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/slab.h>
  35#include <linux/in.h>
  36
  37#include "rds_single_path.h"
  38#include "rds.h"
  39#include "loop.h"
  40
  41static DEFINE_SPINLOCK(loop_conns_lock);
  42static LIST_HEAD(loop_conns);
  43
  44/*
  45 * This 'loopback' transport is a special case for flows that originate
  46 * and terminate on the same machine.
  47 *
  48 * Connection build-up notices if the destination address is thought of
  49 * as a local address by a transport.  At that time it decides to use the
  50 * loopback transport instead of the bound transport of the sending socket.
  51 *
  52 * The loopback transport's sending path just hands the sent rds_message
  53 * straight to the receiving path via an embedded rds_incoming.
  54 */
  55
  56/*
  57 * Usually a message transits both the sender and receiver's conns as it
  58 * flows to the receiver.  In the loopback case, though, the receive path
  59 * is handed the sending conn so the sense of the addresses is reversed.
  60 */
  61static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
  62                         unsigned int hdr_off, unsigned int sg,
  63                         unsigned int off)
  64{
  65        struct scatterlist *sgp = &rm->data.op_sg[sg];
  66        int ret = sizeof(struct rds_header) +
  67                        be32_to_cpu(rm->m_inc.i_hdr.h_len);
  68
  69        /* Do not send cong updates to loopback */
  70        if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
  71                rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
  72                ret = min_t(int, ret, sgp->length - conn->c_xmit_data_off);
  73                goto out;
  74        }
  75
  76        BUG_ON(hdr_off || sg || off);
  77
  78        rds_inc_init(&rm->m_inc, conn, conn->c_laddr);
  79        /* For the embedded inc. Matching put is in loop_inc_free() */
  80        rds_message_addref(rm);
  81
  82        rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc,
  83                          GFP_KERNEL);
  84
  85        rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
  86                            NULL);
  87
  88        rds_inc_put(&rm->m_inc);
  89out:
  90        return ret;
  91}
  92
  93/*
  94 * See rds_loop_xmit(). Since our inc is embedded in the rm, we
  95 * make sure the rm lives at least until the inc is done.
  96 */
  97static void rds_loop_inc_free(struct rds_incoming *inc)
  98{
  99        struct rds_message *rm = container_of(inc, struct rds_message, m_inc);
 100
 101        rds_message_put(rm);
 102}
 103
 104/* we need to at least give the thread something to succeed */
 105static int rds_loop_recv_path(struct rds_conn_path *cp)
 106{
 107        return 0;
 108}
 109
 110struct rds_loop_connection {
 111        struct list_head loop_node;
 112        struct rds_connection *conn;
 113};
 114
 115/*
 116 * Even the loopback transport needs to keep track of its connections,
 117 * so it can call rds_conn_destroy() on them on exit. N.B. there are
 118 * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
 119 * multiple loopback conns allocated, although rather useless.
 120 */
 121static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 122{
 123        struct rds_loop_connection *lc;
 124        unsigned long flags;
 125
 126        lc = kzalloc(sizeof(struct rds_loop_connection), gfp);
 127        if (!lc)
 128                return -ENOMEM;
 129
 130        INIT_LIST_HEAD(&lc->loop_node);
 131        lc->conn = conn;
 132        conn->c_transport_data = lc;
 133
 134        spin_lock_irqsave(&loop_conns_lock, flags);
 135        list_add_tail(&lc->loop_node, &loop_conns);
 136        spin_unlock_irqrestore(&loop_conns_lock, flags);
 137
 138        return 0;
 139}
 140
 141static void rds_loop_conn_free(void *arg)
 142{
 143        struct rds_loop_connection *lc = arg;
 144        unsigned long flags;
 145
 146        rdsdebug("lc %p\n", lc);
 147        spin_lock_irqsave(&loop_conns_lock, flags);
 148        list_del(&lc->loop_node);
 149        spin_unlock_irqrestore(&loop_conns_lock, flags);
 150        kfree(lc);
 151}
 152
 153static int rds_loop_conn_path_connect(struct rds_conn_path *cp)
 154{
 155        rds_connect_complete(cp->cp_conn);
 156        return 0;
 157}
 158
 159static void rds_loop_conn_path_shutdown(struct rds_conn_path *cp)
 160{
 161}
 162
 163void rds_loop_exit(void)
 164{
 165        struct rds_loop_connection *lc, *_lc;
 166        LIST_HEAD(tmp_list);
 167
 168        /* avoid calling conn_destroy with irqs off */
 169        spin_lock_irq(&loop_conns_lock);
 170        list_splice(&loop_conns, &tmp_list);
 171        INIT_LIST_HEAD(&loop_conns);
 172        spin_unlock_irq(&loop_conns_lock);
 173
 174        list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
 175                WARN_ON(lc->conn->c_passive);
 176                rds_conn_destroy(lc->conn);
 177        }
 178}
 179
 180/*
 181 * This is missing .xmit_* because loop doesn't go through generic
 182 * rds_send_xmit() and doesn't call rds_recv_incoming().  .listen_stop and
 183 * .laddr_check are missing because transport.c doesn't iterate over
 184 * rds_loop_transport.
 185 */
 186struct rds_transport rds_loop_transport = {
 187        .xmit                   = rds_loop_xmit,
 188        .recv_path              = rds_loop_recv_path,
 189        .conn_alloc             = rds_loop_conn_alloc,
 190        .conn_free              = rds_loop_conn_free,
 191        .conn_path_connect      = rds_loop_conn_path_connect,
 192        .conn_path_shutdown     = rds_loop_conn_path_shutdown,
 193        .inc_copy_to_user       = rds_message_inc_copy_to_user,
 194        .inc_free               = rds_loop_inc_free,
 195        .t_name                 = "loopback",
 196};
 197