summaryrefslogtreecommitdiffstats
path: root/net/core/link_watch.c
blob: b5f45799c2f3905300fac9d4eb061cae89534731 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
/*
 * Linux network device link state notification
 *
 * Author:
 *     Stefan Rompf <sux@loplof.de>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 */

#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/if.h>
#include <net/sock.h>
#include <net/pkt_sched.h>
#include <linux/rtnetlink.h>
#include <linux/jiffies.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/bitops.h>
#include <asm/types.h>


enum lw_bits {
	LW_RUNNING = 0,
};

static unsigned long linkwatch_flags;
static unsigned long linkwatch_nextevent;

static void linkwatch_event(struct work_struct *dummy);
static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);

static struct net_device *lweventlist;
static DEFINE_SPINLOCK(lweventlist_lock);

static unsigned char default_operstate(const struct net_device *dev)
{
	if (!netif_carrier_ok(dev))
		return (dev->ifindex != dev->iflink ?
			IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN);

	if (netif_dormant(dev))
		return IF_OPER_DORMANT;

	return IF_OPER_UP;
}


static void rfc2863_policy(struct net_device *dev)
{
	unsigned char operstate = default_operstate(dev);

	if (operstate == dev->operstate)
		return;

	write_lock_bh(&dev_base_lock);

	switch(dev->link_mode) {
	case IF_LINK_MODE_DORMANT:
		if (operstate == IF_OPER_UP)
			operstate = IF_OPER_DORMANT;
		break;

	case IF_LINK_MODE_DEFAULT:
	default:
		break;
	}

	dev->operstate = operstate;

	write_unlock_bh(&dev_base_lock);
}


static int linkwatch_urgent_event(struct net_device *dev)
{
	return netif_running(dev) && netif_carrier_ok(dev) &&
	       dev->qdisc != dev->qdisc_sleeping;
}


static void linkwatch_add_event(struct net_device *dev)
{
	unsigned long flags;

	spin_lock_irqsave(&lweventlist_lock, flags);
	dev->link_watch_next = lweventlist;
	lweventlist = dev;
	spin_unlock_irqrestore(&lweventlist_lock, flags);
}


static void linkwatch_schedule_work(unsigned long delay)
{
	if (test_and_set_bit(LW_RUNNING, &linkwatch_flags))
		return;

	/* If we wrap around we'll delay it by at most HZ. */
	if (delay > HZ)
		delay = 0;

	schedule_delayed_work(&linkwatch_work, delay);
}


static void __linkwatch_run_queue(int urgent_only)
{
	struct net_device *next;

	/*
	 * Limit the number of linkwatch events to one
	 * per second so that a runaway driver does not
	 * cause a storm of messages on the netlink
	 * socket.  This limit does not apply to up events
	 * while the device qdisc is down.
	 */
	if (!urgent_only)
		linkwatch_nextevent = jiffies + HZ;
	clear_bit(LW_RUNNING, &linkwatch_flags);

	spin_lock_irq(&lweventlist_lock);
	next = lweventlist;
	lweventlist = NULL;
	spin_unlock_irq(&lweventlist_lock);

	while (next) {
		struct net_device *dev = next;

		next = dev->link_watch_next;

		if (urgent_only && !linkwatch_urgent_event(dev)) {
			linkwatch_add_event(dev);
			continue;
		}

		/*
		 * Make sure the above read is complete since it can be
		 * rewritten as soon as we clear the bit below.
		 */
		smp_mb__before_clear_bit();

		/* We are about to handle this device,
		 * so new events can be accepted
		 */
		clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);

		rfc2863_policy(dev);
		if (dev->flags & IFF_UP) {
			if (netif_carrier_ok(dev)) {
				WARN_ON(dev->qdisc_sleeping == &noop_qdisc);
				dev_activate(dev);
			} else
				dev_deactivate(dev);

			netdev_state_change(dev);
		}

		dev_put(dev);
	}

	if (lweventlist)
		linkwatch_schedule_work(linkwatch_nextevent - jiffies);
}


/* Must be called with the rtnl semaphore held */
void linkwatch_run_queue(void)
{
	__linkwatch_run_queue(0);
}


static void linkwatch_event(struct work_struct *dummy)
{
	rtnl_lock();
	__linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
	rtnl_unlock();
}


void linkwatch_fire_event(struct net_device *dev)
{
	if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
		unsigned long delay;

		dev_hold(dev);

		linkwatch_add_event(dev);

		delay = linkwatch_nextevent - jiffies;

		/* Minimise down-time: drop delay for up event. */
		if (linkwatch_urgent_event(dev))
			delay = 0;

		linkwatch_schedule_work(delay);
	}
}

EXPORT_SYMBOL(linkwatch_fire_event);