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 static bool linkwatch_urgent_event(struct net_device *dev)
81 return netif_running(dev) && netif_carrier_ok(dev) &&
82 qdisc_tx_changing(dev);
86 static void linkwatch_add_event(struct net_device *dev)
90 spin_lock_irqsave(&lweventlist_lock, flags);
91 if (list_empty(&dev->link_watch_list)) {
92 list_add_tail(&dev->link_watch_list, &lweventlist);
95 spin_unlock_irqrestore(&lweventlist_lock, flags);
99 static void linkwatch_schedule_work(int urgent)
101 unsigned long delay = linkwatch_nextevent - jiffies;
103 if (test_bit(LW_URGENT, &linkwatch_flags))
106 /* Minimise down-time: drop delay for up event. */
108 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
113 /* If we wrap around we'll delay it by at most HZ. */
118 * This is true if we've scheduled it immeditately or if we don't
119 * need an immediate execution and it's already pending.
121 if (schedule_delayed_work(&linkwatch_work, delay) == !delay)
124 /* Don't bother if there is nothing urgent. */
125 if (!test_bit(LW_URGENT, &linkwatch_flags))
128 /* It's already running which is good enough. */
129 if (!cancel_delayed_work(&linkwatch_work))
132 /* Otherwise we reschedule it again for immediate execution. */
133 schedule_delayed_work(&linkwatch_work, 0);
137 static void linkwatch_do_dev(struct net_device *dev)
140 * Make sure the above read is complete since it can be
141 * rewritten as soon as we clear the bit below.
143 smp_mb__before_clear_bit();
145 /* We are about to handle this device,
146 * so new events can be accepted
148 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
151 if (dev->flags & IFF_UP) {
152 if (netif_carrier_ok(dev))
157 netdev_state_change(dev);
162 static void __linkwatch_run_queue(int urgent_only)
164 struct net_device *dev;
168 * Limit the number of linkwatch events to one
169 * per second so that a runaway driver does not
170 * cause a storm of messages on the netlink
171 * socket. This limit does not apply to up events
172 * while the device qdisc is down.
175 linkwatch_nextevent = jiffies + HZ;
176 /* Limit wrap-around effect on delay. */
177 else if (time_after(linkwatch_nextevent, jiffies + HZ))
178 linkwatch_nextevent = jiffies;
180 clear_bit(LW_URGENT, &linkwatch_flags);
182 spin_lock_irq(&lweventlist_lock);
183 list_splice_init(&lweventlist, &wrk);
185 while (!list_empty(&wrk)) {
187 dev = list_first_entry(&wrk, struct net_device, link_watch_list);
188 list_del_init(&dev->link_watch_list);
190 if (urgent_only && !linkwatch_urgent_event(dev)) {
191 list_add_tail(&dev->link_watch_list, &lweventlist);
194 spin_unlock_irq(&lweventlist_lock);
195 linkwatch_do_dev(dev);
196 spin_lock_irq(&lweventlist_lock);
199 if (!list_empty(&lweventlist))
200 linkwatch_schedule_work(0);
201 spin_unlock_irq(&lweventlist_lock);
204 void linkwatch_forget_dev(struct net_device *dev)
209 spin_lock_irqsave(&lweventlist_lock, flags);
210 if (!list_empty(&dev->link_watch_list)) {
211 list_del_init(&dev->link_watch_list);
214 spin_unlock_irqrestore(&lweventlist_lock, flags);
216 linkwatch_do_dev(dev);
220 /* Must be called with the rtnl semaphore held */
221 void linkwatch_run_queue(void)
223 __linkwatch_run_queue(0);
227 static void linkwatch_event(struct work_struct *dummy)
230 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
235 void linkwatch_fire_event(struct net_device *dev)
237 bool urgent = linkwatch_urgent_event(dev);
239 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
240 linkwatch_add_event(dev);
244 linkwatch_schedule_work(urgent);
246 EXPORT_SYMBOL(linkwatch_fire_event);