[NET] link_watch: Eliminate potential delay on wrap-around
[linux-2.6] / net / bridge / br_notify.c
1 /*
2  *      Device event handling
3  *      Linux ethernet bridge
4  *
5  *      Authors:
6  *      Lennert Buytenhek               <buytenh@gnu.org>
7  *
8  *      $Id: br_notify.c,v 1.2 2000/02/21 15:51:34 davem Exp $
9  *
10  *      This program is free software; you can redistribute it and/or
11  *      modify it under the terms of the GNU General Public License
12  *      as published by the Free Software Foundation; either version
13  *      2 of the License, or (at your option) any later version.
14  */
15
16 #include <linux/kernel.h>
17 #include <linux/rtnetlink.h>
18
19 #include "br_private.h"
20
21 static int br_device_event(struct notifier_block *unused, unsigned long event, void *ptr);
22
23 struct notifier_block br_device_notifier = {
24         .notifier_call = br_device_event
25 };
26
27 /*
28  * Handle changes in state of network devices enslaved to a bridge.
29  *
30  * Note: don't care about up/down if bridge itself is down, because
31  *     port state is checked when bridge is brought up.
32  */
33 static int br_device_event(struct notifier_block *unused, unsigned long event, void *ptr)
34 {
35         struct net_device *dev = ptr;
36         struct net_bridge_port *p = dev->br_port;
37         struct net_bridge *br;
38
39         /* not a port of a bridge */
40         if (p == NULL)
41                 return NOTIFY_DONE;
42
43         br = p->br;
44
45         switch (event) {
46         case NETDEV_CHANGEMTU:
47                 dev_set_mtu(br->dev, br_min_mtu(br));
48                 break;
49
50         case NETDEV_CHANGEADDR:
51                 spin_lock_bh(&br->lock);
52                 br_fdb_changeaddr(p, dev->dev_addr);
53                 br_stp_recalculate_bridge_id(br);
54                 spin_unlock_bh(&br->lock);
55                 break;
56
57         case NETDEV_CHANGE:
58                 br_port_carrier_check(p);
59                 break;
60
61         case NETDEV_FEAT_CHANGE:
62                 spin_lock_bh(&br->lock);
63                 if (netif_running(br->dev))
64                         br_features_recompute(br);
65                 spin_unlock_bh(&br->lock);
66                 break;
67
68         case NETDEV_DOWN:
69                 spin_lock_bh(&br->lock);
70                 if (br->dev->flags & IFF_UP)
71                         br_stp_disable_port(p);
72                 spin_unlock_bh(&br->lock);
73                 break;
74
75         case NETDEV_UP:
76                 if (netif_carrier_ok(dev) && (br->dev->flags & IFF_UP)) {
77                         spin_lock_bh(&br->lock);
78                         br_stp_enable_port(p);
79                         spin_unlock_bh(&br->lock);
80                 }
81                 break;
82
83         case NETDEV_UNREGISTER:
84                 br_del_if(br, dev);
85                 break;
86         }
87
88         /* Events that may cause spanning tree to refresh */
89         if (event == NETDEV_CHANGEADDR || event == NETDEV_UP ||
90             event == NETDEV_CHANGE || event == NETDEV_DOWN)
91                 br_ifinfo_notify(RTM_NEWLINK, p);
92
93         return NOTIFY_DONE;
94 }