Commit f6ceec64 authored by Ralf Lici's avatar Ralf Lici Committed by Paolo Abeni
Browse files

net: datagram: introduce datagram_poll_queue for custom receive queues 



Some protocols using TCP encapsulation (e.g., espintcp, openvpn) deliver
userspace-bound packets through a custom skb queue rather than the
standard sk_receive_queue.

Introduce datagram_poll_queue that accepts an explicit receive queue,
and convert datagram_poll into a wrapper around datagram_poll_queue.
This allows protocols with custom skb queues to reuse the core polling
logic without relying on sk_receive_queue.

Cc: Sabrina Dubroca <sd@queasysnail.net>
Cc: Antonio Quartulli <antonio@openvpn.net>
Signed-off-by: default avatarRalf Lici <ralf@mandelbit.com>
Reviewed-by: default avatarSabrina Dubroca <sd@queasysnail.net>
Reviewed-by: default avatarAntonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20251021100942.195010-2-ralf@mandelbit.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 10843e14

include/linux/skbuff.h

+3 −0
Original line number Diff line number Diff line
@@ -4204,6 +4204,9 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, 
				    struct sk_buff_head *sk_queue,

				    unsigned int flags, int *off, int *err);

struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags, int *err);

__poll_t datagram_poll_queue(struct file *file, struct socket *sock,

			     struct poll_table_struct *wait,

			     struct sk_buff_head *rcv_queue);

__poll_t datagram_poll(struct file *file, struct socket *sock,

			   struct poll_table_struct *wait);

int skb_copy_datagram_iter(const struct sk_buff *from, int offset,

net/core/datagram.c

+34 −10
Original line number Diff line number Diff line
@@ -920,21 +920,22 @@ int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, 
EXPORT_SYMBOL(skb_copy_and_csum_datagram_msg);



/**

 * 	datagram_poll - generic datagram poll

 *	datagram_poll_queue - same as datagram_poll, but on a specific receive

 *		queue

 *	@file: file struct

 *	@sock: socket

 *	@wait: poll table

 *	@rcv_queue: receive queue to poll

 *

 *	Datagram poll: Again totally generic. This also handles

 *	sequenced packet sockets providing the socket receive queue

 *	is only ever holding data ready to receive.

 *	Performs polling on the given receive queue, handling shutdown, error,

 *	and connection state. This is useful for protocols that deliver

 *	userspace-bound packets through a custom queue instead of

 *	sk->sk_receive_queue.

 *

 *	Note: when you *don't* use this routine for this protocol,

 *	and you use a different write policy from sock_writeable()

 *	then please supply your own write_space callback.

 *	Return: poll bitmask indicating the socket's current state

 */

__poll_t datagram_poll(struct file *file, struct socket *sock,

			   poll_table *wait)

__poll_t datagram_poll_queue(struct file *file, struct socket *sock,

			     poll_table *wait, struct sk_buff_head *rcv_queue)

{

	struct sock *sk = sock->sk;

	__poll_t mask;
@@ -956,7 +957,7 @@ __poll_t datagram_poll(struct file *file, struct socket *sock, 
		mask |= EPOLLHUP;



	/* readable? */

	if (!skb_queue_empty_lockless(&sk->sk_receive_queue))

	if (!skb_queue_empty_lockless(rcv_queue))

		mask |= EPOLLIN | EPOLLRDNORM;



	/* Connection-based need to check for termination and startup */
@@ -978,4 +979,27 @@ __poll_t datagram_poll(struct file *file, struct socket *sock, 


	return mask;

}

EXPORT_SYMBOL(datagram_poll_queue);



/**

 *	datagram_poll - generic datagram poll

 *	@file: file struct

 *	@sock: socket

 *	@wait: poll table

 *

 *	Datagram poll: Again totally generic. This also handles

 *	sequenced packet sockets providing the socket receive queue

 *	is only ever holding data ready to receive.

 *

 *	Note: when you *don't* use this routine for this protocol,

 *	and you use a different write policy from sock_writeable()

 *	then please supply your own write_space callback.

 *

 *	Return: poll bitmask indicating the socket's current state

 */

__poll_t datagram_poll(struct file *file, struct socket *sock, poll_table *wait)

{

	return datagram_poll_queue(file, sock, wait,

				   &sock->sk->sk_receive_queue);

}

EXPORT_SYMBOL(datagram_poll);