1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *	Spanning tree protocol; timer-related code
4 *	Linux ethernet bridge
5 *
6 *	Authors:
7 *	Lennert Buytenhek		<buytenh@gnu.org>
8 */
9
10#include <linux/kernel.h>
11#include <linux/times.h>
12
13#include "br_private.h"
14#include "br_private_stp.h"
15
16/* called under bridge lock */
17static int br_is_designated_for_some_port(const struct net_bridge *br)
18{
19	struct net_bridge_port *p;
20
21	list_for_each_entry(p, &br->port_list, list) {
22		if (p->state != BR_STATE_DISABLED &&
23		    !memcmp(&p->designated_bridge, &br->bridge_id, 8))
24			return 1;
25	}
26
27	return 0;
28}
29
30static void br_hello_timer_expired(struct timer_list *t)
31{
32	struct net_bridge *br = from_timer(br, t, hello_timer);
33
34	br_debug(br, "hello timer expired\n");
35	spin_lock(&br->lock);
36	if (br->dev->flags & IFF_UP) {
37		br_config_bpdu_generation(br);
38
39		if (br->stp_enabled == BR_KERNEL_STP)
40			mod_timer(&br->hello_timer,
41				  round_jiffies(jiffies + br->hello_time));
42	}
43	spin_unlock(&br->lock);
44}
45
46static void br_message_age_timer_expired(struct timer_list *t)
47{
48	struct net_bridge_port *p = from_timer(p, t, message_age_timer);
49	struct net_bridge *br = p->br;
50	const bridge_id *id = &p->designated_bridge;
51	int was_root;
52
53	if (p->state == BR_STATE_DISABLED)
54		return;
55
56	br_info(br, "port %u(%s) neighbor %.2x%.2x.%pM lost\n",
57		(unsigned int) p->port_no, p->dev->name,
58		id->prio[0], id->prio[1], &id->addr);
59
60	/*
61	 * According to the spec, the message age timer cannot be
62	 * running when we are the root bridge. So..  this was_root
63	 * check is redundant. I'm leaving it in for now, though.
64	 */
65	spin_lock(&br->lock);
66	if (p->state == BR_STATE_DISABLED)
67		goto unlock;
68	was_root = br_is_root_bridge(br);
69
70	br_become_designated_port(p);
71	br_configuration_update(br);
72	br_port_state_selection(br);
73	if (br_is_root_bridge(br) && !was_root)
74		br_become_root_bridge(br);
75 unlock:
76	spin_unlock(&br->lock);
77}
78
79static void br_forward_delay_timer_expired(struct timer_list *t)
80{
81	struct net_bridge_port *p = from_timer(p, t, forward_delay_timer);
82	struct net_bridge *br = p->br;
83
84	br_debug(br, "port %u(%s) forward delay timer\n",
85		 (unsigned int) p->port_no, p->dev->name);
86	spin_lock(&br->lock);
87	if (p->state == BR_STATE_LISTENING) {
88		br_set_state(p, BR_STATE_LEARNING);
89		mod_timer(&p->forward_delay_timer,
90			  jiffies + br->forward_delay);
91	} else if (p->state == BR_STATE_LEARNING) {
92		br_set_state(p, BR_STATE_FORWARDING);
93		if (br_is_designated_for_some_port(br))
94			br_topology_change_detection(br);
95		netif_carrier_on(br->dev);
96	}
97	rcu_read_lock();
98	br_ifinfo_notify(RTM_NEWLINK, NULL, p);
99	rcu_read_unlock();
100	spin_unlock(&br->lock);
101}
102
103static void br_tcn_timer_expired(struct timer_list *t)
104{
105	struct net_bridge *br = from_timer(br, t, tcn_timer);
106
107	br_debug(br, "tcn timer expired\n");
108	spin_lock(&br->lock);
109	if (!br_is_root_bridge(br) && (br->dev->flags & IFF_UP)) {
110		br_transmit_tcn(br);
111
112		mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
113	}
114	spin_unlock(&br->lock);
115}
116
117static void br_topology_change_timer_expired(struct timer_list *t)
118{
119	struct net_bridge *br = from_timer(br, t, topology_change_timer);
120
121	br_debug(br, "topo change timer expired\n");
122	spin_lock(&br->lock);
123	br->topology_change_detected = 0;
124	__br_set_topology_change(br, 0);
125	spin_unlock(&br->lock);
126}
127
128static void br_hold_timer_expired(struct timer_list *t)
129{
130	struct net_bridge_port *p = from_timer(p, t, hold_timer);
131
132	br_debug(p->br, "port %u(%s) hold timer expired\n",
133		 (unsigned int) p->port_no, p->dev->name);
134
135	spin_lock(&p->br->lock);
136	if (p->config_pending)
137		br_transmit_config(p);
138	spin_unlock(&p->br->lock);
139}
140
141void br_stp_timer_init(struct net_bridge *br)
142{
143	timer_setup(&br->hello_timer, br_hello_timer_expired, 0);
144	timer_setup(&br->tcn_timer, br_tcn_timer_expired, 0);
145	timer_setup(&br->topology_change_timer,
146		    br_topology_change_timer_expired, 0);
147}
148
149void br_stp_port_timer_init(struct net_bridge_port *p)
150{
151	timer_setup(&p->message_age_timer, br_message_age_timer_expired, 0);
152	timer_setup(&p->forward_delay_timer, br_forward_delay_timer_expired, 0);
153	timer_setup(&p->hold_timer, br_hold_timer_expired, 0);
154}
155
156/* Report ticks left (in USER_HZ) used for API */
157unsigned long br_timer_value(const struct timer_list *timer)
158{
159	return timer_pending(timer)
160		? jiffies_delta_to_clock_t(timer->expires - jiffies) : 0;
161}
162