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1/*
2 * Linux network device link state notification
3 *
4 * Author:
5 * Stefan Rompf <sux@loplof.de>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 *
12 */
13
14#include <linux/module.h>
15#include <linux/netdevice.h>
16#include <linux/if.h>
17#include <net/sock.h>
18#include <net/pkt_sched.h>
19#include <linux/rtnetlink.h>
20#include <linux/jiffies.h>
21#include <linux/spinlock.h>
22#include <linux/workqueue.h>
23#include <linux/bitops.h>
24#include <linux/types.h>
25
26
27enum lw_bits {
28 LW_URGENT = 0,
29};
30
31static unsigned long linkwatch_flags;
32static unsigned long linkwatch_nextevent;
33
34static void linkwatch_event(struct work_struct *dummy);
35static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
36
37static LIST_HEAD(lweventlist);
38static DEFINE_SPINLOCK(lweventlist_lock);
39
40static unsigned char default_operstate(const struct net_device *dev)
41{
42 if (!netif_carrier_ok(dev))
43 return (dev->ifindex != dev_get_iflink(dev) ?
44 IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN);
45
46 if (netif_dormant(dev))
47 return IF_OPER_DORMANT;
48
49 return IF_OPER_UP;
50}
51
52
53static void rfc2863_policy(struct net_device *dev)
54{
55 unsigned char operstate = default_operstate(dev);
56
57 if (operstate == dev->operstate)
58 return;
59
60 write_lock_bh(&dev_base_lock);
61
62 switch(dev->link_mode) {
63 case IF_LINK_MODE_DORMANT:
64 if (operstate == IF_OPER_UP)
65 operstate = IF_OPER_DORMANT;
66 break;
67
68 case IF_LINK_MODE_DEFAULT:
69 default:
70 break;
71 }
72
73 dev->operstate = operstate;
74
75 write_unlock_bh(&dev_base_lock);
76}
77
78
79void linkwatch_init_dev(struct net_device *dev)
80{
81 /* Handle pre-registration link state changes */
82 if (!netif_carrier_ok(dev) || netif_dormant(dev))
83 rfc2863_policy(dev);
84}
85
86
87static bool linkwatch_urgent_event(struct net_device *dev)
88{
89 if (!netif_running(dev))
90 return false;
91
92 if (dev->ifindex != dev_get_iflink(dev))
93 return true;
94
95 if (dev->priv_flags & IFF_TEAM_PORT)
96 return true;
97
98 return netif_carrier_ok(dev) && qdisc_tx_changing(dev);
99}
100
101
102static void linkwatch_add_event(struct net_device *dev)
103{
104 unsigned long flags;
105
106 spin_lock_irqsave(&lweventlist_lock, flags);
107 if (list_empty(&dev->link_watch_list)) {
108 list_add_tail(&dev->link_watch_list, &lweventlist);
109 dev_hold(dev);
110 }
111 spin_unlock_irqrestore(&lweventlist_lock, flags);
112}
113
114
115static void linkwatch_schedule_work(int urgent)
116{
117 unsigned long delay = linkwatch_nextevent - jiffies;
118
119 if (test_bit(LW_URGENT, &linkwatch_flags))
120 return;
121
122 /* Minimise down-time: drop delay for up event. */
123 if (urgent) {
124 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
125 return;
126 delay = 0;
127 }
128
129 /* If we wrap around we'll delay it by at most HZ. */
130 if (delay > HZ)
131 delay = 0;
132
133 /*
134 * If urgent, schedule immediate execution; otherwise, don't
135 * override the existing timer.
136 */
137 if (test_bit(LW_URGENT, &linkwatch_flags))
138 mod_delayed_work(system_wq, &linkwatch_work, 0);
139 else
140 schedule_delayed_work(&linkwatch_work, delay);
141}
142
143
144static void linkwatch_do_dev(struct net_device *dev)
145{
146 /*
147 * Make sure the above read is complete since it can be
148 * rewritten as soon as we clear the bit below.
149 */
150 smp_mb__before_atomic();
151
152 /* We are about to handle this device,
153 * so new events can be accepted
154 */
155 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
156
157 rfc2863_policy(dev);
158 if (dev->flags & IFF_UP) {
159 if (netif_carrier_ok(dev))
160 dev_activate(dev);
161 else
162 dev_deactivate(dev);
163
164 netdev_state_change(dev);
165 }
166 dev_put(dev);
167}
168
169static void __linkwatch_run_queue(int urgent_only)
170{
171 struct net_device *dev;
172 LIST_HEAD(wrk);
173
174 /*
175 * Limit the number of linkwatch events to one
176 * per second so that a runaway driver does not
177 * cause a storm of messages on the netlink
178 * socket. This limit does not apply to up events
179 * while the device qdisc is down.
180 */
181 if (!urgent_only)
182 linkwatch_nextevent = jiffies + HZ;
183 /* Limit wrap-around effect on delay. */
184 else if (time_after(linkwatch_nextevent, jiffies + HZ))
185 linkwatch_nextevent = jiffies;
186
187 clear_bit(LW_URGENT, &linkwatch_flags);
188
189 spin_lock_irq(&lweventlist_lock);
190 list_splice_init(&lweventlist, &wrk);
191
192 while (!list_empty(&wrk)) {
193
194 dev = list_first_entry(&wrk, struct net_device, link_watch_list);
195 list_del_init(&dev->link_watch_list);
196
197 if (urgent_only && !linkwatch_urgent_event(dev)) {
198 list_add_tail(&dev->link_watch_list, &lweventlist);
199 continue;
200 }
201 spin_unlock_irq(&lweventlist_lock);
202 linkwatch_do_dev(dev);
203 spin_lock_irq(&lweventlist_lock);
204 }
205
206 if (!list_empty(&lweventlist))
207 linkwatch_schedule_work(0);
208 spin_unlock_irq(&lweventlist_lock);
209}
210
211void linkwatch_forget_dev(struct net_device *dev)
212{
213 unsigned long flags;
214 int clean = 0;
215
216 spin_lock_irqsave(&lweventlist_lock, flags);
217 if (!list_empty(&dev->link_watch_list)) {
218 list_del_init(&dev->link_watch_list);
219 clean = 1;
220 }
221 spin_unlock_irqrestore(&lweventlist_lock, flags);
222 if (clean)
223 linkwatch_do_dev(dev);
224}
225
226
227/* Must be called with the rtnl semaphore held */
228void linkwatch_run_queue(void)
229{
230 __linkwatch_run_queue(0);
231}
232
233
234static void linkwatch_event(struct work_struct *dummy)
235{
236 rtnl_lock();
237 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
238 rtnl_unlock();
239}
240
241
242void linkwatch_fire_event(struct net_device *dev)
243{
244 bool urgent = linkwatch_urgent_event(dev);
245
246 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
247 linkwatch_add_event(dev);
248 } else if (!urgent)
249 return;
250
251 linkwatch_schedule_work(urgent);
252}
253EXPORT_SYMBOL(linkwatch_fire_event);
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Linux network device link state notification
4 *
5 * Author:
6 * Stefan Rompf <sux@loplof.de>
7 */
8
9#include <linux/module.h>
10#include <linux/netdevice.h>
11#include <linux/if.h>
12#include <net/sock.h>
13#include <net/pkt_sched.h>
14#include <linux/rtnetlink.h>
15#include <linux/jiffies.h>
16#include <linux/spinlock.h>
17#include <linux/workqueue.h>
18#include <linux/bitops.h>
19#include <linux/types.h>
20
21#include "dev.h"
22
23enum lw_bits {
24 LW_URGENT = 0,
25};
26
27static unsigned long linkwatch_flags;
28static unsigned long linkwatch_nextevent;
29
30static void linkwatch_event(struct work_struct *dummy);
31static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
32
33static LIST_HEAD(lweventlist);
34static DEFINE_SPINLOCK(lweventlist_lock);
35
36static unsigned int default_operstate(const struct net_device *dev)
37{
38 if (netif_testing(dev))
39 return IF_OPER_TESTING;
40
41 /* Some uppers (DSA) have additional sources for being down, so
42 * first check whether lower is indeed the source of its down state.
43 */
44 if (!netif_carrier_ok(dev)) {
45 struct net_device *peer;
46 int iflink;
47
48 /* If called from netdev_run_todo()/linkwatch_sync_dev(),
49 * dev_net(dev) can be already freed, and RTNL is not held.
50 */
51 if (dev->reg_state <= NETREG_REGISTERED)
52 iflink = dev_get_iflink(dev);
53 else
54 iflink = dev->ifindex;
55
56 if (iflink == dev->ifindex)
57 return IF_OPER_DOWN;
58
59 ASSERT_RTNL();
60 peer = __dev_get_by_index(dev_net(dev), iflink);
61 if (!peer)
62 return IF_OPER_DOWN;
63
64 return netif_carrier_ok(peer) ? IF_OPER_DOWN :
65 IF_OPER_LOWERLAYERDOWN;
66 }
67
68 if (netif_dormant(dev))
69 return IF_OPER_DORMANT;
70
71 return IF_OPER_UP;
72}
73
74static void rfc2863_policy(struct net_device *dev)
75{
76 unsigned int operstate = default_operstate(dev);
77
78 if (operstate == READ_ONCE(dev->operstate))
79 return;
80
81 switch(dev->link_mode) {
82 case IF_LINK_MODE_TESTING:
83 if (operstate == IF_OPER_UP)
84 operstate = IF_OPER_TESTING;
85 break;
86
87 case IF_LINK_MODE_DORMANT:
88 if (operstate == IF_OPER_UP)
89 operstate = IF_OPER_DORMANT;
90 break;
91 case IF_LINK_MODE_DEFAULT:
92 default:
93 break;
94 }
95
96 WRITE_ONCE(dev->operstate, operstate);
97}
98
99
100void linkwatch_init_dev(struct net_device *dev)
101{
102 /* Handle pre-registration link state changes */
103 if (!netif_carrier_ok(dev) || netif_dormant(dev) ||
104 netif_testing(dev))
105 rfc2863_policy(dev);
106}
107
108
109static bool linkwatch_urgent_event(struct net_device *dev)
110{
111 if (!netif_running(dev))
112 return false;
113
114 if (dev->ifindex != dev_get_iflink(dev))
115 return true;
116
117 if (netif_is_lag_port(dev) || netif_is_lag_master(dev))
118 return true;
119
120 return netif_carrier_ok(dev) && qdisc_tx_changing(dev);
121}
122
123
124static void linkwatch_add_event(struct net_device *dev)
125{
126 unsigned long flags;
127
128 spin_lock_irqsave(&lweventlist_lock, flags);
129 if (list_empty(&dev->link_watch_list)) {
130 list_add_tail(&dev->link_watch_list, &lweventlist);
131 netdev_hold(dev, &dev->linkwatch_dev_tracker, GFP_ATOMIC);
132 }
133 spin_unlock_irqrestore(&lweventlist_lock, flags);
134}
135
136
137static void linkwatch_schedule_work(int urgent)
138{
139 unsigned long delay = linkwatch_nextevent - jiffies;
140
141 if (test_bit(LW_URGENT, &linkwatch_flags))
142 return;
143
144 /* Minimise down-time: drop delay for up event. */
145 if (urgent) {
146 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
147 return;
148 delay = 0;
149 }
150
151 /* If we wrap around we'll delay it by at most HZ. */
152 if (delay > HZ)
153 delay = 0;
154
155 /*
156 * If urgent, schedule immediate execution; otherwise, don't
157 * override the existing timer.
158 */
159 if (test_bit(LW_URGENT, &linkwatch_flags))
160 mod_delayed_work(system_unbound_wq, &linkwatch_work, 0);
161 else
162 queue_delayed_work(system_unbound_wq, &linkwatch_work, delay);
163}
164
165
166static void linkwatch_do_dev(struct net_device *dev)
167{
168 /*
169 * Make sure the above read is complete since it can be
170 * rewritten as soon as we clear the bit below.
171 */
172 smp_mb__before_atomic();
173
174 /* We are about to handle this device,
175 * so new events can be accepted
176 */
177 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
178
179 rfc2863_policy(dev);
180 if (dev->flags & IFF_UP) {
181 if (netif_carrier_ok(dev))
182 dev_activate(dev);
183 else
184 dev_deactivate(dev);
185
186 netdev_state_change(dev);
187 }
188 /* Note: our callers are responsible for calling netdev_tracker_free().
189 * This is the reason we use __dev_put() instead of dev_put().
190 */
191 __dev_put(dev);
192}
193
194static void __linkwatch_run_queue(int urgent_only)
195{
196#define MAX_DO_DEV_PER_LOOP 100
197
198 int do_dev = MAX_DO_DEV_PER_LOOP;
199 /* Use a local list here since we add non-urgent
200 * events back to the global one when called with
201 * urgent_only=1.
202 */
203 LIST_HEAD(wrk);
204
205 /* Give urgent case more budget */
206 if (urgent_only)
207 do_dev += MAX_DO_DEV_PER_LOOP;
208
209 /*
210 * Limit the number of linkwatch events to one
211 * per second so that a runaway driver does not
212 * cause a storm of messages on the netlink
213 * socket. This limit does not apply to up events
214 * while the device qdisc is down.
215 */
216 if (!urgent_only)
217 linkwatch_nextevent = jiffies + HZ;
218 /* Limit wrap-around effect on delay. */
219 else if (time_after(linkwatch_nextevent, jiffies + HZ))
220 linkwatch_nextevent = jiffies;
221
222 clear_bit(LW_URGENT, &linkwatch_flags);
223
224 spin_lock_irq(&lweventlist_lock);
225 list_splice_init(&lweventlist, &wrk);
226
227 while (!list_empty(&wrk) && do_dev > 0) {
228 struct net_device *dev;
229
230 dev = list_first_entry(&wrk, struct net_device, link_watch_list);
231 list_del_init(&dev->link_watch_list);
232
233 if (!netif_device_present(dev) ||
234 (urgent_only && !linkwatch_urgent_event(dev))) {
235 list_add_tail(&dev->link_watch_list, &lweventlist);
236 continue;
237 }
238 /* We must free netdev tracker under
239 * the spinlock protection.
240 */
241 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
242 spin_unlock_irq(&lweventlist_lock);
243 linkwatch_do_dev(dev);
244 do_dev--;
245 spin_lock_irq(&lweventlist_lock);
246 }
247
248 /* Add the remaining work back to lweventlist */
249 list_splice_init(&wrk, &lweventlist);
250
251 if (!list_empty(&lweventlist))
252 linkwatch_schedule_work(0);
253 spin_unlock_irq(&lweventlist_lock);
254}
255
256void linkwatch_sync_dev(struct net_device *dev)
257{
258 unsigned long flags;
259 int clean = 0;
260
261 spin_lock_irqsave(&lweventlist_lock, flags);
262 if (!list_empty(&dev->link_watch_list)) {
263 list_del_init(&dev->link_watch_list);
264 clean = 1;
265 /* We must release netdev tracker under
266 * the spinlock protection.
267 */
268 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
269 }
270 spin_unlock_irqrestore(&lweventlist_lock, flags);
271 if (clean)
272 linkwatch_do_dev(dev);
273}
274
275
276/* Must be called with the rtnl semaphore held */
277void linkwatch_run_queue(void)
278{
279 __linkwatch_run_queue(0);
280}
281
282
283static void linkwatch_event(struct work_struct *dummy)
284{
285 rtnl_lock();
286 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
287 rtnl_unlock();
288}
289
290
291void linkwatch_fire_event(struct net_device *dev)
292{
293 bool urgent = linkwatch_urgent_event(dev);
294
295 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
296 linkwatch_add_event(dev);
297 } else if (!urgent)
298 return;
299
300 linkwatch_schedule_work(urgent);
301}
302EXPORT_SYMBOL(linkwatch_fire_event);