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
22 enum lw_bits {
23 LW_URGENT = 0,
24 };
25
26 static unsigned long linkwatch_flags;
27 static unsigned long linkwatch_nextevent;
28
29 static void linkwatch_event(struct work_struct *dummy);
30 static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
31
32 static LIST_HEAD(lweventlist);
33 static DEFINE_SPINLOCK(lweventlist_lock);
34
default_operstate(const struct net_device * dev)35 static unsigned char default_operstate(const struct net_device *dev)
36 {
37 if (netif_testing(dev))
38 return IF_OPER_TESTING;
39
40 if (!netif_carrier_ok(dev))
41 return (dev->ifindex != dev_get_iflink(dev) ?
42 IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN);
43
44 if (netif_dormant(dev))
45 return IF_OPER_DORMANT;
46
47 return IF_OPER_UP;
48 }
49
50
rfc2863_policy(struct net_device * dev)51 static void rfc2863_policy(struct net_device *dev)
52 {
53 unsigned char operstate = default_operstate(dev);
54
55 if (operstate == dev->operstate)
56 return;
57
58 write_lock_bh(&dev_base_lock);
59
60 switch(dev->link_mode) {
61 case IF_LINK_MODE_TESTING:
62 if (operstate == IF_OPER_UP)
63 operstate = IF_OPER_TESTING;
64 break;
65
66 case IF_LINK_MODE_DORMANT:
67 if (operstate == IF_OPER_UP)
68 operstate = IF_OPER_DORMANT;
69 break;
70 case IF_LINK_MODE_DEFAULT:
71 default:
72 break;
73 }
74
75 dev->operstate = operstate;
76
77 write_unlock_bh(&dev_base_lock);
78 }
79
80
linkwatch_init_dev(struct net_device * dev)81 void linkwatch_init_dev(struct net_device *dev)
82 {
83 /* Handle pre-registration link state changes */
84 if (!netif_carrier_ok(dev) || netif_dormant(dev) ||
85 netif_testing(dev))
86 rfc2863_policy(dev);
87 }
88
89
linkwatch_urgent_event(struct net_device * dev)90 static bool linkwatch_urgent_event(struct net_device *dev)
91 {
92 if (!netif_running(dev))
93 return false;
94
95 if (dev->ifindex != dev_get_iflink(dev))
96 return true;
97
98 if (netif_is_lag_port(dev) || netif_is_lag_master(dev))
99 return true;
100
101 return netif_carrier_ok(dev) && qdisc_tx_changing(dev);
102 }
103
104
linkwatch_add_event(struct net_device * dev)105 static void linkwatch_add_event(struct net_device *dev)
106 {
107 unsigned long flags;
108
109 spin_lock_irqsave(&lweventlist_lock, flags);
110 if (list_empty(&dev->link_watch_list)) {
111 list_add_tail(&dev->link_watch_list, &lweventlist);
112 dev_hold(dev);
113 }
114 spin_unlock_irqrestore(&lweventlist_lock, flags);
115 }
116
117
linkwatch_schedule_work(int urgent)118 static void linkwatch_schedule_work(int urgent)
119 {
120 unsigned long delay = linkwatch_nextevent - jiffies;
121
122 if (test_bit(LW_URGENT, &linkwatch_flags))
123 return;
124
125 /* Minimise down-time: drop delay for up event. */
126 if (urgent) {
127 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
128 return;
129 delay = 0;
130 }
131
132 /* If we wrap around we'll delay it by at most HZ. */
133 if (delay > HZ)
134 delay = 0;
135
136 /*
137 * If urgent, schedule immediate execution; otherwise, don't
138 * override the existing timer.
139 */
140 if (test_bit(LW_URGENT, &linkwatch_flags))
141 mod_delayed_work(system_wq, &linkwatch_work, 0);
142 else
143 schedule_delayed_work(&linkwatch_work, delay);
144 }
145
146
linkwatch_do_dev(struct net_device * dev)147 static void linkwatch_do_dev(struct net_device *dev)
148 {
149 /*
150 * Make sure the above read is complete since it can be
151 * rewritten as soon as we clear the bit below.
152 */
153 smp_mb__before_atomic();
154
155 /* We are about to handle this device,
156 * so new events can be accepted
157 */
158 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
159
160 rfc2863_policy(dev);
161 if (dev->flags & IFF_UP && netif_device_present(dev)) {
162 if (netif_carrier_ok(dev))
163 dev_activate(dev);
164 else
165 dev_deactivate(dev);
166
167 netdev_state_change(dev);
168 }
169 dev_put(dev);
170 }
171
__linkwatch_run_queue(int urgent_only)172 static void __linkwatch_run_queue(int urgent_only)
173 {
174 #define MAX_DO_DEV_PER_LOOP 100
175
176 int do_dev = MAX_DO_DEV_PER_LOOP;
177 struct net_device *dev;
178 LIST_HEAD(wrk);
179
180 /* Give urgent case more budget */
181 if (urgent_only)
182 do_dev += MAX_DO_DEV_PER_LOOP;
183
184 /*
185 * Limit the number of linkwatch events to one
186 * per second so that a runaway driver does not
187 * cause a storm of messages on the netlink
188 * socket. This limit does not apply to up events
189 * while the device qdisc is down.
190 */
191 if (!urgent_only)
192 linkwatch_nextevent = jiffies + HZ;
193 /* Limit wrap-around effect on delay. */
194 else if (time_after(linkwatch_nextevent, jiffies + HZ))
195 linkwatch_nextevent = jiffies;
196
197 clear_bit(LW_URGENT, &linkwatch_flags);
198
199 spin_lock_irq(&lweventlist_lock);
200 list_splice_init(&lweventlist, &wrk);
201
202 while (!list_empty(&wrk) && do_dev > 0) {
203
204 dev = list_first_entry(&wrk, struct net_device, link_watch_list);
205 list_del_init(&dev->link_watch_list);
206
207 if (urgent_only && !linkwatch_urgent_event(dev)) {
208 list_add_tail(&dev->link_watch_list, &lweventlist);
209 continue;
210 }
211 spin_unlock_irq(&lweventlist_lock);
212 linkwatch_do_dev(dev);
213 do_dev--;
214 spin_lock_irq(&lweventlist_lock);
215 }
216
217 /* Add the remaining work back to lweventlist */
218 list_splice_init(&wrk, &lweventlist);
219
220 if (!list_empty(&lweventlist))
221 linkwatch_schedule_work(0);
222 spin_unlock_irq(&lweventlist_lock);
223 }
224
linkwatch_forget_dev(struct net_device * dev)225 void linkwatch_forget_dev(struct net_device *dev)
226 {
227 unsigned long flags;
228 int clean = 0;
229
230 spin_lock_irqsave(&lweventlist_lock, flags);
231 if (!list_empty(&dev->link_watch_list)) {
232 list_del_init(&dev->link_watch_list);
233 clean = 1;
234 }
235 spin_unlock_irqrestore(&lweventlist_lock, flags);
236 if (clean)
237 linkwatch_do_dev(dev);
238 }
239
240
241 /* Must be called with the rtnl semaphore held */
linkwatch_run_queue(void)242 void linkwatch_run_queue(void)
243 {
244 __linkwatch_run_queue(0);
245 }
246
247
linkwatch_event(struct work_struct * dummy)248 static void linkwatch_event(struct work_struct *dummy)
249 {
250 rtnl_lock();
251 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
252 rtnl_unlock();
253 }
254
255
linkwatch_fire_event(struct net_device * dev)256 void linkwatch_fire_event(struct net_device *dev)
257 {
258 bool urgent = linkwatch_urgent_event(dev);
259
260 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
261 linkwatch_add_event(dev);
262 } else if (!urgent)
263 return;
264
265 linkwatch_schedule_work(urgent);
266 }
267 EXPORT_SYMBOL(linkwatch_fire_event);
268