patch-2.3.47 linux/net/bridge/br_stp.c

• Lines: 466
• Date: Sun Feb 20 10:41:18 2000
• Orig file: v2.3.46/linux/net/bridge/br_stp.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.46/linux/net/bridge/br_stp.c linux/net/bridge/br_stp.c
@@ -0,0 +1,465 @@
+/*
+ *	Spanning tree protocol; generic parts
+ *	Linux ethernet bridge
+ *
+ *	Authors:
+ *	Lennert Buytenhek		<buytenh@gnu.org>
+ *
+ *	$Id: br_stp.c,v 1.1 2000/02/18 16:47:13 davem Exp $
+ *
+ *	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/if_bridge.h>
+#include <linux/smp_lock.h>
+#include <asm/uaccess.h>
+#include "br_private.h"
+#include "br_private_stp.h"
+
+
+
+/* called under ioctl_lock or bridge lock */
+int br_is_root_bridge(struct net_bridge *br)
+{
+	return !memcmp(&br->bridge_id, &br->designated_root, 8);
+}
+
+/* called under bridge lock */
+int br_is_designated_port(struct net_bridge_port *p)
+{
+	return !memcmp(&p->designated_bridge, &p->br->bridge_id, 8) &&
+		(p->designated_port == p->port_id);
+}
+
+/* called under ioctl_lock or bridge lock */
+struct net_bridge_port *br_get_port(struct net_bridge *br, int port_no)
+{
+	struct net_bridge_port *p;
+
+	p = br->port_list;
+	while (p != NULL) {
+		if (p->port_no == port_no)
+			return p;
+
+		p = p->next;
+	}
+
+	return NULL;
+}
+
+/* called under bridge lock */
+static int br_should_become_root_port(struct net_bridge_port *p, int 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;
+	int root_port;
+
+	root_port = 0;
+
+	p = br->port_list;
+	while (p != NULL) {
+		if (br_should_become_root_port(p, root_port))
+			root_port = p->port_no;
+
+		p = p->next;
+	}
+
+	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);
+	br_timer_clear(&br->tcn_timer);
+	br_config_bpdu_generation(br);
+	br_timer_set(&br->hello_timer, jiffies);
+}
+
+/* called under bridge lock */
+void br_transmit_config(struct net_bridge_port *p)
+{
+	struct br_config_bpdu bpdu;
+	struct net_bridge *br;
+
+	if (br_timer_is_running(&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;
+	bpdu.message_age = 0;
+	if (!br_is_root_bridge(br)) {
+		struct net_bridge_port *root;
+		unsigned long age;
+
+		root = br_get_port(br, br->root_port);
+		age = br_timer_get_residue(&root->message_age_timer) + 1;
+		bpdu.message_age = age;
+	}
+	bpdu.max_age = br->max_age;
+	bpdu.hello_time = br->hello_time;
+	bpdu.forward_delay = br->forward_delay;
+
+	br_send_config_bpdu(p, &bpdu);
+
+	p->topology_change_ack = 0;
+	p->config_pending = 0;
+	br_timer_set(&p->hold_timer, jiffies);
+}
+
+/* called under bridge lock */
+static void br_record_config_information(struct net_bridge_port *p, 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;
+
+	br_timer_set(&p->message_age_timer, jiffies - bpdu->message_age);
+}
+
+/* called under bridge lock */
+static void br_record_config_timeout_values(struct net_bridge *br, 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(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;
+
+	p = br->port_list;
+	while (p != NULL) {
+		if (p->state != BR_STATE_DISABLED &&
+		    br_should_become_designated_port(p))
+			br_become_designated_port(p);
+
+		p = p->next;
+	}
+}
+
+/* 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 void br_topology_change_acknowledged(struct net_bridge *br)
+{
+	br->topology_change_detected = 0;
+	br_timer_clear(&br->tcn_timer);
+}
+
+/* called under bridge lock */
+void br_topology_change_detection(struct net_bridge *br)
+{
+	printk(KERN_INFO "%s: topology change detected, ", br->name);
+
+	if (br_is_root_bridge(br)) {
+		printk("propagating\n");
+		br->topology_change = 1;
+		br_timer_set(&br->topology_change_timer, jiffies);
+	} else if (!br->topology_change_detected) {
+		printk("sending tcn bpdu\n");
+		br_transmit_tcn(br);
+		br_timer_set(&br->tcn_timer, jiffies);
+	}
+
+	br->topology_change_detected = 1;
+}
+
+/* called under bridge lock */
+void br_config_bpdu_generation(struct net_bridge *br)
+{
+	struct net_bridge_port *p;
+
+	p = br->port_list;
+	while (p != NULL) {
+		if (p->state != BR_STATE_DISABLED &&
+		    br_is_designated_port(p))
+			br_transmit_config(p);
+
+		p = p->next;
+	}
+}
+
+/* called under bridge lock */
+static 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);
+
+		printk(KERN_INFO "%s: port %i(%s) entering %s state\n",
+		       p->br->name, p->port_no, p->dev->name, "blocking");
+
+		p->state = BR_STATE_BLOCKING;
+		br_timer_clear(&p->forward_delay_timer);
+	}
+}
+
+/* called under bridge lock */
+static void br_make_forwarding(struct net_bridge_port *p)
+{
+	if (p->state == BR_STATE_BLOCKING) {
+		printk(KERN_INFO "%s: port %i(%s) entering %s state\n",
+		       p->br->name, p->port_no, p->dev->name, "listening");
+
+		p->state = BR_STATE_LISTENING;
+		br_timer_set(&p->forward_delay_timer, jiffies);
+	}
+}
+
+/* called under bridge lock */
+void br_port_state_selection(struct net_bridge *br)
+{
+	struct net_bridge_port *p;
+
+	p = br->port_list;
+	while (p != NULL) {
+		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)) {
+				br_timer_clear(&p->message_age_timer);
+				br_make_forwarding(p);
+			} else {
+				p->config_pending = 0;
+				p->topology_change_ack = 0;
+				br_make_blocking(p);
+			}
+		}
+
+		p = p->next;
+	}
+}
+
+/* called under bridge lock */
+static void br_topology_change_acknowledge(struct net_bridge_port *p)
+{
+	p->topology_change_ack = 1;
+	br_transmit_config(p);
+}
+
+/* lock-safe */
+void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
+{
+	struct net_bridge *br;
+	int was_root;
+
+	if (p->state == BR_STATE_DISABLED)
+		return;
+
+	br = p->br;
+	read_lock(&br->lock);
+
+	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) {
+			br_timer_clear(&br->hello_timer);
+			if (br->topology_change_detected) {
+				br_timer_clear(&br->topology_change_timer);
+				br_transmit_tcn(br);
+				br_timer_set(&br->tcn_timer, jiffies);
+			}
+		}
+
+		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);		
+	}
+
+	read_unlock(&br->lock);
+}
+
+/* lock-safe */
+void br_received_tcn_bpdu(struct net_bridge_port *p)
+{
+	read_lock(&p->br->lock);
+	if (p->state != BR_STATE_DISABLED &&
+	    br_is_designated_port(p)) {
+		printk(KERN_INFO "%s: received tcn bpdu on port %i(%s)\n",
+		       p->br->name, p->port_no, p->dev->name);
+
+		br_topology_change_detection(p->br);
+		br_topology_change_acknowledge(p);
+	}
+	read_unlock(&p->br->lock);
+}