1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Linux network device link state notification
6 * Stefan Rompf <sux@loplof.de>
9 #include <linux/module.h>
10 #include <linux/netdevice.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>
26 static unsigned long linkwatch_flags;
27 static unsigned long linkwatch_nextevent;
29 static void linkwatch_event(struct work_struct *dummy);
30 static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
32 static LIST_HEAD(lweventlist);
33 static DEFINE_SPINLOCK(lweventlist_lock);
35 static unsigned char default_operstate(const struct net_device *dev)
37 if (netif_testing(dev))
38 return IF_OPER_TESTING;
40 if (!netif_carrier_ok(dev))
41 return (dev->ifindex != dev_get_iflink(dev) ?
42 IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN);
44 if (netif_dormant(dev))
45 return IF_OPER_DORMANT;
51 static void rfc2863_policy(struct net_device *dev)
53 unsigned char operstate = default_operstate(dev);
55 if (operstate == dev->operstate)
58 write_lock(&dev_base_lock);
60 switch(dev->link_mode) {
61 case IF_LINK_MODE_TESTING:
62 if (operstate == IF_OPER_UP)
63 operstate = IF_OPER_TESTING;
66 case IF_LINK_MODE_DORMANT:
67 if (operstate == IF_OPER_UP)
68 operstate = IF_OPER_DORMANT;
70 case IF_LINK_MODE_DEFAULT:
75 dev->operstate = operstate;
77 write_unlock(&dev_base_lock);
81 void linkwatch_init_dev(struct net_device *dev)
83 /* Handle pre-registration link state changes */
84 if (!netif_carrier_ok(dev) || netif_dormant(dev) ||
90 static bool linkwatch_urgent_event(struct net_device *dev)
92 if (!netif_running(dev))
95 if (dev->ifindex != dev_get_iflink(dev))
98 if (netif_is_lag_port(dev) || netif_is_lag_master(dev))
101 return netif_carrier_ok(dev) && qdisc_tx_changing(dev);
105 static void linkwatch_add_event(struct net_device *dev)
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_track(dev, &dev->linkwatch_dev_tracker, GFP_ATOMIC);
114 spin_unlock_irqrestore(&lweventlist_lock, flags);
118 static void linkwatch_schedule_work(int urgent)
120 unsigned long delay = linkwatch_nextevent - jiffies;
122 if (test_bit(LW_URGENT, &linkwatch_flags))
125 /* Minimise down-time: drop delay for up event. */
127 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
132 /* If we wrap around we'll delay it by at most HZ. */
137 * If urgent, schedule immediate execution; otherwise, don't
138 * override the existing timer.
140 if (test_bit(LW_URGENT, &linkwatch_flags))
141 mod_delayed_work(system_wq, &linkwatch_work, 0);
143 schedule_delayed_work(&linkwatch_work, delay);
147 static void linkwatch_do_dev(struct net_device *dev)
150 * Make sure the above read is complete since it can be
151 * rewritten as soon as we clear the bit below.
153 smp_mb__before_atomic();
155 /* We are about to handle this device,
156 * so new events can be accepted
158 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
161 if (dev->flags & IFF_UP) {
162 if (netif_carrier_ok(dev))
167 netdev_state_change(dev);
169 /* Note: our callers are responsible for
170 * calling netdev_tracker_free().
175 static void __linkwatch_run_queue(int urgent_only)
177 #define MAX_DO_DEV_PER_LOOP 100
179 int do_dev = MAX_DO_DEV_PER_LOOP;
180 struct net_device *dev;
183 /* Give urgent case more budget */
185 do_dev += MAX_DO_DEV_PER_LOOP;
188 * Limit the number of linkwatch events to one
189 * per second so that a runaway driver does not
190 * cause a storm of messages on the netlink
191 * socket. This limit does not apply to up events
192 * while the device qdisc is down.
195 linkwatch_nextevent = jiffies + HZ;
196 /* Limit wrap-around effect on delay. */
197 else if (time_after(linkwatch_nextevent, jiffies + HZ))
198 linkwatch_nextevent = jiffies;
200 clear_bit(LW_URGENT, &linkwatch_flags);
202 spin_lock_irq(&lweventlist_lock);
203 list_splice_init(&lweventlist, &wrk);
205 while (!list_empty(&wrk) && do_dev > 0) {
207 dev = list_first_entry(&wrk, struct net_device, link_watch_list);
208 list_del_init(&dev->link_watch_list);
210 if (!netif_device_present(dev) ||
211 (urgent_only && !linkwatch_urgent_event(dev))) {
212 list_add_tail(&dev->link_watch_list, &lweventlist);
215 /* We must free netdev tracker under
216 * the spinlock protection.
218 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
219 spin_unlock_irq(&lweventlist_lock);
220 linkwatch_do_dev(dev);
222 spin_lock_irq(&lweventlist_lock);
225 /* Add the remaining work back to lweventlist */
226 list_splice_init(&wrk, &lweventlist);
228 if (!list_empty(&lweventlist))
229 linkwatch_schedule_work(0);
230 spin_unlock_irq(&lweventlist_lock);
233 void linkwatch_forget_dev(struct net_device *dev)
238 spin_lock_irqsave(&lweventlist_lock, flags);
239 if (!list_empty(&dev->link_watch_list)) {
240 list_del_init(&dev->link_watch_list);
242 /* We must release netdev tracker under
243 * the spinlock protection.
245 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
247 spin_unlock_irqrestore(&lweventlist_lock, flags);
249 linkwatch_do_dev(dev);
253 /* Must be called with the rtnl semaphore held */
254 void linkwatch_run_queue(void)
256 __linkwatch_run_queue(0);
260 static void linkwatch_event(struct work_struct *dummy)
263 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
268 void linkwatch_fire_event(struct net_device *dev)
270 bool urgent = linkwatch_urgent_event(dev);
272 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
273 linkwatch_add_event(dev);
277 linkwatch_schedule_work(urgent);
279 EXPORT_SYMBOL(linkwatch_fire_event);