linux/net/rds/loop.c

/*
 * Copyright (c) 2006, 2017 Oracle and/or its affiliates. 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/slab.h>
#include <linux/in.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <linux/ipv6.h>

#include "rds_single_path.h"
#include "rds.h"
#include "loop.h"

static DEFINE_SPINLOCK(loop_conns_lock);
static LIST_HEAD(loop_conns);
static atomic_t rds_loop_unloading = …;

static void rds_loop_set_unloading(void)
{ … }

static bool rds_loop_is_unloading(struct rds_connection *conn)
{ … }

/*
 * 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)
{ … }

/*
 * See rds_loop_xmit(). Since our inc is embedded in the rm, we
 * make sure the rm lives at least until the inc is done.
 */
static void rds_loop_inc_free(struct rds_incoming *inc)
{ … }

/* we need to at least give the thread something to succeed */
static int rds_loop_recv_path(struct rds_conn_path *cp)
{ … }

struct rds_loop_connection { … };

/*
 * 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)
{ … }

static void rds_loop_conn_free(void *arg)
{ … }

static int rds_loop_conn_path_connect(struct rds_conn_path *cp)
{ … }

static void rds_loop_conn_path_shutdown(struct rds_conn_path *cp)
{ … }

void rds_loop_exit(void)
{ … }

static void rds_loop_kill_conns(struct net *net)
{ … }

static void __net_exit rds_loop_exit_net(struct net *net)
{ … }

static struct pernet_operations rds_loop_net_ops = …;

int rds_loop_net_init(void)
{ … }

void rds_loop_net_exit(void)
{ … }

/*
 * 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 = …;