Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-2.6] / net / core / link_watch.c
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 <net/pkt_sched.h>
20 #include <linux/rtnetlink.h>
21 #include <linux/jiffies.h>
22 #include <linux/spinlock.h>
23 #include <linux/list.h>
24 #include <linux/slab.h>
25 #include <linux/workqueue.h>
26 #include <linux/bitops.h>
27 #include <asm/types.h>
28
29
30 enum lw_bits {
31         LW_RUNNING = 0,
32         LW_SE_USED
33 };
34
35 static unsigned long linkwatch_flags;
36 static unsigned long linkwatch_nextevent;
37
38 static void linkwatch_event(void *dummy);
39 static DECLARE_WORK(linkwatch_work, linkwatch_event, NULL);
40
41 static LIST_HEAD(lweventlist);
42 static DEFINE_SPINLOCK(lweventlist_lock);
43
44 struct lw_event {
45         struct list_head list;
46         struct net_device *dev;
47 };
48
49 /* Avoid kmalloc() for most systems */
50 static struct lw_event singleevent;
51
52 /* Must be called with the rtnl semaphore held */
53 void linkwatch_run_queue(void)
54 {
55         LIST_HEAD(head);
56         struct list_head *n, *next;
57
58         spin_lock_irq(&lweventlist_lock);
59         list_splice_init(&lweventlist, &head);
60         spin_unlock_irq(&lweventlist_lock);
61
62         list_for_each_safe(n, next, &head) {
63                 struct lw_event *event = list_entry(n, struct lw_event, list);
64                 struct net_device *dev = event->dev;
65
66                 if (event == &singleevent) {
67                         clear_bit(LW_SE_USED, &linkwatch_flags);
68                 } else {
69                         kfree(event);
70                 }
71
72                 /* We are about to handle this device,
73                  * so new events can be accepted
74                  */
75                 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
76
77                 if (dev->flags & IFF_UP) {
78                         if (netif_carrier_ok(dev)) {
79                                 WARN_ON(dev->qdisc_sleeping == &noop_qdisc);
80                                 dev_activate(dev);
81                         } else
82                                 dev_deactivate(dev);
83
84                         netdev_state_change(dev);
85                 }
86
87                 dev_put(dev);
88         }
89 }       
90
91
92 static void linkwatch_event(void *dummy)
93 {
94         /* Limit the number of linkwatch events to one
95          * per second so that a runaway driver does not
96          * cause a storm of messages on the netlink
97          * socket
98          */     
99         linkwatch_nextevent = jiffies + HZ;
100         clear_bit(LW_RUNNING, &linkwatch_flags);
101
102         rtnl_shlock();
103         linkwatch_run_queue();
104         rtnl_shunlock();
105 }
106
107
108 void linkwatch_fire_event(struct net_device *dev)
109 {
110         if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
111                 unsigned long flags;
112                 struct lw_event *event;
113
114                 if (test_and_set_bit(LW_SE_USED, &linkwatch_flags)) {
115                         event = kmalloc(sizeof(struct lw_event), GFP_ATOMIC);
116
117                         if (unlikely(event == NULL)) {
118                                 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
119                                 return;
120                         }
121                 } else {
122                         event = &singleevent;
123                 }
124
125                 dev_hold(dev);
126                 event->dev = dev;
127
128                 spin_lock_irqsave(&lweventlist_lock, flags);
129                 list_add_tail(&event->list, &lweventlist);
130                 spin_unlock_irqrestore(&lweventlist_lock, flags);
131
132                 if (!test_and_set_bit(LW_RUNNING, &linkwatch_flags)) {
133                         unsigned long thisevent = jiffies;
134
135                         if (thisevent >= linkwatch_nextevent) {
136                                 schedule_work(&linkwatch_work);
137                         } else {
138                                 schedule_delayed_work(&linkwatch_work, linkwatch_nextevent - thisevent);
139                         }
140                 }
141         }
142 }
143
144 EXPORT_SYMBOL(linkwatch_fire_event);