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1da177e4 LT |
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); |