link.c 85.4 KB
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/*
 * net/tipc/link.c: TIPC link code
 * 
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 * Copyright (c) 1996-2006, Ericsson AB
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 * Copyright (c) 2004-2006, Wind River Systems
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 * All rights reserved.
 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions are met:
 *
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 * 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.
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 *
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 * 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
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 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "core.h"
#include "dbg.h"
#include "link.h"
#include "net.h"
#include "node.h"
#include "port.h"
#include "addr.h"
#include "node_subscr.h"
#include "name_distr.h"
#include "bearer.h"
#include "name_table.h"
#include "discover.h"
#include "config.h"
#include "bcast.h"


/* 
 * Limit for deferred reception queue: 
 */

#define DEF_QUEUE_LIMIT 256u

/* 
 * 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

/**
 * struct link_name - deconstructed link name
 * @addr_local: network address of node at this end
 * @if_local: name of interface at this end
 * @addr_peer: network address of node at far end
 * @if_peer: name of interface at far end
 */

struct link_name {
	u32 addr_local;
	char if_local[TIPC_MAX_IF_NAME];
	u32 addr_peer;
	char if_peer[TIPC_MAX_IF_NAME];
};

#if 0

/* LINK EVENT CODE IS NOT SUPPORTED AT PRESENT */

/** 
 * struct link_event - link up/down event notification
 */

struct link_event {
	u32 addr;
	int up;
	void (*fcn)(u32, char *, int);
	char name[TIPC_MAX_LINK_NAME];
};

#endif

static void link_handle_out_of_seq_msg(struct link *l_ptr,
				       struct sk_buff *buf);
static void link_recv_proto_msg(struct link *l_ptr, struct sk_buff *buf);
static int  link_recv_changeover_msg(struct link **l_ptr, struct sk_buff **buf);
static void link_set_supervision_props(struct link *l_ptr, u32 tolerance);
static int  link_send_sections_long(struct port *sender,
				    struct iovec const *msg_sect,
				    u32 num_sect, u32 destnode);
static void link_check_defragm_bufs(struct link *l_ptr);
static void link_state_event(struct link *l_ptr, u32 event);
static void link_reset_statistics(struct link *l_ptr);
static void link_print(struct link *l_ptr, struct print_buf *buf, 
		       const char *str);

/*
 * Debugging code used by link routines only
 *
 * When debugging link problems on a system that has multiple links,
 * the standard TIPC debugging routines may not be useful since they
 * allow the output from multiple links to be intermixed.  For this reason
 * routines of the form "dbg_link_XXX()" have been created that will capture
 * debug info into a link's personal print buffer, which can then be dumped
 * into the TIPC system log (LOG) upon request.
 *
 * To enable per-link debugging, use LINK_LOG_BUF_SIZE to specify the size
 * of the print buffer used by each link.  If LINK_LOG_BUF_SIZE is set to 0,
 * the dbg_link_XXX() routines simply send their output to the standard 
 * debug print buffer (DBG_OUTPUT), if it has been defined; this can be useful
 * when there is only a single link in the system being debugged.
 *
 * Notes:
 * - When enabled, LINK_LOG_BUF_SIZE should be set to at least 1000 (bytes)
 * - "l_ptr" must be valid when using dbg_link_XXX() macros  
 */

#define LINK_LOG_BUF_SIZE 0

#define dbg_link(fmt, arg...)  do {if (LINK_LOG_BUF_SIZE) tipc_printf(&l_ptr->print_buf, fmt, ## arg); } while(0)
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#define dbg_link_msg(msg, txt) do {if (LINK_LOG_BUF_SIZE) tipc_msg_print(&l_ptr->print_buf, msg, txt); } while(0)
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#define dbg_link_state(txt) do {if (LINK_LOG_BUF_SIZE) link_print(l_ptr, &l_ptr->print_buf, txt); } while(0)
#define dbg_link_dump() do { \
	if (LINK_LOG_BUF_SIZE) { \
		tipc_printf(LOG, "\n\nDumping link <%s>:\n", l_ptr->name); \
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		tipc_printbuf_move(LOG, &l_ptr->print_buf); \
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	} \
} while (0)

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static void dbg_print_link(struct link *l_ptr, const char *str)
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{
	if (DBG_OUTPUT)
		link_print(l_ptr, DBG_OUTPUT, str);
}

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static void dbg_print_buf_chain(struct sk_buff *root_buf)
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{
	if (DBG_OUTPUT) {
		struct sk_buff *buf = root_buf;

		while (buf) {
			msg_dbg(buf_msg(buf), "In chain: ");
			buf = buf->next;
		}
	}
}

/*
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 *  Simple link routines
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 */

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static unsigned int align(unsigned int i)
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{
	return (i + 3) & ~3u;
}

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static int link_working_working(struct link *l_ptr)
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{
	return (l_ptr->state == WORKING_WORKING);
}

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static int link_working_unknown(struct link *l_ptr)
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{
	return (l_ptr->state == WORKING_UNKNOWN);
}

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static int link_reset_unknown(struct link *l_ptr)
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{
	return (l_ptr->state == RESET_UNKNOWN);
}

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static int link_reset_reset(struct link *l_ptr)
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{
	return (l_ptr->state == RESET_RESET);
}

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static int link_blocked(struct link *l_ptr)
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{
	return (l_ptr->exp_msg_count || l_ptr->blocked);
}

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static int link_congested(struct link *l_ptr)
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{
	return (l_ptr->out_queue_size >= l_ptr->queue_limit[0]);
}

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static u32 link_max_pkt(struct link *l_ptr)
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{
	return l_ptr->max_pkt;
}

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static void link_init_max_pkt(struct link *l_ptr)
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{
	u32 max_pkt;
	
	max_pkt = (l_ptr->b_ptr->publ.mtu & ~3);
	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;
}

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static u32 link_next_sent(struct link *l_ptr)
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{
	if (l_ptr->next_out)
		return msg_seqno(buf_msg(l_ptr->next_out));
	return mod(l_ptr->next_out_no);
}

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static u32 link_last_sent(struct link *l_ptr)
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{
	return mod(link_next_sent(l_ptr) - 1);
}

/*
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 *  Simple non-static link routines (i.e. referenced outside this file)
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 */

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int tipc_link_is_up(struct link *l_ptr)
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{
	if (!l_ptr)
		return 0;
	return (link_working_working(l_ptr) || link_working_unknown(l_ptr));
}

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int tipc_link_is_active(struct link *l_ptr)
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{
	return ((l_ptr->owner->active_links[0] == l_ptr) ||
		(l_ptr->owner->active_links[1] == l_ptr));
}

/**
 * link_name_validate - validate & (optionally) deconstruct link name
 * @name - ptr to link name string
 * @name_parts - ptr to area for link name components (or NULL if not needed)
 * 
 * Returns 1 if link name is valid, otherwise 0.
 */

static int link_name_validate(const char *name, struct link_name *name_parts)
{
	char name_copy[TIPC_MAX_LINK_NAME];
	char *addr_local;
	char *if_local;
	char *addr_peer;
	char *if_peer;
	char dummy;
	u32 z_local, c_local, n_local;
	u32 z_peer, c_peer, n_peer;
	u32 if_local_len;
	u32 if_peer_len;

	/* copy link name & ensure length is OK */

	name_copy[TIPC_MAX_LINK_NAME - 1] = 0;
	/* need above in case non-Posix strncpy() doesn't pad with nulls */
	strncpy(name_copy, name, TIPC_MAX_LINK_NAME);
	if (name_copy[TIPC_MAX_LINK_NAME - 1] != 0)
		return 0;

	/* ensure all component parts of link name are present */

	addr_local = name_copy;
	if ((if_local = strchr(addr_local, ':')) == NULL)
		return 0;
	*(if_local++) = 0;
	if ((addr_peer = strchr(if_local, '-')) == NULL)
		return 0;
	*(addr_peer++) = 0;
	if_local_len = addr_peer - if_local;
	if ((if_peer = strchr(addr_peer, ':')) == NULL)
		return 0;
	*(if_peer++) = 0;
	if_peer_len = strlen(if_peer) + 1;

	/* validate component parts of link name */

	if ((sscanf(addr_local, "%u.%u.%u%c",
		    &z_local, &c_local, &n_local, &dummy) != 3) ||
	    (sscanf(addr_peer, "%u.%u.%u%c",
		    &z_peer, &c_peer, &n_peer, &dummy) != 3) ||
	    (z_local > 255) || (c_local > 4095) || (n_local > 4095) ||
	    (z_peer  > 255) || (c_peer  > 4095) || (n_peer  > 4095) ||
	    (if_local_len <= 1) || (if_local_len > TIPC_MAX_IF_NAME) || 
	    (if_peer_len  <= 1) || (if_peer_len  > TIPC_MAX_IF_NAME) || 
	    (strspn(if_local, tipc_alphabet) != (if_local_len - 1)) ||
	    (strspn(if_peer, tipc_alphabet) != (if_peer_len - 1)))
		return 0;

	/* return link name components, if necessary */

	if (name_parts) {
		name_parts->addr_local = tipc_addr(z_local, c_local, n_local);
		strcpy(name_parts->if_local, if_local);
		name_parts->addr_peer = tipc_addr(z_peer, c_peer, n_peer);
		strcpy(name_parts->if_peer, if_peer);
	}
	return 1;
}

/**
 * link_timeout - handle expiration of link timer
 * @l_ptr: pointer to link
 * 
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 * This routine must not grab "tipc_net_lock" to avoid a potential deadlock conflict
 * with tipc_link_delete().  (There is no risk that the node will be deleted by
 * another thread because tipc_link_delete() always cancels the link timer before
 * tipc_node_delete() is called.)
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 */

static void link_timeout(struct link *l_ptr)
{
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	tipc_node_lock(l_ptr->owner);
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	/* update counters used in statistical profiling of send traffic */

	l_ptr->stats.accu_queue_sz += l_ptr->out_queue_size;
	l_ptr->stats.queue_sz_counts++;

	if (l_ptr->out_queue_size > l_ptr->stats.max_queue_sz)
		l_ptr->stats.max_queue_sz = l_ptr->out_queue_size;

	if (l_ptr->first_out) {
		struct tipc_msg *msg = buf_msg(l_ptr->first_out);
		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_check_defragm_bufs(l_ptr);

	link_state_event(l_ptr, TIMEOUT_EVT);

	if (l_ptr->next_out)
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		tipc_link_push_queue(l_ptr);
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	tipc_node_unlock(l_ptr->owner);
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}

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static void link_set_timer(struct link *l_ptr, u32 time)
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{
	k_start_timer(&l_ptr->timer, time);
}

/**
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 * tipc_link_create - create a new link
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 * @b_ptr: pointer to associated bearer
 * @peer: network address of node at other end of link
 * @media_addr: media address to use when sending messages over link
 * 
 * Returns pointer to link.
 */

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struct link *tipc_link_create(struct bearer *b_ptr, const u32 peer,
			      const struct tipc_media_addr *media_addr)
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{
	struct link *l_ptr;
	struct tipc_msg *msg;
	char *if_name;

	l_ptr = (struct link *)kmalloc(sizeof(*l_ptr), GFP_ATOMIC);
	if (!l_ptr) {
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		warn("Link creation failed, no memory\n");
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		return NULL;
	}
	memset(l_ptr, 0, sizeof(*l_ptr));

	l_ptr->addr = peer;
	if_name = strchr(b_ptr->publ.name, ':') + 1;
	sprintf(l_ptr->name, "%u.%u.%u:%s-%u.%u.%u:",
		tipc_zone(tipc_own_addr), tipc_cluster(tipc_own_addr),
		tipc_node(tipc_own_addr), 
		if_name,
		tipc_zone(peer), tipc_cluster(peer), tipc_node(peer));
		/* note: peer i/f is appended to link name by reset/activate */
	memcpy(&l_ptr->media_addr, media_addr, sizeof(*media_addr));
	k_init_timer(&l_ptr->timer, (Handler)link_timeout, (unsigned long)l_ptr);
	list_add_tail(&l_ptr->link_list, &b_ptr->links);
	l_ptr->checkpoint = 1;
	l_ptr->b_ptr = b_ptr;
	link_set_supervision_props(l_ptr, b_ptr->media->tolerance);
	l_ptr->state = RESET_UNKNOWN;

	l_ptr->pmsg = (struct tipc_msg *)&l_ptr->proto_msg;
	msg = l_ptr->pmsg;
	msg_init(msg, LINK_PROTOCOL, RESET_MSG, TIPC_OK, INT_H_SIZE, l_ptr->addr);
	msg_set_size(msg, sizeof(l_ptr->proto_msg));
	msg_set_session(msg, tipc_random);
	msg_set_bearer_id(msg, b_ptr->identity);
	strcpy((char *)msg_data(msg), if_name);

	l_ptr->priority = b_ptr->priority;
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	tipc_link_set_queue_limits(l_ptr, b_ptr->media->window);
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	link_init_max_pkt(l_ptr);

	l_ptr->next_out_no = 1;
	INIT_LIST_HEAD(&l_ptr->waiting_ports);

	link_reset_statistics(l_ptr);

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	l_ptr->owner = tipc_node_attach_link(l_ptr);
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	if (!l_ptr->owner) {
		kfree(l_ptr);
		return NULL;
	}

	if (LINK_LOG_BUF_SIZE) {
		char *pb = kmalloc(LINK_LOG_BUF_SIZE, GFP_ATOMIC);

		if (!pb) {
			kfree(l_ptr);
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			warn("Link creation failed, no memory for print buffer\n");
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			return NULL;
		}
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		tipc_printbuf_init(&l_ptr->print_buf, pb, LINK_LOG_BUF_SIZE);
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	}

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	tipc_k_signal((Handler)tipc_link_start, (unsigned long)l_ptr);
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	dbg("tipc_link_create(): tolerance = %u,cont intv = %u, abort_limit = %u\n",
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	    l_ptr->tolerance, l_ptr->continuity_interval, l_ptr->abort_limit);
	
	return l_ptr;
}

/** 
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 * tipc_link_delete - delete a link
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 * @l_ptr: pointer to link
 * 
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 * Note: 'tipc_net_lock' is write_locked, bearer is locked.
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 * This routine must not grab the node lock until after link timer cancellation
 * to avoid a potential deadlock situation.  
 */

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void tipc_link_delete(struct link *l_ptr)
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{
	if (!l_ptr) {
		err("Attempt to delete non-existent link\n");
		return;
	}

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	dbg("tipc_link_delete()\n");
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	k_cancel_timer(&l_ptr->timer);
	
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	tipc_node_lock(l_ptr->owner);
	tipc_link_reset(l_ptr);
	tipc_node_detach_link(l_ptr->owner, l_ptr);
	tipc_link_stop(l_ptr);
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	list_del_init(&l_ptr->link_list);
	if (LINK_LOG_BUF_SIZE)
		kfree(l_ptr->print_buf.buf);
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	tipc_node_unlock(l_ptr->owner);
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	k_term_timer(&l_ptr->timer);
	kfree(l_ptr);
}

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void tipc_link_start(struct link *l_ptr)
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{
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	dbg("tipc_link_start %x\n", l_ptr);
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	link_state_event(l_ptr, STARTING_EVT);
}

/**
 * link_schedule_port - schedule port for deferred sending 
 * @l_ptr: pointer to link
 * @origport: reference to sending port
 * @sz: amount of data to be sent
 * 
 * Schedules port for renewed sending of messages after link congestion 
 * has abated.
 */

static int link_schedule_port(struct link *l_ptr, u32 origport, u32 sz)
{
	struct port *p_ptr;

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	spin_lock_bh(&tipc_port_list_lock);
	p_ptr = tipc_port_lock(origport);
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	if (p_ptr) {
		if (!p_ptr->wakeup)
			goto exit;
		if (!list_empty(&p_ptr->wait_list))
			goto exit;
		p_ptr->congested_link = l_ptr;
		p_ptr->publ.congested = 1;
		p_ptr->waiting_pkts = 1 + ((sz - 1) / link_max_pkt(l_ptr));
		list_add_tail(&p_ptr->wait_list, &l_ptr->waiting_ports);
		l_ptr->stats.link_congs++;
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		tipc_port_unlock(p_ptr);
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	}
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	spin_unlock_bh(&tipc_port_list_lock);
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	return -ELINKCONG;
}

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void tipc_link_wakeup_ports(struct link *l_ptr, int all)
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{
	struct port *p_ptr;
	struct port *temp_p_ptr;
	int win = l_ptr->queue_limit[0] - l_ptr->out_queue_size;

	if (all)
		win = 100000;
	if (win <= 0)
		return;
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	if (!spin_trylock_bh(&tipc_port_list_lock))
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		return;
	if (link_congested(l_ptr))
		goto exit;
	list_for_each_entry_safe(p_ptr, temp_p_ptr, &l_ptr->waiting_ports, 
				 wait_list) {
		if (win <= 0)
			break;
		list_del_init(&p_ptr->wait_list);
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		p_ptr->congested_link = NULL;
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		spin_lock_bh(p_ptr->publ.lock);
		p_ptr->publ.congested = 0;
		p_ptr->wakeup(&p_ptr->publ);
		win -= p_ptr->waiting_pkts;
		spin_unlock_bh(p_ptr->publ.lock);
	}

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	spin_unlock_bh(&tipc_port_list_lock);
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}

/** 
 * link_release_outqueue - purge link's outbound message queue
 * @l_ptr: pointer to link
 */

static void link_release_outqueue(struct link *l_ptr)
{
	struct sk_buff *buf = l_ptr->first_out;
	struct sk_buff *next;

	while (buf) {
		next = buf->next;
		buf_discard(buf);
		buf = next;
	}
	l_ptr->first_out = NULL;
	l_ptr->out_queue_size = 0;
}

/**
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 * tipc_link_reset_fragments - purge link's inbound message fragments queue
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 * @l_ptr: pointer to link
 */

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void tipc_link_reset_fragments(struct link *l_ptr)
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{
	struct sk_buff *buf = l_ptr->defragm_buf;
	struct sk_buff *next;

	while (buf) {
		next = buf->next;
		buf_discard(buf);
		buf = next;
	}
	l_ptr->defragm_buf = NULL;
}

/** 
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 * tipc_link_stop - purge all inbound and outbound messages associated with link
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 * @l_ptr: pointer to link
 */

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void tipc_link_stop(struct link *l_ptr)
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{
	struct sk_buff *buf;
	struct sk_buff *next;

	buf = l_ptr->oldest_deferred_in;
	while (buf) {
		next = buf->next;
		buf_discard(buf);
		buf = next;
	}

	buf = l_ptr->first_out;
	while (buf) {
		next = buf->next;
		buf_discard(buf);
		buf = next;
	}

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	tipc_link_reset_fragments(l_ptr);
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	buf_discard(l_ptr->proto_msg_queue);
	l_ptr->proto_msg_queue = NULL;
}

#if 0

/* LINK EVENT CODE IS NOT SUPPORTED AT PRESENT */

static void link_recv_event(struct link_event *ev)
{
	ev->fcn(ev->addr, ev->name, ev->up);
	kfree(ev);
}

static void link_send_event(void (*fcn)(u32 a, char *n, int up),
			    struct link *l_ptr, int up)
{
	struct link_event *ev;
	
	ev = kmalloc(sizeof(*ev), GFP_ATOMIC);
	if (!ev) {
		warn("Link event allocation failure\n");
		return;
	}
	ev->addr = l_ptr->addr;
	ev->up = up;
	ev->fcn = fcn;
	memcpy(ev->name, l_ptr->name, TIPC_MAX_LINK_NAME);
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	tipc_k_signal((Handler)link_recv_event, (unsigned long)ev);
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}

#else

#define link_send_event(fcn, l_ptr, up) do { } while (0)

#endif

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void tipc_link_reset(struct link *l_ptr)
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{
	struct sk_buff *buf;
	u32 prev_state = l_ptr->state;
	u32 checkpoint = l_ptr->next_in_no;
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	int was_active_link = tipc_link_is_active(l_ptr);
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	msg_set_session(l_ptr->pmsg, msg_session(l_ptr->pmsg) + 1);

        /* Link is down, accept any session: */
	l_ptr->peer_session = 0;

        /* Prepare for max packet size negotiation */
	link_init_max_pkt(l_ptr);
	
	l_ptr->state = RESET_UNKNOWN;
	dbg_link_state("Resetting Link\n");

	if ((prev_state == RESET_UNKNOWN) || (prev_state == RESET_RESET))
		return;

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	tipc_node_link_down(l_ptr->owner, l_ptr);
	tipc_bearer_remove_dest(l_ptr->b_ptr, l_ptr->addr);
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#if 0
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	tipc_printf(TIPC_CONS, "\nReset link <%s>\n", l_ptr->name);
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	dbg_link_dump();
#endif
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	if (was_active_link && tipc_node_has_active_links(l_ptr->owner) &&
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	    l_ptr->owner->permit_changeover) {
		l_ptr->reset_checkpoint = checkpoint;
		l_ptr->exp_msg_count = START_CHANGEOVER;
	}

	/* Clean up all queues: */

	link_release_outqueue(l_ptr);
	buf_discard(l_ptr->proto_msg_queue);
	l_ptr->proto_msg_queue = NULL;
	buf = l_ptr->oldest_deferred_in;
	while (buf) {
		struct sk_buff *next = buf->next;
		buf_discard(buf);
		buf = next;
	}
	if (!list_empty(&l_ptr->waiting_ports))
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		tipc_link_wakeup_ports(l_ptr, 1);
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	l_ptr->retransm_queue_head = 0;
	l_ptr->retransm_queue_size = 0;
	l_ptr->last_out = NULL;
	l_ptr->first_out = NULL;
	l_ptr->next_out = NULL;
	l_ptr->unacked_window = 0;
	l_ptr->checkpoint = 1;
	l_ptr->next_out_no = 1;
	l_ptr->deferred_inqueue_sz = 0;
	l_ptr->oldest_deferred_in = NULL;
	l_ptr->newest_deferred_in = NULL;
	l_ptr->fsm_msg_cnt = 0;
	l_ptr->stale_count = 0;
	link_reset_statistics(l_ptr);

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	link_send_event(tipc_cfg_link_event, l_ptr, 0);
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	if (!in_own_cluster(l_ptr->addr))
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		link_send_event(tipc_disc_link_event, l_ptr, 0);
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}


static void link_activate(struct link *l_ptr)
{
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	l_ptr->next_in_no = l_ptr->stats.recv_info = 1;
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	tipc_node_link_up(l_ptr->owner, l_ptr);
	tipc_bearer_add_dest(l_ptr->b_ptr, l_ptr->addr);
	link_send_event(tipc_cfg_link_event, l_ptr, 1);
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	if (!in_own_cluster(l_ptr->addr))
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		link_send_event(tipc_disc_link_event, l_ptr, 1);
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}

/**
 * link_state_event - link finite state machine
 * @l_ptr: pointer to link
 * @event: state machine event to process
 */

static void link_state_event(struct link *l_ptr, unsigned event)
{
	struct link *other; 
	u32 cont_intv = l_ptr->continuity_interval;

	if (!l_ptr->started && (event != STARTING_EVT))
		return;		/* Not yet. */

	if (link_blocked(l_ptr)) {
		if (event == TIMEOUT_EVT) {
			link_set_timer(l_ptr, cont_intv);
		}
		return;	  /* Changeover going on */
	}
	dbg_link("STATE_EV: <%s> ", l_ptr->name);

	switch (l_ptr->state) {
	case WORKING_WORKING:
		dbg_link("WW/");
		switch (event) {
		case TRAFFIC_MSG_EVT:
			dbg_link("TRF-");
			/* fall through */
		case ACTIVATE_MSG:
			dbg_link("ACT\n");
			break;
		case TIMEOUT_EVT:
			dbg_link("TIM ");
			if (l_ptr->next_in_no != l_ptr->checkpoint) {
				l_ptr->checkpoint = l_ptr->next_in_no;
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				if (tipc_bclink_acks_missing(l_ptr->owner)) {
					tipc_link_send_proto_msg(l_ptr, STATE_MSG, 
								 0, 0, 0, 0, 0);
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					l_ptr->fsm_msg_cnt++;
				} else if (l_ptr->max_pkt < l_ptr->max_pkt_target) {
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					tipc_link_send_proto_msg(l_ptr, STATE_MSG, 
								 1, 0, 0, 0, 0);
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					l_ptr->fsm_msg_cnt++;
				}
				link_set_timer(l_ptr, cont_intv);
				break;
			}
			dbg_link(" -> WU\n");
			l_ptr->state = WORKING_UNKNOWN;
			l_ptr->fsm_msg_cnt = 0;
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			tipc_link_send_proto_msg(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
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			l_ptr->fsm_msg_cnt++;
			link_set_timer(l_ptr, cont_intv / 4);
			break;
		case RESET_MSG:
			dbg_link("RES -> RR\n");
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			info("Resetting link <%s>, requested by peer\n", 
			     l_ptr->name);
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			tipc_link_reset(l_ptr);
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			l_ptr->state = RESET_RESET;
			l_ptr->fsm_msg_cnt = 0;
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			tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 0, 0, 0, 0, 0);
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			l_ptr->fsm_msg_cnt++;
			link_set_timer(l_ptr, cont_intv);
			break;
		default:
			err("Unknown link event %u in WW state\n", event);
		}
		break;
	case WORKING_UNKNOWN:
		dbg_link("WU/");
		switch (event) {
		case TRAFFIC_MSG_EVT:
			dbg_link("TRF-");
		case ACTIVATE_MSG:
			dbg_link("ACT -> WW\n");
			l_ptr->state = WORKING_WORKING;
			l_ptr->fsm_msg_cnt = 0;
			link_set_timer(l_ptr, cont_intv);
			break;
		case RESET_MSG:
			dbg_link("RES -> RR\n");
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			info("Resetting link <%s>, requested by peer "
			     "while probing\n", l_ptr->name);
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			tipc_link_reset(l_ptr);
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			l_ptr->state = RESET_RESET;
			l_ptr->fsm_msg_cnt = 0;
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			tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 0, 0, 0, 0, 0);
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			l_ptr->fsm_msg_cnt++;
			link_set_timer(l_ptr, cont_intv);
			break;
		case TIMEOUT_EVT:
			dbg_link("TIM ");
			if (l_ptr->next_in_no != l_ptr->checkpoint) {
				dbg_link("-> WW \n");
				l_ptr->state = WORKING_WORKING;
				l_ptr->fsm_msg_cnt = 0;
				l_ptr->checkpoint = l_ptr->next_in_no;
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				if (tipc_bclink_acks_missing(l_ptr->owner)) {
					tipc_link_send_proto_msg(l_ptr, STATE_MSG,
								 0, 0, 0, 0, 0);
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					l_ptr->fsm_msg_cnt++;
				}
				link_set_timer(l_ptr, cont_intv);
			} else if (l_ptr->fsm_msg_cnt < l_ptr->abort_limit) {
				dbg_link("Probing %u/%u,timer = %u ms)\n",
					 l_ptr->fsm_msg_cnt, l_ptr->abort_limit,
					 cont_intv / 4);
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				tipc_link_send_proto_msg(l_ptr, STATE_MSG, 
							 1, 0, 0, 0, 0);
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				l_ptr->fsm_msg_cnt++;
				link_set_timer(l_ptr, cont_intv / 4);
			} else {	/* Link has failed */
				dbg_link("-> RU (%u probes unanswered)\n",
					 l_ptr->fsm_msg_cnt);
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				warn("Resetting link <%s>, peer not responding\n",
				     l_ptr->name);
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				tipc_link_reset(l_ptr);
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				l_ptr->state = RESET_UNKNOWN;
				l_ptr->fsm_msg_cnt = 0;
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				tipc_link_send_proto_msg(l_ptr, RESET_MSG,
							 0, 0, 0, 0, 0);
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				l_ptr->fsm_msg_cnt++;
				link_set_timer(l_ptr, cont_intv);
			}
			break;
		default:
			err("Unknown link event %u in WU state\n", event);
		}
		break;
	case RESET_UNKNOWN:
		dbg_link("RU/");
		switch (event) {
		case TRAFFIC_MSG_EVT:
			dbg_link("TRF-\n");
			break;
		case ACTIVATE_MSG:
			other = l_ptr->owner->active_links[0];
			if (other && link_working_unknown(other)) {
				dbg_link("ACT\n");
				break;
			}
			dbg_link("ACT -> WW\n");
			l_ptr->state = WORKING_WORKING;
			l_ptr->fsm_msg_cnt = 0;
			link_activate(l_ptr);
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			tipc_link_send_proto_msg(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
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			l_ptr->fsm_msg_cnt++;
			link_set_timer(l_ptr, cont_intv);
			break;
		case RESET_MSG:
			dbg_link("RES \n");
			dbg_link(" -> RR\n");
			l_ptr->state = RESET_RESET;
			l_ptr->fsm_msg_cnt = 0;
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			tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 1, 0, 0, 0, 0);
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			l_ptr->fsm_msg_cnt++;
			link_set_timer(l_ptr, cont_intv);
			break;
		case STARTING_EVT:
			dbg_link("START-");
			l_ptr->started = 1;
			/* fall through */
		case TIMEOUT_EVT:
			dbg_link("TIM \n");
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			tipc_link_send_proto_msg(l_ptr, RESET_MSG, 0, 0, 0, 0, 0);
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			l_ptr->fsm_msg_cnt++;
			link_set_timer(l_ptr, cont_intv);
			break;
		default:
			err("Unknown link event %u in RU state\n", event);
		}
		break;
	case RESET_RESET:
		dbg_link("RR/ ");
		switch (event) {
		case TRAFFIC_MSG_EVT:
			dbg_link("TRF-");
			/* fall through */
		case ACTIVATE_MSG:
			other = l_ptr->owner->active_links[0];
			if (other && link_working_unknown(other)) {
				dbg_link("ACT\n");
				break;
			}
			dbg_link("ACT -> WW\n");
			l_ptr->state = WORKING_WORKING;
			l_ptr->fsm_msg_cnt = 0;
			link_activate(l_ptr);
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			tipc_link_send_proto_msg(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
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			l_ptr->fsm_msg_cnt++;
			link_set_timer(l_ptr, cont_intv);
			break;
		case RESET_MSG:
			dbg_link("RES\n");
			break;
		case TIMEOUT_EVT:
			dbg_link("TIM\n");
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			tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 0, 0, 0, 0, 0);
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			l_ptr->fsm_msg_cnt++;
			link_set_timer(l_ptr, cont_intv);
			dbg_link("fsm_msg_cnt %u\n", l_ptr->fsm_msg_cnt);
			break;
		default:
			err("Unknown link event %u in RR state\n", event);
		}
		break;
	default:
		err("Unknown link state %u/%u\n", l_ptr->state, event);
	}
}

/*
 * link_bundle_buf(): Append contents of a buffer to
 * the tail of an existing one. 
 */

static int link_bundle_buf(struct link *l_ptr,
			   struct sk_buff *bundler, 
			   struct sk_buff *buf)
{
	struct tipc_msg *bundler_msg = buf_msg(bundler);
	struct tipc_msg *msg = buf_msg(buf);
	u32 size = msg_size(msg);
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	u32 bundle_size = msg_size(bundler_msg);
	u32 to_pos = align(bundle_size);
	u32 pad = to_pos - bundle_size;
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	if (msg_user(bundler_msg) != MSG_BUNDLER)
		return 0;
	if (msg_type(bundler_msg) != OPEN_MSG)
		return 0;
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	if (skb_tailroom(bundler) < (pad + size))
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		return 0;
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