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