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
  41 static DEFINE_SPINLOCK(loop_conns_lock);
  42 static 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  */
  61 static 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);
  89 out:
  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  */
  97 static 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 */
 105 static int rds_loop_recv_path(struct rds_conn_path *cp)
 106 {
 107         return 0;
 108 }
 109
 110 struct 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  */
 121 static 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
 141 static 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
 153 static int rds_loop_conn_path_connect(struct rds_conn_path *cp)
 154 {
 155         rds_connect_complete(cp->cp_conn);
 156         return 0;
 157 }
 158
 159 static void rds_loop_conn_path_shutdown(struct rds_conn_path *cp)
 160 {
 161 }
 162
 163 void 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  */
 186 struct 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 };