net/tipc/name_distr.c - linux - Git at Google

 /*
  * net/tipc/name_distr.c: TIPC name distribution code
  *
  * Copyright (c) 2000-2006, 2014-2019, Ericsson AB
  * Copyright (c) 2005, 2010-2011, Wind River Systems
  * Copyright (c) 2020-2021, Red Hat Inc
  * 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 "link.h"
 #include "name_distr.h"

 int sysctl_tipc_named_timeout __read_mostly = 2000;

 /**
  * publ_to_item - add publication info to a publication message
  * @p: publication info
  * @i: location of item in the message
  */
 static void publ_to_item(struct distr_item *i, struct publication *p)
 {
 	i->type = htonl(p->sr.type);
 	i->lower = htonl(p->sr.lower);
 	i->upper = htonl(p->sr.upper);
 	i->port = htonl(p->sk.ref);
 	i->key = htonl(p->key);
 }

 /**
  * named_prepare_buf - allocate & initialize a publication message
  * @net: the associated network namespace
  * @type: message type
  * @size: payload size
  * @dest: destination node
  *
  * The buffer returned is of size INT_H_SIZE + payload size
  */
 static struct sk_buff *named_prepare_buf(struct net *net, u32 type, u32 size,
 					 u32 dest)
 {
 	struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE + size, GFP_ATOMIC);
 	u32 self = tipc_own_addr(net);
 	struct tipc_msg *msg;

 	if (buf != NULL) {
 		msg = buf_msg(buf);
 		tipc_msg_init(self, msg, NAME_DISTRIBUTOR,
 			      type, INT_H_SIZE, dest);
 		msg_set_size(msg, INT_H_SIZE + size);
 	}
 	return buf;
 }

 /**
  * tipc_named_publish - tell other nodes about a new publication by this node
  * @net: the associated network namespace
  * @p: the new publication
  */
 struct sk_buff *tipc_named_publish(struct net *net, struct publication *p)
 {
 	struct name_table *nt = tipc_name_table(net);
 	struct distr_item *item;
 	struct sk_buff *skb;

 	if (p->scope == TIPC_NODE_SCOPE) {
 		list_add_tail_rcu(&p->binding_node, &nt->node_scope);
 		return NULL;
 	}
 	write_lock_bh(&nt->cluster_scope_lock);
 	list_add_tail(&p->binding_node, &nt->cluster_scope);
 	write_unlock_bh(&nt->cluster_scope_lock);
 	skb = named_prepare_buf(net, PUBLICATION, ITEM_SIZE, 0);
 	if (!skb) {
 		pr_warn("Publication distribution failure\n");
 		return NULL;
 	}
 	msg_set_named_seqno(buf_msg(skb), nt->snd_nxt++);
 	msg_set_non_legacy(buf_msg(skb));
 	item = (struct distr_item *)msg_data(buf_msg(skb));
 	publ_to_item(item, p);
 	return skb;
 }

 /**
  * tipc_named_withdraw - tell other nodes about a withdrawn publication by this node
  * @net: the associated network namespace
  * @p: the withdrawn publication
  */
 struct sk_buff *tipc_named_withdraw(struct net *net, struct publication *p)
 {
 	struct name_table *nt = tipc_name_table(net);
 	struct distr_item *item;
 	struct sk_buff *skb;

 	write_lock_bh(&nt->cluster_scope_lock);
 	list_del(&p->binding_node);
 	write_unlock_bh(&nt->cluster_scope_lock);
 	if (p->scope == TIPC_NODE_SCOPE)
 		return NULL;

 	skb = named_prepare_buf(net, WITHDRAWAL, ITEM_SIZE, 0);
 	if (!skb) {
 		pr_warn("Withdrawal distribution failure\n");
 		return NULL;
 	}
 	msg_set_named_seqno(buf_msg(skb), nt->snd_nxt++);
 	msg_set_non_legacy(buf_msg(skb));
 	item = (struct distr_item *)msg_data(buf_msg(skb));
 	publ_to_item(item, p);
 	return skb;
 }

 /**
  * named_distribute - prepare name info for bulk distribution to another node
  * @net: the associated network namespace
  * @list: list of messages (buffers) to be returned from this function
  * @dnode: node to be updated
  * @pls: linked list of publication items to be packed into buffer chain
  * @seqno: sequence number for this message
  */
 static void named_distribute(struct net *net, struct sk_buff_head *list,
 			     u32 dnode, struct list_head *pls, u16 seqno)
 {
 	struct publication *publ;
 	struct sk_buff *skb = NULL;
 	struct distr_item *item = NULL;
 	u32 msg_dsz = ((tipc_node_get_mtu(net, dnode, 0, false) - INT_H_SIZE) /
 			ITEM_SIZE) * ITEM_SIZE;
 	u32 msg_rem = msg_dsz;
 	struct tipc_msg *hdr;

 	list_for_each_entry(publ, pls, binding_node) {
 		/* Prepare next buffer: */
 		if (!skb) {
 			skb = named_prepare_buf(net, PUBLICATION, msg_rem,
 						dnode);
 			if (!skb) {
 				pr_warn("Bulk publication failure\n");
 				return;
 			}
 			hdr = buf_msg(skb);
 			msg_set_bc_ack_invalid(hdr, true);
 			msg_set_bulk(hdr);
 			msg_set_non_legacy(hdr);
 			item = (struct distr_item *)msg_data(hdr);
 		}

 		/* Pack publication into message: */
 		publ_to_item(item, publ);
 		item++;
 		msg_rem -= ITEM_SIZE;

 		/* Append full buffer to list: */
 		if (!msg_rem) {
 			__skb_queue_tail(list, skb);
 			skb = NULL;
 			msg_rem = msg_dsz;
 		}
 	}
 	if (skb) {
 		hdr = buf_msg(skb);
 		msg_set_size(hdr, INT_H_SIZE + (msg_dsz - msg_rem));
 		skb_trim(skb, INT_H_SIZE + (msg_dsz - msg_rem));
 		__skb_queue_tail(list, skb);
 	}
 	hdr = buf_msg(skb_peek_tail(list));
 	msg_set_last_bulk(hdr);
 	msg_set_named_seqno(hdr, seqno);
 }

 /**
  * tipc_named_node_up - tell specified node about all publications by this node
  * @net: the associated network namespace
  * @dnode: destination node
  * @capabilities: peer node's capabilities
  */
 void tipc_named_node_up(struct net *net, u32 dnode, u16 capabilities)
 {
 	struct name_table *nt = tipc_name_table(net);
 	struct tipc_net *tn = tipc_net(net);
 	struct sk_buff_head head;
 	u16 seqno;

 	__skb_queue_head_init(&head);
 	spin_lock_bh(&tn->nametbl_lock);
 	if (!(capabilities & TIPC_NAMED_BCAST))
 		nt->rc_dests++;
 	seqno = nt->snd_nxt;
 	spin_unlock_bh(&tn->nametbl_lock);

 	read_lock_bh(&nt->cluster_scope_lock);
 	named_distribute(net, &head, dnode, &nt->cluster_scope, seqno);
 	tipc_node_xmit(net, &head, dnode, 0);
 	read_unlock_bh(&nt->cluster_scope_lock);
 }

 /**
  * tipc_publ_purge - remove publication associated with a failed node
  * @net: the associated network namespace
  * @p: the publication to remove
  * @addr: failed node's address
  *
  * Invoked for each publication issued by a newly failed node.
  * Removes publication structure from name table & deletes it.
  */
 static void tipc_publ_purge(struct net *net, struct publication *p, u32 addr)
 {
 	struct tipc_net *tn = tipc_net(net);
 	struct publication *_p;
 	struct tipc_uaddr ua;

 	tipc_uaddr(&ua, TIPC_SERVICE_RANGE, p->scope, p->sr.type,
 		   p->sr.lower, p->sr.upper);
 	spin_lock_bh(&tn->nametbl_lock);
 	_p = tipc_nametbl_remove_publ(net, &ua, &p->sk, p->key);
 	if (_p)
 		tipc_node_unsubscribe(net, &_p->binding_node, addr);
 	spin_unlock_bh(&tn->nametbl_lock);
 	if (_p)
 		kfree_rcu(_p, rcu);
 }

 void tipc_publ_notify(struct net *net, struct list_head *nsub_list,
 		      u32 addr, u16 capabilities)
 {
 	struct name_table *nt = tipc_name_table(net);
 	struct tipc_net *tn = tipc_net(net);

 	struct publication *publ, *tmp;

 	list_for_each_entry_safe(publ, tmp, nsub_list, binding_node)
 		tipc_publ_purge(net, publ, addr);
 	spin_lock_bh(&tn->nametbl_lock);
 	if (!(capabilities & TIPC_NAMED_BCAST))
 		nt->rc_dests--;
 	spin_unlock_bh(&tn->nametbl_lock);
 }

 /**
  * tipc_update_nametbl - try to process a nametable update and notify
  *			 subscribers
  * @net: the associated network namespace
  * @i: location of item in the message
  * @node: node address
  * @dtype: name distributor message type
  *
  * tipc_nametbl_lock must be held.
  * Return: the publication item if successful, otherwise NULL.
  */
 static bool tipc_update_nametbl(struct net *net, struct distr_item *i,
 				u32 node, u32 dtype)
 {
 	struct publication *p = NULL;
 	struct tipc_socket_addr sk;
 	struct tipc_uaddr ua;
 	u32 key = ntohl(i->key);

 	tipc_uaddr(&ua, TIPC_SERVICE_RANGE, TIPC_CLUSTER_SCOPE,
 		   ntohl(i->type), ntohl(i->lower), ntohl(i->upper));
 	sk.ref = ntohl(i->port);
 	sk.node = node;

 	if (dtype == PUBLICATION) {
 		p = tipc_nametbl_insert_publ(net, &ua, &sk, key);
 		if (p) {
 			tipc_node_subscribe(net, &p->binding_node, node);
 			return true;
 		}
 	} else if (dtype == WITHDRAWAL) {
 		p = tipc_nametbl_remove_publ(net, &ua, &sk, key);
 		if (p) {
 			tipc_node_unsubscribe(net, &p->binding_node, node);
 			kfree_rcu(p, rcu);
 			return true;
 		}
 		pr_warn_ratelimited("Failed to remove binding %u,%u from %u\n",
 				    ua.sr.type, ua.sr.lower, node);
 	} else {
 		pr_warn_ratelimited("Unknown name table message received\n");
 	}
 	return false;
 }

 static struct sk_buff *tipc_named_dequeue(struct sk_buff_head *namedq,
 					  u16 *rcv_nxt, bool *open)
 {
 	struct sk_buff *skb, *tmp;
 	struct tipc_msg *hdr;
 	u16 seqno;

 	spin_lock_bh(&namedq->lock);
 	skb_queue_walk_safe(namedq, skb, tmp) {
 		if (unlikely(skb_linearize(skb))) {
 			__skb_unlink(skb, namedq);
 			kfree_skb(skb);
 			continue;
 		}
 		hdr = buf_msg(skb);
 		seqno = msg_named_seqno(hdr);
 		if (msg_is_last_bulk(hdr)) {
 			*rcv_nxt = seqno;
 			*open = true;
 		}

 		if (msg_is_bulk(hdr) || msg_is_legacy(hdr)) {
 			__skb_unlink(skb, namedq);
 			spin_unlock_bh(&namedq->lock);
 			return skb;
 		}

 		if (*open && (*rcv_nxt == seqno)) {
 			(*rcv_nxt)++;
 			__skb_unlink(skb, namedq);
 			spin_unlock_bh(&namedq->lock);
 			return skb;
 		}

 		if (less(seqno, *rcv_nxt)) {
 			__skb_unlink(skb, namedq);
 			kfree_skb(skb);
 			continue;
 		}
 	}
 	spin_unlock_bh(&namedq->lock);
 	return NULL;
 }

 /**
  * tipc_named_rcv - process name table update messages sent by another node
  * @net: the associated network namespace
  * @namedq: queue to receive from
  * @rcv_nxt: store last received seqno here
  * @open: last bulk msg was received (FIXME)
  */
 void tipc_named_rcv(struct net *net, struct sk_buff_head *namedq,
 		    u16 *rcv_nxt, bool *open)
 {
 	struct tipc_net *tn = tipc_net(net);
 	struct distr_item *item;
 	struct tipc_msg *hdr;
 	struct sk_buff *skb;
 	u32 count, node;

 	spin_lock_bh(&tn->nametbl_lock);
 	while ((skb = tipc_named_dequeue(namedq, rcv_nxt, open))) {
 		hdr = buf_msg(skb);
 		node = msg_orignode(hdr);
 		item = (struct distr_item *)msg_data(hdr);
 		count = msg_data_sz(hdr) / ITEM_SIZE;
 		while (count--) {
 			tipc_update_nametbl(net, item, node, msg_type(hdr));
 			item++;
 		}
 		kfree_skb(skb);
 	}
 	spin_unlock_bh(&tn->nametbl_lock);
 }

 /**
  * tipc_named_reinit - re-initialize local publications
  * @net: the associated network namespace
  *
  * This routine is called whenever TIPC networking is enabled.
  * All name table entries published by this node are updated to reflect
  * the node's new network address.
  */
 void tipc_named_reinit(struct net *net)
 {
 	struct name_table *nt = tipc_name_table(net);
 	struct tipc_net *tn = tipc_net(net);
 	struct publication *p;
 	u32 self = tipc_own_addr(net);

 	spin_lock_bh(&tn->nametbl_lock);

 	list_for_each_entry_rcu(p, &nt->node_scope, binding_node)
 		p->sk.node = self;
 	list_for_each_entry_rcu(p, &nt->cluster_scope, binding_node)
 		p->sk.node = self;
 	nt->rc_dests = 0;
 	spin_unlock_bh(&tn->nametbl_lock);
 }
	/*
	* net/tipc/name_distr.c: TIPC name distribution code
	*
	* Copyright (c) 2000-2006, 2014-2019, Ericsson AB
	* Copyright (c) 2005, 2010-2011, Wind River Systems
	* Copyright (c) 2020-2021, Red Hat Inc
	* 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 "link.h"
	#include "name_distr.h"

	int sysctl_tipc_named_timeout __read_mostly = 2000;

	/**
	* publ_to_item - add publication info to a publication message
	* @p: publication info
	* @i: location of item in the message
	*/
	static void publ_to_item(struct distr_item i, struct publication p)
	{
	i->type = htonl(p->sr.type);
	i->lower = htonl(p->sr.lower);
	i->upper = htonl(p->sr.upper);
	i->port = htonl(p->sk.ref);
	i->key = htonl(p->key);
	}

	/**
	* named_prepare_buf - allocate & initialize a publication message
	* @net: the associated network namespace
	* @type: message type
	* @size: payload size
	* @dest: destination node
	*
	* The buffer returned is of size INT_H_SIZE + payload size
	*/
	static struct sk_buff named_prepare_buf(struct net net, u32 type, u32 size,
	u32 dest)
	{
	struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE + size, GFP_ATOMIC);
	u32 self = tipc_own_addr(net);
	struct tipc_msg *msg;

	if (buf != NULL) {
	msg = buf_msg(buf);
	tipc_msg_init(self, msg, NAME_DISTRIBUTOR,
	type, INT_H_SIZE, dest);
	msg_set_size(msg, INT_H_SIZE + size);
	}
	return buf;
	}

	/**
	* tipc_named_publish - tell other nodes about a new publication by this node
	* @net: the associated network namespace
	* @p: the new publication
	*/
	struct sk_buff tipc_named_publish(struct net net, struct publication *p)
	{
	struct name_table *nt = tipc_name_table(net);
	struct distr_item *item;
	struct sk_buff *skb;

	if (p->scope == TIPC_NODE_SCOPE) {
	list_add_tail_rcu(&p->binding_node, &nt->node_scope);
	return NULL;
	}
	write_lock_bh(&nt->cluster_scope_lock);
	list_add_tail(&p->binding_node, &nt->cluster_scope);
	write_unlock_bh(&nt->cluster_scope_lock);
	skb = named_prepare_buf(net, PUBLICATION, ITEM_SIZE, 0);
	if (!skb) {
	pr_warn("Publication distribution failure\n");
	return NULL;
	}
	msg_set_named_seqno(buf_msg(skb), nt->snd_nxt++);
	msg_set_non_legacy(buf_msg(skb));
	item = (struct distr_item *)msg_data(buf_msg(skb));
	publ_to_item(item, p);
	return skb;
	}

	/**
	* tipc_named_withdraw - tell other nodes about a withdrawn publication by this node
	* @net: the associated network namespace
	* @p: the withdrawn publication
	*/
	struct sk_buff tipc_named_withdraw(struct net net, struct publication *p)
	{
	struct name_table *nt = tipc_name_table(net);
	struct distr_item *item;
	struct sk_buff *skb;

	write_lock_bh(&nt->cluster_scope_lock);
	list_del(&p->binding_node);
	write_unlock_bh(&nt->cluster_scope_lock);
	if (p->scope == TIPC_NODE_SCOPE)
	return NULL;

	skb = named_prepare_buf(net, WITHDRAWAL, ITEM_SIZE, 0);
	if (!skb) {
	pr_warn("Withdrawal distribution failure\n");
	return NULL;
	}
	msg_set_named_seqno(buf_msg(skb), nt->snd_nxt++);
	msg_set_non_legacy(buf_msg(skb));
	item = (struct distr_item *)msg_data(buf_msg(skb));
	publ_to_item(item, p);
	return skb;
	}

	/**
	* named_distribute - prepare name info for bulk distribution to another node
	* @net: the associated network namespace
	* @list: list of messages (buffers) to be returned from this function
	* @dnode: node to be updated
	* @pls: linked list of publication items to be packed into buffer chain
	* @seqno: sequence number for this message
	*/
	static void named_distribute(struct net net, struct sk_buff_head list,
	u32 dnode, struct list_head *pls, u16 seqno)
	{
	struct publication *publ;
	struct sk_buff *skb = NULL;
	struct distr_item *item = NULL;
	u32 msg_dsz = ((tipc_node_get_mtu(net, dnode, 0, false) - INT_H_SIZE) /
	ITEM_SIZE) * ITEM_SIZE;
	u32 msg_rem = msg_dsz;
	struct tipc_msg *hdr;

	list_for_each_entry(publ, pls, binding_node) {
	/* Prepare next buffer: */
	if (!skb) {
	skb = named_prepare_buf(net, PUBLICATION, msg_rem,
	dnode);
	if (!skb) {
	pr_warn("Bulk publication failure\n");
	return;
	}
	hdr = buf_msg(skb);
	msg_set_bc_ack_invalid(hdr, true);
	msg_set_bulk(hdr);
	msg_set_non_legacy(hdr);
	item = (struct distr_item *)msg_data(hdr);
	}

	/* Pack publication into message: */
	publ_to_item(item, publ);
	item++;
	msg_rem -= ITEM_SIZE;

	/* Append full buffer to list: */
	if (!msg_rem) {
	__skb_queue_tail(list, skb);
	skb = NULL;
	msg_rem = msg_dsz;
	}
	}
	if (skb) {
	hdr = buf_msg(skb);
	msg_set_size(hdr, INT_H_SIZE + (msg_dsz - msg_rem));
	skb_trim(skb, INT_H_SIZE + (msg_dsz - msg_rem));
	__skb_queue_tail(list, skb);
	}
	hdr = buf_msg(skb_peek_tail(list));
	msg_set_last_bulk(hdr);
	msg_set_named_seqno(hdr, seqno);
	}

	/**
	* tipc_named_node_up - tell specified node about all publications by this node
	* @net: the associated network namespace
	* @dnode: destination node
	* @capabilities: peer node's capabilities
	*/
	void tipc_named_node_up(struct net *net, u32 dnode, u16 capabilities)
	{
	struct name_table *nt = tipc_name_table(net);
	struct tipc_net *tn = tipc_net(net);
	struct sk_buff_head head;
	u16 seqno;

	__skb_queue_head_init(&head);
	spin_lock_bh(&tn->nametbl_lock);
	if (!(capabilities & TIPC_NAMED_BCAST))
	nt->rc_dests++;
	seqno = nt->snd_nxt;
	spin_unlock_bh(&tn->nametbl_lock);

	read_lock_bh(&nt->cluster_scope_lock);
	named_distribute(net, &head, dnode, &nt->cluster_scope, seqno);
	tipc_node_xmit(net, &head, dnode, 0);
	read_unlock_bh(&nt->cluster_scope_lock);
	}

	/**
	* tipc_publ_purge - remove publication associated with a failed node
	* @net: the associated network namespace
	* @p: the publication to remove
	* @addr: failed node's address
	*
	* Invoked for each publication issued by a newly failed node.
	* Removes publication structure from name table & deletes it.
	*/
	static void tipc_publ_purge(struct net net, struct publication p, u32 addr)
	{
	struct tipc_net *tn = tipc_net(net);
	struct publication *_p;
	struct tipc_uaddr ua;

	tipc_uaddr(&ua, TIPC_SERVICE_RANGE, p->scope, p->sr.type,
	p->sr.lower, p->sr.upper);
	spin_lock_bh(&tn->nametbl_lock);
	_p = tipc_nametbl_remove_publ(net, &ua, &p->sk, p->key);
	if (_p)
	tipc_node_unsubscribe(net, &_p->binding_node, addr);
	spin_unlock_bh(&tn->nametbl_lock);
	if (_p)
	kfree_rcu(_p, rcu);
	}

	void tipc_publ_notify(struct net net, struct list_head nsub_list,
	u32 addr, u16 capabilities)
	{
	struct name_table *nt = tipc_name_table(net);
	struct tipc_net *tn = tipc_net(net);

	struct publication publ, tmp;

	list_for_each_entry_safe(publ, tmp, nsub_list, binding_node)
	tipc_publ_purge(net, publ, addr);
	spin_lock_bh(&tn->nametbl_lock);
	if (!(capabilities & TIPC_NAMED_BCAST))
	nt->rc_dests--;
	spin_unlock_bh(&tn->nametbl_lock);
	}

	/**
	* tipc_update_nametbl - try to process a nametable update and notify
	* subscribers
	* @net: the associated network namespace
	* @i: location of item in the message
	* @node: node address
	* @dtype: name distributor message type
	*
	* tipc_nametbl_lock must be held.
	* Return: the publication item if successful, otherwise NULL.
	*/
	static bool tipc_update_nametbl(struct net net, struct distr_item i,
	u32 node, u32 dtype)
	{
	struct publication *p = NULL;
	struct tipc_socket_addr sk;
	struct tipc_uaddr ua;
	u32 key = ntohl(i->key);

	tipc_uaddr(&ua, TIPC_SERVICE_RANGE, TIPC_CLUSTER_SCOPE,
	ntohl(i->type), ntohl(i->lower), ntohl(i->upper));
	sk.ref = ntohl(i->port);
	sk.node = node;

	if (dtype == PUBLICATION) {
	p = tipc_nametbl_insert_publ(net, &ua, &sk, key);
	if (p) {
	tipc_node_subscribe(net, &p->binding_node, node);
	return true;
	}
	} else if (dtype == WITHDRAWAL) {
	p = tipc_nametbl_remove_publ(net, &ua, &sk, key);
	if (p) {
	tipc_node_unsubscribe(net, &p->binding_node, node);
	kfree_rcu(p, rcu);
	return true;
	}
	pr_warn_ratelimited("Failed to remove binding %u,%u from %u\n",
	ua.sr.type, ua.sr.lower, node);
	} else {
	pr_warn_ratelimited("Unknown name table message received\n");
	}
	return false;
	}

	static struct sk_buff tipc_named_dequeue(struct sk_buff_head namedq,
	u16 rcv_nxt, bool open)
	{
	struct sk_buff skb, tmp;
	struct tipc_msg *hdr;
	u16 seqno;

	spin_lock_bh(&namedq->lock);
	skb_queue_walk_safe(namedq, skb, tmp) {
	if (unlikely(skb_linearize(skb))) {
	__skb_unlink(skb, namedq);
	kfree_skb(skb);
	continue;
	}
	hdr = buf_msg(skb);
	seqno = msg_named_seqno(hdr);
	if (msg_is_last_bulk(hdr)) {
	*rcv_nxt = seqno;
	*open = true;
	}

	if (msg_is_bulk(hdr) \|\| msg_is_legacy(hdr)) {
	__skb_unlink(skb, namedq);
	spin_unlock_bh(&namedq->lock);
	return skb;
	}

	if (open && (rcv_nxt == seqno)) {
	(*rcv_nxt)++;
	__skb_unlink(skb, namedq);
	spin_unlock_bh(&namedq->lock);
	return skb;
	}

	if (less(seqno, *rcv_nxt)) {
	__skb_unlink(skb, namedq);
	kfree_skb(skb);
	continue;
	}
	}
	spin_unlock_bh(&namedq->lock);
	return NULL;
	}

	/**
	* tipc_named_rcv - process name table update messages sent by another node
	* @net: the associated network namespace
	* @namedq: queue to receive from
	* @rcv_nxt: store last received seqno here
	* @open: last bulk msg was received (FIXME)
	*/
	void tipc_named_rcv(struct net net, struct sk_buff_head namedq,
	u16 rcv_nxt, bool open)
	{
	struct tipc_net *tn = tipc_net(net);
	struct distr_item *item;
	struct tipc_msg *hdr;
	struct sk_buff *skb;
	u32 count, node;

	spin_lock_bh(&tn->nametbl_lock);
	while ((skb = tipc_named_dequeue(namedq, rcv_nxt, open))) {
	hdr = buf_msg(skb);
	node = msg_orignode(hdr);
	item = (struct distr_item *)msg_data(hdr);
	count = msg_data_sz(hdr) / ITEM_SIZE;
	while (count--) {
	tipc_update_nametbl(net, item, node, msg_type(hdr));
	item++;
	}
	kfree_skb(skb);
	}
	spin_unlock_bh(&tn->nametbl_lock);
	}

	/**
	* tipc_named_reinit - re-initialize local publications
	* @net: the associated network namespace
	*
	* This routine is called whenever TIPC networking is enabled.
	* All name table entries published by this node are updated to reflect
	* the node's new network address.
	*/
	void tipc_named_reinit(struct net *net)
	{
	struct name_table *nt = tipc_name_table(net);
	struct tipc_net *tn = tipc_net(net);
	struct publication *p;
	u32 self = tipc_own_addr(net);

	spin_lock_bh(&tn->nametbl_lock);

	list_for_each_entry_rcu(p, &nt->node_scope, binding_node)
	p->sk.node = self;
	list_for_each_entry_rcu(p, &nt->cluster_scope, binding_node)
	p->sk.node = self;
	nt->rc_dests = 0;
	spin_unlock_bh(&tn->nametbl_lock);
	}