rds: tcp: send handshake ping-probe from passive endpoint

The RDS handshake ping probe added by commit 5916e2c1554f
("RDS: TCP: Enable multipath RDS for TCP") is sent from rds_sendmsg()
before the first data packet is sent to a peer. If the conversation
is not bidirectional  (i.e., one side is always passive and never
invokes rds_sendmsg()) and the passive side restarts its rds_tcp
module, a new HS ping probe needs to be sent, so that the number
of paths can be re-established.

This patch achieves that by sending a HS ping probe from
rds_tcp_accept_one() when c_npaths is 0 (i.e., we have not done
a handshake probe with this peer yet).

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Tested-by: Jenny Xu <jenny.x.xu@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 8 deletions

diff --git a/net/rds/send.c b/net/rds/send.c
index 3652a50397c7..e81aa176f4e2 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -971,8 +971,6 @@ static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
 	return ret;
 }
 
-static void rds_send_ping(struct rds_connection *conn);
-
 static int rds_send_mprds_hash(struct rds_sock *rs, struct rds_connection *conn)
 {
 	int hash;
@@ -982,7 +980,7 @@ static int rds_send_mprds_hash(struct rds_sock *rs, struct rds_connection *conn)
 	else
 		hash = RDS_MPATH_HASH(rs, conn->c_npaths);
 	if (conn->c_npaths == 0 && hash != 0) {
-		rds_send_ping(conn);
+		rds_send_ping(conn, 0);
 
 		if (conn->c_npaths == 0) {
 			wait_event_interruptible(conn->c_hs_waitq,
@@ -1282,11 +1280,11 @@ rds_send_pong(struct rds_conn_path *cp, __be16 dport)
 	return rds_send_probe(cp, 0, dport, 0);
 }
 
-static void
-rds_send_ping(struct rds_connection *conn)
+void
+rds_send_ping(struct rds_connection *conn, int cp_index)
 {
 	unsigned long flags;
-	struct rds_conn_path *cp = &conn->c_path[0];
+	struct rds_conn_path *cp = &conn->c_path[cp_index];
 
 	spin_lock_irqsave(&cp->cp_lock, flags);
 	if (conn->c_ping_triggered) {
@@ -1295,6 +1293,6 @@ rds_send_ping(struct rds_connection *conn)
 	}
 	conn->c_ping_triggered = 1;
 	spin_unlock_irqrestore(&cp->cp_lock, flags);
-	rds_send_probe(&conn->c_path[0], cpu_to_be16(RDS_FLAG_PROBE_PORT),
-		       0, 0);
+	rds_send_probe(cp, cpu_to_be16(RDS_FLAG_PROBE_PORT), 0, 0);
 }
+EXPORT_SYMBOL_GPL(rds_send_ping);