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DEFINITIONS
This source file includes following definitions.
- br_log_state
- br_get_port
- br_should_become_root_port
- br_root_selection
- br_become_root_bridge
- br_transmit_config
- br_record_config_information
- br_record_config_timeout_values
- br_transmit_tcn
- br_should_become_designated_port
- br_designated_port_selection
- br_supersedes_port_info
- br_topology_change_acknowledged
- br_topology_change_detection
- br_config_bpdu_generation
- br_reply
- br_configuration_update
- br_become_designated_port
- br_make_blocking
- br_make_forwarding
- br_port_state_selection
- br_topology_change_acknowledge
- br_received_config_bpdu
- br_received_tcn_bpdu
/*
* Spanning tree protocol; generic parts
* 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/rculist.h>
#include "br_private.h"
#include "br_private_stp.h"
/* since time values in bpdu are in jiffies and then scaled (1/256)
* before sending, make sure that is at least one.
*/
#define MESSAGE_AGE_INCR ((HZ < 256) ? 1 : (HZ/256))
static const char *br_port_state_names[] = {
[BR_STATE_DISABLED] = "disabled",
[BR_STATE_LISTENING] = "listening",
[BR_STATE_LEARNING] = "learning",
[BR_STATE_FORWARDING] = "forwarding",
[BR_STATE_BLOCKING] = "blocking",
};
void br_log_state(const struct net_bridge_port *p)
{
pr_info("%s: port %d(%s) entering %s state\n",
p->br->dev->name, p->port_no, p->dev->name,
br_port_state_names[p->state]);
}
/* called under bridge lock */
struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
{
struct net_bridge_port *p;
list_for_each_entry_rcu(p, &br->port_list, list) {
if (p->port_no == port_no)
return p;
}
return NULL;
}
/* called under bridge lock */
static int br_should_become_root_port(const struct net_bridge_port *p,
u16 root_port)
{
struct net_bridge *br;
struct net_bridge_port *rp;
int t;
br = p->br;
if (p->state == BR_STATE_DISABLED ||
br_is_designated_port(p))
return 0;
if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
return 0;
if (!root_port)
return 1;
rp = br_get_port(br, root_port);
t = memcmp(&p->designated_root, &rp->designated_root, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (p->designated_cost + p->path_cost <
rp->designated_cost + rp->path_cost)
return 1;
else if (p->designated_cost + p->path_cost >
rp->designated_cost + rp->path_cost)
return 0;
t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (p->designated_port < rp->designated_port)
return 1;
else if (p->designated_port > rp->designated_port)
return 0;
if (p->port_id < rp->port_id)
return 1;
return 0;
}
/* called under bridge lock */
static void br_root_selection(struct net_bridge *br)
{
struct net_bridge_port *p;
u16 root_port = 0;
list_for_each_entry(p, &br->port_list, list) {
if (br_should_become_root_port(p, root_port))
root_port = p->port_no;
}
br->root_port = root_port;
if (!root_port) {
br->designated_root = br->bridge_id;
br->root_path_cost = 0;
} else {
p = br_get_port(br, root_port);
br->designated_root = p->designated_root;
br->root_path_cost = p->designated_cost + p->path_cost;
}
}
/* called under bridge lock */
void br_become_root_bridge(struct net_bridge *br)
{
br->max_age = br->bridge_max_age;
br->hello_time = br->bridge_hello_time;
br->forward_delay = br->bridge_forward_delay;
br_topology_change_detection(br);
del_timer(&br->tcn_timer);
if (br->dev->flags & IFF_UP) {
br_config_bpdu_generation(br);
mod_timer(&br->hello_timer, jiffies + br->hello_time);
}
}
/* called under bridge lock */
void br_transmit_config(struct net_bridge_port *p)
{
struct br_config_bpdu bpdu;
struct net_bridge *br;
if (timer_pending(&p->hold_timer)) {
p->config_pending = 1;
return;
}
br = p->br;
bpdu.topology_change = br->topology_change;
bpdu.topology_change_ack = p->topology_change_ack;
bpdu.root = br->designated_root;
bpdu.root_path_cost = br->root_path_cost;
bpdu.bridge_id = br->bridge_id;
bpdu.port_id = p->port_id;
if (br_is_root_bridge(br))
bpdu.message_age = 0;
else {
struct net_bridge_port *root
= br_get_port(br, br->root_port);
bpdu.message_age = br->max_age
- (root->message_age_timer.expires - jiffies)
+ MESSAGE_AGE_INCR;
}
bpdu.max_age = br->max_age;
bpdu.hello_time = br->hello_time;
bpdu.forward_delay = br->forward_delay;
if (bpdu.message_age < br->max_age) {
br_send_config_bpdu(p, &bpdu);
p->topology_change_ack = 0;
p->config_pending = 0;
mod_timer(&p->hold_timer,
round_jiffies(jiffies + BR_HOLD_TIME));
}
}
/* called under bridge lock */
static inline void br_record_config_information(struct net_bridge_port *p,
const struct br_config_bpdu *bpdu)
{
p->designated_root = bpdu->root;
p->designated_cost = bpdu->root_path_cost;
p->designated_bridge = bpdu->bridge_id;
p->designated_port = bpdu->port_id;
mod_timer(&p->message_age_timer, jiffies
+ (p->br->max_age - bpdu->message_age));
}
/* called under bridge lock */
static inline void br_record_config_timeout_values(struct net_bridge *br,
const struct br_config_bpdu *bpdu)
{
br->max_age = bpdu->max_age;
br->hello_time = bpdu->hello_time;
br->forward_delay = bpdu->forward_delay;
br->topology_change = bpdu->topology_change;
}
/* called under bridge lock */
void br_transmit_tcn(struct net_bridge *br)
{
br_send_tcn_bpdu(br_get_port(br, br->root_port));
}
/* called under bridge lock */
static int br_should_become_designated_port(const struct net_bridge_port *p)
{
struct net_bridge *br;
int t;
br = p->br;
if (br_is_designated_port(p))
return 1;
if (memcmp(&p->designated_root, &br->designated_root, 8))
return 1;
if (br->root_path_cost < p->designated_cost)
return 1;
else if (br->root_path_cost > p->designated_cost)
return 0;
t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (p->port_id < p->designated_port)
return 1;
return 0;
}
/* called under bridge lock */
static void br_designated_port_selection(struct net_bridge *br)
{
struct net_bridge_port *p;
list_for_each_entry(p, &br->port_list, list) {
if (p->state != BR_STATE_DISABLED &&
br_should_become_designated_port(p))
br_become_designated_port(p);
}
}
/* called under bridge lock */
static int br_supersedes_port_info(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
{
int t;
t = memcmp(&bpdu->root, &p->designated_root, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (bpdu->root_path_cost < p->designated_cost)
return 1;
else if (bpdu->root_path_cost > p->designated_cost)
return 0;
t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
return 1;
if (bpdu->port_id <= p->designated_port)
return 1;
return 0;
}
/* called under bridge lock */
static inline void br_topology_change_acknowledged(struct net_bridge *br)
{
br->topology_change_detected = 0;
del_timer(&br->tcn_timer);
}
/* called under bridge lock */
void br_topology_change_detection(struct net_bridge *br)
{
int isroot = br_is_root_bridge(br);
pr_info("%s: topology change detected, %s\n", br->dev->name,
isroot ? "propagating" : "sending tcn bpdu");
if (isroot) {
br->topology_change = 1;
mod_timer(&br->topology_change_timer, jiffies
+ br->bridge_forward_delay + br->bridge_max_age);
} else if (!br->topology_change_detected) {
br_transmit_tcn(br);
mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
}
br->topology_change_detected = 1;
}
/* called under bridge lock */
void br_config_bpdu_generation(struct net_bridge *br)
{
struct net_bridge_port *p;
list_for_each_entry(p, &br->port_list, list) {
if (p->state != BR_STATE_DISABLED &&
br_is_designated_port(p))
br_transmit_config(p);
}
}
/* called under bridge lock */
static inline void br_reply(struct net_bridge_port *p)
{
br_transmit_config(p);
}
/* called under bridge lock */
void br_configuration_update(struct net_bridge *br)
{
br_root_selection(br);
br_designated_port_selection(br);
}
/* called under bridge lock */
void br_become_designated_port(struct net_bridge_port *p)
{
struct net_bridge *br;
br = p->br;
p->designated_root = br->designated_root;
p->designated_cost = br->root_path_cost;
p->designated_bridge = br->bridge_id;
p->designated_port = p->port_id;
}
/* called under bridge lock */
static void br_make_blocking(struct net_bridge_port *p)
{
if (p->state != BR_STATE_DISABLED &&
p->state != BR_STATE_BLOCKING) {
if (p->state == BR_STATE_FORWARDING ||
p->state == BR_STATE_LEARNING)
br_topology_change_detection(p->br);
p->state = BR_STATE_BLOCKING;
br_log_state(p);
del_timer(&p->forward_delay_timer);
}
}
/* called under bridge lock */
static void br_make_forwarding(struct net_bridge_port *p)
{
struct net_bridge *br = p->br;
if (p->state != BR_STATE_BLOCKING)
return;
if (br->forward_delay == 0) {
p->state = BR_STATE_FORWARDING;
br_topology_change_detection(br);
del_timer(&p->forward_delay_timer);
}
else if (p->br->stp_enabled == BR_KERNEL_STP)
p->state = BR_STATE_LISTENING;
else
p->state = BR_STATE_LEARNING;
br_log_state(p);
if (br->forward_delay != 0)
mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
}
/* called under bridge lock */
void br_port_state_selection(struct net_bridge *br)
{
struct net_bridge_port *p;
/* Don't change port states if userspace is handling STP */
if (br->stp_enabled == BR_USER_STP)
return;
list_for_each_entry(p, &br->port_list, list) {
if (p->state != BR_STATE_DISABLED) {
if (p->port_no == br->root_port) {
p->config_pending = 0;
p->topology_change_ack = 0;
br_make_forwarding(p);
} else if (br_is_designated_port(p)) {
del_timer(&p->message_age_timer);
br_make_forwarding(p);
} else {
p->config_pending = 0;
p->topology_change_ack = 0;
br_make_blocking(p);
}
}
}
}
/* called under bridge lock */
static inline void br_topology_change_acknowledge(struct net_bridge_port *p)
{
p->topology_change_ack = 1;
br_transmit_config(p);
}
/* called under bridge lock */
void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
{
struct net_bridge *br;
int was_root;
br = p->br;
was_root = br_is_root_bridge(br);
if (br_supersedes_port_info(p, bpdu)) {
br_record_config_information(p, bpdu);
br_configuration_update(br);
br_port_state_selection(br);
if (!br_is_root_bridge(br) && was_root) {
del_timer(&br->hello_timer);
if (br->topology_change_detected) {
del_timer(&br->topology_change_timer);
br_transmit_tcn(br);
mod_timer(&br->tcn_timer,
jiffies + br->bridge_hello_time);
}
}
if (p->port_no == br->root_port) {
br_record_config_timeout_values(br, bpdu);
br_config_bpdu_generation(br);
if (bpdu->topology_change_ack)
br_topology_change_acknowledged(br);
}
} else if (br_is_designated_port(p)) {
br_reply(p);
}
}
/* called under bridge lock */
void br_received_tcn_bpdu(struct net_bridge_port *p)
{
if (br_is_designated_port(p)) {
pr_info("%s: received tcn bpdu on port %i(%s)\n",
p->br->dev->name, p->port_no, p->dev->name);
br_topology_change_detection(p->br);
br_topology_change_acknowledge(p);
}
}