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/workqueue.h> 23 #include <linux/bitops.h> 24 #include <asm/types.h> 25 26 27 enum lw_bits { 28 LW_URGENT = 0, 29 }; 30 31 static unsigned long linkwatch_flags; 32 static unsigned long linkwatch_nextevent; 33 34 static void linkwatch_event(struct work_struct *dummy); 35 static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event); 36 37 static LIST_HEAD(lweventlist); 38 static DEFINE_SPINLOCK(lweventlist_lock); 39 40 static unsigned char default_operstate(const struct net_device *dev) 41 { 42 if (!netif_carrier_ok(dev)) 43 return (dev->ifindex != dev->iflink ? 44 IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN); 45 46 if (netif_dormant(dev)) 47 return IF_OPER_DORMANT; 48 49 return IF_OPER_UP; 50 } 51 52 53 static void rfc2863_policy(struct net_device *dev) 54 { 55 unsigned char operstate = default_operstate(dev); 56 57 if (operstate == dev->operstate) 58 return; 59 60 write_lock_bh(&dev_base_lock); 61 62 switch(dev->link_mode) { 63 case IF_LINK_MODE_DORMANT: 64 if (operstate == IF_OPER_UP) 65 operstate = IF_OPER_DORMANT; 66 break; 67 68 case IF_LINK_MODE_DEFAULT: 69 default: 70 break; 71 } 72 73 dev->operstate = operstate; 74 75 write_unlock_bh(&dev_base_lock); 76 } 77 78 79 static bool linkwatch_urgent_event(struct net_device *dev) 80 { 81 if (!netif_running(dev)) 82 return false; 83 84 if (dev->ifindex != dev->iflink) 85 return true; 86 87 return netif_carrier_ok(dev) && qdisc_tx_changing(dev); 88 } 89 90 91 static void linkwatch_add_event(struct net_device *dev) 92 { 93 unsigned long flags; 94 95 spin_lock_irqsave(&lweventlist_lock, flags); 96 if (list_empty(&dev->link_watch_list)) { 97 list_add_tail(&dev->link_watch_list, &lweventlist); 98 dev_hold(dev); 99 } 100 spin_unlock_irqrestore(&lweventlist_lock, flags); 101 } 102 103 104 static void linkwatch_schedule_work(int urgent) 105 { 106 unsigned long delay = linkwatch_nextevent - jiffies; 107 108 if (test_bit(LW_URGENT, &linkwatch_flags)) 109 return; 110 111 /* Minimise down-time: drop delay for up event. */ 112 if (urgent) { 113 if (test_and_set_bit(LW_URGENT, &linkwatch_flags)) 114 return; 115 delay = 0; 116 } 117 118 /* If we wrap around we'll delay it by at most HZ. */ 119 if (delay > HZ) 120 delay = 0; 121 122 /* 123 * This is true if we've scheduled it immeditately or if we don't 124 * need an immediate execution and it's already pending. 125 */ 126 if (schedule_delayed_work(&linkwatch_work, delay) == !delay) 127 return; 128 129 /* Don't bother if there is nothing urgent. */ 130 if (!test_bit(LW_URGENT, &linkwatch_flags)) 131 return; 132 133 /* It's already running which is good enough. */ 134 if (!__cancel_delayed_work(&linkwatch_work)) 135 return; 136 137 /* Otherwise we reschedule it again for immediate execution. */ 138 schedule_delayed_work(&linkwatch_work, 0); 139 } 140 141 142 static void linkwatch_do_dev(struct net_device *dev) 143 { 144 /* 145 * Make sure the above read is complete since it can be 146 * rewritten as soon as we clear the bit below. 147 */ 148 smp_mb__before_clear_bit(); 149 150 /* We are about to handle this device, 151 * so new events can be accepted 152 */ 153 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state); 154 155 rfc2863_policy(dev); 156 if (dev->flags & IFF_UP) { 157 if (netif_carrier_ok(dev)) 158 dev_activate(dev); 159 else 160 dev_deactivate(dev); 161 162 netdev_state_change(dev); 163 } 164 dev_put(dev); 165 } 166 167 static void __linkwatch_run_queue(int urgent_only) 168 { 169 struct net_device *dev; 170 LIST_HEAD(wrk); 171 172 /* 173 * Limit the number of linkwatch events to one 174 * per second so that a runaway driver does not 175 * cause a storm of messages on the netlink 176 * socket. This limit does not apply to up events 177 * while the device qdisc is down. 178 */ 179 if (!urgent_only) 180 linkwatch_nextevent = jiffies + HZ; 181 /* Limit wrap-around effect on delay. */ 182 else if (time_after(linkwatch_nextevent, jiffies + HZ)) 183 linkwatch_nextevent = jiffies; 184 185 clear_bit(LW_URGENT, &linkwatch_flags); 186 187 spin_lock_irq(&lweventlist_lock); 188 list_splice_init(&lweventlist, &wrk); 189 190 while (!list_empty(&wrk)) { 191 192 dev = list_first_entry(&wrk, struct net_device, link_watch_list); 193 list_del_init(&dev->link_watch_list); 194 195 if (urgent_only && !linkwatch_urgent_event(dev)) { 196 list_add_tail(&dev->link_watch_list, &lweventlist); 197 continue; 198 } 199 spin_unlock_irq(&lweventlist_lock); 200 linkwatch_do_dev(dev); 201 spin_lock_irq(&lweventlist_lock); 202 } 203 204 if (!list_empty(&lweventlist)) 205 linkwatch_schedule_work(0); 206 spin_unlock_irq(&lweventlist_lock); 207 } 208 209 void linkwatch_forget_dev(struct net_device *dev) 210 { 211 unsigned long flags; 212 int clean = 0; 213 214 spin_lock_irqsave(&lweventlist_lock, flags); 215 if (!list_empty(&dev->link_watch_list)) { 216 list_del_init(&dev->link_watch_list); 217 clean = 1; 218 } 219 spin_unlock_irqrestore(&lweventlist_lock, flags); 220 if (clean) 221 linkwatch_do_dev(dev); 222 } 223 224 225 /* Must be called with the rtnl semaphore held */ 226 void linkwatch_run_queue(void) 227 { 228 __linkwatch_run_queue(0); 229 } 230 231 232 static void linkwatch_event(struct work_struct *dummy) 233 { 234 rtnl_lock(); 235 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies)); 236 rtnl_unlock(); 237 } 238 239 240 void linkwatch_fire_event(struct net_device *dev) 241 { 242 bool urgent = linkwatch_urgent_event(dev); 243 244 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) { 245 linkwatch_add_event(dev); 246 } else if (!urgent) 247 return; 248 249 linkwatch_schedule_work(urgent); 250 } 251 EXPORT_SYMBOL(linkwatch_fire_event); 252