RDS: TCP: Retransmit half-sent datagrams when switching sockets in rds_tcp_reset_callbacks

When we switch a connection's sockets in rds_tcp_rest_callbacks,
any partially sent datagram must be retransmitted on the new
socket so that the receiver can correctly reassmble the RDS
datagram. Use rds_send_reset() which is designed for this purpose.
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/rds/send.c

@@ -99,6 +99,7 @@ void rds_send_reset(struct rds_connection *conn)
 	list_splice_init(&conn->c_retrans, &conn->c_send_queue);
 	spin_unlock_irqrestore(&conn->c_lock, flags);
 }
+EXPORT_SYMBOL_GPL(rds_send_reset);
 
 static int acquire_in_xmit(struct rds_connection *conn)
 {

net/rds/tcp.c

@@ -173,6 +173,7 @@ void rds_tcp_reset_callbacks(struct socket *sock,
 	release_sock(osock->sk);
 	sock_release(osock);
 newsock:
+	rds_send_reset(conn);
 	lock_sock(sock->sk);
 	write_lock_bh(&sock->sk->sk_callback_lock);
 	tc->t_sock = sock;