/*
   *	Spanning tree protocol; timer-related code
   *	Linux ethernet bridge
   *
   *	Authors:
   *	Lennert Buytenhek		<buytenh@gnu.org>
   *

   *	This program is free software; you can redistribute it and/or
   *	modify it under the terms of the GNU General Public License
   *	as published by the Free Software Foundation; either version
   *	2 of the License, or (at your option) any later version.
   */
  
  #include <linux/kernel.h>
  #include <linux/times.h>

  
  #include "br_private.h"
  #include "br_private_stp.h"
  
  /* called under bridge lock */
  static int br_is_designated_for_some_port(const struct net_bridge *br)
  {
  	struct net_bridge_port *p;
  
  	list_for_each_entry(p, &br->port_list, list) {
  		if (p->state != BR_STATE_DISABLED &&

  		    !memcmp(&p->designated_bridge, &br->bridge_id, 8))

  			return 1;
  	}
  
  	return 0;
  }
  
  static void br_hello_timer_expired(unsigned long arg)
  {
  	struct net_bridge *br = (struct net_bridge *)arg;

  	br_debug(br, "hello timer expired
  ");

  	spin_lock(&br->lock);

  	if (br->dev->flags & IFF_UP) {
  		br_config_bpdu_generation(br);

  		mod_timer(&br->hello_timer, round_jiffies(jiffies + br->hello_time));

  	}

  	spin_unlock(&br->lock);

  }
  
  static void br_message_age_timer_expired(unsigned long arg)
  {
  	struct net_bridge_port *p = (struct net_bridge_port *) arg;
  	struct net_bridge *br = p->br;
  	const bridge_id *id = &p->designated_bridge;
  	int was_root;
  
  	if (p->state == BR_STATE_DISABLED)
  		return;

  	br_info(br, "port %u(%s) neighbor %.2x%.2x.%pM lost
  ",
  		(unsigned) p->port_no, p->dev->name,
  		id->prio[0], id->prio[1], &id->addr);

  
  	/*
  	 * According to the spec, the message age timer cannot be
  	 * running when we are the root bridge. So..  this was_root
  	 * check is redundant. I'm leaving it in for now, though.
  	 */

  	spin_lock(&br->lock);

  	if (p->state == BR_STATE_DISABLED)
  		goto unlock;
  	was_root = br_is_root_bridge(br);
  
  	br_become_designated_port(p);
  	br_configuration_update(br);
  	br_port_state_selection(br);
  	if (br_is_root_bridge(br) && !was_root)
  		br_become_root_bridge(br);
   unlock:

  	spin_unlock(&br->lock);

  }
  
  static void br_forward_delay_timer_expired(unsigned long arg)
  {
  	struct net_bridge_port *p = (struct net_bridge_port *) arg;
  	struct net_bridge *br = p->br;

  	br_debug(br, "port %u(%s) forward delay timer
  ",
  		 (unsigned) p->port_no, p->dev->name);

  	spin_lock(&br->lock);

  	if (p->state == BR_STATE_LISTENING) {
  		p->state = BR_STATE_LEARNING;
  		mod_timer(&p->forward_delay_timer,
  			  jiffies + br->forward_delay);
  	} else if (p->state == BR_STATE_LEARNING) {
  		p->state = BR_STATE_FORWARDING;
  		if (br_is_designated_for_some_port(br))
  			br_topology_change_detection(br);

  		netif_carrier_on(br->dev);

  	}
  	br_log_state(p);

  	br_ifinfo_notify(RTM_NEWLINK, p);

  	spin_unlock(&br->lock);

  }
  
  static void br_tcn_timer_expired(unsigned long arg)
  {
  	struct net_bridge *br = (struct net_bridge *) arg;

  	br_debug(br, "tcn timer expired
  ");

  	spin_lock(&br->lock);

  	if (br->dev->flags & IFF_UP) {
  		br_transmit_tcn(br);

  		mod_timer(&br->tcn_timer,jiffies + br->bridge_hello_time);
  	}

  	spin_unlock(&br->lock);

  }
  
  static void br_topology_change_timer_expired(unsigned long arg)
  {
  	struct net_bridge *br = (struct net_bridge *) arg;

  	br_debug(br, "topo change timer expired
  ");

  	spin_lock(&br->lock);

  	br->topology_change_detected = 0;
  	br->topology_change = 0;

  	spin_unlock(&br->lock);

  }
  
  static void br_hold_timer_expired(unsigned long arg)
  {
  	struct net_bridge_port *p = (struct net_bridge_port *) arg;

  	br_debug(p->br, "port %u(%s) hold timer expired
  ",
  		 (unsigned) p->port_no, p->dev->name);

  	spin_lock(&p->br->lock);

  	if (p->config_pending)
  		br_transmit_config(p);

  	spin_unlock(&p->br->lock);

  }

  void br_stp_timer_init(struct net_bridge *br)
  {

  	setup_timer(&br->hello_timer, br_hello_timer_expired,

  		      (unsigned long) br);

  	setup_timer(&br->tcn_timer, br_tcn_timer_expired,

  		      (unsigned long) br);

  	setup_timer(&br->topology_change_timer,

  		      br_topology_change_timer_expired,
  		      (unsigned long) br);

  	setup_timer(&br->gc_timer, br_fdb_cleanup, (unsigned long) br);

  }
  
  void br_stp_port_timer_init(struct net_bridge_port *p)
  {

  	setup_timer(&p->message_age_timer, br_message_age_timer_expired,

  		      (unsigned long) p);

  	setup_timer(&p->forward_delay_timer, br_forward_delay_timer_expired,

  		      (unsigned long) p);

  	setup_timer(&p->hold_timer, br_hold_timer_expired,

  		      (unsigned long) p);

  }

  
  /* Report ticks left (in USER_HZ) used for API */
  unsigned long br_timer_value(const struct timer_list *timer)
  {
  	return timer_pending(timer)
  		? jiffies_to_clock_t(timer->expires - jiffies) : 0;
  }