1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Linux network device link state notification 4 * 5 * Author: 6 * Stefan Rompf <sux@loplof.de> 7 */ 8 9 #include <linux/module.h> 10 #include <linux/netdevice.h> 11 #include <linux/if.h> 12 #include <net/sock.h> 13 #include <net/pkt_sched.h> 14 #include <linux/rtnetlink.h> 15 #include <linux/jiffies.h> 16 #include <linux/spinlock.h> 17 #include <linux/workqueue.h> 18 #include <linux/bitops.h> 19 #include <linux/types.h> 20 21 #include "dev.h" 22 23 enum lw_bits { 24 LW_URGENT = 0, 25 }; 26 27 static unsigned long linkwatch_flags; 28 static unsigned long linkwatch_nextevent; 29 30 static void linkwatch_event(struct work_struct *dummy); 31 static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event); 32 33 static LIST_HEAD(lweventlist); 34 static DEFINE_SPINLOCK(lweventlist_lock); 35 36 static unsigned char default_operstate(const struct net_device *dev) 37 { 38 if (netif_testing(dev)) 39 return IF_OPER_TESTING; 40 41 if (!netif_carrier_ok(dev)) 42 return (dev->ifindex != dev_get_iflink(dev) ? 43 IF_OPER_LOWERLAYERDOWN : IF_OPER_DOWN); 44 45 if (netif_dormant(dev)) 46 return IF_OPER_DORMANT; 47 48 return IF_OPER_UP; 49 } 50 51 52 static void rfc2863_policy(struct net_device *dev) 53 { 54 unsigned char operstate = default_operstate(dev); 55 56 if (operstate == dev->operstate) 57 return; 58 59 write_lock(&dev_base_lock); 60 61 switch(dev->link_mode) { 62 case IF_LINK_MODE_TESTING: 63 if (operstate == IF_OPER_UP) 64 operstate = IF_OPER_TESTING; 65 break; 66 67 case IF_LINK_MODE_DORMANT: 68 if (operstate == IF_OPER_UP) 69 operstate = IF_OPER_DORMANT; 70 break; 71 case IF_LINK_MODE_DEFAULT: 72 default: 73 break; 74 } 75 76 dev->operstate = operstate; 77 78 write_unlock(&dev_base_lock); 79 } 80 81 82 void linkwatch_init_dev(struct net_device *dev) 83 { 84 /* Handle pre-registration link state changes */ 85 if (!netif_carrier_ok(dev) || netif_dormant(dev) || 86 netif_testing(dev)) 87 rfc2863_policy(dev); 88 } 89 90 91 static bool linkwatch_urgent_event(struct net_device *dev) 92 { 93 if (!netif_running(dev)) 94 return false; 95 96 if (dev->ifindex != dev_get_iflink(dev)) 97 return true; 98 99 if (netif_is_lag_port(dev) || netif_is_lag_master(dev)) 100 return true; 101 102 return netif_carrier_ok(dev) && qdisc_tx_changing(dev); 103 } 104 105 106 static void linkwatch_add_event(struct net_device *dev) 107 { 108 unsigned long flags; 109 110 spin_lock_irqsave(&lweventlist_lock, flags); 111 if (list_empty(&dev->link_watch_list)) { 112 list_add_tail(&dev->link_watch_list, &lweventlist); 113 dev_hold_track(dev, &dev->linkwatch_dev_tracker, GFP_ATOMIC); 114 } 115 spin_unlock_irqrestore(&lweventlist_lock, flags); 116 } 117 118 119 static void linkwatch_schedule_work(int urgent) 120 { 121 unsigned long delay = linkwatch_nextevent - jiffies; 122 123 if (test_bit(LW_URGENT, &linkwatch_flags)) 124 return; 125 126 /* Minimise down-time: drop delay for up event. */ 127 if (urgent) { 128 if (test_and_set_bit(LW_URGENT, &linkwatch_flags)) 129 return; 130 delay = 0; 131 } 132 133 /* If we wrap around we'll delay it by at most HZ. */ 134 if (delay > HZ) 135 delay = 0; 136 137 /* 138 * If urgent, schedule immediate execution; otherwise, don't 139 * override the existing timer. 140 */ 141 if (test_bit(LW_URGENT, &linkwatch_flags)) 142 mod_delayed_work(system_wq, &linkwatch_work, 0); 143 else 144 schedule_delayed_work(&linkwatch_work, delay); 145 } 146 147 148 static void linkwatch_do_dev(struct net_device *dev) 149 { 150 /* 151 * Make sure the above read is complete since it can be 152 * rewritten as soon as we clear the bit below. 153 */ 154 smp_mb__before_atomic(); 155 156 /* We are about to handle this device, 157 * so new events can be accepted 158 */ 159 clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state); 160 161 rfc2863_policy(dev); 162 if (dev->flags & IFF_UP) { 163 if (netif_carrier_ok(dev)) 164 dev_activate(dev); 165 else 166 dev_deactivate(dev); 167 168 netdev_state_change(dev); 169 } 170 /* Note: our callers are responsible for calling netdev_tracker_free(). 171 * This is the reason we use __dev_put() instead of dev_put(). 172 */ 173 __dev_put(dev); 174 } 175 176 static void __linkwatch_run_queue(int urgent_only) 177 { 178 #define MAX_DO_DEV_PER_LOOP 100 179 180 int do_dev = MAX_DO_DEV_PER_LOOP; 181 struct net_device *dev; 182 LIST_HEAD(wrk); 183 184 /* Give urgent case more budget */ 185 if (urgent_only) 186 do_dev += MAX_DO_DEV_PER_LOOP; 187 188 /* 189 * Limit the number of linkwatch events to one 190 * per second so that a runaway driver does not 191 * cause a storm of messages on the netlink 192 * socket. This limit does not apply to up events 193 * while the device qdisc is down. 194 */ 195 if (!urgent_only) 196 linkwatch_nextevent = jiffies + HZ; 197 /* Limit wrap-around effect on delay. */ 198 else if (time_after(linkwatch_nextevent, jiffies + HZ)) 199 linkwatch_nextevent = jiffies; 200 201 clear_bit(LW_URGENT, &linkwatch_flags); 202 203 spin_lock_irq(&lweventlist_lock); 204 list_splice_init(&lweventlist, &wrk); 205 206 while (!list_empty(&wrk) && do_dev > 0) { 207 208 dev = list_first_entry(&wrk, struct net_device, link_watch_list); 209 list_del_init(&dev->link_watch_list); 210 211 if (!netif_device_present(dev) || 212 (urgent_only && !linkwatch_urgent_event(dev))) { 213 list_add_tail(&dev->link_watch_list, &lweventlist); 214 continue; 215 } 216 /* We must free netdev tracker under 217 * the spinlock protection. 218 */ 219 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker); 220 spin_unlock_irq(&lweventlist_lock); 221 linkwatch_do_dev(dev); 222 do_dev--; 223 spin_lock_irq(&lweventlist_lock); 224 } 225 226 /* Add the remaining work back to lweventlist */ 227 list_splice_init(&wrk, &lweventlist); 228 229 if (!list_empty(&lweventlist)) 230 linkwatch_schedule_work(0); 231 spin_unlock_irq(&lweventlist_lock); 232 } 233 234 void linkwatch_forget_dev(struct net_device *dev) 235 { 236 unsigned long flags; 237 int clean = 0; 238 239 spin_lock_irqsave(&lweventlist_lock, flags); 240 if (!list_empty(&dev->link_watch_list)) { 241 list_del_init(&dev->link_watch_list); 242 clean = 1; 243 /* We must release netdev tracker under 244 * the spinlock protection. 245 */ 246 netdev_tracker_free(dev, &dev->linkwatch_dev_tracker); 247 } 248 spin_unlock_irqrestore(&lweventlist_lock, flags); 249 if (clean) 250 linkwatch_do_dev(dev); 251 } 252 253 254 /* Must be called with the rtnl semaphore held */ 255 void linkwatch_run_queue(void) 256 { 257 __linkwatch_run_queue(0); 258 } 259 260 261 static void linkwatch_event(struct work_struct *dummy) 262 { 263 rtnl_lock(); 264 __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies)); 265 rtnl_unlock(); 266 } 267 268 269 void linkwatch_fire_event(struct net_device *dev) 270 { 271 bool urgent = linkwatch_urgent_event(dev); 272 273 if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) { 274 linkwatch_add_event(dev); 275 } else if (!urgent) 276 return; 277 278 linkwatch_schedule_work(urgent); 279 } 280 EXPORT_SYMBOL(linkwatch_fire_event); 281