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 int default_operstate(const struct net_device *dev) |
37 | { |
38 | if (netif_testing(dev)) |
39 | return IF_OPER_TESTING; |
40 | |
41 | /* Some uppers (DSA) have additional sources for being down, so |
42 | * first check whether lower is indeed the source of its down state. |
43 | */ |
44 | if (!netif_carrier_ok(dev)) { |
45 | int iflink = dev_get_iflink(dev); |
46 | struct net_device *peer; |
47 | |
48 | if (iflink == dev->ifindex) |
49 | return IF_OPER_DOWN; |
50 | |
51 | peer = __dev_get_by_index(net: dev_net(dev), ifindex: iflink); |
52 | if (!peer) |
53 | return IF_OPER_DOWN; |
54 | |
55 | return netif_carrier_ok(dev: peer) ? IF_OPER_DOWN : |
56 | IF_OPER_LOWERLAYERDOWN; |
57 | } |
58 | |
59 | if (netif_dormant(dev)) |
60 | return IF_OPER_DORMANT; |
61 | |
62 | return IF_OPER_UP; |
63 | } |
64 | |
65 | static void rfc2863_policy(struct net_device *dev) |
66 | { |
67 | unsigned int operstate = default_operstate(dev); |
68 | |
69 | if (operstate == READ_ONCE(dev->operstate)) |
70 | return; |
71 | |
72 | switch(dev->link_mode) { |
73 | case IF_LINK_MODE_TESTING: |
74 | if (operstate == IF_OPER_UP) |
75 | operstate = IF_OPER_TESTING; |
76 | break; |
77 | |
78 | case IF_LINK_MODE_DORMANT: |
79 | if (operstate == IF_OPER_UP) |
80 | operstate = IF_OPER_DORMANT; |
81 | break; |
82 | case IF_LINK_MODE_DEFAULT: |
83 | default: |
84 | break; |
85 | } |
86 | |
87 | WRITE_ONCE(dev->operstate, operstate); |
88 | } |
89 | |
90 | |
91 | void linkwatch_init_dev(struct net_device *dev) |
92 | { |
93 | /* Handle pre-registration link state changes */ |
94 | if (!netif_carrier_ok(dev) || netif_dormant(dev) || |
95 | netif_testing(dev)) |
96 | rfc2863_policy(dev); |
97 | } |
98 | |
99 | |
100 | static bool linkwatch_urgent_event(struct net_device *dev) |
101 | { |
102 | if (!netif_running(dev)) |
103 | return false; |
104 | |
105 | if (dev->ifindex != dev_get_iflink(dev)) |
106 | return true; |
107 | |
108 | if (netif_is_lag_port(dev) || netif_is_lag_master(dev)) |
109 | return true; |
110 | |
111 | return netif_carrier_ok(dev) && qdisc_tx_changing(dev); |
112 | } |
113 | |
114 | |
115 | static void linkwatch_add_event(struct net_device *dev) |
116 | { |
117 | unsigned long flags; |
118 | |
119 | spin_lock_irqsave(&lweventlist_lock, flags); |
120 | if (list_empty(head: &dev->link_watch_list)) { |
121 | list_add_tail(new: &dev->link_watch_list, head: &lweventlist); |
122 | netdev_hold(dev, tracker: &dev->linkwatch_dev_tracker, GFP_ATOMIC); |
123 | } |
124 | spin_unlock_irqrestore(lock: &lweventlist_lock, flags); |
125 | } |
126 | |
127 | |
128 | static void linkwatch_schedule_work(int urgent) |
129 | { |
130 | unsigned long delay = linkwatch_nextevent - jiffies; |
131 | |
132 | if (test_bit(LW_URGENT, &linkwatch_flags)) |
133 | return; |
134 | |
135 | /* Minimise down-time: drop delay for up event. */ |
136 | if (urgent) { |
137 | if (test_and_set_bit(nr: LW_URGENT, addr: &linkwatch_flags)) |
138 | return; |
139 | delay = 0; |
140 | } |
141 | |
142 | /* If we wrap around we'll delay it by at most HZ. */ |
143 | if (delay > HZ) |
144 | delay = 0; |
145 | |
146 | /* |
147 | * If urgent, schedule immediate execution; otherwise, don't |
148 | * override the existing timer. |
149 | */ |
150 | if (test_bit(LW_URGENT, &linkwatch_flags)) |
151 | mod_delayed_work(wq: system_wq, dwork: &linkwatch_work, delay: 0); |
152 | else |
153 | schedule_delayed_work(dwork: &linkwatch_work, delay); |
154 | } |
155 | |
156 | |
157 | static void linkwatch_do_dev(struct net_device *dev) |
158 | { |
159 | /* |
160 | * Make sure the above read is complete since it can be |
161 | * rewritten as soon as we clear the bit below. |
162 | */ |
163 | smp_mb__before_atomic(); |
164 | |
165 | /* We are about to handle this device, |
166 | * so new events can be accepted |
167 | */ |
168 | clear_bit(nr: __LINK_STATE_LINKWATCH_PENDING, addr: &dev->state); |
169 | |
170 | rfc2863_policy(dev); |
171 | if (dev->flags & IFF_UP) { |
172 | if (netif_carrier_ok(dev)) |
173 | dev_activate(dev); |
174 | else |
175 | dev_deactivate(dev); |
176 | |
177 | netdev_state_change(dev); |
178 | } |
179 | /* Note: our callers are responsible for calling netdev_tracker_free(). |
180 | * This is the reason we use __dev_put() instead of dev_put(). |
181 | */ |
182 | __dev_put(dev); |
183 | } |
184 | |
185 | static void __linkwatch_run_queue(int urgent_only) |
186 | { |
187 | #define MAX_DO_DEV_PER_LOOP 100 |
188 | |
189 | int do_dev = MAX_DO_DEV_PER_LOOP; |
190 | /* Use a local list here since we add non-urgent |
191 | * events back to the global one when called with |
192 | * urgent_only=1. |
193 | */ |
194 | LIST_HEAD(wrk); |
195 | |
196 | /* Give urgent case more budget */ |
197 | if (urgent_only) |
198 | do_dev += MAX_DO_DEV_PER_LOOP; |
199 | |
200 | /* |
201 | * Limit the number of linkwatch events to one |
202 | * per second so that a runaway driver does not |
203 | * cause a storm of messages on the netlink |
204 | * socket. This limit does not apply to up events |
205 | * while the device qdisc is down. |
206 | */ |
207 | if (!urgent_only) |
208 | linkwatch_nextevent = jiffies + HZ; |
209 | /* Limit wrap-around effect on delay. */ |
210 | else if (time_after(linkwatch_nextevent, jiffies + HZ)) |
211 | linkwatch_nextevent = jiffies; |
212 | |
213 | clear_bit(nr: LW_URGENT, addr: &linkwatch_flags); |
214 | |
215 | spin_lock_irq(lock: &lweventlist_lock); |
216 | list_splice_init(list: &lweventlist, head: &wrk); |
217 | |
218 | while (!list_empty(head: &wrk) && do_dev > 0) { |
219 | struct net_device *dev; |
220 | |
221 | dev = list_first_entry(&wrk, struct net_device, link_watch_list); |
222 | list_del_init(entry: &dev->link_watch_list); |
223 | |
224 | if (!netif_device_present(dev) || |
225 | (urgent_only && !linkwatch_urgent_event(dev))) { |
226 | list_add_tail(new: &dev->link_watch_list, head: &lweventlist); |
227 | continue; |
228 | } |
229 | /* We must free netdev tracker under |
230 | * the spinlock protection. |
231 | */ |
232 | netdev_tracker_free(dev, tracker: &dev->linkwatch_dev_tracker); |
233 | spin_unlock_irq(lock: &lweventlist_lock); |
234 | linkwatch_do_dev(dev); |
235 | do_dev--; |
236 | spin_lock_irq(lock: &lweventlist_lock); |
237 | } |
238 | |
239 | /* Add the remaining work back to lweventlist */ |
240 | list_splice_init(list: &wrk, head: &lweventlist); |
241 | |
242 | if (!list_empty(head: &lweventlist)) |
243 | linkwatch_schedule_work(urgent: 0); |
244 | spin_unlock_irq(lock: &lweventlist_lock); |
245 | } |
246 | |
247 | void linkwatch_sync_dev(struct net_device *dev) |
248 | { |
249 | unsigned long flags; |
250 | int clean = 0; |
251 | |
252 | spin_lock_irqsave(&lweventlist_lock, flags); |
253 | if (!list_empty(head: &dev->link_watch_list)) { |
254 | list_del_init(entry: &dev->link_watch_list); |
255 | clean = 1; |
256 | /* We must release netdev tracker under |
257 | * the spinlock protection. |
258 | */ |
259 | netdev_tracker_free(dev, tracker: &dev->linkwatch_dev_tracker); |
260 | } |
261 | spin_unlock_irqrestore(lock: &lweventlist_lock, flags); |
262 | if (clean) |
263 | linkwatch_do_dev(dev); |
264 | } |
265 | |
266 | |
267 | /* Must be called with the rtnl semaphore held */ |
268 | void linkwatch_run_queue(void) |
269 | { |
270 | __linkwatch_run_queue(urgent_only: 0); |
271 | } |
272 | |
273 | |
274 | static void linkwatch_event(struct work_struct *dummy) |
275 | { |
276 | rtnl_lock(); |
277 | __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies)); |
278 | rtnl_unlock(); |
279 | } |
280 | |
281 | |
282 | void linkwatch_fire_event(struct net_device *dev) |
283 | { |
284 | bool urgent = linkwatch_urgent_event(dev); |
285 | |
286 | if (!test_and_set_bit(nr: __LINK_STATE_LINKWATCH_PENDING, addr: &dev->state)) { |
287 | linkwatch_add_event(dev); |
288 | } else if (!urgent) |
289 | return; |
290 | |
291 | linkwatch_schedule_work(urgent); |
292 | } |
293 | EXPORT_SYMBOL(linkwatch_fire_event); |
294 | |