RDS: loopback
A simple rds transport to handle loopback connections.
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rds/loop.c b/net/rds/loop.c
new file mode 100644
index 0000000..4a61997
--- /dev/null
+++ b/net/rds/loop.c
@@ -0,0 +1,188 @@
+/*
+ * 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 "rds.h"
+#include "loop.h"
+
+static DEFINE_SPINLOCK(loop_conns_lock);
+static LIST_HEAD(loop_conns);
+
+/*
+ * This 'loopback' transport is a special case for flows that originate
+ * and terminate on the same machine.
+ *
+ * Connection build-up notices if the destination address is thought of
+ * as a local address by a transport. At that time it decides to use the
+ * loopback transport instead of the bound transport of the sending socket.
+ *
+ * The loopback transport's sending path just hands the sent rds_message
+ * straight to the receiving path via an embedded rds_incoming.
+ */
+
+/*
+ * Usually a message transits both the sender and receiver's conns as it
+ * flows to the receiver. In the loopback case, though, the receive path
+ * is handed the sending conn so the sense of the addresses is reversed.
+ */
+static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
+ unsigned int hdr_off, unsigned int sg,
+ unsigned int off)
+{
+ BUG_ON(hdr_off || sg || off);
+
+ rds_inc_init(&rm->m_inc, conn, conn->c_laddr);
+ rds_message_addref(rm); /* for the inc */
+
+ rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc,
+ GFP_KERNEL, KM_USER0);
+
+ rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
+ NULL);
+
+ rds_inc_put(&rm->m_inc);
+
+ return sizeof(struct rds_header) + be32_to_cpu(rm->m_inc.i_hdr.h_len);
+}
+
+static int rds_loop_xmit_cong_map(struct rds_connection *conn,
+ struct rds_cong_map *map,
+ unsigned long offset)
+{
+ unsigned long i;
+
+ BUG_ON(offset);
+ BUG_ON(map != conn->c_lcong);
+
+ for (i = 0; i < RDS_CONG_MAP_PAGES; i++) {
+ memcpy((void *)conn->c_fcong->m_page_addrs[i],
+ (void *)map->m_page_addrs[i], PAGE_SIZE);
+ }
+
+ rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
+
+ return sizeof(struct rds_header) + RDS_CONG_MAP_BYTES;
+}
+
+/* we need to at least give the thread something to succeed */
+static int rds_loop_recv(struct rds_connection *conn)
+{
+ return 0;
+}
+
+struct rds_loop_connection {
+ struct list_head loop_node;
+ struct rds_connection *conn;
+};
+
+/*
+ * Even the loopback transport needs to keep track of its connections,
+ * so it can call rds_conn_destroy() on them on exit. N.B. there are
+ * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
+ * multiple loopback conns allocated, although rather useless.
+ */
+static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
+{
+ struct rds_loop_connection *lc;
+ unsigned long flags;
+
+ lc = kzalloc(sizeof(struct rds_loop_connection), GFP_KERNEL);
+ if (lc == NULL)
+ return -ENOMEM;
+
+ INIT_LIST_HEAD(&lc->loop_node);
+ lc->conn = conn;
+ conn->c_transport_data = lc;
+
+ spin_lock_irqsave(&loop_conns_lock, flags);
+ list_add_tail(&lc->loop_node, &loop_conns);
+ spin_unlock_irqrestore(&loop_conns_lock, flags);
+
+ return 0;
+}
+
+static void rds_loop_conn_free(void *arg)
+{
+ struct rds_loop_connection *lc = arg;
+ rdsdebug("lc %p\n", lc);
+ list_del(&lc->loop_node);
+ kfree(lc);
+}
+
+static int rds_loop_conn_connect(struct rds_connection *conn)
+{
+ rds_connect_complete(conn);
+ return 0;
+}
+
+static void rds_loop_conn_shutdown(struct rds_connection *conn)
+{
+}
+
+void rds_loop_exit(void)
+{
+ struct rds_loop_connection *lc, *_lc;
+ LIST_HEAD(tmp_list);
+
+ /* avoid calling conn_destroy with irqs off */
+ spin_lock_irq(&loop_conns_lock);
+ list_splice(&loop_conns, &tmp_list);
+ INIT_LIST_HEAD(&loop_conns);
+ spin_unlock_irq(&loop_conns_lock);
+
+ list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
+ WARN_ON(lc->conn->c_passive);
+ rds_conn_destroy(lc->conn);
+ }
+}
+
+/*
+ * This is missing .xmit_* because loop doesn't go through generic
+ * rds_send_xmit() and doesn't call rds_recv_incoming(). .listen_stop and
+ * .laddr_check are missing because transport.c doesn't iterate over
+ * rds_loop_transport.
+ */
+struct rds_transport rds_loop_transport = {
+ .xmit = rds_loop_xmit,
+ .xmit_cong_map = rds_loop_xmit_cong_map,
+ .recv = rds_loop_recv,
+ .conn_alloc = rds_loop_conn_alloc,
+ .conn_free = rds_loop_conn_free,
+ .conn_connect = rds_loop_conn_connect,
+ .conn_shutdown = rds_loop_conn_shutdown,
+ .inc_copy_to_user = rds_message_inc_copy_to_user,
+ .inc_purge = rds_message_inc_purge,
+ .inc_free = rds_message_inc_free,
+ .t_name = "loopback",
+};