git.oblomov.eu Git - 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 static int linkwatch_urgent_event(struct net_device *dev)
  81 {
  82         return netif_running(dev) && netif_carrier_ok(dev) &&
  83                dev->qdisc != dev->qdisc_sleeping;
  84 }
  85
  86
  87 static void linkwatch_add_event(struct net_device *dev)
  88 {
  89         unsigned long flags;
  90
  91         spin_lock_irqsave(&lweventlist_lock, flags);
  92         dev->link_watch_next = lweventlist;
  93         lweventlist = dev;
  94         spin_unlock_irqrestore(&lweventlist_lock, flags);
  95 }
  96
  97
  98 static void linkwatch_schedule_work(unsigned long delay)
  99 {
 100         if (test_and_set_bit(LW_RUNNING, &linkwatch_flags))
 101                 return;
 102
 103         /* If we wrap around we'll delay it by at most HZ. */
 104         if (delay > HZ) {
 105                 linkwatch_nextevent = jiffies;
 106                 delay = 0;
 107         }
 108
 109         schedule_delayed_work(&linkwatch_work, delay);
 110 }
 111
 112
 113 static void __linkwatch_run_queue(int urgent_only)
 114 {
 115         struct net_device *next;
 116
 117         /*
 118          * Limit the number of linkwatch events to one
 119          * per second so that a runaway driver does not
 120          * cause a storm of messages on the netlink
 121          * socket.  This limit does not apply to up events
 122          * while the device qdisc is down.
 123          */
 124         if (!urgent_only)
 125                 linkwatch_nextevent = jiffies + HZ;
 126         clear_bit(LW_RUNNING, &linkwatch_flags);
 127
 128         spin_lock_irq(&lweventlist_lock);
 129         next = lweventlist;
 130         lweventlist = NULL;
 131         spin_unlock_irq(&lweventlist_lock);
 132
 133         while (next) {
 134                 struct net_device *dev = next;
 135
 136                 next = dev->link_watch_next;
 137
 138                 if (urgent_only && !linkwatch_urgent_event(dev)) {
 139                         linkwatch_add_event(dev);
 140                         continue;
 141                 }
 142
 143                 /*
 144                  * Make sure the above read is complete since it can be
 145                  * rewritten as soon as we clear the bit below.
 146                  */
 147                 smp_mb__before_clear_bit();
 148
 149                 /* We are about to handle this device,
 150                  * so new events can be accepted
 151                  */
 152                 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
 153
 154                 rfc2863_policy(dev);
 155                 if (dev->flags & IFF_UP) {
 156                         if (netif_carrier_ok(dev)) {
 157                                 WARN_ON(dev->qdisc_sleeping == &noop_qdisc);
 158                                 dev_activate(dev);
 159                         } else
 160                                 dev_deactivate(dev);
 161
 162                         netdev_state_change(dev);
 163                 }
 164
 165                 dev_put(dev);
 166         }
 167
 168         if (lweventlist)
 169                 linkwatch_schedule_work(linkwatch_nextevent - jiffies);
 170 }
 171
 172
 173 /* Must be called with the rtnl semaphore held */
 174 void linkwatch_run_queue(void)
 175 {
 176         __linkwatch_run_queue(0);
 177 }
 178
 179
 180 static void linkwatch_event(struct work_struct *dummy)
 181 {
 182         rtnl_lock();
 183         __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
 184         rtnl_unlock();
 185 }
 186
 187
 188 void linkwatch_fire_event(struct net_device *dev)
 189 {
 190         if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
 191                 unsigned long delay;
 192
 193                 dev_hold(dev);
 194
 195                 linkwatch_add_event(dev);
 196
 197                 delay = linkwatch_nextevent - jiffies;
 198
 199                 /* Minimise down-time: drop delay for up event. */
 200                 if (linkwatch_urgent_event(dev))
 201                         delay = 0;
 202
 203                 linkwatch_schedule_work(delay);
 204         }
 205 }
 206
 207 EXPORT_SYMBOL(linkwatch_fire_event);