Krzysztof Halasa
first discussion/thread:
 http://marc.theaimsgroup.com/?t=105465240900005&r=1&w=2
Patch then posted at:
 http://marc.theaimsgroup.com/?l=linux-kernel&m=105560475819610&w=2

No further discussion seems to appear thereafter.

only in ac/redhat, _NOT_ in 2.6

diff -urN 28rc1/net/unix/af_unix.c 28rc1_aac/net/unix/af_unix.c
--- 28rc1/net/unix/af_unix.c	2002-11-29 01:53:16.000000000 +0200
+++ 28rc1_aac/net/unix/af_unix.c	2004-10-24 00:58:12.000000000 +0300
@@ -1707,6 +1707,39 @@
 	return err;
 }
 
+static unsigned int dgram_poll(struct file * file, struct socket *sock,
+			       poll_table *wait)
+{
+        struct sock *sk = sock->sk;
+        unsigned int mask;
+	unix_socket *other;
+
+        poll_wait(file, sk->sleep, wait);
+        mask = 0;
+
+        /* exceptional events? */
+        if (sk->err || !skb_queue_empty(&sk->error_queue))
+                mask |= POLLERR;
+        if (sk->shutdown == SHUTDOWN_MASK)
+                mask |= POLLHUP;
+
+        /* readable? */
+        if (!skb_queue_empty(&sk->receive_queue) ||
+            (sk->shutdown & RCV_SHUTDOWN))
+                mask |= POLLIN | POLLRDNORM;
+
+        /* writable? */
+	other = unix_peer_get(sk);
+	if (sock_writeable(sk) &&
+	    (other == NULL ||
+	     skb_queue_len(&other->receive_queue) <= other->max_ack_backlog))
+                mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
+        else
+                set_bit(SOCK_ASYNC_NOSPACE, &sk->socket->flags);
+
+	return mask;
+}
+
 static unsigned int unix_poll(struct file * file, struct socket *sock, poll_table *wait)
 {
 	struct sock *sk = sock->sk;
@@ -1836,7 +1869,7 @@
 	socketpair:	unix_socketpair,
 	accept:		sock_no_accept,
 	getname:	unix_getname,
-	poll:		datagram_poll,
+	poll:		dgram_poll,
 	ioctl:		unix_ioctl,
 	listen:		sock_no_listen,
 	shutdown:	unix_shutdown,