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

5 Mar 2026

On Wed, 4 Mar 2026 09:55:21 +1100
David Gibson  wrote:
...
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?
Sure, done. Applied now.

-- 
Stefano

    