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/slab.h>
23 #include <linux/workqueue.h>
24 #include <linux/bitops.h>
25 #include <asm/types.h>
32 static unsigned long linkwatch_flags;
33 static unsigned long linkwatch_nextevent;
35 static void linkwatch_event(struct work_struct *dummy);
36 static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
38 static struct net_device *lweventlist;
39 static DEFINE_SPINLOCK(lweventlist_lock);
41 static unsigned char default_operstate(const struct net_device *dev)
43 if (!netif_carrier_ok(dev))
44 return (dev->ifindex != dev->iflink ?
45 IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN);
47 if (netif_dormant(dev))
48 return IF_OPER_DORMANT;
54 static void rfc2863_policy(struct net_device *dev)
56 unsigned char operstate = default_operstate(dev);
58 if (operstate == dev->operstate)
61 write_lock_bh(&dev_base_lock);
63 switch(dev->link_mode) {
64 case IF_LINK_MODE_DORMANT:
65 if (operstate == IF_OPER_UP)
66 operstate = IF_OPER_DORMANT;
69 case IF_LINK_MODE_DEFAULT:
74 dev->operstate = operstate;
76 write_unlock_bh(&dev_base_lock);
80 static int linkwatch_urgent_event(struct net_device *dev)
82 struct netdev_queue *txq = &dev->tx_queue;
84 return netif_running(dev) && netif_carrier_ok(dev) &&
85 txq->qdisc != txq->qdisc_sleeping;
89 static void linkwatch_add_event(struct net_device *dev)
93 spin_lock_irqsave(&lweventlist_lock, flags);
94 dev->link_watch_next = lweventlist;
96 spin_unlock_irqrestore(&lweventlist_lock, flags);
100 static void linkwatch_schedule_work(int urgent)
102 unsigned long delay = linkwatch_nextevent - jiffies;
104 if (test_bit(LW_URGENT, &linkwatch_flags))
107 /* Minimise down-time: drop delay for up event. */
109 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
114 /* If we wrap around we'll delay it by at most HZ. */
119 * This is true if we've scheduled it immeditately or if we don't
120 * need an immediate execution and it's already pending.
122 if (schedule_delayed_work(&linkwatch_work, delay) == !delay)
125 /* Don't bother if there is nothing urgent. */
126 if (!test_bit(LW_URGENT, &linkwatch_flags))
129 /* It's already running which is good enough. */
130 if (!cancel_delayed_work(&linkwatch_work))
133 /* Otherwise we reschedule it again for immediate exection. */
134 schedule_delayed_work(&linkwatch_work, 0);
138 static void __linkwatch_run_queue(int urgent_only)
140 struct net_device *next;
143 * Limit the number of linkwatch events to one
144 * per second so that a runaway driver does not
145 * cause a storm of messages on the netlink
146 * socket. This limit does not apply to up events
147 * while the device qdisc is down.
150 linkwatch_nextevent = jiffies + HZ;
151 /* Limit wrap-around effect on delay. */
152 else if (time_after(linkwatch_nextevent, jiffies + HZ))
153 linkwatch_nextevent = jiffies;
155 clear_bit(LW_URGENT, &linkwatch_flags);
157 spin_lock_irq(&lweventlist_lock);
160 spin_unlock_irq(&lweventlist_lock);
163 struct net_device *dev = next;
165 next = dev->link_watch_next;
167 if (urgent_only && !linkwatch_urgent_event(dev)) {
168 linkwatch_add_event(dev);
173 * Make sure the above read is complete since it can be
174 * rewritten as soon as we clear the bit below.
176 smp_mb__before_clear_bit();
178 /* We are about to handle this device,
179 * so new events can be accepted
181 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
184 if (dev->flags & IFF_UP) {
185 if (netif_carrier_ok(dev)) {
186 struct netdev_queue *txq = &dev->tx_queue;
188 WARN_ON(txq->qdisc_sleeping == &noop_qdisc);
193 netdev_state_change(dev);
200 linkwatch_schedule_work(0);
204 /* Must be called with the rtnl semaphore held */
205 void linkwatch_run_queue(void)
207 __linkwatch_run_queue(0);
211 static void linkwatch_event(struct work_struct *dummy)
214 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
219 void linkwatch_fire_event(struct net_device *dev)
221 int urgent = linkwatch_urgent_event(dev);
223 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
226 linkwatch_add_event(dev);
230 linkwatch_schedule_work(urgent);
233 EXPORT_SYMBOL(linkwatch_fire_event);