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26 results

link.c

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  • link.c 65.00 KiB
    /*
     * net/tipc/link.c: TIPC link code
     *
     * Copyright (c) 1996-2007, 2012-2014, Ericsson AB
     * Copyright (c) 2004-2007, 2010-2013, 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 "link.h"
    #include "bcast.h"
    #include "socket.h"
    #include "name_distr.h"
    #include "discover.h"
    #include "netlink.h"
    
    #include <linux/pkt_sched.h>
    
    /*
     * Error message prefixes
     */
    static const char *link_co_err = "Link changeover error, ";
    static const char *link_rst_msg = "Resetting link ";
    static const char *link_unk_evt = "Unknown link event ";
    
    static const struct nla_policy tipc_nl_link_policy[TIPC_NLA_LINK_MAX + 1] = {
    	[TIPC_NLA_LINK_UNSPEC]		= { .type = NLA_UNSPEC },
    	[TIPC_NLA_LINK_NAME] = {
    		.type = NLA_STRING,
    		.len = TIPC_MAX_LINK_NAME
    	},
    	[TIPC_NLA_LINK_MTU]		= { .type = NLA_U32 },
    	[TIPC_NLA_LINK_BROADCAST]	= { .type = NLA_FLAG },
    	[TIPC_NLA_LINK_UP]		= { .type = NLA_FLAG },
    	[TIPC_NLA_LINK_ACTIVE]		= { .type = NLA_FLAG },
    	[TIPC_NLA_LINK_PROP]		= { .type = NLA_NESTED },
    	[TIPC_NLA_LINK_STATS]		= { .type = NLA_NESTED },
    	[TIPC_NLA_LINK_RX]		= { .type = NLA_U32 },
    	[TIPC_NLA_LINK_TX]		= { .type = NLA_U32 }
    };
    
    /* Properties valid for media, bearar and link */
    static const struct nla_policy tipc_nl_prop_policy[TIPC_NLA_PROP_MAX + 1] = {
    	[TIPC_NLA_PROP_UNSPEC]		= { .type = NLA_UNSPEC },
    	[TIPC_NLA_PROP_PRIO]		= { .type = NLA_U32 },
    	[TIPC_NLA_PROP_TOL]		= { .type = NLA_U32 },
    	[TIPC_NLA_PROP_WIN]		= { .type = NLA_U32 }
    };
    
    /*
     * Out-of-range value for link session numbers
     */
    #define INVALID_SESSION 0x10000
    
    /*
     * Link state events:
     */
    #define  STARTING_EVT    856384768	/* link processing trigger */
    #define  TRAFFIC_MSG_EVT 560815u	/* rx'd ??? */
    #define  TIMEOUT_EVT     560817u	/* link timer expired */
    
    /*
     * The following two 'message types' is really just implementation
     * data conveniently stored in the message header.
     * They must not be considered part of the protocol
     */
    #define OPEN_MSG   0
    #define CLOSED_MSG 1
    
    /*
     * State value stored in 'exp_msg_count'
     */
    #define START_CHANGEOVER 100000u
    
    static void link_handle_out_of_seq_msg(struct tipc_link *link,
    				       struct sk_buff *skb);
    static void tipc_link_proto_rcv(struct tipc_link *link,
    				struct sk_buff *skb);
    static int  tipc_link_tunnel_rcv(struct tipc_node *node,
    				 struct sk_buff **skb);
    static void link_set_supervision_props(struct tipc_link *l_ptr, u32 tol);
    static void link_state_event(struct tipc_link *l_ptr, u32 event);
    static void link_reset_statistics(struct tipc_link *l_ptr);
    static void link_print(struct tipc_link *l_ptr, const char *str);
    static void tipc_link_sync_xmit(struct tipc_link *l);
    static void tipc_link_sync_rcv(struct tipc_node *n, struct sk_buff *buf);
    static void tipc_link_input(struct tipc_link *l, struct sk_buff *skb);
    static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb);
    
    /*
     *  Simple link routines
     */
    static unsigned int align(unsigned int i)
    {
    	return (i + 3) & ~3u;
    }
    
    static void tipc_link_release(struct kref *kref)
    {
    	kfree(container_of(kref, struct tipc_link, ref));
    }
    
    static void tipc_link_get(struct tipc_link *l_ptr)
    {
    	kref_get(&l_ptr->ref);
    }
    
    static void tipc_link_put(struct tipc_link *l_ptr)
    {
    	kref_put(&l_ptr->ref, tipc_link_release);
    }
    
    static void link_init_max_pkt(struct tipc_link *l_ptr)
    {
    	struct tipc_node *node = l_ptr->owner;
    	struct tipc_net *tn = net_generic(node->net, tipc_net_id);
    	struct tipc_bearer *b_ptr;
    	u32 max_pkt;
    
    	rcu_read_lock();
    	b_ptr = rcu_dereference_rtnl(tn->bearer_list[l_ptr->bearer_id]);
    	if (!b_ptr) {
    		rcu_read_unlock();
    		return;
    	}
    	max_pkt = (b_ptr->mtu & ~3);
    	rcu_read_unlock();
    
    	if (max_pkt > MAX_MSG_SIZE)
    		max_pkt = MAX_MSG_SIZE;
    
    	l_ptr->max_pkt_target = max_pkt;
    	if (l_ptr->max_pkt_target < MAX_PKT_DEFAULT)
    		l_ptr->max_pkt = l_ptr->max_pkt_target;
    	else
    		l_ptr->max_pkt = MAX_PKT_DEFAULT;
    
    	l_ptr->max_pkt_probes = 0;
    }
    
    /*
     *  Simple non-static link routines (i.e. referenced outside this file)
     */
    int tipc_link_is_up(struct tipc_link *l_ptr)
    {
    	if (!l_ptr)
    		return 0;
    	return link_working_working(l_ptr) || link_working_unknown(l_ptr);
    }
    
    int tipc_link_is_active(struct tipc_link *l_ptr)
    {
    	return	(l_ptr->owner->active_links[0] == l_ptr) ||
    		(l_ptr->owner->active_links[1] == l_ptr);
    }
    
    /**
     * link_timeout - handle expiration of link timer
     * @l_ptr: pointer to link
     */
    static void link_timeout(unsigned long data)
    {
    	struct tipc_link *l_ptr = (struct tipc_link *)data;
    	struct sk_buff *skb;
    
    	tipc_node_lock(l_ptr->owner);
    
    	/* update counters used in statistical profiling of send traffic */
    	l_ptr->stats.accu_queue_sz += skb_queue_len(&l_ptr->outqueue);
    	l_ptr->stats.queue_sz_counts++;
    
    	skb = skb_peek(&l_ptr->outqueue);
    	if (skb) {
    		struct tipc_msg *msg = buf_msg(skb);
    		u32 length = msg_size(msg);
    
    		if ((msg_user(msg) == MSG_FRAGMENTER) &&
    		    (msg_type(msg) == FIRST_FRAGMENT)) {
    			length = msg_size(msg_get_wrapped(msg));
    		}
    		if (length) {
    			l_ptr->stats.msg_lengths_total += length;
    			l_ptr->stats.msg_length_counts++;
    			if (length <= 64)
    				l_ptr->stats.msg_length_profile[0]++;
    			else if (length <= 256)
    				l_ptr->stats.msg_length_profile[1]++;
    			else if (length <= 1024)
    				l_ptr->stats.msg_length_profile[2]++;
    			else if (length <= 4096)
    				l_ptr->stats.msg_length_profile[3]++;
    			else if (length <= 16384)
    				l_ptr->stats.msg_length_profile[4]++;
    			else if (length <= 32768)
    				l_ptr->stats.msg_length_profile[5]++;
    			else
    				l_ptr->stats.msg_length_profile[6]++;
    		}
    	}
    
    	/* do all other link processing performed on a periodic basis */
    	link_state_event(l_ptr, TIMEOUT_EVT);
    
    	if (l_ptr->next_out)
    		tipc_link_push_packets(l_ptr);
    
    	tipc_node_unlock(l_ptr->owner);
    	tipc_link_put(l_ptr);
    }
    
    static void link_set_timer(struct tipc_link *link, unsigned long time)
    {
    	if (!mod_timer(&link->timer, jiffies + time))
    		tipc_link_get(link);
    }
    
    /**
     * tipc_link_create - create a new link
     * @n_ptr: pointer to associated node
     * @b_ptr: pointer to associated bearer
     * @media_addr: media address to use when sending messages over link
     *
     * Returns pointer to link.
     */
    struct tipc_link *tipc_link_create(struct tipc_node *n_ptr,
    				   struct tipc_bearer *b_ptr,
    				   const struct tipc_media_addr *media_addr)
    {
    	struct tipc_net *tn = net_generic(n_ptr->net, tipc_net_id);
    	struct tipc_link *l_ptr;
    	struct tipc_msg *msg;
    	char *if_name;
    	char addr_string[16];
    	u32 peer = n_ptr->addr;
    
    	if (n_ptr->link_cnt >= MAX_BEARERS) {
    		tipc_addr_string_fill(addr_string, n_ptr->addr);
    		pr_err("Attempt to establish %uth link to %s. Max %u allowed.\n",
    			n_ptr->link_cnt, addr_string, MAX_BEARERS);
    		return NULL;
    	}
    
    	if (n_ptr->links[b_ptr->identity]) {
    		tipc_addr_string_fill(addr_string, n_ptr->addr);
    		pr_err("Attempt to establish second link on <%s> to %s\n",
    		       b_ptr->name, addr_string);
    		return NULL;
    	}
    
    	l_ptr = kzalloc(sizeof(*l_ptr), GFP_ATOMIC);
    	if (!l_ptr) {
    		pr_warn("Link creation failed, no memory\n");
    		return NULL;
    	}
    	kref_init(&l_ptr->ref);
    	l_ptr->addr = peer;
    	if_name = strchr(b_ptr->name, ':') + 1;
    	sprintf(l_ptr->name, "%u.%u.%u:%s-%u.%u.%u:unknown",
    		tipc_zone(tn->own_addr), tipc_cluster(tn->own_addr),
    		tipc_node(tn->own_addr),
    		if_name,
    		tipc_zone(peer), tipc_cluster(peer), tipc_node(peer));
    		/* note: peer i/f name is updated by reset/activate message */
    	memcpy(&l_ptr->media_addr, media_addr, sizeof(*media_addr));
    	l_ptr->owner = n_ptr;
    	l_ptr->checkpoint = 1;
    	l_ptr->peer_session = INVALID_SESSION;
    	l_ptr->bearer_id = b_ptr->identity;
    	link_set_supervision_props(l_ptr, b_ptr->tolerance);
    	l_ptr->state = RESET_UNKNOWN;
    
    	l_ptr->pmsg = (struct tipc_msg *)&l_ptr->proto_msg;
    	msg = l_ptr->pmsg;
    	tipc_msg_init(tn->own_addr, msg, LINK_PROTOCOL, RESET_MSG, INT_H_SIZE,
    		      l_ptr->addr);
    	msg_set_size(msg, sizeof(l_ptr->proto_msg));
    	msg_set_session(msg, (tn->random & 0xffff));
    	msg_set_bearer_id(msg, b_ptr->identity);
    	strcpy((char *)msg_data(msg), if_name);
    
    	l_ptr->priority = b_ptr->priority;
    	tipc_link_set_queue_limits(l_ptr, b_ptr->window);
    
    	l_ptr->net_plane = b_ptr->net_plane;
    	link_init_max_pkt(l_ptr);
    
    	l_ptr->next_out_no = 1;
    	__skb_queue_head_init(&l_ptr->outqueue);
    	__skb_queue_head_init(&l_ptr->deferred_queue);
    	skb_queue_head_init(&l_ptr->wakeupq);
    	skb_queue_head_init(&l_ptr->inputq);
    	skb_queue_head_init(&l_ptr->namedq);
    	link_reset_statistics(l_ptr);
    	tipc_node_attach_link(n_ptr, l_ptr);
    	setup_timer(&l_ptr->timer, link_timeout, (unsigned long)l_ptr);
    	link_state_event(l_ptr, STARTING_EVT);
    
    	return l_ptr;
    }
    
    /**
     * link_delete - Conditional deletion of link.
     *               If timer still running, real delete is done when it expires
     * @link: link to be deleted
     */
    void tipc_link_delete(struct tipc_link *link)
    {
    	tipc_link_reset_fragments(link);
    	tipc_node_detach_link(link->owner, link);
    	tipc_link_put(link);
    }
    
    void tipc_link_delete_list(struct net *net, unsigned int bearer_id,
    			   bool shutting_down)
    {
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    	struct tipc_link *link;
    	struct tipc_node *node;
    	bool del_link;
    
    	rcu_read_lock();
    	list_for_each_entry_rcu(node, &tn->node_list, list) {
    		tipc_node_lock(node);
    		link = node->links[bearer_id];
    		if (!link) {
    			tipc_node_unlock(node);
    			continue;
    		}
    		del_link = !tipc_link_is_up(link) && !link->exp_msg_count;
    		tipc_link_reset(link);
    		if (del_timer(&link->timer))
    			tipc_link_put(link);
    		link->flags |= LINK_STOPPED;
    		/* Delete link now, or when failover is finished: */
    		if (shutting_down || !tipc_node_is_up(node) || del_link)
    			tipc_link_delete(link);
    		tipc_node_unlock(node);
    	}
    	rcu_read_unlock();
    }
    
    /**
     * link_schedule_user - schedule user for wakeup after congestion
     * @link: congested link
     * @oport: sending port
     * @chain_sz: size of buffer chain that was attempted sent
     * @imp: importance of message attempted sent
     * Create pseudo msg to send back to user when congestion abates
     */
    static bool link_schedule_user(struct tipc_link *link, u32 oport,
    			       uint chain_sz, uint imp)
    {
    	struct sk_buff *buf;
    
    	buf = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
    			      link_own_addr(link), link_own_addr(link),
    			      oport, 0, 0);
    	if (!buf)
    		return false;
    	TIPC_SKB_CB(buf)->chain_sz = chain_sz;
    	TIPC_SKB_CB(buf)->chain_imp = imp;
    	skb_queue_tail(&link->wakeupq, buf);
    	link->stats.link_congs++;
    	return true;
    }
    
    /**
     * link_prepare_wakeup - prepare users for wakeup after congestion
     * @link: congested link
     * Move a number of waiting users, as permitted by available space in
     * the send queue, from link wait queue to node wait queue for wakeup
     */
    void link_prepare_wakeup(struct tipc_link *link)
    {
    	uint pend_qsz = skb_queue_len(&link->outqueue);
    	struct sk_buff *skb, *tmp;
    
    	skb_queue_walk_safe(&link->wakeupq, skb, tmp) {
    		if (pend_qsz >= link->queue_limit[TIPC_SKB_CB(skb)->chain_imp])
    			break;
    		pend_qsz += TIPC_SKB_CB(skb)->chain_sz;
    		skb_unlink(skb, &link->wakeupq);
    		skb_queue_tail(&link->inputq, skb);
    		link->owner->inputq = &link->inputq;
    		link->owner->action_flags |= TIPC_MSG_EVT;
    	}
    }
    
    /**
     * tipc_link_reset_fragments - purge link's inbound message fragments queue
     * @l_ptr: pointer to link
     */
    void tipc_link_reset_fragments(struct tipc_link *l_ptr)
    {
    	kfree_skb(l_ptr->reasm_buf);
    	l_ptr->reasm_buf = NULL;
    }
    
    /**
     * tipc_link_purge_queues - purge all pkt queues associated with link
     * @l_ptr: pointer to link
     */
    void tipc_link_purge_queues(struct tipc_link *l_ptr)
    {
    	__skb_queue_purge(&l_ptr->deferred_queue);
    	__skb_queue_purge(&l_ptr->outqueue);
    	tipc_link_reset_fragments(l_ptr);
    }
    
    void tipc_link_reset(struct tipc_link *l_ptr)
    {
    	u32 prev_state = l_ptr->state;
    	u32 checkpoint = l_ptr->next_in_no;
    	int was_active_link = tipc_link_is_active(l_ptr);
    	struct tipc_node *owner = l_ptr->owner;
    
    	msg_set_session(l_ptr->pmsg, ((msg_session(l_ptr->pmsg) + 1) & 0xffff));
    
    	/* Link is down, accept any session */
    	l_ptr->peer_session = INVALID_SESSION;
    
    	/* Prepare for max packet size negotiation */
    	link_init_max_pkt(l_ptr);
    
    	l_ptr->state = RESET_UNKNOWN;
    
    	if ((prev_state == RESET_UNKNOWN) || (prev_state == RESET_RESET))
    		return;
    
    	tipc_node_link_down(l_ptr->owner, l_ptr);
    	tipc_bearer_remove_dest(owner->net, l_ptr->bearer_id, l_ptr->addr);
    
    	if (was_active_link && tipc_node_active_links(l_ptr->owner)) {
    		l_ptr->reset_checkpoint = checkpoint;
    		l_ptr->exp_msg_count = START_CHANGEOVER;
    	}
    
    	/* Clean up all queues, except inputq: */
    	__skb_queue_purge(&l_ptr->outqueue);
    	__skb_queue_purge(&l_ptr->deferred_queue);
    	if (!owner->inputq)
    		owner->inputq = &l_ptr->inputq;
    	skb_queue_splice_init(&l_ptr->wakeupq, owner->inputq);
    	if (!skb_queue_empty(owner->inputq))
    		owner->action_flags |= TIPC_MSG_EVT;
    	l_ptr->next_out = NULL;
    	l_ptr->unacked_window = 0;
    	l_ptr->checkpoint = 1;
    	l_ptr->next_out_no = 1;
    	l_ptr->fsm_msg_cnt = 0;
    	l_ptr->stale_count = 0;
    	link_reset_statistics(l_ptr);
    }
    
    void tipc_link_reset_list(struct net *net, unsigned int bearer_id)
    {
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    	struct tipc_link *l_ptr;
    	struct tipc_node *n_ptr;
    
    	rcu_read_lock();
    	list_for_each_entry_rcu(n_ptr, &tn->node_list, list) {
    		tipc_node_lock(n_ptr);
    		l_ptr = n_ptr->links[bearer_id];
    		if (l_ptr)
    			tipc_link_reset(l_ptr);
    		tipc_node_unlock(n_ptr);
    	}
    	rcu_read_unlock();
    }
    
    static void link_activate(struct tipc_link *link)
    {
    	struct tipc_node *node = link->owner;
    
    	link->next_in_no = 1;
    	link->stats.recv_info = 1;
    	tipc_node_link_up(node, link);
    	tipc_bearer_add_dest(node->net, link->bearer_id, link->addr);
    }
    
    /**
     * link_state_event - link finite state machine
     * @l_ptr: pointer to link
     * @event: state machine event to process
     */
    static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
    {
    	struct tipc_link *other;
    	unsigned long cont_intv = l_ptr->cont_intv;
    
    	if (l_ptr->flags & LINK_STOPPED)
    		return;
    
    	if (!(l_ptr->flags & LINK_STARTED) && (event != STARTING_EVT))
    		return;		/* Not yet. */
    
    	/* Check whether changeover is going on */
    	if (l_ptr->exp_msg_count) {
    		if (event == TIMEOUT_EVT)
    			link_set_timer(l_ptr, cont_intv);
    		return;
    	}
    
    	switch (l_ptr->state) {
    	case WORKING_WORKING:
    		switch (event) {
    		case TRAFFIC_MSG_EVT:
    		case ACTIVATE_MSG:
    			break;
    		case TIMEOUT_EVT:
    			if (l_ptr->next_in_no != l_ptr->checkpoint) {
    				l_ptr->checkpoint = l_ptr->next_in_no;
    				if (tipc_bclink_acks_missing(l_ptr->owner)) {
    					tipc_link_proto_xmit(l_ptr, STATE_MSG,
    							     0, 0, 0, 0, 0);
    					l_ptr->fsm_msg_cnt++;
    				} else if (l_ptr->max_pkt < l_ptr->max_pkt_target) {
    					tipc_link_proto_xmit(l_ptr, STATE_MSG,
    							     1, 0, 0, 0, 0);
    					l_ptr->fsm_msg_cnt++;
    				}
    				link_set_timer(l_ptr, cont_intv);
    				break;
    			}
    			l_ptr->state = WORKING_UNKNOWN;
    			l_ptr->fsm_msg_cnt = 0;
    			tipc_link_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
    			l_ptr->fsm_msg_cnt++;
    			link_set_timer(l_ptr, cont_intv / 4);
    			break;
    		case RESET_MSG:
    			pr_debug("%s<%s>, requested by peer\n",
    				 link_rst_msg, l_ptr->name);
    			tipc_link_reset(l_ptr);
    			l_ptr->state = RESET_RESET;
    			l_ptr->fsm_msg_cnt = 0;
    			tipc_link_proto_xmit(l_ptr, ACTIVATE_MSG,
    					     0, 0, 0, 0, 0);
    			l_ptr->fsm_msg_cnt++;
    			link_set_timer(l_ptr, cont_intv);
    			break;
    		default:
    			pr_debug("%s%u in WW state\n", link_unk_evt, event);
    		}
    		break;
    	case WORKING_UNKNOWN:
    		switch (event) {
    		case TRAFFIC_MSG_EVT:
    		case ACTIVATE_MSG:
    			l_ptr->state = WORKING_WORKING;
    			l_ptr->fsm_msg_cnt = 0;
    			link_set_timer(l_ptr, cont_intv);
    			break;
    		case RESET_MSG:
    			pr_debug("%s<%s>, requested by peer while probing\n",
    				 link_rst_msg, l_ptr->name);
    			tipc_link_reset(l_ptr);
    			l_ptr->state = RESET_RESET;
    			l_ptr->fsm_msg_cnt = 0;
    			tipc_link_proto_xmit(l_ptr, ACTIVATE_MSG,
    					     0, 0, 0, 0, 0);
    			l_ptr->fsm_msg_cnt++;
    			link_set_timer(l_ptr, cont_intv);
    			break;
    		case TIMEOUT_EVT:
    			if (l_ptr->next_in_no != l_ptr->checkpoint) {
    				l_ptr->state = WORKING_WORKING;
    				l_ptr->fsm_msg_cnt = 0;
    				l_ptr->checkpoint = l_ptr->next_in_no;
    				if (tipc_bclink_acks_missing(l_ptr->owner)) {
    					tipc_link_proto_xmit(l_ptr, STATE_MSG,
    							     0, 0, 0, 0, 0);
    					l_ptr->fsm_msg_cnt++;
    				}
    				link_set_timer(l_ptr, cont_intv);
    			} else if (l_ptr->fsm_msg_cnt < l_ptr->abort_limit) {
    				tipc_link_proto_xmit(l_ptr, STATE_MSG,
    						     1, 0, 0, 0, 0);
    				l_ptr->fsm_msg_cnt++;
    				link_set_timer(l_ptr, cont_intv / 4);
    			} else {	/* Link has failed */
    				pr_debug("%s<%s>, peer not responding\n",
    					 link_rst_msg, l_ptr->name);
    				tipc_link_reset(l_ptr);
    				l_ptr->state = RESET_UNKNOWN;
    				l_ptr->fsm_msg_cnt = 0;
    				tipc_link_proto_xmit(l_ptr, RESET_MSG,
    						     0, 0, 0, 0, 0);
    				l_ptr->fsm_msg_cnt++;
    				link_set_timer(l_ptr, cont_intv);
    			}
    			break;
    		default:
    			pr_err("%s%u in WU state\n", link_unk_evt, event);
    		}
    		break;
    	case RESET_UNKNOWN:
    		switch (event) {
    		case TRAFFIC_MSG_EVT:
    			break;
    		case ACTIVATE_MSG:
    			other = l_ptr->owner->active_links[0];
    			if (other && link_working_unknown(other))
    				break;
    			l_ptr->state = WORKING_WORKING;
    			l_ptr->fsm_msg_cnt = 0;
    			link_activate(l_ptr);
    			tipc_link_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
    			l_ptr->fsm_msg_cnt++;
    			if (l_ptr->owner->working_links == 1)
    				tipc_link_sync_xmit(l_ptr);
    			link_set_timer(l_ptr, cont_intv);
    			break;
    		case RESET_MSG:
    			l_ptr->state = RESET_RESET;
    			l_ptr->fsm_msg_cnt = 0;
    			tipc_link_proto_xmit(l_ptr, ACTIVATE_MSG,
    					     1, 0, 0, 0, 0);
    			l_ptr->fsm_msg_cnt++;
    			link_set_timer(l_ptr, cont_intv);
    			break;
    		case STARTING_EVT:
    			l_ptr->flags |= LINK_STARTED;
    			l_ptr->fsm_msg_cnt++;
    			link_set_timer(l_ptr, cont_intv);
    			break;
    		case TIMEOUT_EVT:
    			tipc_link_proto_xmit(l_ptr, RESET_MSG, 0, 0, 0, 0, 0);
    			l_ptr->fsm_msg_cnt++;
    			link_set_timer(l_ptr, cont_intv);
    			break;
    		default:
    			pr_err("%s%u in RU state\n", link_unk_evt, event);
    		}
    		break;
    	case RESET_RESET:
    		switch (event) {
    		case TRAFFIC_MSG_EVT:
    		case ACTIVATE_MSG:
    			other = l_ptr->owner->active_links[0];
    			if (other && link_working_unknown(other))
    				break;
    			l_ptr->state = WORKING_WORKING;
    			l_ptr->fsm_msg_cnt = 0;
    			link_activate(l_ptr);
    			tipc_link_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
    			l_ptr->fsm_msg_cnt++;
    			if (l_ptr->owner->working_links == 1)
    				tipc_link_sync_xmit(l_ptr);
    			link_set_timer(l_ptr, cont_intv);
    			break;
    		case RESET_MSG:
    			break;
    		case TIMEOUT_EVT:
    			tipc_link_proto_xmit(l_ptr, ACTIVATE_MSG,
    					     0, 0, 0, 0, 0);
    			l_ptr->fsm_msg_cnt++;
    			link_set_timer(l_ptr, cont_intv);
    			break;
    		default:
    			pr_err("%s%u in RR state\n", link_unk_evt, event);
    		}
    		break;
    	default:
    		pr_err("Unknown link state %u/%u\n", l_ptr->state, event);
    	}
    }
    
    /* tipc_link_cong: determine return value and how to treat the
     * sent buffer during link congestion.
     * - For plain, errorless user data messages we keep the buffer and
     *   return -ELINKONG.
     * - For all other messages we discard the buffer and return -EHOSTUNREACH
     * - For TIPC internal messages we also reset the link
     */
    static int tipc_link_cong(struct tipc_link *link, struct sk_buff_head *list)
    {
    	struct sk_buff *skb = skb_peek(list);
    	struct tipc_msg *msg = buf_msg(skb);
    	uint imp = tipc_msg_tot_importance(msg);
    	u32 oport = msg_tot_origport(msg);
    
    	if (unlikely(imp > TIPC_CRITICAL_IMPORTANCE)) {
    		pr_warn("%s<%s>, send queue full", link_rst_msg, link->name);
    		tipc_link_reset(link);
    		goto drop;
    	}
    	if (unlikely(msg_errcode(msg)))
    		goto drop;
    	if (unlikely(msg_reroute_cnt(msg)))
    		goto drop;
    	if (TIPC_SKB_CB(skb)->wakeup_pending)
    		return -ELINKCONG;
    	if (link_schedule_user(link, oport, skb_queue_len(list), imp))
    		return -ELINKCONG;
    drop:
    	__skb_queue_purge(list);
    	return -EHOSTUNREACH;
    }
    
    /**
     * __tipc_link_xmit(): same as tipc_link_xmit, but destlink is known & locked
     * @link: link to use
     * @list: chain of buffers containing message
     *
     * Consumes the buffer chain, except when returning -ELINKCONG
     * Returns 0 if success, otherwise errno: -ELINKCONG, -EMSGSIZE (plain socket
     * user data messages) or -EHOSTUNREACH (all other messages/senders)
     * Only the socket functions tipc_send_stream() and tipc_send_packet() need
     * to act on the return value, since they may need to do more send attempts.
     */
    int __tipc_link_xmit(struct net *net, struct tipc_link *link,
    		     struct sk_buff_head *list)
    {
    	struct tipc_msg *msg = buf_msg(skb_peek(list));
    	uint psz = msg_size(msg);
    	uint sndlim = link->queue_limit[0];
    	uint imp = tipc_msg_tot_importance(msg);
    	uint mtu = link->max_pkt;
    	uint ack = mod(link->next_in_no - 1);
    	uint seqno = link->next_out_no;
    	uint bc_last_in = link->owner->bclink.last_in;
    	struct tipc_media_addr *addr = &link->media_addr;
    	struct sk_buff_head *outqueue = &link->outqueue;
    	struct sk_buff *skb, *tmp;
    
    	/* Match queue limits against msg importance: */
    	if (unlikely(skb_queue_len(outqueue) >= link->queue_limit[imp]))
    		return tipc_link_cong(link, list);
    
    	/* Has valid packet limit been used ? */
    	if (unlikely(psz > mtu)) {
    		__skb_queue_purge(list);
    		return -EMSGSIZE;
    	}
    
    	/* Prepare each packet for sending, and add to outqueue: */
    	skb_queue_walk_safe(list, skb, tmp) {
    		__skb_unlink(skb, list);
    		msg = buf_msg(skb);
    		msg_set_word(msg, 2, ((ack << 16) | mod(seqno)));
    		msg_set_bcast_ack(msg, bc_last_in);
    
    		if (skb_queue_len(outqueue) < sndlim) {
    			__skb_queue_tail(outqueue, skb);
    			tipc_bearer_send(net, link->bearer_id,
    					 skb, addr);
    			link->next_out = NULL;
    			link->unacked_window = 0;
    		} else if (tipc_msg_bundle(outqueue, skb, mtu)) {
    			link->stats.sent_bundled++;
    			continue;
    		} else if (tipc_msg_make_bundle(outqueue, skb, mtu,
    						link->addr)) {
    			link->stats.sent_bundled++;
    			link->stats.sent_bundles++;
    			if (!link->next_out)
    				link->next_out = skb_peek_tail(outqueue);
    		} else {
    			__skb_queue_tail(outqueue, skb);
    			if (!link->next_out)
    				link->next_out = skb;
    		}
    		seqno++;
    	}
    	link->next_out_no = seqno;
    	return 0;
    }
    
    static void skb2list(struct sk_buff *skb, struct sk_buff_head *list)
    {
    	skb_queue_head_init(list);
    	__skb_queue_tail(list, skb);
    }
    
    static int __tipc_link_xmit_skb(struct tipc_link *link, struct sk_buff *skb)
    {
    	struct sk_buff_head head;
    
    	skb2list(skb, &head);
    	return __tipc_link_xmit(link->owner->net, link, &head);
    }
    
    int tipc_link_xmit_skb(struct net *net, struct sk_buff *skb, u32 dnode,
    		       u32 selector)
    {
    	struct sk_buff_head head;
    
    	skb2list(skb, &head);
    	return tipc_link_xmit(net, &head, dnode, selector);
    }
    
    /**
     * tipc_link_xmit() is the general link level function for message sending
     * @net: the applicable net namespace
     * @list: chain of buffers containing message
     * @dsz: amount of user data to be sent
     * @dnode: address of destination node
     * @selector: a number used for deterministic link selection
     * Consumes the buffer chain, except when returning -ELINKCONG
     * Returns 0 if success, otherwise errno: -ELINKCONG,-EHOSTUNREACH,-EMSGSIZE
     */
    int tipc_link_xmit(struct net *net, struct sk_buff_head *list, u32 dnode,
    		   u32 selector)
    {
    	struct tipc_link *link = NULL;
    	struct tipc_node *node;
    	int rc = -EHOSTUNREACH;
    
    	node = tipc_node_find(net, dnode);
    	if (node) {
    		tipc_node_lock(node);
    		link = node->active_links[selector & 1];
    		if (link)
    			rc = __tipc_link_xmit(net, link, list);
    		tipc_node_unlock(node);
    	}
    	if (link)
    		return rc;
    
    	if (likely(in_own_node(net, dnode)))
    		return tipc_sk_rcv(net, list);
    
    	__skb_queue_purge(list);
    	return rc;
    }
    
    /*
     * tipc_link_sync_xmit - synchronize broadcast link endpoints.
     *
     * Give a newly added peer node the sequence number where it should
     * start receiving and acking broadcast packets.
     *
     * Called with node locked
     */
    static void tipc_link_sync_xmit(struct tipc_link *link)
    {
    	struct sk_buff *skb;
    	struct tipc_msg *msg;
    
    	skb = tipc_buf_acquire(INT_H_SIZE);
    	if (!skb)
    		return;
    
    	msg = buf_msg(skb);
    	tipc_msg_init(link_own_addr(link), msg, BCAST_PROTOCOL, STATE_MSG,
    		      INT_H_SIZE, link->addr);
    	msg_set_last_bcast(msg, link->owner->bclink.acked);
    	__tipc_link_xmit_skb(link, skb);
    }
    
    /*
     * tipc_link_sync_rcv - synchronize broadcast link endpoints.
     * Receive the sequence number where we should start receiving and
     * acking broadcast packets from a newly added peer node, and open
     * up for reception of such packets.
     *
     * Called with node locked
     */
    static void tipc_link_sync_rcv(struct tipc_node *n, struct sk_buff *buf)
    {
    	struct tipc_msg *msg = buf_msg(buf);
    
    	n->bclink.last_sent = n->bclink.last_in = msg_last_bcast(msg);
    	n->bclink.recv_permitted = true;
    	kfree_skb(buf);
    }
    
    struct sk_buff *tipc_skb_queue_next(const struct sk_buff_head *list,
    				    const struct sk_buff *skb)
    {
    	if (skb_queue_is_last(list, skb))
    		return NULL;
    	return skb->next;
    }
    
    /*
     * tipc_link_push_packets - push unsent packets to bearer
     *
     * Push out the unsent messages of a link where congestion
     * has abated. Node is locked.
     *
     * Called with node locked
     */
    void tipc_link_push_packets(struct tipc_link *l_ptr)
    {
    	struct sk_buff_head *outqueue = &l_ptr->outqueue;
    	struct sk_buff *skb = l_ptr->next_out;
    	struct tipc_msg *msg;
    	u32 next, first;
    
    	skb_queue_walk_from(outqueue, skb) {
    		msg = buf_msg(skb);
    		next = msg_seqno(msg);
    		first = buf_seqno(skb_peek(outqueue));
    
    		if (mod(next - first) < l_ptr->queue_limit[0]) {
    			msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
    			msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
    			if (msg_user(msg) == MSG_BUNDLER)
    				TIPC_SKB_CB(skb)->bundling = false;
    			tipc_bearer_send(l_ptr->owner->net,
    					 l_ptr->bearer_id, skb,
    					 &l_ptr->media_addr);
    			l_ptr->next_out = tipc_skb_queue_next(outqueue, skb);
    		} else {
    			break;
    		}
    	}
    }
    
    void tipc_link_reset_all(struct tipc_node *node)
    {
    	char addr_string[16];
    	u32 i;
    
    	tipc_node_lock(node);
    
    	pr_warn("Resetting all links to %s\n",
    		tipc_addr_string_fill(addr_string, node->addr));
    
    	for (i = 0; i < MAX_BEARERS; i++) {
    		if (node->links[i]) {
    			link_print(node->links[i], "Resetting link\n");
    			tipc_link_reset(node->links[i]);
    		}
    	}
    
    	tipc_node_unlock(node);
    }
    
    static void link_retransmit_failure(struct tipc_link *l_ptr,
    				    struct sk_buff *buf)
    {
    	struct tipc_msg *msg = buf_msg(buf);
    	struct net *net = l_ptr->owner->net;
    
    	pr_warn("Retransmission failure on link <%s>\n", l_ptr->name);
    
    	if (l_ptr->addr) {
    		/* Handle failure on standard link */
    		link_print(l_ptr, "Resetting link\n");
    		tipc_link_reset(l_ptr);
    
    	} else {
    		/* Handle failure on broadcast link */
    		struct tipc_node *n_ptr;
    		char addr_string[16];
    
    		pr_info("Msg seq number: %u,  ", msg_seqno(msg));
    		pr_cont("Outstanding acks: %lu\n",
    			(unsigned long) TIPC_SKB_CB(buf)->handle);
    
    		n_ptr = tipc_bclink_retransmit_to(net);
    		tipc_node_lock(n_ptr);
    
    		tipc_addr_string_fill(addr_string, n_ptr->addr);
    		pr_info("Broadcast link info for %s\n", addr_string);
    		pr_info("Reception permitted: %d,  Acked: %u\n",
    			n_ptr->bclink.recv_permitted,
    			n_ptr->bclink.acked);
    		pr_info("Last in: %u,  Oos state: %u,  Last sent: %u\n",
    			n_ptr->bclink.last_in,
    			n_ptr->bclink.oos_state,
    			n_ptr->bclink.last_sent);
    
    		tipc_node_unlock(n_ptr);
    
    		tipc_bclink_set_flags(net, TIPC_BCLINK_RESET);
    		l_ptr->stale_count = 0;
    	}
    }
    
    void tipc_link_retransmit(struct tipc_link *l_ptr, struct sk_buff *skb,
    			  u32 retransmits)
    {
    	struct tipc_msg *msg;
    
    	if (!skb)
    		return;
    
    	msg = buf_msg(skb);
    
    	/* Detect repeated retransmit failures */
    	if (l_ptr->last_retransmitted == msg_seqno(msg)) {
    		if (++l_ptr->stale_count > 100) {
    			link_retransmit_failure(l_ptr, skb);
    			return;
    		}
    	} else {
    		l_ptr->last_retransmitted = msg_seqno(msg);
    		l_ptr->stale_count = 1;
    	}
    
    	skb_queue_walk_from(&l_ptr->outqueue, skb) {
    		if (!retransmits || skb == l_ptr->next_out)
    			break;
    		msg = buf_msg(skb);
    		msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
    		msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
    		tipc_bearer_send(l_ptr->owner->net, l_ptr->bearer_id, skb,
    				 &l_ptr->media_addr);
    		retransmits--;
    		l_ptr->stats.retransmitted++;
    	}
    }
    
    static void link_retrieve_defq(struct tipc_link *link,
    			       struct sk_buff_head *list)
    {
    	u32 seq_no;
    
    	if (skb_queue_empty(&link->deferred_queue))
    		return;
    
    	seq_no = buf_seqno(skb_peek(&link->deferred_queue));
    	if (seq_no == mod(link->next_in_no))
    		skb_queue_splice_tail_init(&link->deferred_queue, list);
    }
    
    /**
     * link_recv_buf_validate - validate basic format of received message
     *
     * This routine ensures a TIPC message has an acceptable header, and at least
     * as much data as the header indicates it should.  The routine also ensures
     * that the entire message header is stored in the main fragment of the message
     * buffer, to simplify future access to message header fields.
     *
     * Note: Having extra info present in the message header or data areas is OK.
     * TIPC will ignore the excess, under the assumption that it is optional info
     * introduced by a later release of the protocol.
     */
    static int link_recv_buf_validate(struct sk_buff *buf)
    {
    	static u32 min_data_hdr_size[8] = {
    		SHORT_H_SIZE, MCAST_H_SIZE, NAMED_H_SIZE, BASIC_H_SIZE,
    		MAX_H_SIZE, MAX_H_SIZE, MAX_H_SIZE, MAX_H_SIZE
    		};
    
    	struct tipc_msg *msg;
    	u32 tipc_hdr[2];
    	u32 size;
    	u32 hdr_size;
    	u32 min_hdr_size;
    
    	/* If this packet comes from the defer queue, the skb has already
    	 * been validated
    	 */
    	if (unlikely(TIPC_SKB_CB(buf)->deferred))
    		return 1;
    
    	if (unlikely(buf->len < MIN_H_SIZE))
    		return 0;
    
    	msg = skb_header_pointer(buf, 0, sizeof(tipc_hdr), tipc_hdr);
    	if (msg == NULL)
    		return 0;
    
    	if (unlikely(msg_version(msg) != TIPC_VERSION))
    		return 0;
    
    	size = msg_size(msg);
    	hdr_size = msg_hdr_sz(msg);
    	min_hdr_size = msg_isdata(msg) ?
    		min_data_hdr_size[msg_type(msg)] : INT_H_SIZE;
    
    	if (unlikely((hdr_size < min_hdr_size) ||
    		     (size < hdr_size) ||
    		     (buf->len < size) ||
    		     (size - hdr_size > TIPC_MAX_USER_MSG_SIZE)))
    		return 0;
    
    	return pskb_may_pull(buf, hdr_size);
    }
    
    /**
     * tipc_rcv - process TIPC packets/messages arriving from off-node
     * @net: the applicable net namespace
     * @skb: TIPC packet
     * @b_ptr: pointer to bearer message arrived on
     *
     * Invoked with no locks held.  Bearer pointer must point to a valid bearer
     * structure (i.e. cannot be NULL), but bearer can be inactive.
     */
    void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
    {
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    	struct sk_buff_head head;
    	struct tipc_node *n_ptr;
    	struct tipc_link *l_ptr;
    	struct sk_buff *skb1, *tmp;
    	struct tipc_msg *msg;
    	u32 seq_no;
    	u32 ackd;
    	u32 released;
    
    	skb2list(skb, &head);
    
    	while ((skb = __skb_dequeue(&head))) {
    		/* Ensure message is well-formed */
    		if (unlikely(!link_recv_buf_validate(skb)))
    			goto discard;
    
    		/* Ensure message data is a single contiguous unit */
    		if (unlikely(skb_linearize(skb)))
    			goto discard;
    
    		/* Handle arrival of a non-unicast link message */
    		msg = buf_msg(skb);
    
    		if (unlikely(msg_non_seq(msg))) {
    			if (msg_user(msg) ==  LINK_CONFIG)
    				tipc_disc_rcv(net, skb, b_ptr);
    			else
    				tipc_bclink_rcv(net, skb);
    			continue;
    		}
    
    		/* Discard unicast link messages destined for another node */
    		if (unlikely(!msg_short(msg) &&
    			     (msg_destnode(msg) != tn->own_addr)))
    			goto discard;
    
    		/* Locate neighboring node that sent message */
    		n_ptr = tipc_node_find(net, msg_prevnode(msg));
    		if (unlikely(!n_ptr))
    			goto discard;
    		tipc_node_lock(n_ptr);
    
    		/* Locate unicast link endpoint that should handle message */
    		l_ptr = n_ptr->links[b_ptr->identity];
    		if (unlikely(!l_ptr))
    			goto unlock;
    
    		/* Verify that communication with node is currently allowed */
    		if ((n_ptr->action_flags & TIPC_WAIT_PEER_LINKS_DOWN) &&
    		    msg_user(msg) == LINK_PROTOCOL &&
    		    (msg_type(msg) == RESET_MSG ||
    		    msg_type(msg) == ACTIVATE_MSG) &&
    		    !msg_redundant_link(msg))
    			n_ptr->action_flags &= ~TIPC_WAIT_PEER_LINKS_DOWN;
    
    		if (tipc_node_blocked(n_ptr))
    			goto unlock;
    
    		/* Validate message sequence number info */
    		seq_no = msg_seqno(msg);
    		ackd = msg_ack(msg);
    
    		/* Release acked messages */
    		if (n_ptr->bclink.recv_permitted)
    			tipc_bclink_acknowledge(n_ptr, msg_bcast_ack(msg));
    
    		released = 0;
    		skb_queue_walk_safe(&l_ptr->outqueue, skb1, tmp) {
    			if (skb1 == l_ptr->next_out ||
    			    more(buf_seqno(skb1), ackd))
    				break;
    			 __skb_unlink(skb1, &l_ptr->outqueue);
    			 kfree_skb(skb1);
    			 released = 1;
    		}
    
    		/* Try sending any messages link endpoint has pending */
    		if (unlikely(l_ptr->next_out))
    			tipc_link_push_packets(l_ptr);
    
    		if (released && !skb_queue_empty(&l_ptr->wakeupq))
    			link_prepare_wakeup(l_ptr);
    
    		/* Process the incoming packet */
    		if (unlikely(!link_working_working(l_ptr))) {
    			if (msg_user(msg) == LINK_PROTOCOL) {
    				tipc_link_proto_rcv(l_ptr, skb);
    				link_retrieve_defq(l_ptr, &head);
    				skb = NULL;
    				goto unlock;
    			}
    
    			/* Traffic message. Conditionally activate link */
    			link_state_event(l_ptr, TRAFFIC_MSG_EVT);
    
    			if (link_working_working(l_ptr)) {
    				/* Re-insert buffer in front of queue */
    				__skb_queue_head(&head, skb);
    				skb = NULL;
    				goto unlock;
    			}
    			goto unlock;
    		}
    
    		/* Link is now in state WORKING_WORKING */
    		if (unlikely(seq_no != mod(l_ptr->next_in_no))) {
    			link_handle_out_of_seq_msg(l_ptr, skb);
    			link_retrieve_defq(l_ptr, &head);
    			skb = NULL;
    			goto unlock;
    		}
    		l_ptr->next_in_no++;
    		if (unlikely(!skb_queue_empty(&l_ptr->deferred_queue)))
    			link_retrieve_defq(l_ptr, &head);
    
    		if (unlikely(++l_ptr->unacked_window >= TIPC_MIN_LINK_WIN)) {
    			l_ptr->stats.sent_acks++;
    			tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
    		}
    		tipc_link_input(l_ptr, skb);
    		skb = NULL;
    unlock:
    		tipc_node_unlock(n_ptr);
    discard:
    		if (unlikely(skb))
    			kfree_skb(skb);
    	}
    }
    
    /* tipc_data_input - deliver data and name distr msgs to upper layer
     *
     * Consumes buffer if message is of right type
     * Node lock must be held
     */
    static bool tipc_data_input(struct tipc_link *link, struct sk_buff *skb)
    {
    	struct tipc_node *node = link->owner;
    	struct tipc_msg *msg = buf_msg(skb);
    	u32 dport = msg_destport(msg);
    
    	switch (msg_user(msg)) {
    	case TIPC_LOW_IMPORTANCE:
    	case TIPC_MEDIUM_IMPORTANCE:
    	case TIPC_HIGH_IMPORTANCE:
    	case TIPC_CRITICAL_IMPORTANCE:
    	case CONN_MANAGER:
    		if (tipc_skb_queue_tail(&link->inputq, skb, dport)) {
    			node->inputq = &link->inputq;
    			node->action_flags |= TIPC_MSG_EVT;
    		}
    		return true;
    	case NAME_DISTRIBUTOR:
    		node->bclink.recv_permitted = true;
    		node->namedq = &link->namedq;
    		skb_queue_tail(&link->namedq, skb);
    		if (skb_queue_len(&link->namedq) == 1)
    			node->action_flags |= TIPC_NAMED_MSG_EVT;
    		return true;
    	case MSG_BUNDLER:
    	case CHANGEOVER_PROTOCOL:
    	case MSG_FRAGMENTER:
    	case BCAST_PROTOCOL:
    		return false;
    	default:
    		pr_warn("Dropping received illegal msg type\n");
    		kfree_skb(skb);
    		return false;
    	};
    }
    
    /* tipc_link_input - process packet that has passed link protocol check
     *
     * Consumes buffer
     * Node lock must be held
     */
    static void tipc_link_input(struct tipc_link *link, struct sk_buff *skb)
    {
    	struct tipc_node *node = link->owner;
    	struct tipc_msg *msg = buf_msg(skb);
    	struct sk_buff *iskb;
    	int pos = 0;
    
    	if (likely(tipc_data_input(link, skb)))
    		return;
    
    	switch (msg_user(msg)) {
    	case CHANGEOVER_PROTOCOL:
    		if (!tipc_link_tunnel_rcv(node, &skb))
    			break;
    		if (msg_user(buf_msg(skb)) != MSG_BUNDLER) {
    			tipc_data_input(link, skb);
    			break;
    		}
    	case MSG_BUNDLER:
    		link->stats.recv_bundles++;
    		link->stats.recv_bundled += msg_msgcnt(msg);
    
    		while (tipc_msg_extract(skb, &iskb, &pos))
    			tipc_data_input(link, iskb);
    		break;
    	case MSG_FRAGMENTER:
    		link->stats.recv_fragments++;
    		if (tipc_buf_append(&link->reasm_buf, &skb)) {
    			link->stats.recv_fragmented++;
    			tipc_data_input(link, skb);
    		} else if (!link->reasm_buf) {
    			tipc_link_reset(link);
    		}
    		break;
    	case BCAST_PROTOCOL:
    		tipc_link_sync_rcv(node, skb);
    		break;
    	default:
    		break;
    	};
    }
    
    /**
     * tipc_link_defer_pkt - Add out-of-sequence message to deferred reception queue
     *
     * Returns increase in queue length (i.e. 0 or 1)
     */
    u32 tipc_link_defer_pkt(struct sk_buff_head *list, struct sk_buff *skb)
    {
    	struct sk_buff *skb1;
    	u32 seq_no = buf_seqno(skb);
    
    	/* Empty queue ? */
    	if (skb_queue_empty(list)) {
    		__skb_queue_tail(list, skb);
    		return 1;
    	}
    
    	/* Last ? */
    	if (less(buf_seqno(skb_peek_tail(list)), seq_no)) {
    		__skb_queue_tail(list, skb);
    		return 1;
    	}
    
    	/* Locate insertion point in queue, then insert; discard if duplicate */
    	skb_queue_walk(list, skb1) {
    		u32 curr_seqno = buf_seqno(skb1);
    
    		if (seq_no == curr_seqno) {
    			kfree_skb(skb);
    			return 0;
    		}
    
    		if (less(seq_no, curr_seqno))
    			break;
    	}
    
    	__skb_queue_before(list, skb1, skb);
    	return 1;
    }
    
    /*
     * link_handle_out_of_seq_msg - handle arrival of out-of-sequence packet
     */
    static void link_handle_out_of_seq_msg(struct tipc_link *l_ptr,
    				       struct sk_buff *buf)
    {
    	u32 seq_no = buf_seqno(buf);
    
    	if (likely(msg_user(buf_msg(buf)) == LINK_PROTOCOL)) {
    		tipc_link_proto_rcv(l_ptr, buf);
    		return;
    	}
    
    	/* Record OOS packet arrival (force mismatch on next timeout) */
    	l_ptr->checkpoint--;
    
    	/*
    	 * Discard packet if a duplicate; otherwise add it to deferred queue
    	 * and notify peer of gap as per protocol specification
    	 */
    	if (less(seq_no, mod(l_ptr->next_in_no))) {
    		l_ptr->stats.duplicates++;
    		kfree_skb(buf);
    		return;
    	}
    
    	if (tipc_link_defer_pkt(&l_ptr->deferred_queue, buf)) {
    		l_ptr->stats.deferred_recv++;
    		TIPC_SKB_CB(buf)->deferred = true;
    		if ((skb_queue_len(&l_ptr->deferred_queue) % 16) == 1)
    			tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
    	} else {
    		l_ptr->stats.duplicates++;
    	}
    }
    
    /*
     * Send protocol message to the other endpoint.
     */
    void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
    			  u32 gap, u32 tolerance, u32 priority, u32 ack_mtu)
    {
    	struct sk_buff *buf = NULL;
    	struct tipc_msg *msg = l_ptr->pmsg;
    	u32 msg_size = sizeof(l_ptr->proto_msg);
    	int r_flag;
    
    	/* Don't send protocol message during link changeover */
    	if (l_ptr->exp_msg_count)
    		return;
    
    	/* Abort non-RESET send if communication with node is prohibited */
    	if ((tipc_node_blocked(l_ptr->owner)) && (msg_typ != RESET_MSG))
    		return;
    
    	/* Create protocol message with "out-of-sequence" sequence number */
    	msg_set_type(msg, msg_typ);
    	msg_set_net_plane(msg, l_ptr->net_plane);
    	msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
    	msg_set_last_bcast(msg, tipc_bclink_get_last_sent(l_ptr->owner->net));
    
    	if (msg_typ == STATE_MSG) {
    		u32 next_sent = mod(l_ptr->next_out_no);
    
    		if (!tipc_link_is_up(l_ptr))
    			return;
    		if (l_ptr->next_out)
    			next_sent = buf_seqno(l_ptr->next_out);
    		msg_set_next_sent(msg, next_sent);
    		if (!skb_queue_empty(&l_ptr->deferred_queue)) {
    			u32 rec = buf_seqno(skb_peek(&l_ptr->deferred_queue));
    			gap = mod(rec - mod(l_ptr->next_in_no));
    		}
    		msg_set_seq_gap(msg, gap);
    		if (gap)
    			l_ptr->stats.sent_nacks++;
    		msg_set_link_tolerance(msg, tolerance);
    		msg_set_linkprio(msg, priority);
    		msg_set_max_pkt(msg, ack_mtu);
    		msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
    		msg_set_probe(msg, probe_msg != 0);
    		if (probe_msg) {
    			u32 mtu = l_ptr->max_pkt;
    
    			if ((mtu < l_ptr->max_pkt_target) &&
    			    link_working_working(l_ptr) &&
    			    l_ptr->fsm_msg_cnt) {
    				msg_size = (mtu + (l_ptr->max_pkt_target - mtu)/2 + 2) & ~3;
    				if (l_ptr->max_pkt_probes == 10) {
    					l_ptr->max_pkt_target = (msg_size - 4);
    					l_ptr->max_pkt_probes = 0;
    					msg_size = (mtu + (l_ptr->max_pkt_target - mtu)/2 + 2) & ~3;
    				}
    				l_ptr->max_pkt_probes++;
    			}
    
    			l_ptr->stats.sent_probes++;
    		}
    		l_ptr->stats.sent_states++;
    	} else {		/* RESET_MSG or ACTIVATE_MSG */
    		msg_set_ack(msg, mod(l_ptr->reset_checkpoint - 1));
    		msg_set_seq_gap(msg, 0);
    		msg_set_next_sent(msg, 1);
    		msg_set_probe(msg, 0);
    		msg_set_link_tolerance(msg, l_ptr->tolerance);
    		msg_set_linkprio(msg, l_ptr->priority);
    		msg_set_max_pkt(msg, l_ptr->max_pkt_target);
    	}
    
    	r_flag = (l_ptr->owner->working_links > tipc_link_is_up(l_ptr));
    	msg_set_redundant_link(msg, r_flag);
    	msg_set_linkprio(msg, l_ptr->priority);
    	msg_set_size(msg, msg_size);
    
    	msg_set_seqno(msg, mod(l_ptr->next_out_no + (0xffff/2)));
    
    	buf = tipc_buf_acquire(msg_size);
    	if (!buf)
    		return;
    
    	skb_copy_to_linear_data(buf, msg, sizeof(l_ptr->proto_msg));
    	buf->priority = TC_PRIO_CONTROL;
    
    	tipc_bearer_send(l_ptr->owner->net, l_ptr->bearer_id, buf,
    			 &l_ptr->media_addr);
    	l_ptr->unacked_window = 0;
    	kfree_skb(buf);
    }
    
    /*
     * Receive protocol message :
     * Note that network plane id propagates through the network, and may
     * change at any time. The node with lowest address rules
     */
    static void tipc_link_proto_rcv(struct tipc_link *l_ptr,
    				struct sk_buff *buf)
    {
    	u32 rec_gap = 0;
    	u32 max_pkt_info;
    	u32 max_pkt_ack;
    	u32 msg_tol;
    	struct tipc_msg *msg = buf_msg(buf);
    
    	/* Discard protocol message during link changeover */
    	if (l_ptr->exp_msg_count)
    		goto exit;
    
    	if (l_ptr->net_plane != msg_net_plane(msg))
    		if (link_own_addr(l_ptr) > msg_prevnode(msg))
    			l_ptr->net_plane = msg_net_plane(msg);
    
    	switch (msg_type(msg)) {
    
    	case RESET_MSG:
    		if (!link_working_unknown(l_ptr) &&
    		    (l_ptr->peer_session != INVALID_SESSION)) {
    			if (less_eq(msg_session(msg), l_ptr->peer_session))
    				break; /* duplicate or old reset: ignore */
    		}
    
    		if (!msg_redundant_link(msg) && (link_working_working(l_ptr) ||
    				link_working_unknown(l_ptr))) {
    			/*
    			 * peer has lost contact -- don't allow peer's links
    			 * to reactivate before we recognize loss & clean up
    			 */
    			l_ptr->owner->action_flags |= TIPC_WAIT_OWN_LINKS_DOWN;
    		}
    
    		link_state_event(l_ptr, RESET_MSG);
    
    		/* fall thru' */
    	case ACTIVATE_MSG:
    		/* Update link settings according other endpoint's values */
    		strcpy((strrchr(l_ptr->name, ':') + 1), (char *)msg_data(msg));
    
    		msg_tol = msg_link_tolerance(msg);
    		if (msg_tol > l_ptr->tolerance)
    			link_set_supervision_props(l_ptr, msg_tol);
    
    		if (msg_linkprio(msg) > l_ptr->priority)
    			l_ptr->priority = msg_linkprio(msg);
    
    		max_pkt_info = msg_max_pkt(msg);
    		if (max_pkt_info) {
    			if (max_pkt_info < l_ptr->max_pkt_target)
    				l_ptr->max_pkt_target = max_pkt_info;
    			if (l_ptr->max_pkt > l_ptr->max_pkt_target)
    				l_ptr->max_pkt = l_ptr->max_pkt_target;
    		} else {
    			l_ptr->max_pkt = l_ptr->max_pkt_target;
    		}
    
    		/* Synchronize broadcast link info, if not done previously */
    		if (!tipc_node_is_up(l_ptr->owner)) {
    			l_ptr->owner->bclink.last_sent =
    				l_ptr->owner->bclink.last_in =
    				msg_last_bcast(msg);
    			l_ptr->owner->bclink.oos_state = 0;
    		}
    
    		l_ptr->peer_session = msg_session(msg);
    		l_ptr->peer_bearer_id = msg_bearer_id(msg);
    
    		if (msg_type(msg) == ACTIVATE_MSG)
    			link_state_event(l_ptr, ACTIVATE_MSG);
    		break;
    	case STATE_MSG:
    
    		msg_tol = msg_link_tolerance(msg);
    		if (msg_tol)
    			link_set_supervision_props(l_ptr, msg_tol);
    
    		if (msg_linkprio(msg) &&
    		    (msg_linkprio(msg) != l_ptr->priority)) {
    			pr_debug("%s<%s>, priority change %u->%u\n",
    				 link_rst_msg, l_ptr->name,
    				 l_ptr->priority, msg_linkprio(msg));
    			l_ptr->priority = msg_linkprio(msg);
    			tipc_link_reset(l_ptr); /* Enforce change to take effect */
    			break;
    		}
    
    		/* Record reception; force mismatch at next timeout: */
    		l_ptr->checkpoint--;
    
    		link_state_event(l_ptr, TRAFFIC_MSG_EVT);
    		l_ptr->stats.recv_states++;
    		if (link_reset_unknown(l_ptr))
    			break;
    
    		if (less_eq(mod(l_ptr->next_in_no), msg_next_sent(msg))) {
    			rec_gap = mod(msg_next_sent(msg) -
    				      mod(l_ptr->next_in_no));
    		}
    
    		max_pkt_ack = msg_max_pkt(msg);
    		if (max_pkt_ack > l_ptr->max_pkt) {
    			l_ptr->max_pkt = max_pkt_ack;
    			l_ptr->max_pkt_probes = 0;
    		}
    
    		max_pkt_ack = 0;
    		if (msg_probe(msg)) {
    			l_ptr->stats.recv_probes++;
    			if (msg_size(msg) > sizeof(l_ptr->proto_msg))
    				max_pkt_ack = msg_size(msg);
    		}
    
    		/* Protocol message before retransmits, reduce loss risk */
    		if (l_ptr->owner->bclink.recv_permitted)
    			tipc_bclink_update_link_state(l_ptr->owner,
    						      msg_last_bcast(msg));
    
    		if (rec_gap || (msg_probe(msg))) {
    			tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, rec_gap, 0,
    					     0, max_pkt_ack);
    		}
    		if (msg_seq_gap(msg)) {
    			l_ptr->stats.recv_nacks++;
    			tipc_link_retransmit(l_ptr, skb_peek(&l_ptr->outqueue),
    					     msg_seq_gap(msg));
    		}
    		break;
    	}
    exit:
    	kfree_skb(buf);
    }
    
    
    /* tipc_link_tunnel_xmit(): Tunnel one packet via a link belonging to
     * a different bearer. Owner node is locked.
     */
    static void tipc_link_tunnel_xmit(struct tipc_link *l_ptr,
    				  struct tipc_msg *tunnel_hdr,
    				  struct tipc_msg *msg,
    				  u32 selector)
    {
    	struct tipc_link *tunnel;
    	struct sk_buff *skb;
    	u32 length = msg_size(msg);
    
    	tunnel = l_ptr->owner->active_links[selector & 1];
    	if (!tipc_link_is_up(tunnel)) {
    		pr_warn("%stunnel link no longer available\n", link_co_err);
    		return;
    	}
    	msg_set_size(tunnel_hdr, length + INT_H_SIZE);
    	skb = tipc_buf_acquire(length + INT_H_SIZE);
    	if (!skb) {
    		pr_warn("%sunable to send tunnel msg\n", link_co_err);
    		return;
    	}
    	skb_copy_to_linear_data(skb, tunnel_hdr, INT_H_SIZE);
    	skb_copy_to_linear_data_offset(skb, INT_H_SIZE, msg, length);
    	__tipc_link_xmit_skb(tunnel, skb);
    }
    
    
    /* tipc_link_failover_send_queue(): A link has gone down, but a second
     * link is still active. We can do failover. Tunnel the failing link's
     * whole send queue via the remaining link. This way, we don't lose
     * any packets, and sequence order is preserved for subsequent traffic
     * sent over the remaining link. Owner node is locked.
     */
    void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
    {
    	u32 msgcount = skb_queue_len(&l_ptr->outqueue);
    	struct tipc_link *tunnel = l_ptr->owner->active_links[0];
    	struct tipc_msg tunnel_hdr;
    	struct sk_buff *skb;
    	int split_bundles;
    
    	if (!tunnel)
    		return;
    
    	tipc_msg_init(link_own_addr(l_ptr), &tunnel_hdr, CHANGEOVER_PROTOCOL,
    		      ORIGINAL_MSG, INT_H_SIZE, l_ptr->addr);
    	msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
    	msg_set_msgcnt(&tunnel_hdr, msgcount);
    
    	if (skb_queue_empty(&l_ptr->outqueue)) {
    		skb = tipc_buf_acquire(INT_H_SIZE);
    		if (skb) {
    			skb_copy_to_linear_data(skb, &tunnel_hdr, INT_H_SIZE);
    			msg_set_size(&tunnel_hdr, INT_H_SIZE);
    			__tipc_link_xmit_skb(tunnel, skb);
    		} else {
    			pr_warn("%sunable to send changeover msg\n",
    				link_co_err);
    		}
    		return;
    	}
    
    	split_bundles = (l_ptr->owner->active_links[0] !=
    			 l_ptr->owner->active_links[1]);
    
    	skb_queue_walk(&l_ptr->outqueue, skb) {
    		struct tipc_msg *msg = buf_msg(skb);
    
    		if ((msg_user(msg) == MSG_BUNDLER) && split_bundles) {
    			struct tipc_msg *m = msg_get_wrapped(msg);
    			unchar *pos = (unchar *)m;
    
    			msgcount = msg_msgcnt(msg);
    			while (msgcount--) {
    				msg_set_seqno(m, msg_seqno(msg));
    				tipc_link_tunnel_xmit(l_ptr, &tunnel_hdr, m,
    						      msg_link_selector(m));
    				pos += align(msg_size(m));
    				m = (struct tipc_msg *)pos;
    			}
    		} else {
    			tipc_link_tunnel_xmit(l_ptr, &tunnel_hdr, msg,
    					      msg_link_selector(msg));
    		}
    	}
    }
    
    /* tipc_link_dup_queue_xmit(): A second link has become active. Tunnel a
     * duplicate of the first link's send queue via the new link. This way, we
     * are guaranteed that currently queued packets from a socket are delivered
     * before future traffic from the same socket, even if this is using the
     * new link. The last arriving copy of each duplicate packet is dropped at
     * the receiving end by the regular protocol check, so packet cardinality
     * and sequence order is preserved per sender/receiver socket pair.
     * Owner node is locked.
     */
    void tipc_link_dup_queue_xmit(struct tipc_link *l_ptr,
    			      struct tipc_link *tunnel)
    {
    	struct sk_buff *skb;
    	struct tipc_msg tunnel_hdr;
    
    	tipc_msg_init(link_own_addr(l_ptr), &tunnel_hdr, CHANGEOVER_PROTOCOL,
    		      DUPLICATE_MSG, INT_H_SIZE, l_ptr->addr);
    	msg_set_msgcnt(&tunnel_hdr, skb_queue_len(&l_ptr->outqueue));
    	msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
    	skb_queue_walk(&l_ptr->outqueue, skb) {
    		struct sk_buff *outskb;
    		struct tipc_msg *msg = buf_msg(skb);
    		u32 length = msg_size(msg);
    
    		if (msg_user(msg) == MSG_BUNDLER)
    			msg_set_type(msg, CLOSED_MSG);
    		msg_set_ack(msg, mod(l_ptr->next_in_no - 1));	/* Update */
    		msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
    		msg_set_size(&tunnel_hdr, length + INT_H_SIZE);
    		outskb = tipc_buf_acquire(length + INT_H_SIZE);
    		if (outskb == NULL) {
    			pr_warn("%sunable to send duplicate msg\n",
    				link_co_err);
    			return;
    		}
    		skb_copy_to_linear_data(outskb, &tunnel_hdr, INT_H_SIZE);
    		skb_copy_to_linear_data_offset(outskb, INT_H_SIZE, skb->data,
    					       length);
    		__tipc_link_xmit_skb(tunnel, outskb);
    		if (!tipc_link_is_up(l_ptr))
    			return;
    	}
    }
    
    /**
     * buf_extract - extracts embedded TIPC message from another message
     * @skb: encapsulating message buffer
     * @from_pos: offset to extract from
     *
     * Returns a new message buffer containing an embedded message.  The
     * encapsulating buffer is left unchanged.
     */
    static struct sk_buff *buf_extract(struct sk_buff *skb, u32 from_pos)
    {
    	struct tipc_msg *msg = (struct tipc_msg *)(skb->data + from_pos);
    	u32 size = msg_size(msg);
    	struct sk_buff *eb;
    
    	eb = tipc_buf_acquire(size);
    	if (eb)
    		skb_copy_to_linear_data(eb, msg, size);
    	return eb;
    }
    
    /* tipc_link_dup_rcv(): Receive a tunnelled DUPLICATE_MSG packet.
     * Owner node is locked.
     */
    static void tipc_link_dup_rcv(struct tipc_link *l_ptr,
    			      struct sk_buff *t_buf)
    {
    	struct sk_buff *buf;
    
    	if (!tipc_link_is_up(l_ptr))
    		return;
    
    	buf = buf_extract(t_buf, INT_H_SIZE);
    	if (buf == NULL) {
    		pr_warn("%sfailed to extract inner dup pkt\n", link_co_err);
    		return;
    	}
    
    	/* Add buffer to deferred queue, if applicable: */
    	link_handle_out_of_seq_msg(l_ptr, buf);
    }
    
    /*  tipc_link_failover_rcv(): Receive a tunnelled ORIGINAL_MSG packet
     *  Owner node is locked.
     */
    static struct sk_buff *tipc_link_failover_rcv(struct tipc_link *l_ptr,
    					      struct sk_buff *t_buf)
    {
    	struct tipc_msg *t_msg = buf_msg(t_buf);
    	struct sk_buff *buf = NULL;
    	struct tipc_msg *msg;
    
    	if (tipc_link_is_up(l_ptr))
    		tipc_link_reset(l_ptr);
    
    	/* First failover packet? */
    	if (l_ptr->exp_msg_count == START_CHANGEOVER)
    		l_ptr->exp_msg_count = msg_msgcnt(t_msg);
    
    	/* Should there be an inner packet? */
    	if (l_ptr->exp_msg_count) {
    		l_ptr->exp_msg_count--;
    		buf = buf_extract(t_buf, INT_H_SIZE);
    		if (buf == NULL) {
    			pr_warn("%sno inner failover pkt\n", link_co_err);
    			goto exit;
    		}
    		msg = buf_msg(buf);
    
    		if (less(msg_seqno(msg), l_ptr->reset_checkpoint)) {
    			kfree_skb(buf);
    			buf = NULL;
    			goto exit;
    		}
    		if (msg_user(msg) == MSG_FRAGMENTER) {
    			l_ptr->stats.recv_fragments++;
    			tipc_buf_append(&l_ptr->reasm_buf, &buf);
    		}
    	}
    exit:
    	if ((!l_ptr->exp_msg_count) && (l_ptr->flags & LINK_STOPPED))
    		tipc_link_delete(l_ptr);
    	return buf;
    }
    
    /*  tipc_link_tunnel_rcv(): Receive a tunnelled packet, sent
     *  via other link as result of a failover (ORIGINAL_MSG) or
     *  a new active link (DUPLICATE_MSG). Failover packets are
     *  returned to the active link for delivery upwards.
     *  Owner node is locked.
     */
    static int tipc_link_tunnel_rcv(struct tipc_node *n_ptr,
    				struct sk_buff **buf)
    {
    	struct sk_buff *t_buf = *buf;
    	struct tipc_link *l_ptr;
    	struct tipc_msg *t_msg = buf_msg(t_buf);
    	u32 bearer_id = msg_bearer_id(t_msg);
    
    	*buf = NULL;
    
    	if (bearer_id >= MAX_BEARERS)
    		goto exit;
    
    	l_ptr = n_ptr->links[bearer_id];
    	if (!l_ptr)
    		goto exit;
    
    	if (msg_type(t_msg) == DUPLICATE_MSG)
    		tipc_link_dup_rcv(l_ptr, t_buf);
    	else if (msg_type(t_msg) == ORIGINAL_MSG)
    		*buf = tipc_link_failover_rcv(l_ptr, t_buf);
    	else
    		pr_warn("%sunknown tunnel pkt received\n", link_co_err);
    exit:
    	kfree_skb(t_buf);
    	return *buf != NULL;
    }
    
    static void link_set_supervision_props(struct tipc_link *l_ptr, u32 tol)
    {
    	unsigned long intv = ((tol / 4) > 500) ? 500 : tol / 4;
    
    	if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
    		return;
    
    	l_ptr->tolerance = tol;
    	l_ptr->cont_intv = msecs_to_jiffies(intv);
    	l_ptr->abort_limit = tol / (jiffies_to_msecs(l_ptr->cont_intv) / 4);
    }
    
    void tipc_link_set_queue_limits(struct tipc_link *l_ptr, u32 window)
    {
    	/* Data messages from this node, inclusive FIRST_FRAGM */
    	l_ptr->queue_limit[TIPC_LOW_IMPORTANCE] = window;
    	l_ptr->queue_limit[TIPC_MEDIUM_IMPORTANCE] = (window / 3) * 4;
    	l_ptr->queue_limit[TIPC_HIGH_IMPORTANCE] = (window / 3) * 5;
    	l_ptr->queue_limit[TIPC_CRITICAL_IMPORTANCE] = (window / 3) * 6;
    	/* Transiting data messages,inclusive FIRST_FRAGM */
    	l_ptr->queue_limit[TIPC_LOW_IMPORTANCE + 4] = 300;
    	l_ptr->queue_limit[TIPC_MEDIUM_IMPORTANCE + 4] = 600;
    	l_ptr->queue_limit[TIPC_HIGH_IMPORTANCE + 4] = 900;
    	l_ptr->queue_limit[TIPC_CRITICAL_IMPORTANCE + 4] = 1200;
    	l_ptr->queue_limit[CONN_MANAGER] = 1200;
    	l_ptr->queue_limit[CHANGEOVER_PROTOCOL] = 2500;
    	l_ptr->queue_limit[NAME_DISTRIBUTOR] = 3000;
    	/* FRAGMENT and LAST_FRAGMENT packets */
    	l_ptr->queue_limit[MSG_FRAGMENTER] = 4000;
    }
    
    /* tipc_link_find_owner - locate owner node of link by link's name
     * @net: the applicable net namespace
     * @name: pointer to link name string
     * @bearer_id: pointer to index in 'node->links' array where the link was found.
     *
     * Returns pointer to node owning the link, or 0 if no matching link is found.
     */
    static struct tipc_node *tipc_link_find_owner(struct net *net,
    					      const char *link_name,
    					      unsigned int *bearer_id)
    {
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    	struct tipc_link *l_ptr;
    	struct tipc_node *n_ptr;
    	struct tipc_node *found_node = NULL;
    	int i;
    
    	*bearer_id = 0;
    	rcu_read_lock();
    	list_for_each_entry_rcu(n_ptr, &tn->node_list, list) {
    		tipc_node_lock(n_ptr);
    		for (i = 0; i < MAX_BEARERS; i++) {
    			l_ptr = n_ptr->links[i];
    			if (l_ptr && !strcmp(l_ptr->name, link_name)) {
    				*bearer_id = i;
    				found_node = n_ptr;
    				break;
    			}
    		}
    		tipc_node_unlock(n_ptr);
    		if (found_node)
    			break;
    	}
    	rcu_read_unlock();
    
    	return found_node;
    }
    
    /**
     * link_reset_statistics - reset link statistics
     * @l_ptr: pointer to link
     */
    static void link_reset_statistics(struct tipc_link *l_ptr)
    {
    	memset(&l_ptr->stats, 0, sizeof(l_ptr->stats));
    	l_ptr->stats.sent_info = l_ptr->next_out_no;
    	l_ptr->stats.recv_info = l_ptr->next_in_no;
    }
    
    static void link_print(struct tipc_link *l_ptr, const char *str)
    {
    	struct tipc_net *tn = net_generic(l_ptr->owner->net, tipc_net_id);
    	struct tipc_bearer *b_ptr;
    
    	rcu_read_lock();
    	b_ptr = rcu_dereference_rtnl(tn->bearer_list[l_ptr->bearer_id]);
    	if (b_ptr)
    		pr_info("%s Link %x<%s>:", str, l_ptr->addr, b_ptr->name);
    	rcu_read_unlock();
    
    	if (link_working_unknown(l_ptr))
    		pr_cont(":WU\n");
    	else if (link_reset_reset(l_ptr))
    		pr_cont(":RR\n");
    	else if (link_reset_unknown(l_ptr))
    		pr_cont(":RU\n");
    	else if (link_working_working(l_ptr))
    		pr_cont(":WW\n");
    	else
    		pr_cont("\n");
    }
    
    /* Parse and validate nested (link) properties valid for media, bearer and link
     */
    int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
    {
    	int err;
    
    	err = nla_parse_nested(props, TIPC_NLA_PROP_MAX, prop,
    			       tipc_nl_prop_policy);
    	if (err)
    		return err;
    
    	if (props[TIPC_NLA_PROP_PRIO]) {
    		u32 prio;
    
    		prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
    		if (prio > TIPC_MAX_LINK_PRI)
    			return -EINVAL;
    	}
    
    	if (props[TIPC_NLA_PROP_TOL]) {
    		u32 tol;
    
    		tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
    		if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
    			return -EINVAL;
    	}
    
    	if (props[TIPC_NLA_PROP_WIN]) {
    		u32 win;
    
    		win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
    		if ((win < TIPC_MIN_LINK_WIN) || (win > TIPC_MAX_LINK_WIN))
    			return -EINVAL;
    	}
    
    	return 0;
    }
    
    int tipc_nl_link_set(struct sk_buff *skb, struct genl_info *info)
    {
    	int err;
    	int res = 0;
    	int bearer_id;
    	char *name;
    	struct tipc_link *link;
    	struct tipc_node *node;
    	struct nlattr *attrs[TIPC_NLA_LINK_MAX + 1];
    	struct net *net = sock_net(skb->sk);
    
    	if (!info->attrs[TIPC_NLA_LINK])
    		return -EINVAL;
    
    	err = nla_parse_nested(attrs, TIPC_NLA_LINK_MAX,
    			       info->attrs[TIPC_NLA_LINK],
    			       tipc_nl_link_policy);
    	if (err)
    		return err;
    
    	if (!attrs[TIPC_NLA_LINK_NAME])
    		return -EINVAL;
    
    	name = nla_data(attrs[TIPC_NLA_LINK_NAME]);
    
    	node = tipc_link_find_owner(net, name, &bearer_id);
    	if (!node)
    		return -EINVAL;
    
    	tipc_node_lock(node);
    
    	link = node->links[bearer_id];
    	if (!link) {
    		res = -EINVAL;
    		goto out;
    	}
    
    	if (attrs[TIPC_NLA_LINK_PROP]) {
    		struct nlattr *props[TIPC_NLA_PROP_MAX + 1];
    
    		err = tipc_nl_parse_link_prop(attrs[TIPC_NLA_LINK_PROP],
    					      props);
    		if (err) {
    			res = err;
    			goto out;
    		}
    
    		if (props[TIPC_NLA_PROP_TOL]) {
    			u32 tol;
    
    			tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
    			link_set_supervision_props(link, tol);
    			tipc_link_proto_xmit(link, STATE_MSG, 0, 0, tol, 0, 0);
    		}
    		if (props[TIPC_NLA_PROP_PRIO]) {
    			u32 prio;
    
    			prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
    			link->priority = prio;
    			tipc_link_proto_xmit(link, STATE_MSG, 0, 0, 0, prio, 0);
    		}
    		if (props[TIPC_NLA_PROP_WIN]) {
    			u32 win;
    
    			win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
    			tipc_link_set_queue_limits(link, win);
    		}
    	}
    
    out:
    	tipc_node_unlock(node);
    
    	return res;
    }
    
    static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
    {
    	int i;
    	struct nlattr *stats;
    
    	struct nla_map {
    		u32 key;
    		u32 val;
    	};
    
    	struct nla_map map[] = {
    		{TIPC_NLA_STATS_RX_INFO, s->recv_info},
    		{TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
    		{TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
    		{TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
    		{TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
    		{TIPC_NLA_STATS_TX_INFO, s->sent_info},
    		{TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
    		{TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
    		{TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
    		{TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
    		{TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
    			s->msg_length_counts : 1},
    		{TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
    		{TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
    		{TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
    		{TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
    		{TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
    		{TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
    		{TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
    		{TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
    		{TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
    		{TIPC_NLA_STATS_RX_STATES, s->recv_states},
    		{TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
    		{TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
    		{TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
    		{TIPC_NLA_STATS_TX_STATES, s->sent_states},
    		{TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
    		{TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
    		{TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
    		{TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
    		{TIPC_NLA_STATS_DUPLICATES, s->duplicates},
    		{TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
    		{TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
    		{TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
    			(s->accu_queue_sz / s->queue_sz_counts) : 0}
    	};
    
    	stats = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
    	if (!stats)
    		return -EMSGSIZE;
    
    	for (i = 0; i <  ARRAY_SIZE(map); i++)
    		if (nla_put_u32(skb, map[i].key, map[i].val))
    			goto msg_full;
    
    	nla_nest_end(skb, stats);
    
    	return 0;
    msg_full:
    	nla_nest_cancel(skb, stats);
    
    	return -EMSGSIZE;
    }
    
    /* Caller should hold appropriate locks to protect the link */
    static int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
    			      struct tipc_link *link)
    {
    	int err;
    	void *hdr;
    	struct nlattr *attrs;
    	struct nlattr *prop;
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    
    	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
    			  NLM_F_MULTI, TIPC_NL_LINK_GET);
    	if (!hdr)
    		return -EMSGSIZE;
    
    	attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
    	if (!attrs)
    		goto msg_full;
    
    	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
    		goto attr_msg_full;
    	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST,
    			tipc_cluster_mask(tn->own_addr)))
    		goto attr_msg_full;
    	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->max_pkt))
    		goto attr_msg_full;
    	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->next_in_no))
    		goto attr_msg_full;
    	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->next_out_no))
    		goto attr_msg_full;
    
    	if (tipc_link_is_up(link))
    		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
    			goto attr_msg_full;
    	if (tipc_link_is_active(link))
    		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
    			goto attr_msg_full;
    
    	prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
    	if (!prop)
    		goto attr_msg_full;
    	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
    		goto prop_msg_full;
    	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
    		goto prop_msg_full;
    	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
    			link->queue_limit[TIPC_LOW_IMPORTANCE]))
    		goto prop_msg_full;
    	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
    		goto prop_msg_full;
    	nla_nest_end(msg->skb, prop);
    
    	err = __tipc_nl_add_stats(msg->skb, &link->stats);
    	if (err)
    		goto attr_msg_full;
    
    	nla_nest_end(msg->skb, attrs);
    	genlmsg_end(msg->skb, hdr);
    
    	return 0;
    
    prop_msg_full:
    	nla_nest_cancel(msg->skb, prop);
    attr_msg_full:
    	nla_nest_cancel(msg->skb, attrs);
    msg_full:
    	genlmsg_cancel(msg->skb, hdr);
    
    	return -EMSGSIZE;
    }
    
    /* Caller should hold node lock  */
    static int __tipc_nl_add_node_links(struct net *net, struct tipc_nl_msg *msg,
    				    struct tipc_node *node, u32 *prev_link)
    {
    	u32 i;
    	int err;
    
    	for (i = *prev_link; i < MAX_BEARERS; i++) {
    		*prev_link = i;
    
    		if (!node->links[i])
    			continue;
    
    		err = __tipc_nl_add_link(net, msg, node->links[i]);
    		if (err)
    			return err;
    	}
    	*prev_link = 0;
    
    	return 0;
    }
    
    int tipc_nl_link_dump(struct sk_buff *skb, struct netlink_callback *cb)
    {
    	struct net *net = sock_net(skb->sk);
    	struct tipc_net *tn = net_generic(net, tipc_net_id);
    	struct tipc_node *node;
    	struct tipc_nl_msg msg;
    	u32 prev_node = cb->args[0];
    	u32 prev_link = cb->args[1];
    	int done = cb->args[2];
    	int err;
    
    	if (done)
    		return 0;
    
    	msg.skb = skb;
    	msg.portid = NETLINK_CB(cb->skb).portid;
    	msg.seq = cb->nlh->nlmsg_seq;
    
    	rcu_read_lock();
    
    	if (prev_node) {
    		node = tipc_node_find(net, prev_node);
    		if (!node) {
    			/* We never set seq or call nl_dump_check_consistent()
    			 * this means that setting prev_seq here will cause the
    			 * consistence check to fail in the netlink callback
    			 * handler. Resulting in the last NLMSG_DONE message
    			 * having the NLM_F_DUMP_INTR flag set.
    			 */
    			cb->prev_seq = 1;
    			goto out;
    		}
    
    		list_for_each_entry_continue_rcu(node, &tn->node_list,
    						 list) {
    			tipc_node_lock(node);
    			err = __tipc_nl_add_node_links(net, &msg, node,
    						       &prev_link);
    			tipc_node_unlock(node);
    			if (err)
    				goto out;
    
    			prev_node = node->addr;
    		}
    	} else {
    		err = tipc_nl_add_bc_link(net, &msg);
    		if (err)
    			goto out;
    
    		list_for_each_entry_rcu(node, &tn->node_list, list) {
    			tipc_node_lock(node);
    			err = __tipc_nl_add_node_links(net, &msg, node,
    						       &prev_link);
    			tipc_node_unlock(node);
    			if (err)
    				goto out;
    
    			prev_node = node->addr;
    		}
    	}
    	done = 1;
    out:
    	rcu_read_unlock();
    
    	cb->args[0] = prev_node;
    	cb->args[1] = prev_link;
    	cb->args[2] = done;
    
    	return skb->len;
    }
    
    int tipc_nl_link_get(struct sk_buff *skb, struct genl_info *info)
    {
    	struct net *net = genl_info_net(info);
    	struct sk_buff *ans_skb;
    	struct tipc_nl_msg msg;
    	struct tipc_link *link;
    	struct tipc_node *node;
    	char *name;
    	int bearer_id;
    	int err;
    
    	if (!info->attrs[TIPC_NLA_LINK_NAME])
    		return -EINVAL;
    
    	name = nla_data(info->attrs[TIPC_NLA_LINK_NAME]);
    	node = tipc_link_find_owner(net, name, &bearer_id);
    	if (!node)
    		return -EINVAL;
    
    	ans_skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
    	if (!ans_skb)
    		return -ENOMEM;
    
    	msg.skb = ans_skb;
    	msg.portid = info->snd_portid;
    	msg.seq = info->snd_seq;
    
    	tipc_node_lock(node);
    	link = node->links[bearer_id];
    	if (!link) {
    		err = -EINVAL;
    		goto err_out;
    	}
    
    	err = __tipc_nl_add_link(net, &msg, link);
    	if (err)
    		goto err_out;
    
    	tipc_node_unlock(node);
    
    	return genlmsg_reply(ans_skb, info);
    
    err_out:
    	tipc_node_unlock(node);
    	nlmsg_free(ans_skb);
    
    	return err;
    }
    
    int tipc_nl_link_reset_stats(struct sk_buff *skb, struct genl_info *info)
    {
    	int err;
    	char *link_name;
    	unsigned int bearer_id;
    	struct tipc_link *link;
    	struct tipc_node *node;
    	struct nlattr *attrs[TIPC_NLA_LINK_MAX + 1];
    	struct net *net = sock_net(skb->sk);
    
    	if (!info->attrs[TIPC_NLA_LINK])
    		return -EINVAL;
    
    	err = nla_parse_nested(attrs, TIPC_NLA_LINK_MAX,
    			       info->attrs[TIPC_NLA_LINK],
    			       tipc_nl_link_policy);
    	if (err)
    		return err;
    
    	if (!attrs[TIPC_NLA_LINK_NAME])
    		return -EINVAL;
    
    	link_name = nla_data(attrs[TIPC_NLA_LINK_NAME]);
    
    	if (strcmp(link_name, tipc_bclink_name) == 0) {
    		err = tipc_bclink_reset_stats(net);
    		if (err)
    			return err;
    		return 0;
    	}
    
    	node = tipc_link_find_owner(net, link_name, &bearer_id);
    	if (!node)
    		return -EINVAL;
    
    	tipc_node_lock(node);
    
    	link = node->links[bearer_id];
    	if (!link) {
    		tipc_node_unlock(node);
    		return -EINVAL;
    	}
    
    	link_reset_statistics(link);
    
    	tipc_node_unlock(node);
    
    	return 0;
    }