tcp: Unify part of spliced and non-spliced conn_from_sock path

In tcp_sock_handler() we split off to handle spliced sockets before
checking anything else.  However the first steps of the "new connection"
path for each case are the same: allocate a connection entry and accept()
the connection.

Remove this duplication by making tcp_conn_from_sock() handle both spliced
and non-spliced cases, with help from more specific tcp_tap_conn_from_sock
and tcp_splice_conn_from_sock functions for the later stages which differ.

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

tcp.c

@@ -2753,28 +2753,19 @@ static void tcp_connect_finish(struct ctx *c, struct tcp_tap_conn *conn)
 }
 
 /**
- * tcp_conn_from_sock() - Handle new connection request from listening socket
+ * tcp_tap_conn_from_sock() - Initialize state for non-spliced connection
  * @c:		Execution context
  * @ref:	epoll reference of listening socket
+ * @conn:	connection structure to initialize
+ * @s:		Accepted socket
+ * @sa:		Peer socket address (from accept())
  * @now:	Current timestamp
  */
-static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
+static void tcp_tap_conn_from_sock(struct ctx *c, union epoll_ref ref,
-			       const struct timespec *now)
+				   struct tcp_tap_conn *conn, int s,
+				   struct sockaddr *sa,
+				   const struct timespec *now)
 {
-	struct sockaddr_storage sa;
-	struct tcp_tap_conn *conn;
-	socklen_t sl;
-	int s;
-
-	if (c->tcp.conn_count >= TCP_MAX_CONNS)
-		return;
-
-	sl = sizeof(sa);
-	s = accept4(ref.r.s, (struct sockaddr *)&sa, &sl, SOCK_NONBLOCK);
-	if (s < 0)
-		return;
-
-	conn = CONN(c->tcp.conn_count++);
 	conn->c.spliced = false;
 	conn->sock = s;
 	conn->timer = -1;
@@ -2784,7 +2775,7 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 	if (ref.r.p.tcp.tcp.v6) {
 		struct sockaddr_in6 sa6;
 
-		memcpy(&sa6, &sa, sizeof(sa6));
+		memcpy(&sa6, sa, sizeof(sa6));
 
 		if (IN6_IS_ADDR_LOOPBACK(&sa6.sin6_addr) ||
 		    IN6_ARE_ADDR_EQUAL(&sa6.sin6_addr, &c->ip6.addr_seen) ||
@@ -2813,7 +2804,7 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 	} else {
 		struct sockaddr_in sa4;
 
-		memcpy(&sa4, &sa, sizeof(sa4));
+		memcpy(&sa4, sa, sizeof(sa4));
 
 		memset(&conn->a.a4.zero,   0, sizeof(conn->a.a4.zero));
 		memset(&conn->a.a4.one, 0xff, sizeof(conn->a.a4.one));
@@ -2846,6 +2837,37 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 	tcp_get_sndbuf(conn);
 }
 
+/**
+ * tcp_conn_from_sock() - Handle new connection request from listening socket
+ * @c:		Execution context
+ * @ref:	epoll reference of listening socket
+ * @now:	Current timestamp
+ */
+static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
+			       const struct timespec *now)
+{
+	struct sockaddr_storage sa;
+	union tcp_conn *conn;
+	socklen_t sl;
+	int s;
+
+	if (c->tcp.conn_count >= TCP_MAX_CONNS)
+		return;
+
+	sl = sizeof(sa);
+	s = accept4(ref.r.s, (struct sockaddr *)&sa, &sl, SOCK_NONBLOCK);
+	if (s < 0)
+		return;
+
+	conn = tc + c->tcp.conn_count++;
+
+	if (ref.r.p.tcp.tcp.splice)
+		tcp_splice_conn_from_sock(c, ref, &conn->splice, s);
+	else
+		tcp_tap_conn_from_sock(c, ref, &conn->tap, s,
+				       (struct sockaddr *)&sa, now);
+}
+
 /**
  * tcp_timer_handler() - timerfd events: close, send ACK, retransmit, or reset
  * @c:		Execution context
@@ -2925,13 +2947,13 @@ void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 		return;
 	}
 
-	if (ref.r.p.tcp.tcp.splice) {
+	if (ref.r.p.tcp.tcp.listen) {
-		tcp_sock_handler_splice(c, ref, events);
+		tcp_conn_from_sock(c, ref, now);
 		return;
 	}
 
-	if (ref.r.p.tcp.tcp.listen) {
+	if (ref.r.p.tcp.tcp.splice) {
-		tcp_conn_from_sock(c, ref, now);
+		tcp_sock_handler_splice(c, ref, events);
 		return;
 	}
 

tcp_splice.c

@@ -501,6 +501,33 @@ static void tcp_splice_dir(struct tcp_splice_conn *conn, int ref_sock,
 	*pipes = *from == conn->a ? conn->pipe_a_b : conn->pipe_b_a;
 }
 
+/**
+ * tcp_splice_conn_from_sock() - Initialize state for spliced connection
+ * @c:		Execution context
+ * @ref:	epoll reference of listening socket
+ * @conn:	connection structure to initialize
+ * @s:		Accepted socket
+ *
+ * #syscalls:pasta setsockopt
+ */
+void tcp_splice_conn_from_sock(struct ctx *c, union epoll_ref ref,
+			       struct tcp_splice_conn *conn, int s)
+{
+	assert(c->mode == MODE_PASTA);
+
+	if (setsockopt(s, SOL_TCP, TCP_QUICKACK, &((int){ 1 }), sizeof(int)))
+		trace("TCP (spliced): failed to set TCP_QUICKACK on %i", s);
+
+	conn->c.spliced = true;
+	c->tcp.splice_conn_count++;
+	conn->a = s;
+	conn->flags = ref.r.p.tcp.tcp.v6 ? SPLICE_V6 : 0;
+
+	if (tcp_splice_new(c, conn, ref.r.p.tcp.tcp.index,
+			   ref.r.p.tcp.tcp.outbound))
+		conn_flag(c, conn, CLOSING);
+}
+
 /**
  * tcp_sock_handler_splice() - Handler for socket mapped to spliced connection
  * @c:		Execution context
@@ -517,33 +544,7 @@ void tcp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 	uint32_t *seq_read, *seq_write;
 	struct tcp_splice_conn *conn;
 
-	if (ref.r.p.tcp.tcp.listen) {
+	assert(!ref.r.p.tcp.tcp.listen);
-		int s;
-
-		if (c->tcp.conn_count >= TCP_MAX_CONNS)
-			return;
-
-		if ((s = accept4(ref.r.s, NULL, NULL, SOCK_NONBLOCK)) < 0)
-			return;
-
-		if (setsockopt(s, SOL_TCP, TCP_QUICKACK, &((int){ 1 }),
-			       sizeof(int))) {
-			trace("TCP (spliced): failed to set TCP_QUICKACK on %i",
-			      s);
-		}
-
-		conn = CONN(c->tcp.conn_count++);
-		conn->c.spliced = true;
-		c->tcp.splice_conn_count++;
-		conn->a = s;
-		conn->flags = ref.r.p.tcp.tcp.v6 ? SPLICE_V6 : 0;
-
-		if (tcp_splice_new(c, conn, ref.r.p.tcp.tcp.index,
-				   ref.r.p.tcp.tcp.outbound))
-			conn_flag(c, conn, CLOSING);
-
-		return;
-	}
 
 	conn = CONN(ref.r.p.tcp.tcp.index);
 

tcp_splice.h

@@ -6,8 +6,12 @@
 #ifndef TCP_SPLICE_H
 #define TCP_SPLICE_H
 
+struct tcp_splice_conn;
+
 void tcp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 			     uint32_t events);
+void tcp_splice_conn_from_sock(struct ctx *c, union epoll_ref ref,
+			       struct tcp_splice_conn *conn, int s);
 void tcp_splice_init(struct ctx *c);
 
 #endif /* TCP_SPLICE_H */