err.no 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_URGENT = 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         struct netdev_queue *txq = &dev->tx_queue;
  83
  84         return netif_running(dev) && netif_carrier_ok(dev) &&
  85                txq->qdisc != txq->qdisc_sleeping;
  86 }
  87
  88
  89 static void linkwatch_add_event(struct net_device *dev)
  90 {
  91         unsigned long flags;
  92
  93         spin_lock_irqsave(&lweventlist_lock, flags);
  94         dev->link_watch_next = lweventlist;
  95         lweventlist = dev;
  96         spin_unlock_irqrestore(&lweventlist_lock, flags);
  97 }
  98
  99
 100 static void linkwatch_schedule_work(int urgent)
 101 {
 102         unsigned long delay = linkwatch_nextevent - jiffies;
 103
 104         if (test_bit(LW_URGENT, &linkwatch_flags))
 105                 return;
 106
 107         /* Minimise down-time: drop delay for up event. */
 108         if (urgent) {
 109                 if (test_and_set_bit(LW_URGENT, &linkwatch_flags))
 110                         return;
 111                 delay = 0;
 112         }
 113
 114         /* If we wrap around we'll delay it by at most HZ. */
 115         if (delay > HZ)
 116                 delay = 0;
 117
 118         /*
 119          * This is true if we've scheduled it immeditately or if we don't
 120          * need an immediate execution and it's already pending.
 121          */
 122         if (schedule_delayed_work(&linkwatch_work, delay) == !delay)
 123                 return;
 124
 125         /* Don't bother if there is nothing urgent. */
 126         if (!test_bit(LW_URGENT, &linkwatch_flags))
 127                 return;
 128
 129         /* It's already running which is good enough. */
 130         if (!cancel_delayed_work(&linkwatch_work))
 131                 return;
 132
 133         /* Otherwise we reschedule it again for immediate exection. */
 134         schedule_delayed_work(&linkwatch_work, 0);
 135 }
 136
 137
 138 static void __linkwatch_run_queue(int urgent_only)
 139 {
 140         struct net_device *next;
 141
 142         /*
 143          * Limit the number of linkwatch events to one
 144          * per second so that a runaway driver does not
 145          * cause a storm of messages on the netlink
 146          * socket.  This limit does not apply to up events
 147          * while the device qdisc is down.
 148          */
 149         if (!urgent_only)
 150                 linkwatch_nextevent = jiffies + HZ;
 151         /* Limit wrap-around effect on delay. */
 152         else if (time_after(linkwatch_nextevent, jiffies + HZ))
 153                 linkwatch_nextevent = jiffies;
 154
 155         clear_bit(LW_URGENT, &linkwatch_flags);
 156
 157         spin_lock_irq(&lweventlist_lock);
 158         next = lweventlist;
 159         lweventlist = NULL;
 160         spin_unlock_irq(&lweventlist_lock);
 161
 162         while (next) {
 163                 struct net_device *dev = next;
 164
 165                 next = dev->link_watch_next;
 166
 167                 if (urgent_only && !linkwatch_urgent_event(dev)) {
 168                         linkwatch_add_event(dev);
 169                         continue;
 170                 }
 171
 172                 /*
 173                  * Make sure the above read is complete since it can be
 174                  * rewritten as soon as we clear the bit below.
 175                  */
 176                 smp_mb__before_clear_bit();
 177
 178                 /* We are about to handle this device,
 179                  * so new events can be accepted
 180                  */
 181                 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
 182
 183                 rfc2863_policy(dev);
 184                 if (dev->flags & IFF_UP) {
 185                         if (netif_carrier_ok(dev)) {
 186                                 struct netdev_queue *txq = &dev->tx_queue;
 187
 188                                 WARN_ON(txq->qdisc_sleeping == &noop_qdisc);
 189                                 dev_activate(dev);
 190                         } else
 191                                 dev_deactivate(dev);
 192
 193                         netdev_state_change(dev);
 194                 }
 195
 196                 dev_put(dev);
 197         }
 198
 199         if (lweventlist)
 200                 linkwatch_schedule_work(0);
 201 }
 202
 203
 204 /* Must be called with the rtnl semaphore held */
 205 void linkwatch_run_queue(void)
 206 {
 207         __linkwatch_run_queue(0);
 208 }
 209
 210
 211 static void linkwatch_event(struct work_struct *dummy)
 212 {
 213         rtnl_lock();
 214         __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
 215         rtnl_unlock();
 216 }
 217
 218
 219 void linkwatch_fire_event(struct net_device *dev)
 220 {
 221         int urgent = linkwatch_urgent_event(dev);
 222
 223         if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
 224                 dev_hold(dev);
 225
 226                 linkwatch_add_event(dev);
 227         } else if (!urgent)
 228                 return;
 229
 230         linkwatch_schedule_work(urgent);
 231 }
 232
 233 EXPORT_SYMBOL(linkwatch_fire_event);