GNU Linux-libre 5.10.219-gnu1
[releases.git] / net / core / link_watch.c
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
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
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
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
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
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
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
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) {
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
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 (!netif_device_present(dev) ||
208                     (urgent_only && !linkwatch_urgent_event(dev))) {
209                         list_add_tail(&dev->link_watch_list, &lweventlist);
210                         continue;
211                 }
212                 spin_unlock_irq(&lweventlist_lock);
213                 linkwatch_do_dev(dev);
214                 do_dev--;
215                 spin_lock_irq(&lweventlist_lock);
216         }
217
218         /* Add the remaining work back to lweventlist */
219         list_splice_init(&wrk, &lweventlist);
220
221         if (!list_empty(&lweventlist))
222                 linkwatch_schedule_work(0);
223         spin_unlock_irq(&lweventlist_lock);
224 }
225
226 void linkwatch_forget_dev(struct net_device *dev)
227 {
228         unsigned long flags;
229         int clean = 0;
230
231         spin_lock_irqsave(&lweventlist_lock, flags);
232         if (!list_empty(&dev->link_watch_list)) {
233                 list_del_init(&dev->link_watch_list);
234                 clean = 1;
235         }
236         spin_unlock_irqrestore(&lweventlist_lock, flags);
237         if (clean)
238                 linkwatch_do_dev(dev);
239 }
240
241
242 /* Must be called with the rtnl semaphore held */
243 void linkwatch_run_queue(void)
244 {
245         __linkwatch_run_queue(0);
246 }
247
248
249 static void linkwatch_event(struct work_struct *dummy)
250 {
251         rtnl_lock();
252         __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
253         rtnl_unlock();
254 }
255
256
257 void linkwatch_fire_event(struct net_device *dev)
258 {
259         bool urgent = linkwatch_urgent_event(dev);
260
261         if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
262                 linkwatch_add_event(dev);
263         } else if (!urgent)
264                 return;
265
266         linkwatch_schedule_work(urgent);
267 }
268 EXPORT_SYMBOL(linkwatch_fire_event);