1 /*
2 * Linux network device link state notification
3 *
4 * Author:
5 * Stefan Rompf <sux@loplof.de>
6 *
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.
11 *
12 */
13
14 #include <linux/config.h>
15 #include <linux/module.h>
16 #include <linux/netdevice.h>
17 #include <linux/if.h>
18 #include <net/sock.h>
19 #include <linux/rtnetlink.h>
20 #include <linux/jiffies.h>
21 #include <linux/spinlock.h>
22 #include <linux/list.h>
23 #include <linux/slab.h>
24 #include <linux/workqueue.h>
25 #include <linux/bitops.h>
26 #include <asm/types.h>
27
28
29 enum lw_bits {
30 LW_RUNNING = 0,
31 LW_SE_USED
32 };
33
34 static unsigned long linkwatch_flags;
35 static unsigned long linkwatch_nextevent;
36
37 static void linkwatch_event(void *dummy);
38 static DECLARE_WORK(linkwatch_work, linkwatch_event, NULL);
39
40 static LIST_HEAD(lweventlist);
41 static DEFINE_SPINLOCK(lweventlist_lock);
42
43 struct lw_event {
44 struct list_head list;
45 struct net_device *dev;
46 };
47
48 /* Avoid kmalloc() for most systems */
49 static struct lw_event singleevent;
50
51 /* Must be called with the rtnl semaphore held */
52 void linkwatch_run_queue(void)
53 {
54 LIST_HEAD(head);
55 struct list_head *n, *next;
56
57 spin_lock_irq(&lweventlist_lock);
58 list_splice_init(&lweventlist, &head);
59 spin_unlock_irq(&lweventlist_lock);
60
61 list_for_each_safe(n, next, &head) {
62 struct lw_event *event = list_entry(n, struct lw_event, list);
63 struct net_device *dev = event->dev;
64
65 if (event == &singleevent) {
66 clear_bit(LW_SE_USED, &linkwatch_flags);
67 } else {
68 kfree(event);
69 }
70
71 /* We are about to handle this device,
72 * so new events can be accepted
73 */
74 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
75
76 if (dev->flags & IFF_UP) {
77 netdev_state_change(dev);
78 }
79
80 dev_put(dev);
81 }
82 }
83
84
85 static void linkwatch_event(void *dummy)
86 {
87 /* Limit the number of linkwatch events to one
88 * per second so that a runaway driver does not
89 * cause a storm of messages on the netlink
90 * socket
91 */
92 linkwatch_nextevent = jiffies + HZ;
93 clear_bit(LW_RUNNING, &linkwatch_flags);
94
95 rtnl_shlock();
96 linkwatch_run_queue();
97 rtnl_shunlock();
98 }
99
100
101 void linkwatch_fire_event(struct net_device *dev)
102 {
103 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
104 unsigned long flags;
105 struct lw_event *event;
106
107 if (test_and_set_bit(LW_SE_USED, &linkwatch_flags)) {
108 event = kmalloc(sizeof(struct lw_event), GFP_ATOMIC);
109
110 if (unlikely(event == NULL)) {
111 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
112 return;
113 }
114 } else {
115 event = &singleevent;
116 }
117
118 dev_hold(dev);
119 event->dev = dev;
120
121 spin_lock_irqsave(&lweventlist_lock, flags);
122 list_add_tail(&event->list, &lweventlist);
123 spin_unlock_irqrestore(&lweventlist_lock, flags);
124
125 if (!test_and_set_bit(LW_RUNNING, &linkwatch_flags)) {
126 unsigned long thisevent = jiffies;
127
128 if (thisevent >= linkwatch_nextevent) {
129 schedule_work(&linkwatch_work);
130 } else {
131 schedule_delayed_work(&linkwatch_work, linkwatch_nextevent - thisevent);
132 }
133 }
134 }
135 }
136
137 EXPORT_SYMBOL(linkwatch_fire_event);
138
|
This page was automatically generated by the
LXR engine.
|