SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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/module.h>
  15 #include <linux/netdevice.h>
  16 #include <linux/if.h>
  17 #include <net/sock.h>
  18 #include <net/pkt_sched.h>
  19 #include <linux/rtnetlink.h>
  20 #include <linux/jiffies.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/slab.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/bitops.h>
  25 #include <asm/types.h>
  26
  27
  28 enum lw_bits {
  29         LW_RUNNING = 0,
  30 };
  31
  32 static unsigned long linkwatch_flags;
  33 static unsigned long linkwatch_nextevent;
  34
  35 static void linkwatch_event(struct work_struct *dummy);
  36 static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
  37
  38 static struct net_device *lweventlist;
  39 static DEFINE_SPINLOCK(lweventlist_lock);
  40
  41 static unsigned char default_operstate(const struct net_device *dev)
  42 {
  43         if (!netif_carrier_ok(dev))
  44                 return (dev->ifindex != dev->iflink ?
  45                         IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN);
  46
  47         if (netif_dormant(dev))
  48                 return IF_OPER_DORMANT;
  49
  50         return IF_OPER_UP;
  51 }
  52
  53
  54 static void rfc2863_policy(struct net_device *dev)
  55 {
  56         unsigned char operstate = default_operstate(dev);
  57
  58         if (operstate == dev->operstate)
  59                 return;
  60
  61         write_lock_bh(&dev_base_lock);
  62
  63         switch(dev->link_mode) {
  64         case IF_LINK_MODE_DORMANT:
  65                 if (operstate == IF_OPER_UP)
  66                         operstate = IF_OPER_DORMANT;
  67                 break;
  68
  69         case IF_LINK_MODE_DEFAULT:
  70         default:
  71                 break;
  72         }
  73
  74         dev->operstate = operstate;
  75
  76         write_unlock_bh(&dev_base_lock);
  77 }
  78
  79
  80 /* Must be called with the rtnl semaphore held */
  81 void linkwatch_run_queue(void)
  82 {
  83         struct net_device *next;
  84
  85         spin_lock_irq(&lweventlist_lock);
  86         next = lweventlist;
  87         lweventlist = NULL;
  88         spin_unlock_irq(&lweventlist_lock);
  89
  90         while (next) {
  91                 struct net_device *dev = next;
  92
  93                 next = dev->link_watch_next;
  94
  95                 /*
  96                  * Make sure the above read is complete since it can be
  97                  * rewritten as soon as we clear the bit below.
  98                  */
  99                 smp_mb__before_clear_bit();
 100
 101                 /* We are about to handle this device,
 102                  * so new events can be accepted
 103                  */
 104                 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
 105
 106                 rfc2863_policy(dev);
 107                 if (dev->flags & IFF_UP) {
 108                         if (netif_carrier_ok(dev)) {
 109                                 WARN_ON(dev->qdisc_sleeping == &noop_qdisc);
 110                                 dev_activate(dev);
 111                         } else
 112                                 dev_deactivate(dev);
 113
 114                         netdev_state_change(dev);
 115                 }
 116
 117                 dev_put(dev);
 118         }
 119 }
 120
 121
 122 static void linkwatch_event(struct work_struct *dummy)
 123 {
 124         /* Limit the number of linkwatch events to one
 125          * per second so that a runaway driver does not
 126          * cause a storm of messages on the netlink
 127          * socket
 128          */
 129         linkwatch_nextevent = jiffies + HZ;
 130         clear_bit(LW_RUNNING, &linkwatch_flags);
 131
 132         rtnl_lock();
 133         linkwatch_run_queue();
 134         rtnl_unlock();
 135 }
 136
 137
 138 void linkwatch_fire_event(struct net_device *dev)
 139 {
 140         if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
 141                 unsigned long flags;
 142
 143                 dev_hold(dev);
 144
 145                 spin_lock_irqsave(&lweventlist_lock, flags);
 146                 dev->link_watch_next = lweventlist;
 147                 lweventlist = dev;
 148                 spin_unlock_irqrestore(&lweventlist_lock, flags);
 149
 150                 if (!test_and_set_bit(LW_RUNNING, &linkwatch_flags)) {
 151                         unsigned long delay = linkwatch_nextevent - jiffies;
 152
 153                         /* If we wrap around we'll delay it by at most HZ. */
 154                         if (delay > HZ)
 155                                 delay = 0;
 156                         schedule_delayed_work(&linkwatch_work, delay);
 157                 }
 158         }
 159 }
 160
 161 EXPORT_SYMBOL(linkwatch_fire_event);