15] quic: add stream management Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 07/15] quic: add connection id management Xin Long
2026-01-29 12:33 ` Paolo Abeni
2026-01-26 14:51 ` [PATCH net-next v8 08/15] quic: add path management Xin Long
2026-01-29 16:20 ` Paolo Abeni
2026-01-29 20:46 ` Xin Long [this message]
2026-01-26 14:51 ` [PATCH net-next v8 09/15] quic: add congestion control Xin Long
2026-01-28 16:15 ` [net-next,v8,09/15] " Simon Horman
2026-01-29 19:44 ` Xin Long
2026-02-02 14:40 ` Simon Horman
2026-01-26 14:51 ` [PATCH net-next v8 10/15] quic: add packet number space Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 11/15] quic: add crypto key derivation and installation Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 12/15] quic: add crypto packet encryption and decryption Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 13/15] quic: add timer management Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 14/15] quic: add packet builder base Xin Long
2026-01-29 16:40 ` Paolo Abeni
2026-01-29 19:39 ` Xin Long
2026-01-26 14:51 ` [PATCH net-next v8 15/15] quic: add packet parser base Xin Long
2026-01-29 16:53 ` Paolo Abeni
2026-01-29 19:37 ` Xin Long
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CADvbK_f3v+0hXyBHiZeR0uFEn+rvq_wT=QDv8G-e8qvB-e-3rQ@mail.gmail.com' \
--to=lucien.xin@gmail.com \
--cc=aahringo@redhat.com \
--cc=alibuda@linux.alibaba.com \
--cc=andrew.gospodarek@broadcom.com \
--cc=chuck.lever@oracle.com \
--cc=daniel@haxx.se \
--cc=davem@davemloft.net \
--cc=dhowells@redhat.com \
--cc=dreibh@simula.no \
--cc=edumazet@google.com \
--cc=hare@suse.de \
--cc=hepengtao@xiaomi.com \
--cc=horms@kernel.org \
--cc=illiliti@protonmail.com \
--cc=jbaron@akamai.com \
--cc=jlayton@kernel.org \
--cc=kernel-tls-handshake@lists.linux.dev \
--cc=kuba@kernel.org \
--cc=linkinjeon@kernel.org \
--cc=linux-cifs@vger.kernel.org \
--cc=mail@johnericson.me \
--cc=marcelo.leitner@gmail.com \
--cc=matttbe@kernel.org \
--cc=mbuhl@openbsd.org \
--cc=metze@samba.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=pc@manguebit.com \
--cc=quic@lists.linux.dev \
--cc=sd@queasysnail.net \
--cc=smfrench@gmail.com \
--cc=steved@redhat.com \
--cc=tfanelli@redhat.com \
--cc=tom@talpey.com \
--cc=xiyou.wangcong@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox