[PATCH 04/16] tcp_splice: Simplify clean up logic

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

Currently tcp_splice_flow_defer() contains specific logic to determine if
we're far enough initialised that we need to close pipes and/or sockets.
This is potentially fragile if we change something about the order in which
we do things.  We can simplify this by initialising the pipe and socket
fields to -1 very early, then close()ing them if and only if they're non
negative.

This lets us remove a special case cleanup if our connect() fails.  This
will already trigger a CLOSING event, and the socket fd in question is
populated in the connection structure.  Thus we can let the new cleanup
logic handle it rather than requiring an explicit close().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 tcp_splice.c | 27 +++++++++++----------------
 1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/tcp_splice.c b/tcp_splice.c
index b8d64eba..76258e89 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -246,16 +246,14 @@ bool tcp_splice_flow_defer(union flow *flow)
 		return false;
 
 	for (side = 0; side < SIDES; side++) {
-		if (conn->events & SPLICE_ESTABLISHED) {
-			/* Flushing might need to block: don't recycle them. */
-			if (conn->pipe[side][0] != -1) {
-				close(conn->pipe[side][0]);
-				close(conn->pipe[side][1]);
-				conn->pipe[side][0] = conn->pipe[side][1] = -1;
-			}
+		/* Flushing might need to block: don't recycle them. */
+		if (conn->pipe[side][0] >= 0) {
+			close(conn->pipe[side][0]);
+			close(conn->pipe[side][1]);
+			conn->pipe[side][0] = conn->pipe[side][1] = -1;
 		}
 
-		if (side == 0 || conn->events & SPLICE_CONNECT) {
+		if (conn->s[side] >= 0) {
 			close(conn->s[side]);
 			conn->s[side] = -1;
 		}
@@ -284,8 +282,6 @@ static int tcp_splice_connect_finish(const struct ctx *c,
 	int i = 0;
 
 	for (side = 0; side < SIDES; side++) {
-		conn->pipe[side][0] = conn->pipe[side][1] = -1;
-
 		for (; i < TCP_SPLICE_PIPE_POOL_SIZE; i++) {
 			if (splice_pipe_pool[i][0] >= 0) {
 				SWAP(conn->pipe[side][0],
@@ -361,12 +357,8 @@ static int tcp_splice_connect(const struct ctx *c, struct tcp_splice_conn *conn,
 	}
 
 	if (connect(conn->s[1], sa, sl)) {
-		if (errno != EINPROGRESS) {
-			int ret = -errno;
-
-			close(sock_conn);
-			return ret;
-		}
+		if (errno != EINPROGRESS)
+			return -errno;
 		conn_event(c, conn, SPLICE_CONNECT);
 	} else {
 		conn_event(c, conn, SPLICE_ESTABLISHED);
@@ -468,6 +460,9 @@ bool tcp_splice_conn_from_sock(const struct ctx *c,
 
 	conn->f.type = FLOW_TCP_SPLICE;
 	conn->s[0] = s;
+	conn->s[1] = -1;
+	conn->pipe[0][0] = conn->pipe[0][1] = -1;
+	conn->pipe[1][0] = conn->pipe[1][1] = -1;
 
 	if (tcp_splice_new(c, conn, ref.port, ref.pif))
 		conn_flag(c, conn, CLOSING);
-- 
@@ -246,16 +246,14 @@ bool tcp_splice_flow_defer(union flow *flow)
 		return false;
 
 	for (side = 0; side < SIDES; side++) {
-		if (conn->events & SPLICE_ESTABLISHED) {
-			/* Flushing might need to block: don't recycle them. */
-			if (conn->pipe[side][0] != -1) {
-				close(conn->pipe[side][0]);
-				close(conn->pipe[side][1]);
-				conn->pipe[side][0] = conn->pipe[side][1] = -1;
-			}
+		/* Flushing might need to block: don't recycle them. */
+		if (conn->pipe[side][0] >= 0) {
+			close(conn->pipe[side][0]);
+			close(conn->pipe[side][1]);
+			conn->pipe[side][0] = conn->pipe[side][1] = -1;
 		}
 
-		if (side == 0 || conn->events & SPLICE_CONNECT) {
+		if (conn->s[side] >= 0) {
 			close(conn->s[side]);
 			conn->s[side] = -1;
 		}
@@ -284,8 +282,6 @@ static int tcp_splice_connect_finish(const struct ctx *c,
 	int i = 0;
 
 	for (side = 0; side < SIDES; side++) {
-		conn->pipe[side][0] = conn->pipe[side][1] = -1;
-
 		for (; i < TCP_SPLICE_PIPE_POOL_SIZE; i++) {
 			if (splice_pipe_pool[i][0] >= 0) {
 				SWAP(conn->pipe[side][0],
@@ -361,12 +357,8 @@ static int tcp_splice_connect(const struct ctx *c, struct tcp_splice_conn *conn,
 	}
 
 	if (connect(conn->s[1], sa, sl)) {
-		if (errno != EINPROGRESS) {
-			int ret = -errno;
-
-			close(sock_conn);
-			return ret;
-		}
+		if (errno != EINPROGRESS)
+			return -errno;
 		conn_event(c, conn, SPLICE_CONNECT);
 	} else {
 		conn_event(c, conn, SPLICE_ESTABLISHED);
@@ -468,6 +460,9 @@ bool tcp_splice_conn_from_sock(const struct ctx *c,
 
 	conn->f.type = FLOW_TCP_SPLICE;
 	conn->s[0] = s;
+	conn->s[1] = -1;
+	conn->pipe[0][0] = conn->pipe[0][1] = -1;
+	conn->pipe[1][0] = conn->pipe[1][1] = -1;
 
 	if (tcp_splice_new(c, conn, ref.port, ref.pif))
 		conn_flag(c, conn, CLOSING);
-- 
2.43.0