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![Linus Torvalds](/assets/img/avatar_default.png)
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
459 lines
11 KiB
C
459 lines
11 KiB
C
/*
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* Spanning tree protocol; generic parts
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* Linux ethernet bridge
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*
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* Authors:
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* Lennert Buytenhek <buytenh@gnu.org>
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*
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* $Id: br_stp.c,v 1.4 2000/06/19 10:13:35 davem Exp $
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/smp_lock.h>
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#include "br_private.h"
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#include "br_private_stp.h"
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/* since time values in bpdu are in jiffies and then scaled (1/256)
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* before sending, make sure that is at least one.
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*/
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#define MESSAGE_AGE_INCR ((HZ < 256) ? 1 : (HZ/256))
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static const char *br_port_state_names[] = {
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[BR_STATE_DISABLED] = "disabled",
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[BR_STATE_LISTENING] = "listening",
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[BR_STATE_LEARNING] = "learning",
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[BR_STATE_FORWARDING] = "forwarding",
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[BR_STATE_BLOCKING] = "blocking",
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};
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void br_log_state(const struct net_bridge_port *p)
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{
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pr_info("%s: port %d(%s) entering %s state\n",
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p->br->dev->name, p->port_no, p->dev->name,
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br_port_state_names[p->state]);
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}
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/* called under bridge lock */
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struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
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{
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struct net_bridge_port *p;
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list_for_each_entry_rcu(p, &br->port_list, list) {
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if (p->port_no == port_no)
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return p;
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}
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return NULL;
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}
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/* called under bridge lock */
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static int br_should_become_root_port(const struct net_bridge_port *p,
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u16 root_port)
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{
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struct net_bridge *br;
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struct net_bridge_port *rp;
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int t;
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br = p->br;
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if (p->state == BR_STATE_DISABLED ||
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br_is_designated_port(p))
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return 0;
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if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
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return 0;
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if (!root_port)
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return 1;
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rp = br_get_port(br, root_port);
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t = memcmp(&p->designated_root, &rp->designated_root, 8);
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if (t < 0)
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return 1;
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else if (t > 0)
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return 0;
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if (p->designated_cost + p->path_cost <
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rp->designated_cost + rp->path_cost)
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return 1;
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else if (p->designated_cost + p->path_cost >
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rp->designated_cost + rp->path_cost)
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return 0;
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t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
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if (t < 0)
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return 1;
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else if (t > 0)
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return 0;
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if (p->designated_port < rp->designated_port)
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return 1;
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else if (p->designated_port > rp->designated_port)
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return 0;
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if (p->port_id < rp->port_id)
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return 1;
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return 0;
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}
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/* called under bridge lock */
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static void br_root_selection(struct net_bridge *br)
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{
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struct net_bridge_port *p;
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u16 root_port = 0;
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list_for_each_entry(p, &br->port_list, list) {
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if (br_should_become_root_port(p, root_port))
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root_port = p->port_no;
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}
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br->root_port = root_port;
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if (!root_port) {
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br->designated_root = br->bridge_id;
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br->root_path_cost = 0;
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} else {
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p = br_get_port(br, root_port);
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br->designated_root = p->designated_root;
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br->root_path_cost = p->designated_cost + p->path_cost;
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}
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}
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/* called under bridge lock */
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void br_become_root_bridge(struct net_bridge *br)
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{
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br->max_age = br->bridge_max_age;
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br->hello_time = br->bridge_hello_time;
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br->forward_delay = br->bridge_forward_delay;
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br_topology_change_detection(br);
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del_timer(&br->tcn_timer);
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if (br->dev->flags & IFF_UP) {
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br_config_bpdu_generation(br);
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mod_timer(&br->hello_timer, jiffies + br->hello_time);
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}
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}
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/* called under bridge lock */
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void br_transmit_config(struct net_bridge_port *p)
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{
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struct br_config_bpdu bpdu;
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struct net_bridge *br;
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if (timer_pending(&p->hold_timer)) {
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p->config_pending = 1;
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return;
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}
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br = p->br;
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bpdu.topology_change = br->topology_change;
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bpdu.topology_change_ack = p->topology_change_ack;
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bpdu.root = br->designated_root;
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bpdu.root_path_cost = br->root_path_cost;
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bpdu.bridge_id = br->bridge_id;
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bpdu.port_id = p->port_id;
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if (br_is_root_bridge(br))
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bpdu.message_age = 0;
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else {
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struct net_bridge_port *root
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= br_get_port(br, br->root_port);
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bpdu.message_age = br->max_age
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- (root->message_age_timer.expires - jiffies)
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+ MESSAGE_AGE_INCR;
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}
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bpdu.max_age = br->max_age;
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bpdu.hello_time = br->hello_time;
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bpdu.forward_delay = br->forward_delay;
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if (bpdu.message_age < br->max_age) {
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br_send_config_bpdu(p, &bpdu);
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p->topology_change_ack = 0;
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p->config_pending = 0;
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mod_timer(&p->hold_timer, jiffies + BR_HOLD_TIME);
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}
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}
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/* called under bridge lock */
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static inline void br_record_config_information(struct net_bridge_port *p,
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const struct br_config_bpdu *bpdu)
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{
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p->designated_root = bpdu->root;
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p->designated_cost = bpdu->root_path_cost;
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p->designated_bridge = bpdu->bridge_id;
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p->designated_port = bpdu->port_id;
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mod_timer(&p->message_age_timer, jiffies
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+ (p->br->max_age - bpdu->message_age));
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}
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/* called under bridge lock */
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static inline void br_record_config_timeout_values(struct net_bridge *br,
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const struct br_config_bpdu *bpdu)
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{
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br->max_age = bpdu->max_age;
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br->hello_time = bpdu->hello_time;
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br->forward_delay = bpdu->forward_delay;
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br->topology_change = bpdu->topology_change;
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}
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/* called under bridge lock */
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void br_transmit_tcn(struct net_bridge *br)
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{
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br_send_tcn_bpdu(br_get_port(br, br->root_port));
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}
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/* called under bridge lock */
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static int br_should_become_designated_port(const struct net_bridge_port *p)
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{
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struct net_bridge *br;
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int t;
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br = p->br;
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if (br_is_designated_port(p))
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return 1;
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if (memcmp(&p->designated_root, &br->designated_root, 8))
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return 1;
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if (br->root_path_cost < p->designated_cost)
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return 1;
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else if (br->root_path_cost > p->designated_cost)
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return 0;
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t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
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if (t < 0)
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return 1;
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else if (t > 0)
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return 0;
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if (p->port_id < p->designated_port)
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return 1;
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return 0;
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}
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/* called under bridge lock */
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static void br_designated_port_selection(struct net_bridge *br)
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{
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struct net_bridge_port *p;
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list_for_each_entry(p, &br->port_list, list) {
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if (p->state != BR_STATE_DISABLED &&
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br_should_become_designated_port(p))
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br_become_designated_port(p);
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}
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}
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/* called under bridge lock */
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static int br_supersedes_port_info(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
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{
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int t;
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t = memcmp(&bpdu->root, &p->designated_root, 8);
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if (t < 0)
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return 1;
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else if (t > 0)
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return 0;
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if (bpdu->root_path_cost < p->designated_cost)
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return 1;
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else if (bpdu->root_path_cost > p->designated_cost)
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return 0;
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t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
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if (t < 0)
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return 1;
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else if (t > 0)
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return 0;
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if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
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return 1;
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if (bpdu->port_id <= p->designated_port)
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return 1;
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return 0;
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}
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/* called under bridge lock */
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static inline void br_topology_change_acknowledged(struct net_bridge *br)
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{
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br->topology_change_detected = 0;
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del_timer(&br->tcn_timer);
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}
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/* called under bridge lock */
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void br_topology_change_detection(struct net_bridge *br)
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{
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int isroot = br_is_root_bridge(br);
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pr_info("%s: topology change detected, %s\n", br->dev->name,
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isroot ? "propagating" : "sending tcn bpdu");
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if (isroot) {
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br->topology_change = 1;
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mod_timer(&br->topology_change_timer, jiffies
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+ br->bridge_forward_delay + br->bridge_max_age);
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} else if (!br->topology_change_detected) {
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br_transmit_tcn(br);
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mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
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}
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br->topology_change_detected = 1;
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}
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/* called under bridge lock */
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void br_config_bpdu_generation(struct net_bridge *br)
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{
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struct net_bridge_port *p;
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list_for_each_entry(p, &br->port_list, list) {
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if (p->state != BR_STATE_DISABLED &&
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br_is_designated_port(p))
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br_transmit_config(p);
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}
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}
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/* called under bridge lock */
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static inline void br_reply(struct net_bridge_port *p)
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{
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br_transmit_config(p);
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}
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/* called under bridge lock */
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void br_configuration_update(struct net_bridge *br)
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{
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br_root_selection(br);
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br_designated_port_selection(br);
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}
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/* called under bridge lock */
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void br_become_designated_port(struct net_bridge_port *p)
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{
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struct net_bridge *br;
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br = p->br;
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p->designated_root = br->designated_root;
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p->designated_cost = br->root_path_cost;
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p->designated_bridge = br->bridge_id;
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p->designated_port = p->port_id;
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}
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/* called under bridge lock */
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static void br_make_blocking(struct net_bridge_port *p)
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{
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if (p->state != BR_STATE_DISABLED &&
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p->state != BR_STATE_BLOCKING) {
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if (p->state == BR_STATE_FORWARDING ||
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p->state == BR_STATE_LEARNING)
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br_topology_change_detection(p->br);
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p->state = BR_STATE_BLOCKING;
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br_log_state(p);
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del_timer(&p->forward_delay_timer);
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}
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}
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/* called under bridge lock */
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static void br_make_forwarding(struct net_bridge_port *p)
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{
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if (p->state == BR_STATE_BLOCKING) {
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if (p->br->stp_enabled) {
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p->state = BR_STATE_LISTENING;
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} else {
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p->state = BR_STATE_LEARNING;
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}
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br_log_state(p);
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mod_timer(&p->forward_delay_timer, jiffies + p->br->forward_delay); }
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}
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/* called under bridge lock */
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void br_port_state_selection(struct net_bridge *br)
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{
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struct net_bridge_port *p;
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list_for_each_entry(p, &br->port_list, list) {
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if (p->state != BR_STATE_DISABLED) {
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if (p->port_no == br->root_port) {
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p->config_pending = 0;
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p->topology_change_ack = 0;
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br_make_forwarding(p);
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} else if (br_is_designated_port(p)) {
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del_timer(&p->message_age_timer);
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br_make_forwarding(p);
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} else {
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p->config_pending = 0;
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p->topology_change_ack = 0;
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br_make_blocking(p);
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}
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}
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}
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}
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/* called under bridge lock */
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static inline void br_topology_change_acknowledge(struct net_bridge_port *p)
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{
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p->topology_change_ack = 1;
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br_transmit_config(p);
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}
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/* called under bridge lock */
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void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
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{
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struct net_bridge *br;
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int was_root;
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br = p->br;
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was_root = br_is_root_bridge(br);
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if (br_supersedes_port_info(p, bpdu)) {
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br_record_config_information(p, bpdu);
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br_configuration_update(br);
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br_port_state_selection(br);
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if (!br_is_root_bridge(br) && was_root) {
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del_timer(&br->hello_timer);
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if (br->topology_change_detected) {
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del_timer(&br->topology_change_timer);
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br_transmit_tcn(br);
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mod_timer(&br->tcn_timer,
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jiffies + br->bridge_hello_time);
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}
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}
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if (p->port_no == br->root_port) {
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br_record_config_timeout_values(br, bpdu);
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br_config_bpdu_generation(br);
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if (bpdu->topology_change_ack)
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br_topology_change_acknowledged(br);
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}
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} else if (br_is_designated_port(p)) {
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br_reply(p);
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}
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}
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/* called under bridge lock */
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void br_received_tcn_bpdu(struct net_bridge_port *p)
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{
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if (br_is_designated_port(p)) {
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pr_info("%s: received tcn bpdu on port %i(%s)\n",
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p->br->dev->name, p->port_no, p->dev->name);
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br_topology_change_detection(p->br);
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br_topology_change_acknowledge(p);
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}
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}
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