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 static unsigned char default_operstate(const struct net_device *dev) 53 { 54 if (!netif_carrier_ok(dev)) 55 return (dev->ifindex != dev->iflink ? 56 IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN); 57 58 if (netif_dormant(dev)) 59 return IF_OPER_DORMANT; 60 61 return IF_OPER_UP; 62 } 63 64 65 static void rfc2863_policy(struct net_device *dev) 66 { 67 unsigned char operstate = default_operstate(dev); 68 69 if (operstate == dev->operstate) 70 return; 71 72 write_lock_bh(&dev_base_lock); 73 74 switch(dev->link_mode) { 75 case IF_LINK_MODE_DORMANT: 76 if (operstate == IF_OPER_UP) 77 operstate = IF_OPER_DORMANT; 78 break; 79 80 case IF_LINK_MODE_DEFAULT: 81 default: 82 break; 83 }; 84 85 dev->operstate = operstate; 86 87 write_unlock_bh(&dev_base_lock); 88 } 89 90 91 /* Must be called with the rtnl semaphore held */ 92 void linkwatch_run_queue(void) 93 { 94 struct list_head head, *n, *next; 95 96 spin_lock_irq(&lweventlist_lock); 97 list_replace_init(&lweventlist, &head); 98 spin_unlock_irq(&lweventlist_lock); 99 100 list_for_each_safe(n, next, &head) { 101 struct lw_event *event = list_entry(n, struct lw_event, list); 102 struct net_device *dev = event->dev; 103 104 if (event == &singleevent) { 105 clear_bit(LW_SE_USED, &linkwatch_flags); 106 } else { 107 kfree(event); 108 } 109 110 /* We are about to handle this device, 111 * so new events can be accepted 112 */ 113 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state); 114 115 rfc2863_policy(dev); 116 if (dev->flags & IFF_UP) { 117 if (netif_carrier_ok(dev)) { 118 WARN_ON(dev->qdisc_sleeping == &noop_qdisc); 119 dev_activate(dev); 120 } else 121 dev_deactivate(dev); 122 123 netdev_state_change(dev); 124 } 125 126 dev_put(dev); 127 } 128 } 129 130 131 static void linkwatch_event(void *dummy) 132 { 133 /* Limit the number of linkwatch events to one 134 * per second so that a runaway driver does not 135 * cause a storm of messages on the netlink 136 * socket 137 */ 138 linkwatch_nextevent = jiffies + HZ; 139 clear_bit(LW_RUNNING, &linkwatch_flags); 140 141 rtnl_lock(); 142 linkwatch_run_queue(); 143 rtnl_unlock(); 144 } 145 146 147 void linkwatch_fire_event(struct net_device *dev) 148 { 149 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) { 150 unsigned long flags; 151 struct lw_event *event; 152 153 if (test_and_set_bit(LW_SE_USED, &linkwatch_flags)) { 154 event = kmalloc(sizeof(struct lw_event), GFP_ATOMIC); 155 156 if (unlikely(event == NULL)) { 157 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state); 158 return; 159 } 160 } else { 161 event = &singleevent; 162 } 163 164 dev_hold(dev); 165 event->dev = dev; 166 167 spin_lock_irqsave(&lweventlist_lock, flags); 168 list_add_tail(&event->list, &lweventlist); 169 spin_unlock_irqrestore(&lweventlist_lock, flags); 170 171 if (!test_and_set_bit(LW_RUNNING, &linkwatch_flags)) { 172 unsigned long delay = linkwatch_nextevent - jiffies; 173 174 /* If we wrap around we'll delay it by at most HZ. */ 175 if (!delay || delay > HZ) 176 schedule_work(&linkwatch_work); 177 else 178 schedule_delayed_work(&linkwatch_work, delay); 179 } 180 } 181 } 182 183 EXPORT_SYMBOL(linkwatch_fire_event); 184