net/tipc/net.c

   1 /*
   2  * net/tipc/net.c: TIPC network routing code
   3  *
   4  * Copyright (c) 1995-2006, Ericsson AB
   5  * Copyright (c) 2005, 2010-2011, Wind River Systems
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the names of the copyright holders nor the names of its
  17  *    contributors may be used to endorse or promote products derived from
  18  *    this software without specific prior written permission.
  19  *
  20  * Alternatively, this software may be distributed under the terms of the
  21  * GNU General Public License ("GPL") version 2 as published by the Free
  22  * Software Foundation.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  25  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34  * POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "core.h"
  38 #include "net.h"
  39 #include "name_distr.h"
  40 #include "subscr.h"
  41 #include "port.h"
  42 #include "node.h"
  43 #include "config.h"
  44
  45 /*
  46  * The TIPC locking policy is designed to ensure a very fine locking
  47  * granularity, permitting complete parallel access to individual
  48  * port and node/link instances. The code consists of three major
  49  * locking domains, each protected with their own disjunct set of locks.
  50  *
  51  * 1: The routing hierarchy.
  52  *    Comprises the structures 'zone', 'cluster', 'node', 'link'
  53  *    and 'bearer'. The whole hierarchy is protected by a big
  54  *    read/write lock, tipc_net_lock, to enssure that nothing is added
  55  *    or removed while code is accessing any of these structures.
  56  *    This layer must not be called from the two others while they
  57  *    hold any of their own locks.
  58  *    Neither must it itself do any upcalls to the other two before
  59  *    it has released tipc_net_lock and other protective locks.
  60  *
  61  *   Within the tipc_net_lock domain there are two sub-domains;'node' and
  62  *   'bearer', where local write operations are permitted,
  63  *   provided that those are protected by individual spin_locks
  64  *   per instance. Code holding tipc_net_lock(read) and a node spin_lock
  65  *   is permitted to poke around in both the node itself and its
  66  *   subordinate links. I.e, it can update link counters and queues,
  67  *   change link state, send protocol messages, and alter the
  68  *   "active_links" array in the node; but it can _not_ remove a link
  69  *   or a node from the overall structure.
  70  *   Correspondingly, individual bearers may change status within a
  71  *   tipc_net_lock(read), protected by an individual spin_lock ber bearer
  72  *   instance, but it needs tipc_net_lock(write) to remove/add any bearers.
  73  *
  74  *
  75  *  2: The transport level of the protocol.
  76  *     This consists of the structures port, (and its user level
  77  *     representations, such as user_port and tipc_sock), reference and
  78  *     tipc_user (port.c, reg.c, socket.c).
  79  *
  80  *     This layer has four different locks:
  81  *     - The tipc_port spin_lock. This is protecting each port instance
  82  *       from parallel data access and removal. Since we can not place
  83  *       this lock in the port itself, it has been placed in the
  84  *       corresponding reference table entry, which has the same life
  85  *       cycle as the module. This entry is difficult to access from
  86  *       outside the TIPC core, however, so a pointer to the lock has
  87  *       been added in the port instance, -to be used for unlocking
  88  *       only.
  89  *     - A read/write lock to protect the reference table itself (teg.c).
  90  *       (Nobody is using read-only access to this, so it can just as
  91  *       well be changed to a spin_lock)
  92  *     - A spin lock to protect the registry of kernel/driver users (reg.c)
  93  *     - A global spin_lock (tipc_port_lock), which only task is to ensure
  94  *       consistency where more than one port is involved in an operation,
  95  *       i.e., whe a port is part of a linked list of ports.
  96  *       There are two such lists; 'port_list', which is used for management,
  97  *       and 'wait_list', which is used to queue ports during congestion.
  98  *
  99  *  3: The name table (name_table.c, name_distr.c, subscription.c)
 100  *     - There is one big read/write-lock (tipc_nametbl_lock) protecting the
 101  *       overall name table structure. Nothing must be added/removed to
 102  *       this structure without holding write access to it.
 103  *     - There is one local spin_lock per sub_sequence, which can be seen
 104  *       as a sub-domain to the tipc_nametbl_lock domain. It is used only
 105  *       for translation operations, and is needed because a translation
 106  *       steps the root of the 'publication' linked list between each lookup.
 107  *       This is always used within the scope of a tipc_nametbl_lock(read).
 108  *     - A local spin_lock protecting the queue of subscriber events.
 109 */
 110
 111 DEFINE_RWLOCK(tipc_net_lock);
 112
 113 static void net_route_named_msg(struct sk_buff *buf)
 114 {
 115         struct tipc_msg *msg = buf_msg(buf);
 116         u32 dnode;
 117         u32 dport;
 118
 119         if (!msg_named(msg)) {
 120                 buf_discard(buf);
 121                 return;
 122         }
 123
 124         dnode = addr_domain(msg_lookup_scope(msg));
 125         dport = tipc_nametbl_translate(msg_nametype(msg), msg_nameinst(msg), &dnode);
 126         if (dport) {
 127                 msg_set_destnode(msg, dnode);
 128                 msg_set_destport(msg, dport);
 129                 tipc_net_route_msg(buf);
 130                 return;
 131         }
 132         tipc_reject_msg(buf, TIPC_ERR_NO_NAME);
 133 }
 134
 135 void tipc_net_route_msg(struct sk_buff *buf)
 136 {
 137         struct tipc_msg *msg;
 138         u32 dnode;
 139
 140         if (!buf)
 141                 return;
 142         msg = buf_msg(buf);
 143
 144         msg_incr_reroute_cnt(msg);
 145         if (msg_reroute_cnt(msg) > 6) {
 146                 if (msg_errcode(msg)) {
 147                         buf_discard(buf);
 148                 } else {
 149                         tipc_reject_msg(buf, msg_destport(msg) ?
 150                                         TIPC_ERR_NO_PORT : TIPC_ERR_NO_NAME);
 151                 }
 152                 return;
 153         }
 154
 155         /* Handle message for this node */
 156         dnode = msg_short(msg) ? tipc_own_addr : msg_destnode(msg);
 157         if (tipc_in_scope(dnode, tipc_own_addr)) {
 158                 if (msg_isdata(msg)) {
 159                         if (msg_mcast(msg))
 160                                 tipc_port_recv_mcast(buf, NULL);
 161                         else if (msg_destport(msg))
 162                                 tipc_port_recv_msg(buf);
 163                         else
 164                                 net_route_named_msg(buf);
 165                         return;
 166                 }
 167                 switch (msg_user(msg)) {
 168                 case NAME_DISTRIBUTOR:
 169                         tipc_named_recv(buf);
 170                         break;
 171                 case CONN_MANAGER:
 172                         tipc_port_recv_proto_msg(buf);
 173                         break;
 174                 default:
 175                         buf_discard(buf);
 176                 }
 177                 return;
 178         }
 179
 180         /* Handle message for another node */
 181         skb_trim(buf, msg_size(msg));
 182         tipc_link_send(buf, dnode, msg_link_selector(msg));
 183 }
 184
 185 int tipc_net_start(u32 addr)
 186 {
 187         char addr_string[16];
 188         int res;
 189
 190         if (tipc_mode != TIPC_NODE_MODE)
 191                 return -ENOPROTOOPT;
 192
 193         tipc_subscr_stop();
 194         tipc_cfg_stop();
 195
 196         tipc_own_addr = addr;
 197         tipc_mode = TIPC_NET_MODE;
 198         tipc_named_reinit();
 199         tipc_port_reinit();
 200
 201         res = tipc_bclink_init();
 202         if (res)
 203                 return res;
 204
 205         tipc_k_signal((Handler)tipc_subscr_start, 0);
 206         tipc_k_signal((Handler)tipc_cfg_init, 0);
 207
 208         info("Started in network mode\n");
 209         info("Own node address %s, network identity %u\n",
 210              tipc_addr_string_fill(addr_string, tipc_own_addr), tipc_net_id);
 211         return 0;
 212 }
 213
 214 void tipc_net_stop(void)
 215 {
 216         struct tipc_node *node, *t_node;
 217
 218         if (tipc_mode != TIPC_NET_MODE)
 219                 return;
 220         write_lock_bh(&tipc_net_lock);
 221         tipc_bearer_stop();
 222         tipc_mode = TIPC_NODE_MODE;
 223         tipc_bclink_stop();
 224         list_for_each_entry_safe(node, t_node, &tipc_node_list, list)
 225                 tipc_node_delete(node);
 226         write_unlock_bh(&tipc_net_lock);
 227         info("Left network mode\n");
 228 }