/*
   * net/tipc/net.c: TIPC network routing code
   *
   * Copyright (c) 1995-2006, Ericsson AB
   * Copyright (c) 2005, 2010-2011, Wind River Systems
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the names of the copyright holders nor the names of its
   *    contributors may be used to endorse or promote products derived from
   *    this software without specific prior written permission.
   *
   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "core.h"
  #include "net.h"
  #include "name_distr.h"
  #include "subscr.h"
  #include "port.h"
  #include "node.h"
  #include "config.h"
  
  /*
   * The TIPC locking policy is designed to ensure a very fine locking
   * granularity, permitting complete parallel access to individual
   * port and node/link instances. The code consists of three major
   * locking domains, each protected with their own disjunct set of locks.
   *
   * 1: The routing hierarchy.
   *    Comprises the structures 'zone', 'cluster', 'node', 'link'
   *    and 'bearer'. The whole hierarchy is protected by a big
   *    read/write lock, tipc_net_lock, to enssure that nothing is added
   *    or removed while code is accessing any of these structures.
   *    This layer must not be called from the two others while they
   *    hold any of their own locks.
   *    Neither must it itself do any upcalls to the other two before
   *    it has released tipc_net_lock and other protective locks.
   *
   *   Within the tipc_net_lock domain there are two sub-domains;'node' and
   *   'bearer', where local write operations are permitted,
   *   provided that those are protected by individual spin_locks
   *   per instance. Code holding tipc_net_lock(read) and a node spin_lock
   *   is permitted to poke around in both the node itself and its
   *   subordinate links. I.e, it can update link counters and queues,
   *   change link state, send protocol messages, and alter the
   *   "active_links" array in the node; but it can _not_ remove a link
   *   or a node from the overall structure.
   *   Correspondingly, individual bearers may change status within a
   *   tipc_net_lock(read), protected by an individual spin_lock ber bearer
   *   instance, but it needs tipc_net_lock(write) to remove/add any bearers.
   *
   *
   *  2: The transport level of the protocol.
   *     This consists of the structures port, (and its user level
   *     representations, such as user_port and tipc_sock), reference and
   *     tipc_user (port.c, reg.c, socket.c).
   *
   *     This layer has four different locks:
   *     - The tipc_port spin_lock. This is protecting each port instance
   *       from parallel data access and removal. Since we can not place
   *       this lock in the port itself, it has been placed in the
   *       corresponding reference table entry, which has the same life
   *       cycle as the module. This entry is difficult to access from
   *       outside the TIPC core, however, so a pointer to the lock has
   *       been added in the port instance, -to be used for unlocking
   *       only.
   *     - A read/write lock to protect the reference table itself (teg.c).
   *       (Nobody is using read-only access to this, so it can just as
   *       well be changed to a spin_lock)
   *     - A spin lock to protect the registry of kernel/driver users (reg.c)
   *     - A global spin_lock (tipc_port_lock), which only task is to ensure
   *       consistency where more than one port is involved in an operation,
   *       i.e., whe a port is part of a linked list of ports.
   *       There are two such lists; 'port_list', which is used for management,
   *       and 'wait_list', which is used to queue ports during congestion.
   *
   *  3: The name table (name_table.c, name_distr.c, subscription.c)
   *     - There is one big read/write-lock (tipc_nametbl_lock) protecting the
   *       overall name table structure. Nothing must be added/removed to
   *       this structure without holding write access to it.
   *     - There is one local spin_lock per sub_sequence, which can be seen
   *       as a sub-domain to the tipc_nametbl_lock domain. It is used only
   *       for translation operations, and is needed because a translation
   *       steps the root of the 'publication' linked list between each lookup.
   *       This is always used within the scope of a tipc_nametbl_lock(read).
   *     - A local spin_lock protecting the queue of subscriber events.
  */
  
  DEFINE_RWLOCK(tipc_net_lock);
  
  static void net_route_named_msg(struct sk_buff *buf)
  {
  	struct tipc_msg *msg = buf_msg(buf);
  	u32 dnode;
  	u32 dport;
  
  	if (!msg_named(msg)) {
  		kfree_skb(buf);
  		return;
  	}
  
  	dnode = addr_domain(msg_lookup_scope(msg));
  	dport = tipc_nametbl_translate(msg_nametype(msg), msg_nameinst(msg), &dnode);
  	if (dport) {
  		msg_set_destnode(msg, dnode);
  		msg_set_destport(msg, dport);
  		tipc_net_route_msg(buf);
  		return;
  	}
  	tipc_reject_msg(buf, TIPC_ERR_NO_NAME);
  }
  
  void tipc_net_route_msg(struct sk_buff *buf)
  {
  	struct tipc_msg *msg;
  	u32 dnode;
  
  	if (!buf)
  		return;
  	msg = buf_msg(buf);
  
  	/* Handle message for this node */
  	dnode = msg_short(msg) ? tipc_own_addr : msg_destnode(msg);
  	if (tipc_in_scope(dnode, tipc_own_addr)) {
  		if (msg_isdata(msg)) {
  			if (msg_mcast(msg))
  				tipc_port_recv_mcast(buf, NULL);
  			else if (msg_destport(msg))
  				tipc_port_recv_msg(buf);
  			else
  				net_route_named_msg(buf);
  			return;
  		}
  		switch (msg_user(msg)) {
  		case NAME_DISTRIBUTOR:
  			tipc_named_recv(buf);
  			break;
  		case CONN_MANAGER:
  			tipc_port_recv_proto_msg(buf);
  			break;
  		default:
  			kfree_skb(buf);
  		}
  		return;
  	}
  
  	/* Handle message for another node */
  	skb_trim(buf, msg_size(msg));
  	tipc_link_send(buf, dnode, msg_link_selector(msg));
  }
  
  void tipc_net_start(u32 addr)
  {
  	char addr_string[16];
  
  	write_lock_bh(&tipc_net_lock);
  	tipc_own_addr = addr;
  	tipc_named_reinit();
  	tipc_port_reinit();
  	tipc_bclink_init();
  	write_unlock_bh(&tipc_net_lock);
  
  	tipc_cfg_reinit();
  
  	pr_info("Started in network mode
  ");
  	pr_info("Own node address %s, network identity %u
  ",
  		tipc_addr_string_fill(addr_string, tipc_own_addr), tipc_net_id);
  }
  
  void tipc_net_stop(void)
  {
  	struct tipc_node *node, *t_node;
  
  	if (!tipc_own_addr)
  		return;
  	write_lock_bh(&tipc_net_lock);
  	tipc_bearer_stop();
  	tipc_bclink_stop();
  	list_for_each_entry_safe(node, t_node, &tipc_node_list, list)
  		tipc_node_delete(node);
  	write_unlock_bh(&tipc_net_lock);
  	pr_info("Left network mode
  ");
  }