[PATCH v3 11/20] tcp_splice: More specific variable names in new splice path

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

In tcp_splice_conn_from_sock(), the 'port' variable stores the source
port of the connection on the originating side.  In tcp_splice_new(),
called directly from it, the 'port' parameter gives the _destination_
port of the originating connection and is then updated to the
destination port of the connection on the other side.

Similarly, in tcp_splice_conn_from_sock(), 's' is the fd of the
accetped socket (on side 0), whereas in tcp_splice_new(), 's' is the
fd of the connecting socket (side 1).

I, for one, find having the same variable name with different meanings
in such close proximity in the flow of control pretty confusing.
Alter the names for greater specificity and clarity.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 tcp_splice.c | 38 +++++++++++++++++++-------------------
 tcp_splice.h |  2 +-
 2 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/tcp_splice.c b/tcp_splice.c
index 2411a949..9bd50e3e 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -407,25 +407,25 @@ static int tcp_conn_sock_ns(const struct ctx *c, sa_family_t af)
  * Return: return code from connect()
  */
 static int tcp_splice_new(const struct ctx *c, struct tcp_splice_conn *conn,
-			  in_port_t port, uint8_t pif)
+			  in_port_t dstport, uint8_t pif)
 {
 	sa_family_t af = CONN_V6(conn) ? AF_INET6 : AF_INET;
-	int s = -1;
+	int s1;
 
 	if (pif == PIF_SPLICE) {
-		port += c->tcp.fwd_out.delta[port];
-		s = tcp_conn_sock(c, af);
+		dstport += c->tcp.fwd_out.delta[dstport];
+		s1 = tcp_conn_sock(c, af);
 	} else {
 		ASSERT(pif == PIF_HOST);
 
-		port += c->tcp.fwd_in.delta[port];
-		s = tcp_conn_sock_ns(c, af);
+		dstport += c->tcp.fwd_in.delta[dstport];
+		s1 = tcp_conn_sock_ns(c, af);
 	}
 
-	if (s < 0)
-		return s;
+	if (s1 < 0)
+		return s1;
 
-	return tcp_splice_connect(c, conn, s, port);
+	return tcp_splice_connect(c, conn, s1, dstport);
 }
 
 /**
@@ -433,7 +433,7 @@ static int tcp_splice_new(const struct ctx *c, struct tcp_splice_conn *conn,
  * @c:		Execution context
  * @ref:	epoll reference of listening socket
  * @flow:	flow to initialise
- * @s:		Accepted socket
+ * @s0:		Accepted (side 0) socket
  * @sa:		Peer address of connection
  *
  * Return: true if able to create a spliced connection, false otherwise
@@ -441,28 +441,28 @@ static int tcp_splice_new(const struct ctx *c, struct tcp_splice_conn *conn,
  */
 bool tcp_splice_conn_from_sock(const struct ctx *c,
 			       union tcp_listen_epoll_ref ref, union flow *flow,
-			       int s, const union sockaddr_inany *sa)
+			       int s0, const union sockaddr_inany *sa)
 {
 	struct tcp_splice_conn *conn;
-	union inany_addr aany;
-	in_port_t port;
+	union inany_addr src;
+	in_port_t srcport;
 
 	ASSERT(c->mode == MODE_PASTA);
 
-	inany_from_sockaddr(&aany, &port, sa);
-	if (!inany_is_loopback(&aany))
+	inany_from_sockaddr(&src, &srcport, sa);
+	if (!inany_is_loopback(&src))
 		return false;
 
 	conn = FLOW_START(flow, FLOW_TCP_SPLICE, tcp_splice, 0);
 
-	conn->flags = inany_v4(&aany) ? 0 : SPLICE_V6;
-	conn->s[0] = s;
+	conn->flags = inany_v4(&src) ? 0 : SPLICE_V6;
+	conn->s[0] = s0;
 	conn->s[1] = -1;
 	conn->pipe[0][0] = conn->pipe[0][1] = -1;
 	conn->pipe[1][0] = conn->pipe[1][1] = -1;
 
-	if (setsockopt(s, SOL_TCP, TCP_QUICKACK, &((int){ 1 }), sizeof(int)))
-		flow_trace(conn, "failed to set TCP_QUICKACK on %i", s);
+	if (setsockopt(s0, SOL_TCP, TCP_QUICKACK, &((int){ 1 }), sizeof(int)))
+		flow_trace(conn, "failed to set TCP_QUICKACK on %i", s0);
 
 	if (tcp_splice_new(c, conn, ref.port, ref.pif))
 		conn_flag(c, conn, CLOSING);
diff --git a/tcp_splice.h b/tcp_splice.h
index 5a471af0..d0c6ff79 100644
--- a/tcp_splice.h
+++ b/tcp_splice.h
@@ -13,7 +13,7 @@ void tcp_splice_sock_handler(struct ctx *c, union epoll_ref ref,
 			     uint32_t events);
 bool tcp_splice_conn_from_sock(const struct ctx *c,
 			       union tcp_listen_epoll_ref ref, union flow *flow,
-			       int s, const union sockaddr_inany *sa);
+			       int s0, const union sockaddr_inany *sa);
 void tcp_splice_init(struct ctx *c);
 
 #endif /* TCP_SPLICE_H */
-- 
@@ -13,7 +13,7 @@ void tcp_splice_sock_handler(struct ctx *c, union epoll_ref ref,
 			     uint32_t events);
 bool tcp_splice_conn_from_sock(const struct ctx *c,
 			       union tcp_listen_epoll_ref ref, union flow *flow,
-			       int s, const union sockaddr_inany *sa);
+			       int s0, const union sockaddr_inany *sa);
 void tcp_splice_init(struct ctx *c);
 
 #endif /* TCP_SPLICE_H */
-- 
2.43.2