[PATCH net v2 3/3] ovpn: use datagram_poll_queue for socket readiness in TCP
From: Ralf Lici <hidden>
Date: 2025-10-20 07:38:04
Subsystem:
networking drivers, openvpn data channel offload, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Antonio Quartulli, Linus Torvalds
openvpn TCP encapsulation uses a custom queue to deliver packets to
userspace. Currently it relies on datagram_poll, which checks
sk_receive_queue, leading to false readiness signals when that queue
contains non-userspace packets.
Switch ovpn_tcp_poll to use datagram_poll_queue with the peer's
user_queue, ensuring poll only signals readiness when userspace data is
actually available. Also refactor ovpn_tcp_poll in order to enforce the
assumption we can make on the lifetime of ovpn_sock and peer.
Fixes: 11851cbd60ea ("ovpn: implement TCP transport")
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Signed-off-by: Ralf Lici <redacted>
---
drivers/net/ovpn/tcp.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ovpn/tcp.c b/drivers/net/ovpn/tcp.c
index 289f62c5d2c7..308fdbb75cea 100644
--- a/drivers/net/ovpn/tcp.c
+++ b/drivers/net/ovpn/tcp.c@@ -560,16 +560,34 @@ static void ovpn_tcp_close(struct sock *sk, long timeout) static __poll_t ovpn_tcp_poll(struct file *file, struct socket *sock, poll_table *wait) { - __poll_t mask = datagram_poll(file, sock, wait); + struct sk_buff_head *queue = &sock->sk->sk_receive_queue; struct ovpn_socket *ovpn_sock; + struct ovpn_peer *peer = NULL; + __poll_t mask; rcu_read_lock(); ovpn_sock = rcu_dereference_sk_user_data(sock->sk); - if (ovpn_sock && ovpn_sock->peer && - !skb_queue_empty(&ovpn_sock->peer->tcp.user_queue)) - mask |= EPOLLIN | EPOLLRDNORM; + /* if we landed in this callback, we expect to have a + * meaningful state. The ovpn_socket lifecycle would + * prevent it otherwise. + */ + if (WARN_ON(!ovpn_sock || !ovpn_sock->peer)) { + rcu_read_unlock(); + pr_err_ratelimited("ovpn: null state in ovpn_tcp_poll!\n"); + return 0; + } + + if (ovpn_peer_hold(ovpn_sock->peer)) { + peer = ovpn_sock->peer; + queue = &peer->tcp.user_queue; + } rcu_read_unlock(); + mask = datagram_poll_queue(file, sock, wait, queue); + + if (peer) + ovpn_peer_put(peer); + return mask; }
--
2.51.0