net/rds/loop.c

   1 /*
   2  * Copyright (c) 2006, 2017 Oracle and/or its affiliates. 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 #include <net/net_namespace.h>
  37 #include <net/netns/generic.h>
  38 #include <linux/ipv6.h>
  39
  40 #include "rds_single_path.h"
  41 #include "rds.h"
  42 #include "loop.h"
  43
  44 static DEFINE_SPINLOCK(loop_conns_lock);
  45 static LIST_HEAD(loop_conns);
  46 static atomic_t rds_loop_unloading = ATOMIC_INIT(0);
  47
  48 static void rds_loop_set_unloading(void)
  49 {
  50         atomic_set(&rds_loop_unloading, 1);
  51 }
  52
  53 static bool rds_loop_is_unloading(struct rds_connection *conn)
  54 {
  55         return atomic_read(&rds_loop_unloading) != 0;
  56 }
  57
  58 /*
  59  * This 'loopback' transport is a special case for flows that originate
  60  * and terminate on the same machine.
  61  *
  62  * Connection build-up notices if the destination address is thought of
  63  * as a local address by a transport.  At that time it decides to use the
  64  * loopback transport instead of the bound transport of the sending socket.
  65  *
  66  * The loopback transport's sending path just hands the sent rds_message
  67  * straight to the receiving path via an embedded rds_incoming.
  68  */
  69
  70 /*
  71  * Usually a message transits both the sender and receiver's conns as it
  72  * flows to the receiver.  In the loopback case, though, the receive path
  73  * is handed the sending conn so the sense of the addresses is reversed.
  74  */
  75 static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
  76                          unsigned int hdr_off, unsigned int sg,
  77                          unsigned int off)
  78 {
  79         struct scatterlist *sgp = &rm->data.op_sg[sg];
  80         int ret = sizeof(struct rds_header) +
  81                         be32_to_cpu(rm->m_inc.i_hdr.h_len);
  82
  83         /* Do not send cong updates to loopback */
  84         if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
  85                 rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
  86                 ret = min_t(int, ret, sgp->length - conn->c_xmit_data_off);
  87                 goto out;
  88         }
  89
  90         BUG_ON(hdr_off || sg || off);
  91
  92         rds_inc_init(&rm->m_inc, conn, &conn->c_laddr);
  93         /* For the embedded inc. Matching put is in loop_inc_free() */
  94         rds_message_addref(rm);
  95
  96         rds_recv_incoming(conn, &conn->c_laddr, &conn->c_faddr, &rm->m_inc,
  97                           GFP_KERNEL);
  98
  99         rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
 100                             NULL);
 101
 102         rds_inc_put(&rm->m_inc);
 103 out:
 104         return ret;
 105 }
 106
 107 /*
 108  * See rds_loop_xmit(). Since our inc is embedded in the rm, we
 109  * make sure the rm lives at least until the inc is done.
 110  */
 111 static void rds_loop_inc_free(struct rds_incoming *inc)
 112 {
 113         struct rds_message *rm = container_of(inc, struct rds_message, m_inc);
 114
 115         rds_message_put(rm);
 116 }
 117
 118 /* we need to at least give the thread something to succeed */
 119 static int rds_loop_recv_path(struct rds_conn_path *cp)
 120 {
 121         return 0;
 122 }
 123
 124 struct rds_loop_connection {
 125         struct list_head loop_node;
 126         struct rds_connection *conn;
 127 };
 128
 129 /*
 130  * Even the loopback transport needs to keep track of its connections,
 131  * so it can call rds_conn_destroy() on them on exit. N.B. there are
 132  * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
 133  * multiple loopback conns allocated, although rather useless.
 134  */
 135 static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 136 {
 137         struct rds_loop_connection *lc;
 138         unsigned long flags;
 139
 140         lc = kzalloc(sizeof(struct rds_loop_connection), gfp);
 141         if (!lc)
 142                 return -ENOMEM;
 143
 144         INIT_LIST_HEAD(&lc->loop_node);
 145         lc->conn = conn;
 146         conn->c_transport_data = lc;
 147
 148         spin_lock_irqsave(&loop_conns_lock, flags);
 149         list_add_tail(&lc->loop_node, &loop_conns);
 150         spin_unlock_irqrestore(&loop_conns_lock, flags);
 151
 152         return 0;
 153 }
 154
 155 static void rds_loop_conn_free(void *arg)
 156 {
 157         struct rds_loop_connection *lc = arg;
 158         unsigned long flags;
 159
 160         rdsdebug("lc %p\n", lc);
 161         spin_lock_irqsave(&loop_conns_lock, flags);
 162         list_del(&lc->loop_node);
 163         spin_unlock_irqrestore(&loop_conns_lock, flags);
 164         kfree(lc);
 165 }
 166
 167 static int rds_loop_conn_path_connect(struct rds_conn_path *cp)
 168 {
 169         rds_connect_complete(cp->cp_conn);
 170         return 0;
 171 }
 172
 173 static void rds_loop_conn_path_shutdown(struct rds_conn_path *cp)
 174 {
 175 }
 176
 177 void rds_loop_exit(void)
 178 {
 179         struct rds_loop_connection *lc, *_lc;
 180         LIST_HEAD(tmp_list);
 181
 182         rds_loop_set_unloading();
 183         synchronize_rcu();
 184         /* avoid calling conn_destroy with irqs off */
 185         spin_lock_irq(&loop_conns_lock);
 186         list_splice(&loop_conns, &tmp_list);
 187         INIT_LIST_HEAD(&loop_conns);
 188         spin_unlock_irq(&loop_conns_lock);
 189
 190         list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
 191                 WARN_ON(lc->conn->c_passive);
 192                 rds_conn_destroy(lc->conn);
 193         }
 194 }
 195
 196 static void rds_loop_kill_conns(struct net *net)
 197 {
 198         struct rds_loop_connection *lc, *_lc;
 199         LIST_HEAD(tmp_list);
 200
 201         spin_lock_irq(&loop_conns_lock);
 202         list_for_each_entry_safe(lc, _lc, &loop_conns, loop_node)  {
 203                 struct net *c_net = read_pnet(&lc->conn->c_net);
 204
 205                 if (net != c_net)
 206                         continue;
 207                 list_move_tail(&lc->loop_node, &tmp_list);
 208         }
 209         spin_unlock_irq(&loop_conns_lock);
 210
 211         list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
 212                 WARN_ON(lc->conn->c_passive);
 213                 rds_conn_destroy(lc->conn);
 214         }
 215 }
 216
 217 static void __net_exit rds_loop_exit_net(struct net *net)
 218 {
 219         rds_loop_kill_conns(net);
 220 }
 221
 222 static struct pernet_operations rds_loop_net_ops = {
 223         .exit = rds_loop_exit_net,
 224 };
 225
 226 int rds_loop_net_init(void)
 227 {
 228         return register_pernet_device(&rds_loop_net_ops);
 229 }
 230
 231 void rds_loop_net_exit(void)
 232 {
 233         unregister_pernet_device(&rds_loop_net_ops);
 234 }
 235
 236 /*
 237  * This is missing .xmit_* because loop doesn't go through generic
 238  * rds_send_xmit() and doesn't call rds_recv_incoming().  .listen_stop and
 239  * .laddr_check are missing because transport.c doesn't iterate over
 240  * rds_loop_transport.
 241  */
 242 struct rds_transport rds_loop_transport = {
 243         .xmit                   = rds_loop_xmit,
 244         .recv_path              = rds_loop_recv_path,
 245         .conn_alloc             = rds_loop_conn_alloc,
 246         .conn_free              = rds_loop_conn_free,
 247         .conn_path_connect      = rds_loop_conn_path_connect,
 248         .conn_path_shutdown     = rds_loop_conn_path_shutdown,
 249         .inc_copy_to_user       = rds_message_inc_copy_to_user,
 250         .inc_free               = rds_loop_inc_free,
 251         .t_name                 = "loopback",
 252         .t_type                 = RDS_TRANS_LOOP,
 253         .t_unloading            = rds_loop_is_unloading,
 254 };