Re: [PATCH 2/3] fwd, pif: Replace with pif_sock_l4() with pif_listen()

On Tue, Mar 03, 2026 at 08:11:39PM +0100, Stefano Brivio wrote:

On Mon, 2 Mar 2026 15:31:34 +1100 David Gibson wrote:

...

It turns out all users of pif_sock_l4() use it for "listening" sockets, which now all have a common epoll reference format. We can take advantage of that to pass the necessary epoll information into pif_sock_l4() in a more natural way, rather than as an opaque u32.

That in turn allows union fwd_listen_ref can become a struct, since the union only exist to allow the meaningful fields to be coerced into a u32 for pif_sock_l4().

Rename pif_sock_l4() to pif_listen() to reflect the new semantics. While we're there, remove the static_assert() on the fwd_listen_ref's size. We do still need it to fit into 32 bits, but that constraint is imposed only by the fact that it needs to fit into the whole, epoll_ref structure, which we already check with a static_assert() in epoll_ctl.h.

Signed-off-by: David Gibson --- epoll_ctl.h | 2 +- fwd.h | 14 +++++--------- pif.c | 14 ++++++++------ pif.h | 6 +++--- tcp.c | 8 +------- udp.c | 8 +------- 6 files changed, 19 insertions(+), 33 deletions(-)

diff --git a/epoll_ctl.h b/epoll_ctl.h index 2c103cde..879763cb 100644 --- a/epoll_ctl.h +++ b/epoll_ctl.h @@ -35,7 +35,7 @@ union epoll_ref { union { uint32_t flow; flow_sidx_t flowside; - union fwd_listen_ref listen; + struct fwd_listen_ref listen; uint32_t data; int nsdir_fd; int queue; diff --git a/fwd.h b/fwd.h index 16070111..b0e2373d 100644 --- a/fwd.h +++ b/fwd.h @@ -49,20 +49,16 @@ struct fwd_rule { #define FWD_NO_HINT (-1)

/** - * union fwd_listen_ref - information about a single listening socket + * struct fwd_listen_ref - information about a single listening socket * @port: Bound port number of the socket * @pif: pif in which the socket is listening * @rule: Index of forwarding rule */ -union fwd_listen_ref { - struct { - in_port_t port; - uint8_t pif; - unsigned rule :FWD_RULE_BITS; - }; - uint32_t u32; +struct fwd_listen_ref { + in_port_t port; + uint8_t pif; + unsigned rule :FWD_RULE_BITS; }; -static_assert(sizeof(union fwd_listen_ref) == sizeof(uint32_t));

Reported-by: Peter Foley

Good point. Can you add this on merge?

...

enum fwd_ports_mode { FWD_UNSET = 0, diff --git a/pif.c b/pif.c index 6ae970a0..82a3b5e4 100644 --- a/pif.c +++ b/pif.c @@ -62,23 +62,23 @@ void pif_sockaddr(const struct ctx *c, union sockaddr_inany *sa, } }

-/** pif_sock_l4() - Open a socket bound to an address on a specified interface +/** pif_listen() - Open a listening socket on a specified pif * @c: Execution context * @type: Socket epoll type * @pif: Interface for this socket * @addr: Address to bind to, or NULL for dual-stack any * @ifname: Interface for binding, NULL for any * @port: Port number to bind to (host byte order) - * @data: epoll reference portion for protocol handlers + * @rule: Forwarding rule index this socket belongs to * * NOTE: For namespace pifs, this must be called having already entered the * relevant namespace. * * Return: newly created socket, negative error code on failure */ -int pif_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif, - const union inany_addr *addr, const char *ifname, - in_port_t port, uint32_t data) +int pif_listen(const struct ctx *c, enum epoll_type type, uint8_t pif, + const union inany_addr *addr, const char *ifname, + in_port_t port, unsigned rule) { union epoll_ref ref; int ret; @@ -98,7 +98,9 @@ int pif_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif, return ref.fd;

ref.type = type; - ref.data = data; + ref.listen.port = port; + ref.listen.pif = pif; + ref.listen.rule = rule;

ret = epoll_add(c->epollfd, EPOLLIN, ref); if (ret < 0) { diff --git a/pif.h b/pif.h index 0f7f6672..0eb3626a 100644 --- a/pif.h +++ b/pif.h @@ -59,8 +59,8 @@ static inline bool pif_is_socket(uint8_t pif)

void pif_sockaddr(const struct ctx *c, union sockaddr_inany *sa, uint8_t pif, const union inany_addr *addr, in_port_t port); -int pif_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif, - const union inany_addr *addr, const char *ifname, - in_port_t port, uint32_t data); +int pif_listen(const struct ctx *c, enum epoll_type type, uint8_t pif, + const union inany_addr *addr, const char *ifname, + in_port_t port, unsigned rule);

#endif /* PIF_H */ diff --git a/tcp.c b/tcp.c index 16470703..a0d7cd86 100644 --- a/tcp.c +++ b/tcp.c @@ -2698,11 +2698,6 @@ void tcp_sock_handler(const struct ctx *c, union epoll_ref ref, int tcp_listen(const struct ctx *c, uint8_t pif, unsigned rule, const union inany_addr *addr, const char *ifname, in_port_t port) { - union fwd_listen_ref ref = { - .port = port, - .pif = pif, - .rule = rule, - }; int s;

ASSERT(!c->no_tcp); @@ -2722,8 +2717,7 @@ int tcp_listen(const struct ctx *c, uint8_t pif, unsigned rule, return -EAFNOSUPPORT; }

- s = pif_sock_l4(c, EPOLL_TYPE_TCP_LISTEN, pif, addr, ifname, - port, ref.u32); + s = pif_listen(c, EPOLL_TYPE_TCP_LISTEN, pif, addr, ifname, port, rule);

return s; } diff --git a/udp.c b/udp.c index 19adda06..464aa093 100644 --- a/udp.c +++ b/udp.c @@ -1139,11 +1139,6 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif, int udp_listen(const struct ctx *c, uint8_t pif, unsigned rule, const union inany_addr *addr, const char *ifname, in_port_t port) { - union fwd_listen_ref ref = { - .pif = pif, - .port = port, - .rule = rule, - }; int s;

ASSERT(!c->no_udp); @@ -1163,8 +1158,7 @@ int udp_listen(const struct ctx *c, uint8_t pif, unsigned rule, return -EAFNOSUPPORT; }

- s = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, pif, - addr, ifname, port, ref.u32); + s = pif_listen(c, EPOLL_TYPE_UDP_LISTEN, pif, addr, ifname, port, rule);

return s; }

-- Stefano

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson