[TIPC] Initial merge

TIPC (Transparent Inter Process Communication) is a protocol designed for
intra cluster communication. For more information see
http://tipc.sourceforge.net

Signed-off-by: Per Liden <per.liden@nospam.ericsson.com>

1 files changed, 676 insertions, 0 deletions

diff --git a/net/tipc/node.c b/net/tipc/node.c
new file mode 100644
index 0000000..e311638
--- /dev/null
+++ b/net/tipc/node.c
@@ -0,0 +1,676 @@
+/*
+ * net/tipc/node.c: TIPC node management routines
+ * 
+ * Copyright (c) 2003-2005, Ericsson Research Canada
+ * Copyright (c) 2005, Wind River Systems
+ * Copyright (c) 2005-2006, Ericsson AB
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without 
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this 
+ * list of conditions and the following disclaimer.
+ * 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.
+ * 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.
+ *
+ * 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 "config.h"
+#include "node.h"
+#include "cluster.h"
+#include "net.h"
+#include "addr.h"
+#include "node_subscr.h"
+#include "link.h"
+#include "port.h"
+#include "bearer.h"
+#include "name_distr.h"
+#include "net.h"
+
+void node_print(struct print_buf *buf, struct node *n_ptr, char *str);
+static void node_lost_contact(struct node *n_ptr);
+static void node_established_contact(struct node *n_ptr);
+
+struct node *nodes = NULL;	/* sorted list of nodes within cluster */
+
+u32 tipc_own_tag = 0;
+
+struct node *node_create(u32 addr)
+{
+	struct cluster *c_ptr;
+	struct node *n_ptr;
+        struct node **curr_node;
+
+	n_ptr = kmalloc(sizeof(*n_ptr),GFP_ATOMIC);
+        if (n_ptr != NULL) {
+                memset(n_ptr, 0, sizeof(*n_ptr));
+                n_ptr->addr = addr;
+                n_ptr->lock =  SPIN_LOCK_UNLOCKED;	
+                INIT_LIST_HEAD(&n_ptr->nsub);
+	
+		c_ptr = cluster_find(addr);
+                if (c_ptr == NULL)
+                        c_ptr = cluster_create(addr);
+                if (c_ptr != NULL) {
+                        n_ptr->owner = c_ptr;
+                        cluster_attach_node(c_ptr, n_ptr);
+                        n_ptr->last_router = -1;
+
+                        /* Insert node into ordered list */
+                        for (curr_node = &nodes; *curr_node; 
+			     curr_node = &(*curr_node)->next) {
+                                if (addr < (*curr_node)->addr) {
+                                        n_ptr->next = *curr_node;
+                                        break;
+                                }
+                        }
+                        (*curr_node) = n_ptr;
+                } else {
+                        kfree(n_ptr);
+                        n_ptr = NULL;
+                }
+        }
+	return n_ptr;
+}
+
+void node_delete(struct node *n_ptr)
+{
+	if (!n_ptr)
+		return;
+
+#if 0
+	/* Not needed because links are already deleted via bearer_stop() */
+
+	u32 l_num;
+
+	for (l_num = 0; l_num < MAX_BEARERS; l_num++) {
+		link_delete(n_ptr->links[l_num]);
+	}
+#endif
+
+	dbg("node %x deleted\n", n_ptr->addr);
+	kfree(n_ptr);
+}
+
+
+/**
+ * node_link_up - handle addition of link
+ * 
+ * Link becomes active (alone or shared) or standby, depending on its priority.
+ */
+
+void node_link_up(struct node *n_ptr, struct link *l_ptr)
+{
+	struct link **active = &n_ptr->active_links[0];
+
+	info("Established link <%s> on network plane %c\n",
+	     l_ptr->name, l_ptr->b_ptr->net_plane);
+	
+	if (!active[0]) {
+		dbg(" link %x into %x/%x\n", l_ptr, &active[0], &active[1]);
+		active[0] = active[1] = l_ptr;
+		node_established_contact(n_ptr);
+		return;
+	}
+	if (l_ptr->priority < active[0]->priority) { 
+		info("Link is standby\n");
+		return;
+	}
+	link_send_duplicate(active[0], l_ptr);
+	if (l_ptr->priority == active[0]->priority) { 
+		active[0] = l_ptr;
+		return;
+	}
+	info("Link <%s> on network plane %c becomes standby\n",
+	     active[0]->name, active[0]->b_ptr->net_plane);
+	active[0] = active[1] = l_ptr;
+}
+
+/**
+ * node_select_active_links - select active link
+ */
+
+static void node_select_active_links(struct node *n_ptr)
+{
+	struct link **active = &n_ptr->active_links[0];
+	u32 i;
+	u32 highest_prio = 0;
+
+        active[0] = active[1] = 0;
+
+	for (i = 0; i < MAX_BEARERS; i++) {
+                struct link *l_ptr = n_ptr->links[i];
+
+		if (!l_ptr || !link_is_up(l_ptr) ||
+		    (l_ptr->priority < highest_prio))
+			continue;
+
+		if (l_ptr->priority > highest_prio) {
+                        highest_prio = l_ptr->priority;
+			active[0] = active[1] = l_ptr;
+		} else {
+			active[1] = l_ptr;
+		}
+	}
+}
+
+/**
+ * node_link_down - handle loss of link
+ */
+
+void node_link_down(struct node *n_ptr, struct link *l_ptr)
+{
+	struct link **active;
+
+	if (!link_is_active(l_ptr)) {
+		info("Lost standby link <%s> on network plane %c\n",
+		     l_ptr->name, l_ptr->b_ptr->net_plane);
+		return;
+	}
+	info("Lost link <%s> on network plane %c\n",
+		l_ptr->name, l_ptr->b_ptr->net_plane);
+
+	active = &n_ptr->active_links[0];
+	if (active[0] == l_ptr)
+		active[0] = active[1];
+	if (active[1] == l_ptr)
+		active[1] = active[0];
+	if (active[0] == l_ptr)
+		node_select_active_links(n_ptr);
+	if (node_is_up(n_ptr)) 
+		link_changeover(l_ptr);
+	else 
+		node_lost_contact(n_ptr);
+}
+
+int node_has_active_links(struct node *n_ptr)
+{
+	return (n_ptr && 
+		((n_ptr->active_links[0]) || (n_ptr->active_links[1])));
+}
+
+int node_has_redundant_links(struct node *n_ptr)
+{
+	return (node_has_active_links(n_ptr) &&
+		(n_ptr->active_links[0] != n_ptr->active_links[1]));
+}
+
+int node_has_active_routes(struct node *n_ptr)
+{
+	return (n_ptr && (n_ptr->last_router >= 0));
+}
+
+int node_is_up(struct node *n_ptr)
+{
+	return (node_has_active_links(n_ptr) || node_has_active_routes(n_ptr));
+}
+
+struct node *node_attach_link(struct link *l_ptr)
+{
+	struct node *n_ptr = node_find(l_ptr->addr);
+
+	if (!n_ptr)
+		n_ptr = node_create(l_ptr->addr);
+        if (n_ptr) {
+		u32 bearer_id = l_ptr->b_ptr->identity;
+		char addr_string[16];
+
+                assert(bearer_id < MAX_BEARERS);
+                if (n_ptr->link_cnt >= 2) {
+			char addr_string[16];
+
+                        err("Attempt to create third link to %s\n",
+			    addr_string_fill(addr_string, n_ptr->addr));
+                        return 0;
+                }
+
+                if (!n_ptr->links[bearer_id]) {
+                        n_ptr->links[bearer_id] = l_ptr;
+                        net.zones[tipc_zone(l_ptr->addr)]->links++;
+                        n_ptr->link_cnt++;
+                        return n_ptr;
+                }
+                err("Attempt to establish second link on <%s> to <%s> \n",
+                    l_ptr->b_ptr->publ.name, 
+		    addr_string_fill(addr_string, l_ptr->addr));
+        }
+	return 0;
+}
+
+void node_detach_link(struct node *n_ptr, struct link *l_ptr)
+{
+	n_ptr->links[l_ptr->b_ptr->identity] = 0;
+	net.zones[tipc_zone(l_ptr->addr)]->links--;
+	n_ptr->link_cnt--;
+}
+
+/*
+ * Routing table management - five cases to handle:
+ *
+ * 1: A link towards a zone/cluster external node comes up.
+ *    => Send a multicast message updating routing tables of all 
+ *    system nodes within own cluster that the new destination 
+ *    can be reached via this node. 
+ *    (node.establishedContact()=>cluster.multicastNewRoute())
+ *
+ * 2: A link towards a slave node comes up.
+ *    => Send a multicast message updating routing tables of all 
+ *    system nodes within own cluster that the new destination 
+ *    can be reached via this node. 
+ *    (node.establishedContact()=>cluster.multicastNewRoute())
+ *    => Send a  message to the slave node about existence 
+ *    of all system nodes within cluster:
+ *    (node.establishedContact()=>cluster.sendLocalRoutes())
+ *
+ * 3: A new cluster local system node becomes available.
+ *    => Send message(s) to this particular node containing
+ *    information about all cluster external and slave
+ *     nodes which can be reached via this node.
+ *    (node.establishedContact()==>network.sendExternalRoutes())
+ *    (node.establishedContact()==>network.sendSlaveRoutes())
+ *    => Send messages to all directly connected slave nodes 
+ *    containing information about the existence of the new node
+ *    (node.establishedContact()=>cluster.multicastNewRoute())
+ *    
+ * 4: The link towards a zone/cluster external node or slave
+ *    node goes down.
+ *    => Send a multcast message updating routing tables of all 
+ *    nodes within cluster that the new destination can not any
+ *    longer be reached via this node.
+ *    (node.lostAllLinks()=>cluster.bcastLostRoute())
+ *
+ * 5: A cluster local system node becomes unavailable.
+ *    => Remove all references to this node from the local
+ *    routing tables. Note: This is a completely node
+ *    local operation.
+ *    (node.lostAllLinks()=>network.removeAsRouter())
+ *    => Send messages to all directly connected slave nodes 
+ *    containing information about loss of the node
+ *    (node.establishedContact()=>cluster.multicastLostRoute())
+ *
+ */
+
+static void node_established_contact(struct node *n_ptr)
+{
+	struct cluster *c_ptr;
+
+	dbg("node_established_contact:-> %x\n", n_ptr->addr);
+	if (!node_has_active_routes(n_ptr)) { 
+		k_signal((Handler)named_node_up, n_ptr->addr);
+	}
+
+        /* Syncronize broadcast acks */
+        n_ptr->bclink.acked = bclink_get_last_sent();
+
+	if (is_slave(tipc_own_addr))
+		return;
+	if (!in_own_cluster(n_ptr->addr)) {
+		/* Usage case 1 (see above) */
+		c_ptr = cluster_find(tipc_own_addr);
+		if (!c_ptr)
+			c_ptr = cluster_create(tipc_own_addr);
+                if (c_ptr)
+                        cluster_bcast_new_route(c_ptr, n_ptr->addr, 1, 
+						tipc_max_nodes);
+		return;
+	} 
+
+	c_ptr = n_ptr->owner;
+	if (is_slave(n_ptr->addr)) {
+		/* Usage case 2 (see above) */
+		cluster_bcast_new_route(c_ptr, n_ptr->addr, 1, tipc_max_nodes);
+		cluster_send_local_routes(c_ptr, n_ptr->addr);
+		return;
+	}
+
+	if (n_ptr->bclink.supported) {
+		nmap_add(&cluster_bcast_nodes, n_ptr->addr);
+		if (n_ptr->addr < tipc_own_addr)
+			tipc_own_tag++;
+	}
+
+	/* Case 3 (see above) */
+	net_send_external_routes(n_ptr->addr);
+	cluster_send_slave_routes(c_ptr, n_ptr->addr);
+	cluster_bcast_new_route(c_ptr, n_ptr->addr, LOWEST_SLAVE,
+				highest_allowed_slave);
+}
+
+static void node_lost_contact(struct node *n_ptr)
+{
+	struct cluster *c_ptr;
+	struct node_subscr *ns, *tns;
+	char addr_string[16];
+	u32 i;
+
+        /* Clean up broadcast reception remains */
+        n_ptr->bclink.gap_after = n_ptr->bclink.gap_to = 0;
+        while (n_ptr->bclink.deferred_head) {
+                struct sk_buff* buf = n_ptr->bclink.deferred_head;
+                n_ptr->bclink.deferred_head = buf->next;
+                buf_discard(buf);
+        }
+        if (n_ptr->bclink.defragm) {
+                buf_discard(n_ptr->bclink.defragm);  
+                n_ptr->bclink.defragm = NULL;
+        }            
+        if (in_own_cluster(n_ptr->addr) && n_ptr->bclink.supported) { 
+                bclink_acknowledge(n_ptr, mod(n_ptr->bclink.acked + 10000));
+        }
+
+        /* Update routing tables */
+	if (is_slave(tipc_own_addr)) {
+		net_remove_as_router(n_ptr->addr);
+	} else {
+		if (!in_own_cluster(n_ptr->addr)) { 
+			/* Case 4 (see above) */
+			c_ptr = cluster_find(tipc_own_addr);
+			cluster_bcast_lost_route(c_ptr, n_ptr->addr, 1,
+						 tipc_max_nodes);
+		} else {
+			/* Case 5 (see above) */
+			c_ptr = cluster_find(n_ptr->addr);
+			if (is_slave(n_ptr->addr)) {
+				cluster_bcast_lost_route(c_ptr, n_ptr->addr, 1,
+							 tipc_max_nodes);
+			} else {
+				if (n_ptr->bclink.supported) {
+					nmap_remove(&cluster_bcast_nodes, 
+						    n_ptr->addr);
+					if (n_ptr->addr < tipc_own_addr)
+						tipc_own_tag--;
+				}
+				net_remove_as_router(n_ptr->addr);
+				cluster_bcast_lost_route(c_ptr, n_ptr->addr,
+							 LOWEST_SLAVE,
+							 highest_allowed_slave);
+			}
+		}
+	}
+	if (node_has_active_routes(n_ptr))
+		return;
+
+	info("Lost contact with %s\n", 
+	     addr_string_fill(addr_string, n_ptr->addr));
+
+	/* Abort link changeover */
+	for (i = 0; i < MAX_BEARERS; i++) {
+		struct link *l_ptr = n_ptr->links[i];
+		if (!l_ptr) 
+			continue;
+		l_ptr->reset_checkpoint = l_ptr->next_in_no;
+		l_ptr->exp_msg_count = 0;
+		link_reset_fragments(l_ptr);
+	}
+
+	/* Notify subscribers */
+	list_for_each_entry_safe(ns, tns, &n_ptr->nsub, nodesub_list) {
+                ns->node = 0;
+		list_del_init(&ns->nodesub_list);
+		k_signal((Handler)ns->handle_node_down,
+			 (unsigned long)ns->usr_handle);
+	}
+}
+
+/**
+ * node_select_next_hop - find the next-hop node for a message
+ * 
+ * Called by when cluster local lookup has failed.
+ */
+
+struct node *node_select_next_hop(u32 addr, u32 selector)
+{
+	struct node *n_ptr;
+	u32 router_addr;
+
+        if (!addr_domain_valid(addr))
+                return 0;
+
+	/* Look for direct link to destination processsor */
+	n_ptr = node_find(addr);
+	if (n_ptr && node_has_active_links(n_ptr))
+                return n_ptr;
+
+	/* Cluster local system nodes *must* have direct links */
+	if (!is_slave(addr) && in_own_cluster(addr))
+		return 0;
+
+	/* Look for cluster local router with direct link to node */
+	router_addr = node_select_router(n_ptr, selector);
+	if (router_addr) 
+                return node_select(router_addr, selector);
+
+	/* Slave nodes can only be accessed within own cluster via a 
+	   known router with direct link -- if no router was found,give up */
+	if (is_slave(addr))
+		return 0;
+
+	/* Inter zone/cluster -- find any direct link to remote cluster */
+	addr = tipc_addr(tipc_zone(addr), tipc_cluster(addr), 0);
+	n_ptr = net_select_remote_node(addr, selector);
+	if (n_ptr && node_has_active_links(n_ptr))
+                return n_ptr;
+
+	/* Last resort -- look for any router to anywhere in remote zone */
+	router_addr =  net_select_router(addr, selector);
+	if (router_addr) 
+                return node_select(router_addr, selector);
+
+        return 0;
+}
+
+/**
+ * node_select_router - select router to reach specified node
+ * 
+ * Uses a deterministic and fair algorithm for selecting router node. 
+ */
+
+u32 node_select_router(struct node *n_ptr, u32 ref)
+{
+	u32 ulim;
+	u32 mask;
+	u32 start;
+	u32 r;
+
+        if (!n_ptr)
+                return 0;
+
+	if (n_ptr->last_router < 0)
+		return 0;
+	ulim = ((n_ptr->last_router + 1) * 32) - 1;
+
+	/* Start entry must be random */
+	mask = tipc_max_nodes;
+	while (mask > ulim)
+		mask >>= 1;
+	start = ref & mask;
+	r = start;
+
+	/* Lookup upwards with wrap-around */
+	do {
+		if (((n_ptr->routers[r / 32]) >> (r % 32)) & 1)
+			break;
+	} while (++r <= ulim);
+	if (r > ulim) {
+		r = 1;
+		do {
+			if (((n_ptr->routers[r / 32]) >> (r % 32)) & 1)
+				break;
+		} while (++r < start);
+		assert(r != start);
+	}
+	assert(r && (r <= ulim));
+	return tipc_addr(own_zone(), own_cluster(), r);
+}
+
+void node_add_router(struct node *n_ptr, u32 router)
+{
+	u32 r_num = tipc_node(router);
+
+	n_ptr->routers[r_num / 32] = 
+		((1 << (r_num % 32)) | n_ptr->routers[r_num / 32]);
+	n_ptr->last_router = tipc_max_nodes / 32;
+	while ((--n_ptr->last_router >= 0) && 
+	       !n_ptr->routers[n_ptr->last_router]);
+}
+
+void node_remove_router(struct node *n_ptr, u32 router)
+{
+	u32 r_num = tipc_node(router);
+
+	if (n_ptr->last_router < 0)
+		return;		/* No routes */
+
+	n_ptr->routers[r_num / 32] =
+		((~(1 << (r_num % 32))) & (n_ptr->routers[r_num / 32]));
+	n_ptr->last_router = tipc_max_nodes / 32;
+	while ((--n_ptr->last_router >= 0) && 
+	       !n_ptr->routers[n_ptr->last_router]);
+
+	if (!node_is_up(n_ptr))
+		node_lost_contact(n_ptr);
+}
+
+#if 0
+void node_print(struct print_buf *buf, struct node *n_ptr, char *str)
+{
+	u32 i;
+
+	tipc_printf(buf, "\n\n%s", str);
+	for (i = 0; i < MAX_BEARERS; i++) {
+		if (!n_ptr->links[i]) 
+			continue;
+		tipc_printf(buf, "Links[%u]: %x, ", i, n_ptr->links[i]);
+	}
+	tipc_printf(buf, "Active links: [%x,%x]\n",
+		    n_ptr->active_links[0], n_ptr->active_links[1]);
+}
+#endif
+
+u32 tipc_available_nodes(const u32 domain)
+{
+	struct node *n_ptr;
+	u32 cnt = 0;
+
+	for (n_ptr = nodes; n_ptr; n_ptr = n_ptr->next) {
+		if (!in_scope(domain, n_ptr->addr))
+			continue;
+		if (node_is_up(n_ptr))
+			cnt++;
+	}
+	return cnt;
+}
+
+struct sk_buff *node_get_nodes(const void *req_tlv_area, int req_tlv_space)
+{
+	u32 domain;
+	struct sk_buff *buf;
+	struct node *n_ptr;
+        struct tipc_node_info node_info;
+
+	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
+		return cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
+
+	domain = *(u32 *)TLV_DATA(req_tlv_area);
+	domain = ntohl(domain);
+	if (!addr_domain_valid(domain))
+		return cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
+					      " (network address)");
+
+        if (!nodes)
+                return cfg_reply_none();
+
+	/* For now, get space for all other nodes 
+	   (will need to modify this when slave nodes are supported */
+
+	buf = cfg_reply_alloc(TLV_SPACE(sizeof(node_info)) *
+			    (tipc_max_nodes - 1));
+	if (!buf)
+		return NULL;
+
+	/* Add TLVs for all nodes in scope */
+
+	for (n_ptr = nodes; n_ptr; n_ptr = n_ptr->next) {
+		if (!in_scope(domain, n_ptr->addr))
+			continue;
+                node_info.addr = htonl(n_ptr->addr);
+                node_info.up = htonl(node_is_up(n_ptr));
+		cfg_append_tlv(buf, TIPC_TLV_NODE_INFO, 
+			       &node_info, sizeof(node_info));
+	}
+
+	return buf;
+}
+
+struct sk_buff *node_get_links(const void *req_tlv_area, int req_tlv_space)
+{
+	u32 domain;
+	struct sk_buff *buf;
+	struct node *n_ptr;
+        struct tipc_link_info link_info;
+
+	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
+		return cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
+
+	domain = *(u32 *)TLV_DATA(req_tlv_area);
+	domain = ntohl(domain);
+	if (!addr_domain_valid(domain))
+		return cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
+					      " (network address)");
+
+        if (!nodes)
+                return cfg_reply_none();
+
+	/* For now, get space for 2 links to all other nodes + bcast link 
+	   (will need to modify this when slave nodes are supported */
+
+	buf = cfg_reply_alloc(TLV_SPACE(sizeof(link_info)) *
+			    (2 * (tipc_max_nodes - 1) + 1));
+	if (!buf)
+		return NULL;
+
+	/* Add TLV for broadcast link */
+
+        link_info.dest = tipc_own_addr & 0xfffff00;
+	link_info.dest = htonl(link_info.dest);
+        link_info.up = htonl(1);
+        sprintf(link_info.str, bc_link_name);
+	cfg_append_tlv(buf, TIPC_TLV_LINK_INFO, &link_info, sizeof(link_info));
+
+	/* Add TLVs for any other links in scope */
+
+	for (n_ptr = nodes; n_ptr; n_ptr = n_ptr->next) {
+                u32 i;
+
+		if (!in_scope(domain, n_ptr->addr))
+			continue;
+                for (i = 0; i < MAX_BEARERS; i++) {
+                        if (!n_ptr->links[i]) 
+                                continue;
+                        link_info.dest = htonl(n_ptr->addr);
+                        link_info.up = htonl(link_is_up(n_ptr->links[i]));
+                        strcpy(link_info.str, n_ptr->links[i]->name);
+			cfg_append_tlv(buf, TIPC_TLV_LINK_INFO, 
+				       &link_info, sizeof(link_info));
+                }
+	}
+
+	return buf;
+}