A bridge topology with three systems: +------+ +------+ | A(2) |--| B(1) | +------+ +------+ \ / +------+ | C(3) | +------+ What is supposed to happen: * bridge with the lowest ID is elected root (for example: B) * C detects that A->C is higher cost path and puts in blocking state What happens. Bridge with lowest id (B) is elected correctly as root and things start out fine initially. But then config BPDU doesn't get transmitted from A -> C. Because of that the link from A-C is transistioned to the forwarding state. The root cause of this is that the configuration messages is generated with bogus message age, and dropped before sending. In the standardmessage_age is supposed to be: the time since the generation of the Configuration BPDU by the Root that instigated the generation of this Configuration BPDU. Reimplement this by recording the timestamp (age + jiffies) when recording config information. The old code incorrectly used the time elapsed on the ageing timer which was incorrect. See also: https://bugzilla.vyatta.com/show_bug.cgi?id=7164 Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: David S. Miller <davem@davemloft.net>
534 lines
12 KiB
C
534 lines
12 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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* 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/rculist.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 *const 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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br_info(p->br, "port %u(%s) entering %s state\n",
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(unsigned) 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 = (jiffies - root->designated_age)
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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,
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round_jiffies(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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p->designated_age = jiffies + bpdu->message_age;
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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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if (br->stp_enabled != BR_KERNEL_STP)
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return;
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br_info(br, "topology change detected, %s\n",
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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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struct net_bridge *br = p->br;
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if (p->state != BR_STATE_BLOCKING)
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return;
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if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) {
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p->state = BR_STATE_FORWARDING;
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br_topology_change_detection(br);
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del_timer(&p->forward_delay_timer);
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}
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else if (br->stp_enabled == BR_KERNEL_STP)
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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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br_multicast_enable_port(p);
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br_log_state(p);
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if (br->forward_delay != 0)
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mod_timer(&p->forward_delay_timer, jiffies + 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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unsigned int liveports = 0;
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/* Don't change port states if userspace is handling STP */
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if (br->stp_enabled == BR_USER_STP)
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return;
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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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continue;
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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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if (p->state == BR_STATE_FORWARDING)
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++liveports;
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}
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if (liveports == 0)
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netif_carrier_off(br->dev);
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else
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netif_carrier_on(br->dev);
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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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br_info(p->br, "port %u(%s) received tcn bpdu\n",
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(unsigned) 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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/* Change bridge STP parameter */
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int br_set_hello_time(struct net_bridge *br, unsigned long val)
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{
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unsigned long t = clock_t_to_jiffies(val);
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if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME)
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return -ERANGE;
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spin_lock_bh(&br->lock);
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br->bridge_hello_time = t;
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if (br_is_root_bridge(br))
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br->hello_time = br->bridge_hello_time;
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spin_unlock_bh(&br->lock);
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return 0;
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}
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int br_set_max_age(struct net_bridge *br, unsigned long val)
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{
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unsigned long t = clock_t_to_jiffies(val);
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if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE)
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|
return -ERANGE;
|
|
|
|
spin_lock_bh(&br->lock);
|
|
br->bridge_max_age = t;
|
|
if (br_is_root_bridge(br))
|
|
br->max_age = br->bridge_max_age;
|
|
spin_unlock_bh(&br->lock);
|
|
return 0;
|
|
|
|
}
|
|
|
|
int br_set_forward_delay(struct net_bridge *br, unsigned long val)
|
|
{
|
|
unsigned long t = clock_t_to_jiffies(val);
|
|
|
|
if (br->stp_enabled != BR_NO_STP &&
|
|
(t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
|
|
return -ERANGE;
|
|
|
|
spin_lock_bh(&br->lock);
|
|
br->bridge_forward_delay = t;
|
|
if (br_is_root_bridge(br))
|
|
br->forward_delay = br->bridge_forward_delay;
|
|
spin_unlock_bh(&br->lock);
|
|
return 0;
|
|
}
|