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 return netif_running(dev) && netif_carrier_ok(dev) && 82 qdisc_tx_changing(dev); 83 } 84 85 86 static void linkwatch_add_event(struct net_device *dev) 87 { 88 unsigned long flags; 89 90 spin_lock_irqsave(&lweventlist_lock, flags); 91 if (list_empty(&dev->link_watch_list)) { 92 list_add_tail(&dev->link_watch_list, &lweventlist); 93 dev_hold(dev); 94 } 95 spin_unlock_irqrestore(&lweventlist_lock, flags); 96 } 97 98 99 static void linkwatch_schedule_work(int urgent) 100 { 101 unsigned long delay = linkwatch_nextevent - jiffies; 102 103 if (test_bit(LW_URGENT, &linkwatch_flags)) 104 return; 105 106 /* Minimise down-time: drop delay for up event. */ 107 if (urgent) { 108 if (test_and_set_bit(LW_URGENT, &linkwatch_flags)) 109 return; 110 delay = 0; 111 } 112 113 /* If we wrap around we'll delay it by at most HZ. */ 114 if (delay > HZ) 115 delay = 0; 116 117 /* 118 * This is true if we've scheduled it immeditately or if we don't 119 * need an immediate execution and it's already pending. 120 */ 121 if (schedule_delayed_work(&linkwatch_work, delay) == !delay) 122 return; 123 124 /* Don't bother if there is nothing urgent. */ 125 if (!test_bit(LW_URGENT, &linkwatch_flags)) 126 return; 127 128 /* It's already running which is good enough. */ 129 if (!cancel_delayed_work(&linkwatch_work)) 130 return; 131 132 /* Otherwise we reschedule it again for immediate execution. */ 133 schedule_delayed_work(&linkwatch_work, 0); 134 } 135 136 137 static void linkwatch_do_dev(struct net_device *dev) 138 { 139 /* 140 * Make sure the above read is complete since it can be 141 * rewritten as soon as we clear the bit below. 142 */ 143 smp_mb__before_clear_bit(); 144 145 /* We are about to handle this device, 146 * so new events can be accepted 147 */ 148 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state); 149 150 rfc2863_policy(dev); 151 if (dev->flags & IFF_UP) { 152 if (netif_carrier_ok(dev)) 153 dev_activate(dev); 154 else 155 dev_deactivate(dev); 156 157 netdev_state_change(dev); 158 } 159 dev_put(dev); 160 } 161 162 static void __linkwatch_run_queue(int urgent_only) 163 { 164 struct net_device *dev; 165 LIST_HEAD(wrk); 166 167 /* 168 * Limit the number of linkwatch events to one 169 * per second so that a runaway driver does not 170 * cause a storm of messages on the netlink 171 * socket. This limit does not apply to up events 172 * while the device qdisc is down. 173 */ 174 if (!urgent_only) 175 linkwatch_nextevent = jiffies + HZ; 176 /* Limit wrap-around effect on delay. */ 177 else if (time_after(linkwatch_nextevent, jiffies + HZ)) 178 linkwatch_nextevent = jiffies; 179 180 clear_bit(LW_URGENT, &linkwatch_flags); 181 182 spin_lock_irq(&lweventlist_lock); 183 list_splice_init(&lweventlist, &wrk); 184 185 while (!list_empty(&wrk)) { 186 187 dev = list_first_entry(&wrk, struct net_device, link_watch_list); 188 list_del_init(&dev->link_watch_list); 189 190 if (urgent_only && !linkwatch_urgent_event(dev)) { 191 list_add_tail(&dev->link_watch_list, &lweventlist); 192 continue; 193 } 194 spin_unlock_irq(&lweventlist_lock); 195 linkwatch_do_dev(dev); 196 spin_lock_irq(&lweventlist_lock); 197 } 198 199 if (!list_empty(&lweventlist)) 200 linkwatch_schedule_work(0); 201 spin_unlock_irq(&lweventlist_lock); 202 } 203 204 void linkwatch_forget_dev(struct net_device *dev) 205 { 206 unsigned long flags; 207 int clean = 0; 208 209 spin_lock_irqsave(&lweventlist_lock, flags); 210 if (!list_empty(&dev->link_watch_list)) { 211 list_del_init(&dev->link_watch_list); 212 clean = 1; 213 } 214 spin_unlock_irqrestore(&lweventlist_lock, flags); 215 if (clean) 216 linkwatch_do_dev(dev); 217 } 218 219 220 /* Must be called with the rtnl semaphore held */ 221 void linkwatch_run_queue(void) 222 { 223 __linkwatch_run_queue(0); 224 } 225 226 227 static void linkwatch_event(struct work_struct *dummy) 228 { 229 rtnl_lock(); 230 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies)); 231 rtnl_unlock(); 232 } 233 234 235 void linkwatch_fire_event(struct net_device *dev) 236 { 237 bool urgent = linkwatch_urgent_event(dev); 238 239 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) { 240 linkwatch_add_event(dev); 241 } else if (!urgent) 242 return; 243 244 linkwatch_schedule_work(urgent); 245 } 246 EXPORT_SYMBOL(linkwatch_fire_event); 247