![Allan Stephens](/assets/img/avatar_default.png)
Prevents a null pointer dereference from occurring if a node subscription is triggered at the same time that the subscribing port or publication is terminating the subscription. The problem arises if the triggering routine asynchronously activates and deregisters the node subscription while deregistration is already underway -- the deregistration routine may find that the pointer it has just verified to be non-NULL is now NULL. To avoid this race condition the triggering routine now simply marks the node subscription as defunct (to prevent it from re-activating) instead of deregistering it. The subscription is now both deregistered and destroyed only when the subscribing port or publication code terminates the node subscription. Signed-off-by: Allan Stephens <Allan.Stephens@windriver.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
321 lines
8.9 KiB
C
321 lines
8.9 KiB
C
/*
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* net/tipc/name_distr.c: TIPC name distribution code
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*
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* Copyright (c) 2000-2006, Ericsson AB
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* Copyright (c) 2005, 2010-2011, Wind River Systems
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "core.h"
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#include "link.h"
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#include "name_distr.h"
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#define ITEM_SIZE sizeof(struct distr_item)
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/**
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* struct distr_item - publication info distributed to other nodes
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* @type: name sequence type
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* @lower: name sequence lower bound
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* @upper: name sequence upper bound
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* @ref: publishing port reference
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* @key: publication key
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*
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* ===> All fields are stored in network byte order. <===
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*
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* First 3 fields identify (name or) name sequence being published.
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* Reference field uniquely identifies port that published name sequence.
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* Key field uniquely identifies publication, in the event a port has
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* multiple publications of the same name sequence.
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*
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* Note: There is no field that identifies the publishing node because it is
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* the same for all items contained within a publication message.
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*/
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struct distr_item {
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__be32 type;
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__be32 lower;
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__be32 upper;
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__be32 ref;
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__be32 key;
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};
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/**
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* List of externally visible publications by this node --
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* that is, all publications having scope > TIPC_NODE_SCOPE.
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*/
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static LIST_HEAD(publ_root);
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static u32 publ_cnt;
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/**
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* publ_to_item - add publication info to a publication message
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*/
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static void publ_to_item(struct distr_item *i, struct publication *p)
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{
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i->type = htonl(p->type);
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i->lower = htonl(p->lower);
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i->upper = htonl(p->upper);
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i->ref = htonl(p->ref);
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i->key = htonl(p->key);
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}
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/**
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* named_prepare_buf - allocate & initialize a publication message
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*/
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static struct sk_buff *named_prepare_buf(u32 type, u32 size, u32 dest)
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{
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struct sk_buff *buf = tipc_buf_acquire(LONG_H_SIZE + size);
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struct tipc_msg *msg;
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if (buf != NULL) {
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msg = buf_msg(buf);
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tipc_msg_init(msg, NAME_DISTRIBUTOR, type, LONG_H_SIZE, dest);
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msg_set_size(msg, LONG_H_SIZE + size);
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}
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return buf;
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}
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static void named_cluster_distribute(struct sk_buff *buf)
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{
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struct sk_buff *buf_copy;
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struct tipc_node *n_ptr;
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u32 n_num;
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for (n_num = 1; n_num <= tipc_net.highest_node; n_num++) {
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n_ptr = tipc_net.nodes[n_num];
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if (n_ptr && tipc_node_has_active_links(n_ptr)) {
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buf_copy = skb_copy(buf, GFP_ATOMIC);
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if (!buf_copy)
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break;
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msg_set_destnode(buf_msg(buf_copy), n_ptr->addr);
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tipc_link_send(buf_copy, n_ptr->addr, n_ptr->addr);
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}
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}
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buf_discard(buf);
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}
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/**
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* tipc_named_publish - tell other nodes about a new publication by this node
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*/
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void tipc_named_publish(struct publication *publ)
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{
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struct sk_buff *buf;
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struct distr_item *item;
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list_add_tail(&publ->local_list, &publ_root);
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publ_cnt++;
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buf = named_prepare_buf(PUBLICATION, ITEM_SIZE, 0);
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if (!buf) {
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warn("Publication distribution failure\n");
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return;
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}
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item = (struct distr_item *)msg_data(buf_msg(buf));
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publ_to_item(item, publ);
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named_cluster_distribute(buf);
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}
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/**
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* tipc_named_withdraw - tell other nodes about a withdrawn publication by this node
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*/
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void tipc_named_withdraw(struct publication *publ)
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{
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struct sk_buff *buf;
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struct distr_item *item;
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list_del(&publ->local_list);
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publ_cnt--;
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buf = named_prepare_buf(WITHDRAWAL, ITEM_SIZE, 0);
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if (!buf) {
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warn("Withdrawl distribution failure\n");
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return;
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}
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item = (struct distr_item *)msg_data(buf_msg(buf));
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publ_to_item(item, publ);
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named_cluster_distribute(buf);
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}
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/**
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* tipc_named_node_up - tell specified node about all publications by this node
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*/
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void tipc_named_node_up(unsigned long node)
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{
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struct publication *publ;
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struct distr_item *item = NULL;
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struct sk_buff *buf = NULL;
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u32 left = 0;
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u32 rest;
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u32 max_item_buf;
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read_lock_bh(&tipc_nametbl_lock);
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max_item_buf = TIPC_MAX_USER_MSG_SIZE / ITEM_SIZE;
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max_item_buf *= ITEM_SIZE;
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rest = publ_cnt * ITEM_SIZE;
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list_for_each_entry(publ, &publ_root, local_list) {
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if (!buf) {
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left = (rest <= max_item_buf) ? rest : max_item_buf;
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rest -= left;
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buf = named_prepare_buf(PUBLICATION, left, node);
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if (!buf) {
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warn("Bulk publication distribution failure\n");
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goto exit;
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}
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item = (struct distr_item *)msg_data(buf_msg(buf));
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}
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publ_to_item(item, publ);
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item++;
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left -= ITEM_SIZE;
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if (!left) {
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msg_set_link_selector(buf_msg(buf), node);
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tipc_link_send(buf, node, node);
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buf = NULL;
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}
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}
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exit:
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read_unlock_bh(&tipc_nametbl_lock);
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}
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/**
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* node_is_down - remove publication associated with a failed node
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*
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* Invoked for each publication issued by a newly failed node.
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* Removes publication structure from name table & deletes it.
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* In rare cases the link may have come back up again when this
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* function is called, and we have two items representing the same
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* publication. Nudge this item's key to distinguish it from the other.
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*/
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static void node_is_down(struct publication *publ)
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{
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struct publication *p;
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write_lock_bh(&tipc_nametbl_lock);
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publ->key += 1222345;
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p = tipc_nametbl_remove_publ(publ->type, publ->lower,
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publ->node, publ->ref, publ->key);
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if (p)
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tipc_nodesub_unsubscribe(&p->subscr);
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write_unlock_bh(&tipc_nametbl_lock);
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if (p != publ) {
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err("Unable to remove publication from failed node\n"
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"(type=%u, lower=%u, node=0x%x, ref=%u, key=%u)\n",
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publ->type, publ->lower, publ->node, publ->ref, publ->key);
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}
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kfree(p);
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}
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/**
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* tipc_named_recv - process name table update message sent by another node
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*/
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void tipc_named_recv(struct sk_buff *buf)
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{
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struct publication *publ;
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struct tipc_msg *msg = buf_msg(buf);
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struct distr_item *item = (struct distr_item *)msg_data(msg);
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u32 count = msg_data_sz(msg) / ITEM_SIZE;
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write_lock_bh(&tipc_nametbl_lock);
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while (count--) {
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if (msg_type(msg) == PUBLICATION) {
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publ = tipc_nametbl_insert_publ(ntohl(item->type),
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ntohl(item->lower),
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ntohl(item->upper),
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TIPC_CLUSTER_SCOPE,
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msg_orignode(msg),
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ntohl(item->ref),
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ntohl(item->key));
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if (publ) {
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tipc_nodesub_subscribe(&publ->subscr,
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msg_orignode(msg),
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publ,
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(net_ev_handler)node_is_down);
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}
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} else if (msg_type(msg) == WITHDRAWAL) {
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publ = tipc_nametbl_remove_publ(ntohl(item->type),
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ntohl(item->lower),
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msg_orignode(msg),
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ntohl(item->ref),
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ntohl(item->key));
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if (publ) {
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tipc_nodesub_unsubscribe(&publ->subscr);
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kfree(publ);
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} else {
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err("Unable to remove publication by node 0x%x\n"
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"(type=%u, lower=%u, ref=%u, key=%u)\n",
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msg_orignode(msg),
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ntohl(item->type), ntohl(item->lower),
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ntohl(item->ref), ntohl(item->key));
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}
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} else {
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warn("Unrecognized name table message received\n");
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}
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item++;
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}
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write_unlock_bh(&tipc_nametbl_lock);
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buf_discard(buf);
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}
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/**
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* tipc_named_reinit - re-initialize local publication list
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*
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* This routine is called whenever TIPC networking is (re)enabled.
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* All existing publications by this node that have "cluster" or "zone" scope
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* are updated to reflect the node's current network address.
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* (If the node's address is unchanged, the update loop terminates immediately.)
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*/
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void tipc_named_reinit(void)
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{
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struct publication *publ;
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write_lock_bh(&tipc_nametbl_lock);
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list_for_each_entry(publ, &publ_root, local_list) {
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if (publ->node == tipc_own_addr)
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break;
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publ->node = tipc_own_addr;
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}
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write_unlock_bh(&tipc_nametbl_lock);
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}
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