LXR linux/net/bridge/br_stp

   1/*
   2 *      Spanning tree protocol; timer-related code
   3 *      Linux ethernet bridge
   4 *
   5 *      Authors:
   6 *      Lennert Buytenhek               <buytenh@gnu.org>
   7 *
   8 *      This program is free software; you can redistribute it and/or
   9 *      modify it under the terms of the GNU General Public License
  10 *      as published by the Free Software Foundation; either version
  11 *      2 of the License, or (at your option) any later version.
  12 */
  13
  14#include <linux/kernel.h>
  15#include <linux/times.h>
  16
  17#include "br_private.h"
  18#include "br_private_stp.h"
  19
  20/* called under bridge lock */
  21static int br_is_designated_for_some_port(const struct net_bridge *br)
  22{
  23        struct net_bridge_port *p;
  24
  25        list_for_each_entry(p, &br->port_list, list) {
  26                if (p->state != BR_STATE_DISABLED &&
  27                    !memcmp(&p->designated_bridge, &br->bridge_id, 8))
  28                        return 1;
  29        }
  30
  31        return 0;
  32}
  33
  34static void br_hello_timer_expired(struct timer_list *t)
  35{
  36        struct net_bridge *br = from_timer(br, t, hello_timer);
  37
  38        br_debug(br, "hello timer expired\n");
  39        spin_lock(&br->lock);
  40        if (br->dev->flags & IFF_UP) {
  41                br_config_bpdu_generation(br);
  42
  43                if (br->stp_enabled == BR_KERNEL_STP)
  44                        mod_timer(&br->hello_timer,
  45                                  round_jiffies(jiffies + br->hello_time));
  46        }
  47        spin_unlock(&br->lock);
  48}
  49
  50static void br_message_age_timer_expired(struct timer_list *t)
  51{
  52        struct net_bridge_port *p = from_timer(p, t, message_age_timer);
  53        struct net_bridge *br = p->br;
  54        const bridge_id *id = &p->designated_bridge;
  55        int was_root;
  56
  57        if (p->state == BR_STATE_DISABLED)
  58                return;
  59
  60        br_info(br, "port %u(%s) neighbor %.2x%.2x.%pM lost\n",
  61                (unsigned int) p->port_no, p->dev->name,
  62                id->prio[0], id->prio[1], &id->addr);
  63
  64        /*
  65         * According to the spec, the message age timer cannot be
  66         * running when we are the root bridge. So..  this was_root
  67         * check is redundant. I'm leaving it in for now, though.
  68         */
  69        spin_lock(&br->lock);
  70        if (p->state == BR_STATE_DISABLED)
  71                goto unlock;
  72        was_root = br_is_root_bridge(br);
  73
  74        br_become_designated_port(p);
  75        br_configuration_update(br);
  76        br_port_state_selection(br);
  77        if (br_is_root_bridge(br) && !was_root)
  78                br_become_root_bridge(br);
  79 unlock:
  80        spin_unlock(&br->lock);
  81}
  82
  83static void br_forward_delay_timer_expired(struct timer_list *t)
  84{
  85        struct net_bridge_port *p = from_timer(p, t, forward_delay_timer);
  86        struct net_bridge *br = p->br;
  87
  88        br_debug(br, "port %u(%s) forward delay timer\n",
  89                 (unsigned int) p->port_no, p->dev->name);
  90        spin_lock(&br->lock);
  91        if (p->state == BR_STATE_LISTENING) {
  92                br_set_state(p, BR_STATE_LEARNING);
  93                mod_timer(&p->forward_delay_timer,
  94                          jiffies + br->forward_delay);
  95        } else if (p->state == BR_STATE_LEARNING) {
  96                br_set_state(p, BR_STATE_FORWARDING);
  97                if (br_is_designated_for_some_port(br))
  98                        br_topology_change_detection(br);
  99                netif_carrier_on(br->dev);
 100        }
 101        rcu_read_lock();
 102        br_ifinfo_notify(RTM_NEWLINK, NULL, p);
 103        rcu_read_unlock();
 104        spin_unlock(&br->lock);
 105}
 106
 107static void br_tcn_timer_expired(struct timer_list *t)
 108{
 109        struct net_bridge *br = from_timer(br, t, tcn_timer);
 110
 111        br_debug(br, "tcn timer expired\n");
 112        spin_lock(&br->lock);
 113        if (!br_is_root_bridge(br) && (br->dev->flags & IFF_UP)) {
 114                br_transmit_tcn(br);
 115
 116                mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
 117        }
 118        spin_unlock(&br->lock);
 119}
 120
 121static void br_topology_change_timer_expired(struct timer_list *t)
 122{
 123        struct net_bridge *br = from_timer(br, t, topology_change_timer);
 124
 125        br_debug(br, "topo change timer expired\n");
 126        spin_lock(&br->lock);
 127        br->topology_change_detected = 0;
 128        __br_set_topology_change(br, 0);
 129        spin_unlock(&br->lock);
 130}
 131
 132static void br_hold_timer_expired(struct timer_list *t)
 133{
 134        struct net_bridge_port *p = from_timer(p, t, hold_timer);
 135
 136        br_debug(p->br, "port %u(%s) hold timer expired\n",
 137                 (unsigned int) p->port_no, p->dev->name);
 138
 139        spin_lock(&p->br->lock);
 140        if (p->config_pending)
 141                br_transmit_config(p);
 142        spin_unlock(&p->br->lock);
 143}
 144
 145void br_stp_timer_init(struct net_bridge *br)
 146{
 147        timer_setup(&br->hello_timer, br_hello_timer_expired, 0);
 148        timer_setup(&br->tcn_timer, br_tcn_timer_expired, 0);
 149        timer_setup(&br->topology_change_timer,
 150                    br_topology_change_timer_expired, 0);
 151}
 152
 153void br_stp_port_timer_init(struct net_bridge_port *p)
 154{
 155        timer_setup(&p->message_age_timer, br_message_age_timer_expired, 0);
 156        timer_setup(&p->forward_delay_timer, br_forward_delay_timer_expired, 0);
 157        timer_setup(&p->hold_timer, br_hold_timer_expired, 0);
 158}
 159
 160/* Report ticks left (in USER_HZ) used for API */
 161unsigned long br_timer_value(const struct timer_list *timer)
 162{
 163        return timer_pending(timer)
 164                ? jiffies_delta_to_clock_t(timer->expires - jiffies) : 0;
 165}
 166