[PATCH 3/4] tcp: unify l2 TCPv4 and TCPv6 queues and structures

[Jon Maloy <jmaloy@redhat.com>]

Following the preparations in the previous commits, we can now
remove the queues dedicated for TCPv6 and move that traffic over
to the queues currently used for TCPv4.

Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
 tcp.c     |   8 ++-
 tcp_buf.c | 158 +++++++++---------------------------------------------
 tcp_buf.h |   1 +
 3 files changed, 28 insertions(+), 139 deletions(-)

diff --git a/tcp.c b/tcp.c
index 006e503..19cf9e5 100644
--- a/tcp.c
+++ b/tcp.c
@@ -998,12 +998,14 @@ size_t tcp_l2_buf_fill_headers(const struct tcp_tap_conn *conn,
 
 	if (a4) {
 		iov[TCP_IOV_IP].iov_len = sizeof(struct iphdr);
+		tcp4_eth_src.h_proto = htons_constant(ETH_P_IP);
 		return tcp_fill_headers4(conn, iov[TCP_IOV_TAP].iov_base,
 					 iov[TCP_IOV_IP].iov_base,
 					 iov[TCP_IOV_PAYLOAD].iov_base, dlen,
 					 check, seq);
 	} else {
 		iov[TCP_IOV_IP].iov_len = sizeof(struct ipv6hdr);
+		tcp4_eth_src.h_proto = htons_constant(ETH_P_IPV6);
 		return tcp_fill_headers6(conn, iov[TCP_IOV_TAP].iov_base,
 					 iov[TCP_IOV_IP].iov_base,
 					 iov[TCP_IOV_PAYLOAD].iov_base, dlen,
@@ -2508,11 +2510,7 @@ int tcp_init(struct ctx *c)
 {
 	ASSERT(!c->no_tcp);
 
-	if (c->ifi4)
-		tcp_sock4_iov_init(c);
-
-	if (c->ifi6)
-		tcp_sock6_iov_init(c);
+	tcp_sock4_iov_init(c);
 
 	memset(init_sock_pool4,		0xff,	sizeof(init_sock_pool4));
 	memset(init_sock_pool6,		0xff,	sizeof(init_sock_pool6));
diff --git a/tcp_buf.c b/tcp_buf.c
index 6e6549f..92c4d73 100644
--- a/tcp_buf.c
+++ b/tcp_buf.c
@@ -80,7 +80,7 @@ struct tcp_flags_t {
 #endif
 
 /* Ethernet header for IPv4 frames */
-static struct ethhdr		tcp4_eth_src;
+struct ethhdr		tcp4_eth_src;
 
 static struct tap_hdr		tcp4_payload_tap_hdr[TCP_FRAMES_MEM];
 /* IPv4 headers */
@@ -104,36 +104,14 @@ static struct tcp_flags_t	tcp4_flags[TCP_FRAMES_MEM];
 static unsigned int tcp4_flags_used;
 
 /* Ethernet header for IPv6 frames */
-static struct ethhdr		tcp6_eth_src;
-
-static struct tap_hdr		tcp6_payload_tap_hdr[TCP_FRAMES_MEM];
-/* IPv6 headers */
-struct ipv6hdr		tcp_payload_ip6;
-static struct iphdr_t		tcp6_payload_ip[TCP_FRAMES_MEM];
-/* TCP headers and data for IPv6 frames */
-static struct tcp_payload_t	tcp6_payload[TCP_FRAMES_MEM];
-
-static_assert(MSS6 <= sizeof(tcp6_payload[0].data), "MSS6 is greater than 65516");
-
-/* References tracking the owner connection of frames in the tap outqueue */
-static struct tcp_tap_conn *tcp6_frame_conns[TCP_FRAMES_MEM];
-static unsigned int tcp6_payload_used;
-
-static struct tap_hdr		tcp6_flags_tap_hdr[TCP_FRAMES_MEM];
-/* IPv6 headers for TCP segment without payload */
-static struct iphdr_t		tcp6_flags_ip[TCP_FRAMES_MEM];
-/* TCP segment without payload for IPv6 frames */
-static struct tcp_flags_t	tcp6_flags[TCP_FRAMES_MEM];
-
-static unsigned int tcp6_flags_used;
+struct ipv6hdr tcp_payload_ip6;
 
 /* recvmsg()/sendmsg() data for tap */
 static struct iovec	iov_sock		[TCP_FRAMES_MEM + 1];
 
 static struct iovec	tcp4_l2_iov		[TCP_FRAMES_MEM][TCP_NUM_IOVS];
-static struct iovec	tcp6_l2_iov		[TCP_FRAMES_MEM][TCP_NUM_IOVS];
 static struct iovec	tcp4_l2_flags_iov	[TCP_FRAMES_MEM][TCP_NUM_IOVS];
-static struct iovec	tcp6_l2_flags_iov	[TCP_FRAMES_MEM][TCP_NUM_IOVS];
+
 /**
  * tcp_update_l2_buf() - Update Ethernet header buffers with addresses
  * @eth_d:	Ethernet destination address, NULL if unchanged
@@ -142,7 +120,6 @@ static struct iovec	tcp6_l2_flags_iov	[TCP_FRAMES_MEM][TCP_NUM_IOVS];
 void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s)
 {
 	eth_update_mac(&tcp4_eth_src, eth_d, eth_s);
-	eth_update_mac(&tcp6_eth_src, eth_d, eth_s);
 }
 
 /**
@@ -191,61 +168,12 @@ void tcp_sock4_iov_init(const struct ctx *c)
 	}
 }
 
-/**
- * tcp_sock6_iov_init() - Initialise scatter-gather L2 buffers for IPv6 sockets
- * @c:		Execution context
- */
-void tcp_sock6_iov_init(const struct ctx *c)
-{
-	struct ipv6hdr ip6 = L2_BUF_IP6_INIT(IPPROTO_TCP);
-	struct iovec *iov;
-	int i;
-
-	tcp6_eth_src.h_proto = htons_constant(ETH_P_IPV6);
-	tcp_payload_ip6 = ip6;
-
-	for (i = 0; i < ARRAY_SIZE(tcp6_payload); i++) {
-		tcp6_payload[i].th.doff = sizeof(struct tcphdr) / 4;
-		tcp6_payload[i].th.ack = 1;
-	}
-
-	for (i = 0; i < ARRAY_SIZE(tcp6_flags); i++) {
-		tcp6_flags_ip[i].ip6 = ip6;
-		tcp6_flags[i].th.doff = sizeof(struct tcphdr) / 4;
-		tcp6_flags[i].th .ack = 1;
-	}
-
-	for (i = 0; i < TCP_FRAMES_MEM; i++) {
-		iov = tcp6_l2_iov[i];
-
-		iov[TCP_IOV_TAP] = tap_hdr_iov(c, &tcp6_payload_tap_hdr[i]);
-		iov[TCP_IOV_ETH] = IOV_OF_LVALUE(tcp6_eth_src);
-		iov[TCP_IOV_IP].iov_base = &tcp6_payload_ip[i];
-		iov[TCP_IOV_IP].iov_len = sizeof(tcp6_payload_ip[i].ip6);
-		iov[TCP_IOV_PAYLOAD].iov_base = &tcp6_payload[i];
-	}
-
-	for (i = 0; i < TCP_FRAMES_MEM; i++) {
-		iov = tcp6_l2_flags_iov[i];
-
-		iov[TCP_IOV_TAP] = tap_hdr_iov(c, &tcp6_flags_tap_hdr[i]);
-		iov[TCP_IOV_ETH] = IOV_OF_LVALUE(tcp6_eth_src);
-		iov[TCP_IOV_IP].iov_base = &tcp6_flags_ip[i];
-		iov[TCP_IOV_IP].iov_len = sizeof(tcp6_flags_ip[i].ip6);
-		iov[TCP_IOV_PAYLOAD].iov_base = &tcp6_flags[i];
-	}
-}
-
 /**
  * tcp_flags_flush() - Send out buffers for segments with no data (flags)
  * @c:		Execution context
  */
 void tcp_flags_flush(const struct ctx *c)
 {
-	tap_send_frames(c, &tcp6_l2_flags_iov[0][0], TCP_NUM_IOVS,
-			tcp6_flags_used);
-	tcp6_flags_used = 0;
-
 	tap_send_frames(c, &tcp4_l2_flags_iov[0][0], TCP_NUM_IOVS,
 			tcp4_flags_used);
 	tcp4_flags_used = 0;
@@ -287,14 +215,6 @@ void tcp_payload_flush(struct ctx *c)
 {
 	size_t m;
 
-	m = tap_send_frames(c, &tcp6_l2_iov[0][0], TCP_NUM_IOVS,
-			    tcp6_payload_used);
-	if (m != tcp6_payload_used) {
-		tcp_revert_seq(c, &tcp6_frame_conns[m], &tcp6_l2_iov[m],
-			       tcp6_payload_used - m);
-	}
-	tcp6_payload_used = 0;
-
 	m = tap_send_frames(c, &tcp4_l2_iov[0][0], TCP_NUM_IOVS,
 			    tcp4_payload_used);
 	if (m != tcp4_payload_used) {
@@ -321,21 +241,13 @@ int tcp_buf_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 	uint32_t seq;
 	int ret;
 
-	if (CONN_V4(conn))
-		iov = tcp4_l2_flags_iov[tcp4_flags_used++];
-	else
-		iov = tcp6_l2_flags_iov[tcp6_flags_used++];
-
+	iov = tcp4_l2_flags_iov[tcp4_flags_used++];
 	payload = iov[TCP_IOV_PAYLOAD].iov_base;
-
 	seq = conn->seq_to_tap;
 	ret = tcp_prepare_flags(c, conn, flags, &payload->th,
 				payload->opts, &optlen);
 	if (ret <= 0) {
-		if (CONN_V4(conn))
-			tcp4_flags_used--;
-		else
-			tcp6_flags_used--;
+		tcp4_flags_used--;
 		return ret;
 	}
 
@@ -346,10 +258,7 @@ int tcp_buf_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 		struct iovec *dup_iov;
 		int i;
 
-		if (CONN_V4(conn))
-			dup_iov = tcp4_l2_flags_iov[tcp4_flags_used++];
-		else
-			dup_iov = tcp6_l2_flags_iov[tcp6_flags_used++];
+		dup_iov = tcp4_l2_flags_iov[tcp4_flags_used++];
 
 		for (i = 0; i < TCP_NUM_IOVS; i++)
 			memcpy(dup_iov[i].iov_base, iov[i].iov_base,
@@ -357,13 +266,8 @@ int tcp_buf_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 		dup_iov[TCP_IOV_PAYLOAD].iov_len = iov[TCP_IOV_PAYLOAD].iov_len;
 	}
 
-	if (CONN_V4(conn)) {
-		if (tcp4_flags_used > TCP_FRAMES_MEM - 2)
-			tcp_flags_flush(c);
-	} else {
-		if (tcp6_flags_used > TCP_FRAMES_MEM - 2)
-			tcp_flags_flush(c);
-	}
+	if (tcp4_flags_used > TCP_FRAMES_MEM - 2)
+		tcp_flags_flush(c);
 
 	return 0;
 }
@@ -379,36 +283,26 @@ int tcp_buf_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 static void tcp_data_to_tap(struct ctx *c, struct tcp_tap_conn *conn,
 			    ssize_t dlen, int no_csum, uint32_t seq)
 {
+	struct iovec *iov_prev = tcp4_l2_iov[tcp4_payload_used - 1];
+	const uint16_t *check = NULL;
 	struct iovec *iov;
 	size_t l4len;
 
 	conn->seq_to_tap = seq + dlen;
 
-	if (CONN_V4(conn)) {
-		struct iovec *iov_prev = tcp4_l2_iov[tcp4_payload_used - 1];
-		const uint16_t *check = NULL;
-
-		if (no_csum) {
-			struct iphdr *iph = iov_prev[TCP_IOV_IP].iov_base;
-			check = &iph->check;
-		}
+	if (CONN_V4(conn) && no_csum) {
+		struct iphdr *iph = iov_prev[TCP_IOV_IP].iov_base;
 
-		tcp4_frame_conns[tcp4_payload_used] = conn;
-
-		iov = tcp4_l2_iov[tcp4_payload_used++];
-		l4len = tcp_l2_buf_fill_headers(conn, iov, dlen, check, seq);
-		iov[TCP_IOV_PAYLOAD].iov_len = l4len;
-		if (tcp4_payload_used > TCP_FRAMES_MEM - 1)
-			tcp_payload_flush(c);
-	} else if (CONN_V6(conn)) {
-		tcp6_frame_conns[tcp6_payload_used] = conn;
-
-		iov = tcp6_l2_iov[tcp6_payload_used++];
-		l4len = tcp_l2_buf_fill_headers(conn, iov, dlen, NULL, seq);
-		iov[TCP_IOV_PAYLOAD].iov_len = l4len;
-		if (tcp6_payload_used > TCP_FRAMES_MEM - 1)
-			tcp_payload_flush(c);
+		check = &iph->check;
 	}
+
+	tcp4_frame_conns[tcp4_payload_used] = conn;
+
+	iov = tcp4_l2_iov[tcp4_payload_used++];
+	l4len = tcp_l2_buf_fill_headers(conn, iov, dlen, check, seq);
+	iov[TCP_IOV_PAYLOAD].iov_len = l4len;
+	if (tcp4_payload_used > TCP_FRAMES_MEM - 1)
+		tcp_payload_flush(c);
 }
 
 /**
@@ -472,19 +366,15 @@ int tcp_buf_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn)
 		mh_sock.msg_iovlen = fill_bufs;
 	}
 
-	if (( v4 && tcp4_payload_used + fill_bufs > TCP_FRAMES_MEM) ||
-	    (!v4 && tcp6_payload_used + fill_bufs > TCP_FRAMES_MEM)) {
+	if ((v4 && tcp4_payload_used + fill_bufs > TCP_FRAMES_MEM)) {
 		tcp_payload_flush(c);
 
 		/* Silence Coverity CWE-125 false positive */
-		tcp4_payload_used = tcp6_payload_used = 0;
+		tcp4_payload_used = 0;
 	}
 
 	for (i = 0, iov = iov_sock + 1; i < fill_bufs; i++, iov++) {
-		if (v4)
-			iov->iov_base = &tcp4_payload[tcp4_payload_used + i].data;
-		else
-			iov->iov_base = &tcp6_payload[tcp6_payload_used + i].data;
+		iov->iov_base = &tcp4_payload[tcp4_payload_used + i].data;
 		iov->iov_len = mss;
 	}
 	if (iov_rem)
diff --git a/tcp_buf.h b/tcp_buf.h
index d3d0d7f..d7cdbaf 100644
--- a/tcp_buf.h
+++ b/tcp_buf.h
@@ -13,6 +13,7 @@ void tcp_payload_flush(struct ctx *c);
 int tcp_buf_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn);
 int tcp_buf_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags);
 
+extern struct ethhdr		tcp4_eth_src;
 extern struct iphdr		tcp_payload_ip4;
 extern struct ipv6hdr		tcp_payload_ip6;
 #endif  /*TCP_BUF_H */
-- 
@@ -13,6 +13,7 @@ void tcp_payload_flush(struct ctx *c);
 int tcp_buf_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn);
 int tcp_buf_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags);
 
+extern struct ethhdr		tcp4_eth_src;
 extern struct iphdr		tcp_payload_ip4;
 extern struct ipv6hdr		tcp_payload_ip6;
 #endif  /*TCP_BUF_H */
-- 
2.45.2