[PATCH v2 13/22] 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 | 40 ++++++++++++++++++++--------------------
 tcp_splice.h |  2 +-
 2 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/tcp_splice.c b/tcp_splice.c
index 609f3242..d1263f21 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -378,29 +378,29 @@ static int tcp_splice_connect(const struct ctx *c, struct tcp_splice_conn *conn,
  * 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];
+		dstport += c->tcp.fwd_out.delta[dstport];
 
-		s = tcp_conn_sock(c, af);
+		s1 = tcp_conn_sock(c, af);
 	} else {
 		ASSERT(pif == PIF_HOST);
 
-		port += c->tcp.fwd_in.delta[port];
+		dstport += c->tcp.fwd_in.delta[dstport];
 
-		s = tcp_conn_sock_ns(c, af);
+		s1 = tcp_conn_sock_ns(c, af);
 	}
 
-	if (s < 0) {
-		warn("Couldn't open connectable socket for splice (%d)", s);
-		return s;
+	if (s1 < 0) {
+		warn("Couldn't open connectable socket for splice (%d)", s1);
+		return s1;
 	}
 
-	return tcp_splice_connect(c, conn, s, port);
+	return tcp_splice_connect(c, conn, s1, dstport);
 }
 
 /**
@@ -408,7 +408,7 @@ 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
@@ -416,28 +416,28 @@ 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 */
-- 
2.43.0