udp: Unify udp[46]_mh_splice

We have separate mmsghdr arrays for splicing IPv4 and IPv6 packets, where
the only difference is that they point to different sockaddr buffers for
the destination address.

Unify these by having the common array point at a sockaddr_inany as the
address.  This does mean slightly more work when we're about to splice,
because we need to write the whole socket address, rather than just the
port.  However it removes 32 mmsghdr structures and we're going to need
more flexibility constructing that target address for the flow table.

Because future changes might mean that the address isn't always loopback,
change the name of the common address from *_localname  to udp_splicename.

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

1 files changed, 20 insertions, 27 deletions

diff --git a/udp.c b/udp.c
index 43ed643..2d34f6a 100644
--- a/udp.c
+++ b/udp.c
@@ -235,18 +235,10 @@ static struct mmsghdr	udp4_mh_recv		[UDP_MAX_FRAMES];
 static struct mmsghdr	udp6_mh_recv		[UDP_MAX_FRAMES];
 
 /* IOVs and msghdr arrays for sending "spliced" datagrams to sockets */
-static struct sockaddr_in udp4_splice_to = {
-	.sin_family = AF_INET,
-	.sin_addr = IN4ADDR_LOOPBACK_INIT,
-};
-static struct sockaddr_in6 udp6_splice_to = {
-	.sin6_family = AF_INET6,
-	.sin6_addr = IN6ADDR_LOOPBACK_INIT,
-};
+static union sockaddr_inany udp_splice_to;
 
 static struct iovec	udp_iov_splice		[UDP_MAX_FRAMES];
-static struct mmsghdr	udp4_mh_splice		[UDP_MAX_FRAMES];
-static struct mmsghdr	udp6_mh_splice		[UDP_MAX_FRAMES];
+static struct mmsghdr	udp_mh_splice		[UDP_MAX_FRAMES];
 
 /* IOVs for L2 frames */
 static struct iovec	udp4_l2_iov		[UDP_MAX_FRAMES][UDP_NUM_IOVS];
@@ -523,7 +515,7 @@ static unsigned udp_splice_send(const struct ctx *c, size_t start, size_t n,
 				const struct timespec *now)
 {
 	in_port_t src = udp_meta[start].splicesrc;
-	struct mmsghdr *mmh_recv, *mmh_send;
+	struct mmsghdr *mmh_recv;
 	unsigned int i = start;
 	int s;
 
@@ -532,16 +524,22 @@ static unsigned udp_splice_send(const struct ctx *c, size_t start, size_t n,
 
 	if (ref.udp.v6) {
 		mmh_recv = udp6_mh_recv;
-		mmh_send = udp6_mh_splice;
-		udp6_splice_to.sin6_port = htons(dst);
+		udp_splice_to.sa6 = (struct sockaddr_in6) {
+			.sin6_family = AF_INET6,
+			.sin6_addr = in6addr_loopback,
+			.sin6_port = htons(dst),
+		};
 	} else {
 		mmh_recv = udp4_mh_recv;
-		mmh_send = udp4_mh_splice;
-		udp4_splice_to.sin_port = htons(dst);
+		udp_splice_to.sa4 = (struct sockaddr_in) {
+			.sin_family = AF_INET,
+			.sin_addr = in4addr_loopback,
+			.sin_port = htons(dst),
+		};
 	}
 
 	do {
-		mmh_send[i].msg_hdr.msg_iov->iov_len = mmh_recv[i].msg_len;
+		udp_mh_splice[i].msg_hdr.msg_iov->iov_len = mmh_recv[i].msg_len;
 
 		if (++i >= n)
 			break;
@@ -579,7 +577,7 @@ static unsigned udp_splice_send(const struct ctx *c, size_t start, size_t n,
 		udp_splice_ns[ref.udp.v6][src].ts = now->tv_sec;
 	}
 
-	sendmmsg(s, mmh_send + start, i - start, MSG_NOSIGNAL);
+	sendmmsg(s, udp_mh_splice + start, i - start, MSG_NOSIGNAL);
 out:
 	return i - start;
 }
@@ -1094,20 +1092,15 @@ static void udp_splice_iov_init(void)
 	int i;
 
 	for (i = 0; i < UDP_MAX_FRAMES; i++) {
-		struct msghdr *mh4 = &udp4_mh_splice[i].msg_hdr;
-		struct msghdr *mh6 = &udp6_mh_splice[i].msg_hdr;
-
-		mh4->msg_name = &udp4_splice_to;
-		mh4->msg_namelen = sizeof(udp4_splice_to);
+		struct msghdr *mh = &udp_mh_splice[i].msg_hdr;
 
-		mh6->msg_name = &udp6_splice_to;
-		mh6->msg_namelen = sizeof(udp6_splice_to);
+		mh->msg_name = &udp_splice_to;
+		mh->msg_namelen = sizeof(udp_splice_to);
 
 		udp_iov_splice[i].iov_base = udp_payload[i].data;
 
-		mh4->msg_iov = &udp_iov_splice[i];
-		mh6->msg_iov = &udp_iov_splice[i];
-		mh4->msg_iovlen = mh6->msg_iovlen = 1;
+		mh->msg_iov = &udp_iov_splice[i];
+		mh->msg_iovlen = 1;
 	}
 }