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 void linkwatch_init_dev(struct net_device *dev) 80 { 81 /* Handle pre-registration link state changes */ 82 if (!netif_carrier_ok(dev) || netif_dormant(dev)) 83 rfc2863_policy(dev); 84 } 85 86 87 static bool linkwatch_urgent_event(struct net_device *dev) 88 { 89 if (!netif_running(dev)) 90 return false; 91 92 if (dev->ifindex != dev->iflink) 93 return true; 94 95 return netif_carrier_ok(dev) && qdisc_tx_changing(dev); 96 } 97 98 99 static void linkwatch_add_event(struct net_device *dev) 100 { 101 unsigned long flags; 102 103 spin_lock_irqsave(&lweventlist_lock, flags); 104 if (list_empty(&dev->link_watch_list)) { 105 list_add_tail(&dev->link_watch_list, &lweventlist); 106 dev_hold(dev); 107 } 108 spin_unlock_irqrestore(&lweventlist_lock, flags); 109 } 110 111 112 static void linkwatch_schedule_work(int urgent) 113 { 114 unsigned long delay = linkwatch_nextevent - jiffies; 115 116 if (test_bit(LW_URGENT, &linkwatch_flags)) 117 return; 118 119 /* Minimise down-time: drop delay for up event. */ 120 if (urgent) { 121 if (test_and_set_bit(LW_URGENT, &linkwatch_flags)) 122 return; 123 delay = 0; 124 } 125 126 /* If we wrap around we'll delay it by at most HZ. */ 127 if (delay > HZ) 128 delay = 0; 129 130 /* 131 * If urgent, schedule immediate execution; otherwise, don't 132 * override the existing timer. 133 */ 134 if (test_bit(LW_URGENT, &linkwatch_flags)) 135 mod_delayed_work(system_wq, &linkwatch_work, 0); 136 else 137 schedule_delayed_work(&linkwatch_work, delay); 138 } 139 140 141 static void linkwatch_do_dev(struct net_device *dev) 142 { 143 /* 144 * Make sure the above read is complete since it can be 145 * rewritten as soon as we clear the bit below. 146 */ 147 smp_mb__before_clear_bit(); 148 149 /* We are about to handle this device, 150 * so new events can be accepted 151 */ 152 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state); 153 154 rfc2863_policy(dev); 155 if (dev->flags & IFF_UP) { 156 if (netif_carrier_ok(dev)) 157 dev_activate(dev); 158 else 159 dev_deactivate(dev); 160 161 netdev_state_change(dev); 162 } 163 dev_put(dev); 164 } 165 166 static void __linkwatch_run_queue(int urgent_only) 167 { 168 struct net_device *dev; 169 LIST_HEAD(wrk); 170 171 /* 172 * Limit the number of linkwatch events to one 173 * per second so that a runaway driver does not 174 * cause a storm of messages on the netlink 175 * socket. This limit does not apply to up events 176 * while the device qdisc is down. 177 */ 178 if (!urgent_only) 179 linkwatch_nextevent = jiffies + HZ; 180 /* Limit wrap-around effect on delay. */ 181 else if (time_after(linkwatch_nextevent, jiffies + HZ)) 182 linkwatch_nextevent = jiffies; 183 184 clear_bit(LW_URGENT, &linkwatch_flags); 185 186 spin_lock_irq(&lweventlist_lock); 187 list_splice_init(&lweventlist, &wrk); 188 189 while (!list_empty(&wrk)) { 190 191 dev = list_first_entry(&wrk, struct net_device, link_watch_list); 192 list_del_init(&dev->link_watch_list); 193 194 if (urgent_only && !linkwatch_urgent_event(dev)) { 195 list_add_tail(&dev->link_watch_list, &lweventlist); 196 continue; 197 } 198 spin_unlock_irq(&lweventlist_lock); 199 linkwatch_do_dev(dev); 200 spin_lock_irq(&lweventlist_lock); 201 } 202 203 if (!list_empty(&lweventlist)) 204 linkwatch_schedule_work(0); 205 spin_unlock_irq(&lweventlist_lock); 206 } 207 208 void linkwatch_forget_dev(struct net_device *dev) 209 { 210 unsigned long flags; 211 int clean = 0; 212 213 spin_lock_irqsave(&lweventlist_lock, flags); 214 if (!list_empty(&dev->link_watch_list)) { 215 list_del_init(&dev->link_watch_list); 216 clean = 1; 217 } 218 spin_unlock_irqrestore(&lweventlist_lock, flags); 219 if (clean) 220 linkwatch_do_dev(dev); 221 } 222 223 224 /* Must be called with the rtnl semaphore held */ 225 void linkwatch_run_queue(void) 226 { 227 __linkwatch_run_queue(0); 228 } 229 230 231 static void linkwatch_event(struct work_struct *dummy) 232 { 233 rtnl_lock(); 234 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies)); 235 rtnl_unlock(); 236 } 237 238 239 void linkwatch_fire_event(struct net_device *dev) 240 { 241 bool urgent = linkwatch_urgent_event(dev); 242 243 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) { 244 linkwatch_add_event(dev); 245 } else if (!urgent) 246 return; 247 248 linkwatch_schedule_work(urgent); 249 } 250 EXPORT_SYMBOL(linkwatch_fire_event); 251