[PATCH 3/4] udp_vu: Factor things out of udp_vu_reply_sock_data() loop

[David Gibson <david@gibson.dropbear.id.au>]

At the start of every cycle of the loop in udp_vu_reply_sock_data() we:
 - ASSERT that uflow is not NULL
 - Check if the target pif is PIF_TAP
 - Initialize the v6 boolean

However, all of these depend only on the flow, which doesn't change across
the loop.  This is probably a duplication from udp_vu_listen_sock_data(),
where the flow can be different for each packet.  For the reply socket
case, however, factor that logic out of the loop.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 udp_vu.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/udp_vu.c b/udp_vu.c
index 698667f6..6e1823a9 100644
--- a/udp_vu.c
+++ b/udp_vu.c
@@ -281,30 +281,28 @@ void udp_vu_reply_sock_data(const struct ctx *c, union epoll_ref ref,
 {
 	flow_sidx_t tosidx = flow_sidx_opposite(ref.flowside);
 	const struct flowside *toside = flowside_at_sidx(tosidx);
+	bool v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
 	struct udp_flow *uflow = udp_at_sidx(ref.flowside);
 	int from_s = uflow->s[ref.flowside.sidei];
 	struct vu_dev *vdev = c->vdev;
 	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+	uint8_t topif = pif_at_sidx(tosidx);
 	int i;
 
-	for (i = 0; i < UDP_MAX_FRAMES; i++) {
-		uint8_t topif = pif_at_sidx(tosidx);
-		ssize_t dlen;
-		int iov_used;
-		bool v6;
-
-		ASSERT(uflow);
+	ASSERT(uflow);
 
-		if (topif != PIF_TAP) {
-			uint8_t frompif = pif_at_sidx(ref.flowside);
+	if (topif != PIF_TAP) {
+		uint8_t frompif = pif_at_sidx(ref.flowside);
 
-			flow_err(uflow,
-				 "No support for forwarding UDP from %s to %s",
-				 pif_name(frompif), pif_name(topif));
-			continue;
-		}
+		flow_err(uflow,
+			 "No support for forwarding UDP from %s to %s",
+			 pif_name(frompif), pif_name(topif));
+		return;
+	}
 
-		v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
+	for (i = 0; i < UDP_MAX_FRAMES; i++) {
+		ssize_t dlen;
+		int iov_used;
 
 		iov_used = udp_vu_sock_recv(c, from_s, v6, &dlen);
 		if (iov_used <= 0)
-- 
@@ -281,30 +281,28 @@ void udp_vu_reply_sock_data(const struct ctx *c, union epoll_ref ref,
 {
 	flow_sidx_t tosidx = flow_sidx_opposite(ref.flowside);
 	const struct flowside *toside = flowside_at_sidx(tosidx);
+	bool v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
 	struct udp_flow *uflow = udp_at_sidx(ref.flowside);
 	int from_s = uflow->s[ref.flowside.sidei];
 	struct vu_dev *vdev = c->vdev;
 	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+	uint8_t topif = pif_at_sidx(tosidx);
 	int i;
 
-	for (i = 0; i < UDP_MAX_FRAMES; i++) {
-		uint8_t topif = pif_at_sidx(tosidx);
-		ssize_t dlen;
-		int iov_used;
-		bool v6;
-
-		ASSERT(uflow);
+	ASSERT(uflow);
 
-		if (topif != PIF_TAP) {
-			uint8_t frompif = pif_at_sidx(ref.flowside);
+	if (topif != PIF_TAP) {
+		uint8_t frompif = pif_at_sidx(ref.flowside);
 
-			flow_err(uflow,
-				 "No support for forwarding UDP from %s to %s",
-				 pif_name(frompif), pif_name(topif));
-			continue;
-		}
+		flow_err(uflow,
+			 "No support for forwarding UDP from %s to %s",
+			 pif_name(frompif), pif_name(topif));
+		return;
+	}
 
-		v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
+	for (i = 0; i < UDP_MAX_FRAMES; i++) {
+		ssize_t dlen;
+		int iov_used;
 
 		iov_used = udp_vu_sock_recv(c, from_s, v6, &dlen);
 		if (iov_used <= 0)
-- 
2.49.0