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
23 enum lw_bits {
24 LW_URGENT = 0,
25 };
26
27 static unsigned long linkwatch_flags;
28 static unsigned long linkwatch_nextevent;
29
30 static void linkwatch_event(struct work_struct *dummy);
31 static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
32
33 static LIST_HEAD(lweventlist);
34 static DEFINE_SPINLOCK(lweventlist_lock);
35
36 static unsigned char default_operstate(const struct net_device *dev)
37 {
38 if (netif_testing(dev))
39 return IF_OPER_TESTING;
40
41 if (!netif_carrier_ok(dev))
42 return (dev->ifindex != dev_get_iflink(dev) ?
43 IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN);
44
45 if (netif_dormant(dev))
46 return IF_OPER_DORMANT;
47
48 return IF_OPER_UP;
49 }
50
51
52 static void rfc2863_policy(struct net_device *dev)
53 {
54 unsigned char operstate = default_operstate(dev);
55
56 if (operstate == dev->operstate)
57 return;
58
59 write_lock(&dev_base_lock);
60
61 switch(dev->link_mode) {
62 case IF_LINK_MODE_TESTING:
63 if (operstate == IF_OPER_UP)
64 operstate = IF_OPER_TESTING;
65 break;
66
67 case IF_LINK_MODE_DORMANT:
68 if (operstate == IF_OPER_UP)
69 operstate = IF_OPER_DORMANT;
70 break;
71 case IF_LINK_MODE_DEFAULT:
72 default:
73 break;
74 }
75
76 dev->operstate = operstate;
77
78 write_unlock(&dev_base_lock);
79 }
80
81
82 void linkwatch_init_dev(struct net_device *dev)
83 {
84 /* Handle pre-registration link state changes */
85 if (!netif_carrier_ok(dev) || netif_dormant(dev) ||
86 netif_testing(dev))
87 rfc2863_policy(dev);
88 }
89
90
91 static bool linkwatch_urgent_event(struct net_device *dev)
92 {
93 if (!netif_running(dev))
94 return false;
95
96 if (dev->ifindex != dev_get_iflink(dev))
97 return true;
98
99 if (netif_is_lag_port(dev) || netif_is_lag_master(dev))
100 return true;
101
102 return netif_carrier_ok(dev) && qdisc_tx_changing(dev);
103 }
104
105
106 static void linkwatch_add_event(struct net_device *dev)
107 {
108 unsigned long flags;
109
110 spin_lock_irqsave(&lweventlist_lock, flags);
111 if (list_empty(&dev->link_watch_list)) {
112 list_add_tail(&dev->link_watch_list, &lweventlist);
113 netdev_hold(dev, &dev->linkwatch_dev_tracker, GFP_ATOMIC);
114 }
115 spin_unlock_irqrestore(&lweventlist_lock, flags);
116 }
117
118
119 static void linkwatch_schedule_work(int urgent)
120 {
121 unsigned long delay = linkwatch_nextevent - jiffies;
122
123 if (test_bit(LW_URGENT, &linkwatch_flags))
124 return;
125
126 /* Minimise down-time: drop delay for up event. */
127 if (urgent) {
128 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
129 return;
130 delay = 0;
131 }
132
133 /* If we wrap around we'll delay it by at most HZ. */
134 if (delay > HZ)
135 delay = 0;
136
137 /*
138 * If urgent, schedule immediate execution; otherwise, don't
139 * override the existing timer.
140 */
141 if (test_bit(LW_URGENT, &linkwatch_flags))
142 mod_delayed_work(system_wq, &linkwatch_work, 0);
143 else
144 schedule_delayed_work(&linkwatch_work, delay);
145 }
146
147
148 static void linkwatch_do_dev(struct net_device *dev)
149 {
150 /*
151 * Make sure the above read is complete since it can be
152 * rewritten as soon as we clear the bit below.
153 */
154 smp_mb__before_atomic();
155
156 /* We are about to handle this device,
157 * so new events can be accepted
158 */
159 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
160
161 rfc2863_policy(dev);
162 if (dev->flags & IFF_UP) {
163 if (netif_carrier_ok(dev))
164 dev_activate(dev);
165 else
166 dev_deactivate(dev);
167
168 netdev_state_change(dev);
169 }
170 /* Note: our callers are responsible for calling netdev_tracker_free().
171 * This is the reason we use __dev_put() instead of dev_put().
172 */
173 __dev_put(dev);
174 }
175
176 static void __linkwatch_run_queue(int urgent_only)
177 {
178 #define MAX_DO_DEV_PER_LOOP 100
179
180 int do_dev = MAX_DO_DEV_PER_LOOP;
181 struct net_device *dev;
182 LIST_HEAD(wrk);
183
184 /* Give urgent case more budget */
185 if (urgent_only)
186 do_dev += MAX_DO_DEV_PER_LOOP;
187
188 /*
189 * Limit the number of linkwatch events to one
190 * per second so that a runaway driver does not
191 * cause a storm of messages on the netlink
192 * socket. This limit does not apply to up events
193 * while the device qdisc is down.
194 */
195 if (!urgent_only)
196 linkwatch_nextevent = jiffies + HZ;
197 /* Limit wrap-around effect on delay. */
198 else if (time_after(linkwatch_nextevent, jiffies + HZ))
199 linkwatch_nextevent = jiffies;
200
201 clear_bit(LW_URGENT, &linkwatch_flags);
202
203 spin_lock_irq(&lweventlist_lock);
204 list_splice_init(&lweventlist, &wrk);
205
206 while (!list_empty(&wrk) && do_dev > 0) {
207
208 dev = list_first_entry(&wrk, struct net_device, link_watch_list);
209 list_del_init(&dev->link_watch_list);
210
211 if (!netif_device_present(dev) ||
212 (urgent_only && !linkwatch_urgent_event(dev))) {
213 list_add_tail(&dev->link_watch_list, &lweventlist);
214 continue;
215 }
216 /* We must free netdev tracker under
217 * the spinlock protection.
218 */
219 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
220 spin_unlock_irq(&lweventlist_lock);
221 linkwatch_do_dev(dev);
222 do_dev--;
223 spin_lock_irq(&lweventlist_lock);
224 }
225
226 /* Add the remaining work back to lweventlist */
227 list_splice_init(&wrk, &lweventlist);
228
229 if (!list_empty(&lweventlist))
230 linkwatch_schedule_work(0);
231 spin_unlock_irq(&lweventlist_lock);
232 }
233
234 void linkwatch_forget_dev(struct net_device *dev)
235 {
236 unsigned long flags;
237 int clean = 0;
238
239 spin_lock_irqsave(&lweventlist_lock, flags);
240 if (!list_empty(&dev->link_watch_list)) {
241 list_del_init(&dev->link_watch_list);
242 clean = 1;
243 /* We must release netdev tracker under
244 * the spinlock protection.
245 */
246 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
247 }
248 spin_unlock_irqrestore(&lweventlist_lock, flags);
249 if (clean)
250 linkwatch_do_dev(dev);
251 }
252
253
254 /* Must be called with the rtnl semaphore held */
255 void linkwatch_run_queue(void)
256 {
257 __linkwatch_run_queue(0);
258 }
259
260
261 static void linkwatch_event(struct work_struct *dummy)
262 {
263 rtnl_lock();
264 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
265 rtnl_unlock();
266 }
267
268
269 void linkwatch_fire_event(struct net_device *dev)
270 {
271 bool urgent = linkwatch_urgent_event(dev);
272
273 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
274 linkwatch_add_event(dev);
275 } else if (!urgent)
276 return;
277
278 linkwatch_schedule_work(urgent);
279 }
280 EXPORT_SYMBOL(linkwatch_fire_event);
281
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