/*
 *      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;

        pr_debug("%s: hello timer expired\n", br->dev->name);
        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;


        pr_info("%s: neighbor %.2x%.2x.%.2x:%.2x:%.2x:%.2x:%.2x:%.2x lost on port %d(%s)\n",
                br->dev->name,
                id->prio[0], id->prio[1],
                id->addr[0], id->addr[1], id->addr[2],
                id->addr[3], id->addr[4], id->addr[5],
                p->port_no, p->dev->name);

        /*
         * 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;

        pr_debug("%s: %d(%s) forward delay timer\n",
                 br->dev->name, 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);
        }
        br_log_state(p);
        spin_unlock(&br->lock);
}

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

        pr_debug("%s: tcn timer expired\n", br->dev->name);
        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;

        pr_debug("%s: topo change timer expired\n", br->dev->name);
        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;

        pr_debug("%s: %d(%s) hold timer expired\n",
                 p->br->dev->name,  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;
}