RDS: Add TCP transport to RDS

This code allows RDS to be tunneled over a TCP connection.

RDMA operations are disabled when using TCP transport,
but this frees RDS from the IB/RDMA stack dependency, and allows
it to be used with standard Ethernet adapters, or in a VM.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rds/tcp_connect.c

@@ -0,0 +1,153 @@
+/*
+ * Copyright (c) 2006 Oracle.  All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/in.h>
+#include <net/tcp.h>
+
+#include "rds.h"
+#include "tcp.h"
+
+void rds_tcp_state_change(struct sock *sk)
+{
+	void (*state_change)(struct sock *sk);
+	struct rds_connection *conn;
+	struct rds_tcp_connection *tc;
+
+	read_lock(&sk->sk_callback_lock);
+	conn = sk->sk_user_data;
+	if (conn == NULL) {
+		state_change = sk->sk_state_change;
+		goto out;
+	}
+	tc = conn->c_transport_data;
+	state_change = tc->t_orig_state_change;
+
+	rdsdebug("sock %p state_change to %d\n", tc->t_sock, sk->sk_state);
+
+	switch(sk->sk_state) {
+		/* ignore connecting sockets as they make progress */
+		case TCP_SYN_SENT:
+		case TCP_SYN_RECV:
+			break;
+		case TCP_ESTABLISHED:
+			rds_connect_complete(conn);
+			break;
+		case TCP_CLOSE:
+			rds_conn_drop(conn);
+		default:
+			break;
+	}
+out:
+	read_unlock(&sk->sk_callback_lock);
+	state_change(sk);
+}
+
+int rds_tcp_conn_connect(struct rds_connection *conn)
+{
+	struct socket *sock = NULL;
+	struct sockaddr_in src, dest;
+	int ret;
+
+	ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
+	if (ret < 0)
+		goto out;
+
+	rds_tcp_tune(sock);
+
+	src.sin_family = AF_INET;
+	src.sin_addr.s_addr = (__force u32)conn->c_laddr;
+	src.sin_port = (__force u16)htons(0);
+
+	ret = sock->ops->bind(sock, (struct sockaddr *)&src, sizeof(src));
+	if (ret) {
+		rdsdebug("bind failed with %d at address %u.%u.%u.%u\n",
+		     ret, NIPQUAD(conn->c_laddr));
+		goto out;
+	}
+
+	dest.sin_family = AF_INET;
+	dest.sin_addr.s_addr = (__force u32)conn->c_faddr;
+	dest.sin_port = (__force u16)htons(RDS_TCP_PORT);
+
+	/*
+	 * once we call connect() we can start getting callbacks and they
+	 * own the socket
+	 */
+	rds_tcp_set_callbacks(sock, conn);
+	ret = sock->ops->connect(sock, (struct sockaddr *)&dest, sizeof(dest),
+				 O_NONBLOCK);
+	sock = NULL;
+
+	rdsdebug("connect to address %u.%u.%u.%u returned %d\n",
+		 NIPQUAD(conn->c_faddr), ret);
+	if (ret == -EINPROGRESS)
+		ret = 0;
+
+out:
+	if (sock)
+		sock_release(sock);
+	return ret;
+}
+
+/*
+ * Before killing the tcp socket this needs to serialize with callbacks.  The
+ * caller has already grabbed the sending sem so we're serialized with other
+ * senders.
+ *
+ * TCP calls the callbacks with the sock lock so we hold it while we reset the
+ * callbacks to those set by TCP.  Our callbacks won't execute again once we
+ * hold the sock lock.
+ */
+void rds_tcp_conn_shutdown(struct rds_connection *conn)
+{
+	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct socket *sock = tc->t_sock;
+
+	rdsdebug("shutting down conn %p tc %p sock %p\n", conn, tc, sock);
+
+	if (sock) {
+		sock->ops->shutdown(sock, RCV_SHUTDOWN | SEND_SHUTDOWN);
+		lock_sock(sock->sk);
+		rds_tcp_restore_callbacks(sock, tc); /* tc->tc_sock = NULL */
+
+		release_sock(sock->sk);
+		sock_release(sock);
+	};
+
+	if (tc->t_tinc) {
+		rds_inc_put(&tc->t_tinc->ti_inc);
+		tc->t_tinc = NULL;
+	}
+	tc->t_tinc_hdr_rem = sizeof(struct rds_header);
+	tc->t_tinc_data_rem = 0;
+}