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>
27 static unsigned long linkwatch_flags;
28 static unsigned long linkwatch_nextevent;
30 static void linkwatch_event(struct work_struct *dummy);
31 static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
33 static LIST_HEAD(lweventlist);
34 static DEFINE_SPINLOCK(lweventlist_lock);
36 static unsigned char default_operstate(const struct net_device *dev)
38 if (netif_testing(dev))
39 return IF_OPER_TESTING;
41 /* Some uppers (DSA) have additional sources for being down, so
42 * first check whether lower is indeed the source of its down state.
44 if (!netif_carrier_ok(dev)) {
45 int iflink = dev_get_iflink(dev);
46 struct net_device *peer;
48 if (iflink == dev->ifindex)
51 peer = __dev_get_by_index(dev_net(dev), iflink);
55 return netif_carrier_ok(peer) ? IF_OPER_DOWN :
56 IF_OPER_LOWERLAYERDOWN;
59 if (netif_dormant(dev))
60 return IF_OPER_DORMANT;
66 static void rfc2863_policy(struct net_device *dev)
68 unsigned char operstate = default_operstate(dev);
70 if (operstate == dev->operstate)
73 write_lock(&dev_base_lock);
75 switch(dev->link_mode) {
76 case IF_LINK_MODE_TESTING:
77 if (operstate == IF_OPER_UP)
78 operstate = IF_OPER_TESTING;
81 case IF_LINK_MODE_DORMANT:
82 if (operstate == IF_OPER_UP)
83 operstate = IF_OPER_DORMANT;
85 case IF_LINK_MODE_DEFAULT:
90 dev->operstate = operstate;
92 write_unlock(&dev_base_lock);
96 void linkwatch_init_dev(struct net_device *dev)
98 /* Handle pre-registration link state changes */
99 if (!netif_carrier_ok(dev) || netif_dormant(dev) ||
105 static bool linkwatch_urgent_event(struct net_device *dev)
107 if (!netif_running(dev))
110 if (dev->ifindex != dev_get_iflink(dev))
113 if (netif_is_lag_port(dev) || netif_is_lag_master(dev))
116 return netif_carrier_ok(dev) && qdisc_tx_changing(dev);
120 static void linkwatch_add_event(struct net_device *dev)
124 spin_lock_irqsave(&lweventlist_lock, flags);
125 if (list_empty(&dev->link_watch_list)) {
126 list_add_tail(&dev->link_watch_list, &lweventlist);
127 netdev_hold(dev, &dev->linkwatch_dev_tracker, GFP_ATOMIC);
129 spin_unlock_irqrestore(&lweventlist_lock, flags);
133 static void linkwatch_schedule_work(int urgent)
135 unsigned long delay = linkwatch_nextevent - jiffies;
137 if (test_bit(LW_URGENT, &linkwatch_flags))
140 /* Minimise down-time: drop delay for up event. */
142 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
147 /* If we wrap around we'll delay it by at most HZ. */
152 * If urgent, schedule immediate execution; otherwise, don't
153 * override the existing timer.
155 if (test_bit(LW_URGENT, &linkwatch_flags))
156 mod_delayed_work(system_wq, &linkwatch_work, 0);
158 schedule_delayed_work(&linkwatch_work, delay);
162 static void linkwatch_do_dev(struct net_device *dev)
165 * Make sure the above read is complete since it can be
166 * rewritten as soon as we clear the bit below.
168 smp_mb__before_atomic();
170 /* We are about to handle this device,
171 * so new events can be accepted
173 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
176 if (dev->flags & IFF_UP) {
177 if (netif_carrier_ok(dev))
182 netdev_state_change(dev);
184 /* Note: our callers are responsible for calling netdev_tracker_free().
185 * This is the reason we use __dev_put() instead of dev_put().
190 static void __linkwatch_run_queue(int urgent_only)
192 #define MAX_DO_DEV_PER_LOOP 100
194 int do_dev = MAX_DO_DEV_PER_LOOP;
195 /* Use a local list here since we add non-urgent
196 * events back to the global one when called with
201 /* Give urgent case more budget */
203 do_dev += MAX_DO_DEV_PER_LOOP;
206 * Limit the number of linkwatch events to one
207 * per second so that a runaway driver does not
208 * cause a storm of messages on the netlink
209 * socket. This limit does not apply to up events
210 * while the device qdisc is down.
213 linkwatch_nextevent = jiffies + HZ;
214 /* Limit wrap-around effect on delay. */
215 else if (time_after(linkwatch_nextevent, jiffies + HZ))
216 linkwatch_nextevent = jiffies;
218 clear_bit(LW_URGENT, &linkwatch_flags);
220 spin_lock_irq(&lweventlist_lock);
221 list_splice_init(&lweventlist, &wrk);
223 while (!list_empty(&wrk) && do_dev > 0) {
224 struct net_device *dev;
226 dev = list_first_entry(&wrk, struct net_device, link_watch_list);
227 list_del_init(&dev->link_watch_list);
229 if (!netif_device_present(dev) ||
230 (urgent_only && !linkwatch_urgent_event(dev))) {
231 list_add_tail(&dev->link_watch_list, &lweventlist);
234 /* We must free netdev tracker under
235 * the spinlock protection.
237 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
238 spin_unlock_irq(&lweventlist_lock);
239 linkwatch_do_dev(dev);
241 spin_lock_irq(&lweventlist_lock);
244 /* Add the remaining work back to lweventlist */
245 list_splice_init(&wrk, &lweventlist);
247 if (!list_empty(&lweventlist))
248 linkwatch_schedule_work(0);
249 spin_unlock_irq(&lweventlist_lock);
252 void linkwatch_sync_dev(struct net_device *dev)
257 spin_lock_irqsave(&lweventlist_lock, flags);
258 if (!list_empty(&dev->link_watch_list)) {
259 list_del_init(&dev->link_watch_list);
261 /* We must release netdev tracker under
262 * the spinlock protection.
264 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker);
266 spin_unlock_irqrestore(&lweventlist_lock, flags);
268 linkwatch_do_dev(dev);
272 /* Must be called with the rtnl semaphore held */
273 void linkwatch_run_queue(void)
275 __linkwatch_run_queue(0);
279 static void linkwatch_event(struct work_struct *dummy)
282 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
287 void linkwatch_fire_event(struct net_device *dev)
289 bool urgent = linkwatch_urgent_event(dev);
291 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
292 linkwatch_add_event(dev);
296 linkwatch_schedule_work(urgent);
298 EXPORT_SYMBOL(linkwatch_fire_event);