udp: Merge vhost-user and "buf" listening socket paths

udp_buf_listen_sock_data() and udp_vu_listen_sock_data() now have
effectively identical structure.  The forwarding functions used for flow
specific sockets (udp_buf_sock_to_tap(), udp_vu_sock_to_tap() and
udp_sock_to_sock()) also now take a number of datagrams.  This means we
can re-use them for the listening socket path, just passing '1' so they
handle a single datagram at a time.

This allows us to merge both the vhost-user and flow specific paths into
a single, simpler udp_listen_sock_data().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

udp.c

@@ -629,7 +629,7 @@ static int udp_sock_errs(const struct ctx *c, union epoll_ref ref)
  *
  * Return: 0 on success, -1 otherwise
  */
-int udp_peek_addr(int s, union sockaddr_inany *src)
+static int udp_peek_addr(int s, union sockaddr_inany *src)
 {
 	struct msghdr msg = {
 		.msg_name = src,
@@ -714,12 +714,12 @@ static void udp_buf_sock_to_tap(const struct ctx *c, int s, int n,
 }
 
 /**
- * udp_buf_listen_sock_data() - Handle new data from socket
+ * udp_listen_sock_data() - Handle new data from listening socket
  * @c:		Execution context
  * @ref:	epoll reference
  * @now:	Current timestamp
  */
-static void udp_buf_listen_sock_data(const struct ctx *c, union epoll_ref ref,
+static void udp_listen_sock_data(const struct ctx *c, union epoll_ref ref,
 				     const struct timespec *now)
 {
 	union sockaddr_inany src;
@@ -728,16 +728,13 @@ static void udp_buf_listen_sock_data(const struct ctx *c, union epoll_ref ref,
 		flow_sidx_t tosidx = udp_flow_from_sock(c, ref, &src, now);
 		uint8_t topif = pif_at_sidx(tosidx);
 
-		if (udp_sock_recv(c, ref.fd, udp_mh_recv, 1) <= 0)
-			break;
-
 		if (pif_is_socket(topif)) {
-			udp_splice_prepare(udp_mh_recv, 0);
+			udp_sock_to_sock(c, ref.fd, 1, tosidx);
-			udp_splice_send(c, 0, 1, tosidx);
 		} else if (topif == PIF_TAP) {
-			udp_tap_prepare(udp_mh_recv, 0, flowside_at_sidx(tosidx),
+			if (c->mode == MODE_VU)
-					false);
+				udp_vu_sock_to_tap(c, ref.fd, 1, tosidx);
-			tap_send_frames(c, &udp_l2_iov[0][0], UDP_NUM_IOVS, 1);
+			else
+				udp_buf_sock_to_tap(c, ref.fd, 1, tosidx);
 		} else if (flow_sidx_valid(tosidx)) {
 			flow_sidx_t fromsidx = flow_sidx_opposite(tosidx);
 			struct udp_flow *uflow = udp_at_sidx(tosidx);
@@ -772,12 +769,8 @@ void udp_listen_sock_handler(const struct ctx *c,
 		}
 	}
 
-	if (events & EPOLLIN) {
+	if (events & EPOLLIN)
-		if (c->mode == MODE_VU)
+		udp_listen_sock_data(c, ref, now);
-			udp_vu_listen_sock_data(c, ref, now);
-		else
-			udp_buf_listen_sock_data(c, ref, now);
-	}
 }
 
 /**

udp_internal.h

@@ -30,6 +30,5 @@ size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp,
 size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp,
                        const struct flowside *toside, size_t dlen,
 		       bool no_udp_csum);
-int udp_peek_addr(int s, union sockaddr_inany *src);
 
 #endif /* UDP_INTERNAL_H */

udp_vu.c

@@ -191,68 +191,6 @@ static void udp_vu_csum(const struct flowside *toside, int iov_used)
 	}
 }
 
-/**
- * udp_vu_listen_sock_data() - Handle new data from socket
- * @c:		Execution context
- * @ref:	epoll reference
- * @now:	Current timestamp
- */
-void udp_vu_listen_sock_data(const struct ctx *c, union epoll_ref ref,
-			     const struct timespec *now)
-{
-	struct vu_dev *vdev = c->vdev;
-	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
-	int i;
-
-	for (i = 0; i < UDP_MAX_FRAMES; i++) {
-		const struct flowside *toside;
-		union sockaddr_inany s_in;
-		flow_sidx_t sidx;
-		uint8_t pif;
-		ssize_t dlen;
-		int iov_used;
-		bool v6;
-
-		if (udp_peek_addr(ref.fd, &s_in) < 0)
-			break;
-
-		sidx = udp_flow_from_sock(c, ref, &s_in, now);
-		pif = pif_at_sidx(sidx);
-
-		if (pif != PIF_TAP) {
-			if (flow_sidx_valid(sidx)) {
-				flow_sidx_t fromsidx = flow_sidx_opposite(sidx);
-				struct udp_flow *uflow = udp_at_sidx(sidx);
-
-				flow_err(uflow,
-					"No support for forwarding UDP from %s to %s",
-					pif_name(pif_at_sidx(fromsidx)),
-					pif_name(pif));
-			} else {
-				debug("Discarding 1 datagram without flow");
-			}
-
-			continue;
-		}
-
-		toside = flowside_at_sidx(sidx);
-
-		v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
-
-		iov_used = udp_vu_sock_recv(c, ref.fd, v6, &dlen);
-		if (iov_used <= 0)
-			break;
-
-		udp_vu_prepare(c, toside, dlen);
-		if (*c->pcap) {
-			udp_vu_csum(toside, iov_used);
-			pcap_iov(iov_vu, iov_used,
-				 sizeof(struct virtio_net_hdr_mrg_rxbuf));
-		}
-		vu_flush(vdev, vq, elem, iov_used);
-	}
-}
-
 /**
  * udp_vu_sock_to_tap() - Forward datagrams from socket to tap
  * @c:		Execution context