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 LIST_HEAD(head); 95 struct list_head *n, *next; 96 97 spin_lock_irq(&lweventlist_lock); 98 list_splice_init(&lweventlist, &head); 99 spin_unlock_irq(&lweventlist_lock); 100 101 list_for_each_safe(n, next, &head) { 102 struct lw_event *event = list_entry(n, struct lw_event, list); 103 struct net_device *dev = event->dev; 104 105 if (event == &singleevent) { 106 clear_bit(LW_SE_USED, &linkwatch_flags); 107 } else { 108 kfree(event); 109 } 110 111 /* We are about to handle this device, 112 * so new events can be accepted 113 */ 114 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state); 115 116 rfc2863_policy(dev); 117 if (dev->flags & IFF_UP) { 118 if (netif_carrier_ok(dev)) { 119 WARN_ON(dev->qdisc_sleeping == &noop_qdisc); 120 dev_activate(dev); 121 } else 122 dev_deactivate(dev); 123 124 netdev_state_change(dev); 125 } 126 127 dev_put(dev); 128 } 129 } 130 131 132 static void linkwatch_event(void *dummy) 133 { 134 /* Limit the number of linkwatch events to one 135 * per second so that a runaway driver does not 136 * cause a storm of messages on the netlink 137 * socket 138 */ 139 linkwatch_nextevent = jiffies + HZ; 140 clear_bit(LW_RUNNING, &linkwatch_flags); 141 142 rtnl_lock(); 143 linkwatch_run_queue(); 144 rtnl_unlock(); 145 } 146 147 148 void linkwatch_fire_event(struct net_device *dev) 149 { 150 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) { 151 unsigned long flags; 152 struct lw_event *event; 153 154 if (test_and_set_bit(LW_SE_USED, &linkwatch_flags)) { 155 event = kmalloc(sizeof(struct lw_event), GFP_ATOMIC); 156 157 if (unlikely(event == NULL)) { 158 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state); 159 return; 160 } 161 } else { 162 event = &singleevent; 163 } 164 165 dev_hold(dev); 166 event->dev = dev; 167 168 spin_lock_irqsave(&lweventlist_lock, flags); 169 list_add_tail(&event->list, &lweventlist); 170 spin_unlock_irqrestore(&lweventlist_lock, flags); 171 172 if (!test_and_set_bit(LW_RUNNING, &linkwatch_flags)) { 173 unsigned long delay = linkwatch_nextevent - jiffies; 174 175 /* If we wrap around we'll delay it by at most HZ. */ 176 if (!delay || delay > HZ) 177 schedule_work(&linkwatch_work); 178 else 179 schedule_delayed_work(&linkwatch_work, delay); 180 } 181 } 182 } 183 184 EXPORT_SYMBOL(linkwatch_fire_event); 185