2 * Linux network device link state notification
5 * Stefan Rompf <sux@loplof.de>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
14 #include <linux/module.h>
15 #include <linux/netdevice.h>
18 #include <net/pkt_sched.h>
19 #include <linux/rtnetlink.h>
20 #include <linux/jiffies.h>
21 #include <linux/spinlock.h>
22 #include <linux/workqueue.h>
23 #include <linux/bitops.h>
24 #include <asm/types.h>
31 static unsigned long linkwatch_flags;
32 static unsigned long linkwatch_nextevent;
34 static void linkwatch_event(struct work_struct *dummy);
35 static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
37 static LIST_HEAD(lweventlist);
38 static DEFINE_SPINLOCK(lweventlist_lock);
40 static unsigned char default_operstate(const struct net_device *dev)
42 if (!netif_carrier_ok(dev))
43 return (dev->ifindex != dev->iflink ?
44 IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN);
46 if (netif_dormant(dev))
47 return IF_OPER_DORMANT;
53 static void rfc2863_policy(struct net_device *dev)
55 unsigned char operstate = default_operstate(dev);
57 if (operstate == dev->operstate)
60 write_lock_bh(&dev_base_lock);
62 switch(dev->link_mode) {
63 case IF_LINK_MODE_DORMANT:
64 if (operstate == IF_OPER_UP)
65 operstate = IF_OPER_DORMANT;
68 case IF_LINK_MODE_DEFAULT:
73 dev->operstate = operstate;
75 write_unlock_bh(&dev_base_lock);
79 void linkwatch_init_dev(struct net_device *dev)
81 /* Handle pre-registration link state changes */
82 if (!netif_carrier_ok(dev) || netif_dormant(dev))
87 static bool linkwatch_urgent_event(struct net_device *dev)
89 if (!netif_running(dev))
92 if (dev->ifindex != dev->iflink)
95 return netif_carrier_ok(dev) && qdisc_tx_changing(dev);
99 static void linkwatch_add_event(struct net_device *dev)
103 spin_lock_irqsave(&lweventlist_lock, flags);
104 if (list_empty(&dev->link_watch_list)) {
105 list_add_tail(&dev->link_watch_list, &lweventlist);
108 spin_unlock_irqrestore(&lweventlist_lock, flags);
112 static void linkwatch_schedule_work(int urgent)
114 unsigned long delay = linkwatch_nextevent - jiffies;
116 if (test_bit(LW_URGENT, &linkwatch_flags))
119 /* Minimise down-time: drop delay for up event. */
121 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
126 /* If we wrap around we'll delay it by at most HZ. */
131 * This is true if we've scheduled it immeditately or if we don't
132 * need an immediate execution and it's already pending.
134 if (schedule_delayed_work(&linkwatch_work, delay) == !delay)
137 /* Don't bother if there is nothing urgent. */
138 if (!test_bit(LW_URGENT, &linkwatch_flags))
141 /* It's already running which is good enough. */
142 if (!__cancel_delayed_work(&linkwatch_work))
145 /* Otherwise we reschedule it again for immediate execution. */
146 schedule_delayed_work(&linkwatch_work, 0);
150 static void linkwatch_do_dev(struct net_device *dev)
153 * Make sure the above read is complete since it can be
154 * rewritten as soon as we clear the bit below.
156 smp_mb__before_clear_bit();
158 /* We are about to handle this device,
159 * so new events can be accepted
161 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
164 if (dev->flags & IFF_UP) {
165 if (netif_carrier_ok(dev))
170 netdev_state_change(dev);
175 static void __linkwatch_run_queue(int urgent_only)
177 struct net_device *dev;
181 * Limit the number of linkwatch events to one
182 * per second so that a runaway driver does not
183 * cause a storm of messages on the netlink
184 * socket. This limit does not apply to up events
185 * while the device qdisc is down.
188 linkwatch_nextevent = jiffies + HZ;
189 /* Limit wrap-around effect on delay. */
190 else if (time_after(linkwatch_nextevent, jiffies + HZ))
191 linkwatch_nextevent = jiffies;
193 clear_bit(LW_URGENT, &linkwatch_flags);
195 spin_lock_irq(&lweventlist_lock);
196 list_splice_init(&lweventlist, &wrk);
198 while (!list_empty(&wrk)) {
200 dev = list_first_entry(&wrk, struct net_device, link_watch_list);
201 list_del_init(&dev->link_watch_list);
203 if (urgent_only && !linkwatch_urgent_event(dev)) {
204 list_add_tail(&dev->link_watch_list, &lweventlist);
207 spin_unlock_irq(&lweventlist_lock);
208 linkwatch_do_dev(dev);
209 spin_lock_irq(&lweventlist_lock);
212 if (!list_empty(&lweventlist))
213 linkwatch_schedule_work(0);
214 spin_unlock_irq(&lweventlist_lock);
217 void linkwatch_forget_dev(struct net_device *dev)
222 spin_lock_irqsave(&lweventlist_lock, flags);
223 if (!list_empty(&dev->link_watch_list)) {
224 list_del_init(&dev->link_watch_list);
227 spin_unlock_irqrestore(&lweventlist_lock, flags);
229 linkwatch_do_dev(dev);
233 /* Must be called with the rtnl semaphore held */
234 void linkwatch_run_queue(void)
236 __linkwatch_run_queue(0);
240 static void linkwatch_event(struct work_struct *dummy)
243 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
248 void linkwatch_fire_event(struct net_device *dev)
250 bool urgent = linkwatch_urgent_event(dev);
252 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
253 linkwatch_add_event(dev);
257 linkwatch_schedule_work(urgent);
259 EXPORT_SYMBOL(linkwatch_fire_event);