// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      Spanning tree protocol; timer-related code
 *      Linux ethernet bridge
 *
 *      Authors:
 *      Lennert Buytenhek               <buytenh@gnu.org>
 */

#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(struct timer_list *t)
{
        struct net_bridge *br = timer_container_of(br, t, hello_timer);

        br_debug(br, "hello timer expired\n");
        spin_lock(&br->lock);
        if (br->dev->flags & IFF_UP) {
                br_config_bpdu_generation(br);

                if (br->stp_enabled == BR_KERNEL_STP)
                        mod_timer(&br->hello_timer,
                                  round_jiffies(jiffies + br->hello_time));
        }
        spin_unlock(&br->lock);
}

static void br_message_age_timer_expired(struct timer_list *t)
{
        struct net_bridge_port *p = timer_container_of(p, t,
                                                       message_age_timer);
        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\n",
                (unsigned int) 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(struct timer_list *t)
{
        struct net_bridge_port *p = timer_container_of(p, t,
                                                       forward_delay_timer);
        struct net_bridge *br = p->br;

        br_debug(br, "port %u(%s) forward delay timer\n",
                 (unsigned int) p->port_no, p->dev->name);
        spin_lock(&br->lock);
        if (p->state == BR_STATE_LISTENING) {
                br_set_state(p, BR_STATE_LEARNING);
                mod_timer(&p->forward_delay_timer,
                          jiffies + br->forward_delay);
        } else if (p->state == BR_STATE_LEARNING) {
                br_set_state(p, BR_STATE_FORWARDING);
                if (br_is_designated_for_some_port(br))
                        br_topology_change_detection(br);
                netif_carrier_on(br->dev);
        }
        rcu_read_lock();
        br_ifinfo_notify(RTM_NEWLINK, NULL, p);
        rcu_read_unlock();
        spin_unlock(&br->lock);
}

static void br_tcn_timer_expired(struct timer_list *t)
{
        struct net_bridge *br = timer_container_of(br, t, tcn_timer);

        br_debug(br, "tcn timer expired\n");
        spin_lock(&br->lock);
        if (!br_is_root_bridge(br) && (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(struct timer_list *t)
{
        struct net_bridge *br = timer_container_of(br, t,
                                                   topology_change_timer);

        br_debug(br, "topo change timer expired\n");
        spin_lock(&br->lock);
        br->topology_change_detected = 0;
        __br_set_topology_change(br, 0);
        spin_unlock(&br->lock);
}

static void br_hold_timer_expired(struct timer_list *t)
{
        struct net_bridge_port *p = timer_container_of(p, t, hold_timer);

        br_debug(p->br, "port %u(%s) hold timer expired\n",
                 (unsigned int) 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)
{
        timer_setup(&br->hello_timer, br_hello_timer_expired, 0);
        timer_setup(&br->tcn_timer, br_tcn_timer_expired, 0);
        timer_setup(&br->topology_change_timer,
                    br_topology_change_timer_expired, 0);
}

void br_stp_port_timer_init(struct net_bridge_port *p)
{
        timer_setup(&p->message_age_timer, br_message_age_timer_expired, 0);
        timer_setup(&p->forward_delay_timer, br_forward_delay_timer_expired, 0);
        timer_setup(&p->hold_timer, br_hold_timer_expired, 0);
}

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