net/tipc/net.c

   1 /*
   2  * net/tipc/net.c: TIPC network routing code
   3  *
   4  * Copyright (c) 1995-2006, 2014, 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 "socket.h"
  43 #include "node.h"
  44 #include "config.h"
  45
  46 /*
  47  * The TIPC locking policy is designed to ensure a very fine locking
  48  * granularity, permitting complete parallel access to individual
  49  * port and node/link instances. The code consists of four major
  50  * locking domains, each protected with their own disjunct set of locks.
  51  *
  52  * 1: The bearer level.
  53  *    RTNL lock is used to serialize the process of configuring bearer
  54  *    on update side, and RCU lock is applied on read side to make
  55  *    bearer instance valid on both paths of message transmission and
  56  *    reception.
  57  *
  58  * 2: The node and link level.
  59  *    All node instances are saved into two tipc_node_list and node_htable
  60  *    lists. The two lists are protected by node_list_lock on write side,
  61  *    and they are guarded with RCU lock on read side. Especially node
  62  *    instance is destroyed only when TIPC module is removed, and we can
  63  *    confirm that there has no any user who is accessing the node at the
  64  *    moment. Therefore, Except for iterating the two lists within RCU
  65  *    protection, it's no needed to hold RCU that we access node instance
  66  *    in other places.
  67  *
  68  *    In addition, all members in node structure including link instances
  69  *    are protected by node spin lock.
  70  *
  71  * 3: The transport level of the protocol.
  72  *    This consists of the structures port, (and its user level
  73  *    representations, such as user_port and tipc_sock), reference and
  74  *    tipc_user (port.c, reg.c, socket.c).
  75  *
  76  *    This layer has four different locks:
  77  *     - The tipc_port spin_lock. This is protecting each port instance
  78  *       from parallel data access and removal. Since we can not place
  79  *       this lock in the port itself, it has been placed in the
  80  *       corresponding reference table entry, which has the same life
  81  *       cycle as the module. This entry is difficult to access from
  82  *       outside the TIPC core, however, so a pointer to the lock has
  83  *       been added in the port instance, -to be used for unlocking
  84  *       only.
  85  *     - A read/write lock to protect the reference table itself (teg.c).
  86  *       (Nobody is using read-only access to this, so it can just as
  87  *       well be changed to a spin_lock)
  88  *     - A spin lock to protect the registry of kernel/driver users (reg.c)
  89  *     - A global spin_lock (tipc_port_lock), which only task is to ensure
  90  *       consistency where more than one port is involved in an operation,
  91  *       i.e., whe a port is part of a linked list of ports.
  92  *       There are two such lists; 'port_list', which is used for management,
  93  *       and 'wait_list', which is used to queue ports during congestion.
  94  *
  95  *  4: The name table (name_table.c, name_distr.c, subscription.c)
  96  *     - There is one big read/write-lock (tipc_nametbl_lock) protecting the
  97  *       overall name table structure. Nothing must be added/removed to
  98  *       this structure without holding write access to it.
  99  *     - There is one local spin_lock per sub_sequence, which can be seen
 100  *       as a sub-domain to the tipc_nametbl_lock domain. It is used only
 101  *       for translation operations, and is needed because a translation
 102  *       steps the root of the 'publication' linked list between each lookup.
 103  *       This is always used within the scope of a tipc_nametbl_lock(read).
 104  *     - A local spin_lock protecting the queue of subscriber events.
 105 */
 106
 107 int tipc_net_start(u32 addr)
 108 {
 109         char addr_string[16];
 110         int res;
 111
 112         tipc_own_addr = addr;
 113         tipc_named_reinit();
 114         tipc_port_reinit();
 115         res = tipc_bclink_init();
 116         if (res)
 117                 return res;
 118
 119         tipc_nametbl_publish(TIPC_CFG_SRV, tipc_own_addr, tipc_own_addr,
 120                              TIPC_ZONE_SCOPE, 0, tipc_own_addr);
 121
 122         pr_info("Started in network mode\n");
 123         pr_info("Own node address %s, network identity %u\n",
 124                 tipc_addr_string_fill(addr_string, tipc_own_addr), tipc_net_id);
 125         return 0;
 126 }
 127
 128 void tipc_net_stop(void)
 129 {
 130         if (!tipc_own_addr)
 131                 return;
 132
 133         tipc_nametbl_withdraw(TIPC_CFG_SRV, tipc_own_addr, 0, tipc_own_addr);
 134         rtnl_lock();
 135         tipc_bearer_stop();
 136         tipc_bclink_stop();
 137         tipc_node_stop();
 138         rtnl_unlock();
 139
 140         pr_info("Left network mode\n");
 141 }