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.h"
  38 #include "loop.h"
  39
  40 static DEFINE_SPINLOCK(loop_conns_lock);
  41 static LIST_HEAD(loop_conns);
  42
  43 /*
  44  * This 'loopback' transport is a special case for flows that originate
  45  * and terminate on the same machine.
  46  *
  47  * Connection build-up notices if the destination address is thought of
  48  * as a local address by a transport.  At that time it decides to use the
  49  * loopback transport instead of the bound transport of the sending socket.
  50  *
  51  * The loopback transport's sending path just hands the sent rds_message
  52  * straight to the receiving path via an embedded rds_incoming.
  53  */
  54
  55 /*
  56  * Usually a message transits both the sender and receiver's conns as it
  57  * flows to the receiver.  In the loopback case, though, the receive path
  58  * is handed the sending conn so the sense of the addresses is reversed.
  59  */
  60 static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
  61                          unsigned int hdr_off, unsigned int sg,
  62                          unsigned int off)
  63 {
  64         struct scatterlist *sgp = &rm->data.op_sg[sg];
  65         int ret = sizeof(struct rds_header) +
  66                         be32_to_cpu(rm->m_inc.i_hdr.h_len);
  67
  68         /* Do not send cong updates to loopback */
  69         if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
  70                 rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
  71                 ret = min_t(int, ret, sgp->length - conn->c_xmit_data_off);
  72                 goto out;
  73         }
  74
  75         BUG_ON(hdr_off || sg || off);
  76
  77         rds_inc_init(&rm->m_inc, conn, conn->c_laddr);
  78         /* For the embedded inc. Matching put is in loop_inc_free() */
  79         rds_message_addref(rm);
  80
  81         rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc,
  82                           GFP_KERNEL, KM_USER0);
  83
  84         rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
  85                             NULL);
  86
  87         rds_inc_put(&rm->m_inc);
  88 out:
  89         return ret;
  90 }
  91
  92 /*
  93  * See rds_loop_xmit(). Since our inc is embedded in the rm, we
  94  * make sure the rm lives at least until the inc is done.
  95  */
  96 static void rds_loop_inc_free(struct rds_incoming *inc)
  97 {
  98         struct rds_message *rm = container_of(inc, struct rds_message, m_inc);
  99         rds_message_put(rm);
 100 }
 101
 102 /* we need to at least give the thread something to succeed */
 103 static int rds_loop_recv(struct rds_connection *conn)
 104 {
 105         return 0;
 106 }
 107
 108 struct rds_loop_connection {
 109         struct list_head loop_node;
 110         struct rds_connection *conn;
 111 };
 112
 113 /*
 114  * Even the loopback transport needs to keep track of its connections,
 115  * so it can call rds_conn_destroy() on them on exit. N.B. there are
 116  * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
 117  * multiple loopback conns allocated, although rather useless.
 118  */
 119 static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 120 {
 121         struct rds_loop_connection *lc;
 122         unsigned long flags;
 123
 124         lc = kzalloc(sizeof(struct rds_loop_connection), GFP_KERNEL);
 125         if (!lc)
 126                 return -ENOMEM;
 127
 128         INIT_LIST_HEAD(&lc->loop_node);
 129         lc->conn = conn;
 130         conn->c_transport_data = lc;
 131
 132         spin_lock_irqsave(&loop_conns_lock, flags);
 133         list_add_tail(&lc->loop_node, &loop_conns);
 134         spin_unlock_irqrestore(&loop_conns_lock, flags);
 135
 136         return 0;
 137 }
 138
 139 static void rds_loop_conn_free(void *arg)
 140 {
 141         struct rds_loop_connection *lc = arg;
 142         unsigned long flags;
 143
 144         rdsdebug("lc %p\n", lc);
 145         spin_lock_irqsave(&loop_conns_lock, flags);
 146         list_del(&lc->loop_node);
 147         spin_unlock_irqrestore(&loop_conns_lock, flags);
 148         kfree(lc);
 149 }
 150
 151 static int rds_loop_conn_connect(struct rds_connection *conn)
 152 {
 153         rds_connect_complete(conn);
 154         return 0;
 155 }
 156
 157 static void rds_loop_conn_shutdown(struct rds_connection *conn)
 158 {
 159 }
 160
 161 void rds_loop_exit(void)
 162 {
 163         struct rds_loop_connection *lc, *_lc;
 164         LIST_HEAD(tmp_list);
 165
 166         /* avoid calling conn_destroy with irqs off */
 167         spin_lock_irq(&loop_conns_lock);
 168         list_splice(&loop_conns, &tmp_list);
 169         INIT_LIST_HEAD(&loop_conns);
 170         spin_unlock_irq(&loop_conns_lock);
 171
 172         list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
 173                 WARN_ON(lc->conn->c_passive);
 174                 rds_conn_destroy(lc->conn);
 175         }
 176 }
 177
 178 /*
 179  * This is missing .xmit_* because loop doesn't go through generic
 180  * rds_send_xmit() and doesn't call rds_recv_incoming().  .listen_stop and
 181  * .laddr_check are missing because transport.c doesn't iterate over
 182  * rds_loop_transport.
 183  */
 184 struct rds_transport rds_loop_transport = {
 185         .xmit                   = rds_loop_xmit,
 186         .recv                   = rds_loop_recv,
 187         .conn_alloc             = rds_loop_conn_alloc,
 188         .conn_free              = rds_loop_conn_free,
 189         .conn_connect           = rds_loop_conn_connect,
 190         .conn_shutdown          = rds_loop_conn_shutdown,
 191         .inc_copy_to_user       = rds_message_inc_copy_to_user,
 192         .inc_free               = rds_loop_inc_free,
 193         .t_name                 = "loopback",
 194 };