LXR linux/net/rds/loop.c

   1/*
   2 * Copyright (c) 2006 Oracle.  All rights reserved.
   3 *
   4 * This software is available to you under a choice of one of two
   5 * licenses.  You may choose to be licensed under the terms of the GNU
   6 * General Public License (GPL) Version 2, available from the file
   7 * COPYING in the main directory of this source tree, or the
   8 * OpenIB.org BSD license below:
   9 *
  10 *     Redistribution and use in source and binary forms, with or
  11 *     without modification, are permitted provided that the following
  12 *     conditions are met:
  13 *
  14 *      - Redistributions of source code must retain the above
  15 *        copyright notice, this list of conditions and the following
  16 *        disclaimer.
  17 *
  18 *      - Redistributions in binary form must reproduce the above
  19 *        copyright notice, this list of conditions and the following
  20 *        disclaimer in the documentation and/or other materials
  21 *        provided with the distribution.
  22 *
  23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30 * SOFTWARE.
  31 *
  32 */
  33#include <linux/kernel.h>
  34#include <linux/in.h>
  35
  36#include "rds.h"
  37#include "loop.h"
  38
  39static DEFINE_SPINLOCK(loop_conns_lock);
  40static LIST_HEAD(loop_conns);
  41
  42/*
  43 * This 'loopback' transport is a special case for flows that originate
  44 * and terminate on the same machine.
  45 *
  46 * Connection build-up notices if the destination address is thought of
  47 * as a local address by a transport.  At that time it decides to use the
  48 * loopback transport instead of the bound transport of the sending socket.
  49 *
  50 * The loopback transport's sending path just hands the sent rds_message
  51 * straight to the receiving path via an embedded rds_incoming.
  52 */
  53
  54/*
  55 * Usually a message transits both the sender and receiver's conns as it
  56 * flows to the receiver.  In the loopback case, though, the receive path
  57 * is handed the sending conn so the sense of the addresses is reversed.
  58 */
  59static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
  60                         unsigned int hdr_off, unsigned int sg,
  61                         unsigned int off)
  62{
  63        BUG_ON(hdr_off || sg || off);
  64
  65        rds_inc_init(&rm->m_inc, conn, conn->c_laddr);
  66        rds_message_addref(rm); /* for the inc */
  67
  68        rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc,
  69                          GFP_KERNEL, KM_USER0);
  70
  71        rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
  72                            NULL);
  73
  74        rds_inc_put(&rm->m_inc);
  75
  76        return sizeof(struct rds_header) + be32_to_cpu(rm->m_inc.i_hdr.h_len);
  77}
  78
  79static int rds_loop_xmit_cong_map(struct rds_connection *conn,
  80                                  struct rds_cong_map *map,
  81                                  unsigned long offset)
  82{
  83        unsigned long i;
  84
  85        BUG_ON(offset);
  86        BUG_ON(map != conn->c_lcong);
  87
  88        for (i = 0; i < RDS_CONG_MAP_PAGES; i++) {
  89                memcpy((void *)conn->c_fcong->m_page_addrs[i],
  90                       (void *)map->m_page_addrs[i], PAGE_SIZE);
  91        }
  92
  93        rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
  94
  95        return sizeof(struct rds_header) + RDS_CONG_MAP_BYTES;
  96}
  97
  98/* we need to at least give the thread something to succeed */
  99static int rds_loop_recv(struct rds_connection *conn)
 100{
 101        return 0;
 102}
 103
 104struct rds_loop_connection {
 105        struct list_head loop_node;
 106        struct rds_connection *conn;
 107};
 108
 109/*
 110 * Even the loopback transport needs to keep track of its connections,
 111 * so it can call rds_conn_destroy() on them on exit. N.B. there are
 112 * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
 113 * multiple loopback conns allocated, although rather useless.
 114 */
 115static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 116{
 117        struct rds_loop_connection *lc;
 118        unsigned long flags;
 119
 120        lc = kzalloc(sizeof(struct rds_loop_connection), GFP_KERNEL);
 121        if (lc == NULL)
 122                return -ENOMEM;
 123
 124        INIT_LIST_HEAD(&lc->loop_node);
 125        lc->conn = conn;
 126        conn->c_transport_data = lc;
 127
 128        spin_lock_irqsave(&loop_conns_lock, flags);
 129        list_add_tail(&lc->loop_node, &loop_conns);
 130        spin_unlock_irqrestore(&loop_conns_lock, flags);
 131
 132        return 0;
 133}
 134
 135static void rds_loop_conn_free(void *arg)
 136{
 137        struct rds_loop_connection *lc = arg;
 138        rdsdebug("lc %p\n", lc);
 139        list_del(&lc->loop_node);
 140        kfree(lc);
 141}
 142
 143static int rds_loop_conn_connect(struct rds_connection *conn)
 144{
 145        rds_connect_complete(conn);
 146        return 0;
 147}
 148
 149static void rds_loop_conn_shutdown(struct rds_connection *conn)
 150{
 151}
 152
 153void rds_loop_exit(void)
 154{
 155        struct rds_loop_connection *lc, *_lc;
 156        LIST_HEAD(tmp_list);
 157
 158        /* avoid calling conn_destroy with irqs off */
 159        spin_lock_irq(&loop_conns_lock);
 160        list_splice(&loop_conns, &tmp_list);
 161        INIT_LIST_HEAD(&loop_conns);
 162        spin_unlock_irq(&loop_conns_lock);
 163
 164        list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
 165                WARN_ON(lc->conn->c_passive);
 166                rds_conn_destroy(lc->conn);
 167        }
 168}
 169
 170/*
 171 * This is missing .xmit_* because loop doesn't go through generic
 172 * rds_send_xmit() and doesn't call rds_recv_incoming().  .listen_stop and
 173 * .laddr_check are missing because transport.c doesn't iterate over
 174 * rds_loop_transport.
 175 */
 176struct rds_transport rds_loop_transport = {
 177        .xmit                   = rds_loop_xmit,
 178        .xmit_cong_map          = rds_loop_xmit_cong_map,
 179        .recv                   = rds_loop_recv,
 180        .conn_alloc             = rds_loop_conn_alloc,
 181        .conn_free              = rds_loop_conn_free,
 182        .conn_connect           = rds_loop_conn_connect,
 183        .conn_shutdown          = rds_loop_conn_shutdown,
 184        .inc_copy_to_user       = rds_message_inc_copy_to_user,
 185        .inc_purge              = rds_message_inc_purge,
 186        .inc_free               = rds_message_inc_free,
 187        .t_name                 = "loopback",
 188};
 189