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1 | /* | |
2 | * Monitoring code for network dropped packet alerts | |
3 | * | |
4 | * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com> | |
5 | */ | |
6 | ||
7 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
8 | ||
9 | #include <linux/netdevice.h> | |
10 | #include <linux/etherdevice.h> | |
11 | #include <linux/string.h> | |
12 | #include <linux/if_arp.h> | |
13 | #include <linux/inetdevice.h> | |
14 | #include <linux/inet.h> | |
15 | #include <linux/interrupt.h> | |
16 | #include <linux/netpoll.h> | |
17 | #include <linux/sched.h> | |
18 | #include <linux/delay.h> | |
19 | #include <linux/types.h> | |
20 | #include <linux/workqueue.h> | |
21 | #include <linux/netlink.h> | |
22 | #include <linux/net_dropmon.h> | |
23 | #include <linux/percpu.h> | |
24 | #include <linux/timer.h> | |
25 | #include <linux/bitops.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/module.h> | |
28 | #include <net/genetlink.h> | |
29 | #include <net/netevent.h> | |
30 | ||
31 | #include <trace/events/skb.h> | |
32 | #include <trace/events/napi.h> | |
33 | ||
34 | #include <asm/unaligned.h> | |
35 | ||
36 | #define TRACE_ON 1 | |
37 | #define TRACE_OFF 0 | |
38 | ||
39 | /* | |
40 | * Globals, our netlink socket pointer | |
41 | * and the work handle that will send up | |
42 | * netlink alerts | |
43 | */ | |
44 | static int trace_state = TRACE_OFF; | |
45 | static DEFINE_MUTEX(trace_state_mutex); | |
46 | ||
47 | struct per_cpu_dm_data { | |
48 | spinlock_t lock; | |
49 | struct sk_buff *skb; | |
50 | struct work_struct dm_alert_work; | |
51 | struct timer_list send_timer; | |
52 | }; | |
53 | ||
54 | struct dm_hw_stat_delta { | |
55 | struct net_device *dev; | |
56 | unsigned long last_rx; | |
57 | struct list_head list; | |
58 | struct rcu_head rcu; | |
59 | unsigned long last_drop_val; | |
60 | }; | |
61 | ||
62 | static struct genl_family net_drop_monitor_family; | |
63 | ||
64 | static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data); | |
65 | ||
66 | static int dm_hit_limit = 64; | |
67 | static int dm_delay = 1; | |
68 | static unsigned long dm_hw_check_delta = 2*HZ; | |
69 | static LIST_HEAD(hw_stats_list); | |
70 | ||
71 | static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data) | |
72 | { | |
73 | size_t al; | |
74 | struct net_dm_alert_msg *msg; | |
75 | struct nlattr *nla; | |
76 | struct sk_buff *skb; | |
77 | unsigned long flags; | |
78 | void *msg_header; | |
79 | ||
80 | al = sizeof(struct net_dm_alert_msg); | |
81 | al += dm_hit_limit * sizeof(struct net_dm_drop_point); | |
82 | al += sizeof(struct nlattr); | |
83 | ||
84 | skb = genlmsg_new(al, GFP_KERNEL); | |
85 | ||
86 | if (!skb) | |
87 | goto err; | |
88 | ||
89 | msg_header = genlmsg_put(skb, 0, 0, &net_drop_monitor_family, | |
90 | 0, NET_DM_CMD_ALERT); | |
91 | if (!msg_header) { | |
92 | nlmsg_free(skb); | |
93 | skb = NULL; | |
94 | goto err; | |
95 | } | |
96 | nla = nla_reserve(skb, NLA_UNSPEC, | |
97 | sizeof(struct net_dm_alert_msg)); | |
98 | if (!nla) { | |
99 | nlmsg_free(skb); | |
100 | skb = NULL; | |
101 | goto err; | |
102 | } | |
103 | msg = nla_data(nla); | |
104 | memset(msg, 0, al); | |
105 | goto out; | |
106 | ||
107 | err: | |
108 | mod_timer(&data->send_timer, jiffies + HZ / 10); | |
109 | out: | |
110 | spin_lock_irqsave(&data->lock, flags); | |
111 | swap(data->skb, skb); | |
112 | spin_unlock_irqrestore(&data->lock, flags); | |
113 | ||
114 | if (skb) { | |
115 | struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data; | |
116 | struct genlmsghdr *gnlh = (struct genlmsghdr *)nlmsg_data(nlh); | |
117 | ||
118 | genlmsg_end(skb, genlmsg_data(gnlh)); | |
119 | } | |
120 | ||
121 | return skb; | |
122 | } | |
123 | ||
124 | static const struct genl_multicast_group dropmon_mcgrps[] = { | |
125 | { .name = "events", }, | |
126 | }; | |
127 | ||
128 | static void send_dm_alert(struct work_struct *work) | |
129 | { | |
130 | struct sk_buff *skb; | |
131 | struct per_cpu_dm_data *data; | |
132 | ||
133 | data = container_of(work, struct per_cpu_dm_data, dm_alert_work); | |
134 | ||
135 | skb = reset_per_cpu_data(data); | |
136 | ||
137 | if (skb) | |
138 | genlmsg_multicast(&net_drop_monitor_family, skb, 0, | |
139 | 0, GFP_KERNEL); | |
140 | } | |
141 | ||
142 | /* | |
143 | * This is the timer function to delay the sending of an alert | |
144 | * in the event that more drops will arrive during the | |
145 | * hysteresis period. | |
146 | */ | |
147 | static void sched_send_work(unsigned long _data) | |
148 | { | |
149 | struct per_cpu_dm_data *data = (struct per_cpu_dm_data *)_data; | |
150 | ||
151 | schedule_work(&data->dm_alert_work); | |
152 | } | |
153 | ||
154 | static void trace_drop_common(struct sk_buff *skb, void *location) | |
155 | { | |
156 | struct net_dm_alert_msg *msg; | |
157 | struct nlmsghdr *nlh; | |
158 | struct nlattr *nla; | |
159 | int i; | |
160 | struct sk_buff *dskb; | |
161 | struct per_cpu_dm_data *data; | |
162 | unsigned long flags; | |
163 | ||
164 | local_irq_save(flags); | |
165 | data = this_cpu_ptr(&dm_cpu_data); | |
166 | spin_lock(&data->lock); | |
167 | dskb = data->skb; | |
168 | ||
169 | if (!dskb) | |
170 | goto out; | |
171 | ||
172 | nlh = (struct nlmsghdr *)dskb->data; | |
173 | nla = genlmsg_data(nlmsg_data(nlh)); | |
174 | msg = nla_data(nla); | |
175 | for (i = 0; i < msg->entries; i++) { | |
176 | if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) { | |
177 | msg->points[i].count++; | |
178 | goto out; | |
179 | } | |
180 | } | |
181 | if (msg->entries == dm_hit_limit) | |
182 | goto out; | |
183 | /* | |
184 | * We need to create a new entry | |
185 | */ | |
186 | __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point)); | |
187 | nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point)); | |
188 | memcpy(msg->points[msg->entries].pc, &location, sizeof(void *)); | |
189 | msg->points[msg->entries].count = 1; | |
190 | msg->entries++; | |
191 | ||
192 | if (!timer_pending(&data->send_timer)) { | |
193 | data->send_timer.expires = jiffies + dm_delay * HZ; | |
194 | add_timer(&data->send_timer); | |
195 | } | |
196 | ||
197 | out: | |
198 | spin_unlock_irqrestore(&data->lock, flags); | |
199 | } | |
200 | ||
201 | static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location) | |
202 | { | |
203 | trace_drop_common(skb, location); | |
204 | } | |
205 | ||
206 | static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi, | |
207 | int work, int budget) | |
208 | { | |
209 | struct dm_hw_stat_delta *new_stat; | |
210 | ||
211 | /* | |
212 | * Don't check napi structures with no associated device | |
213 | */ | |
214 | if (!napi->dev) | |
215 | return; | |
216 | ||
217 | rcu_read_lock(); | |
218 | list_for_each_entry_rcu(new_stat, &hw_stats_list, list) { | |
219 | /* | |
220 | * only add a note to our monitor buffer if: | |
221 | * 1) this is the dev we received on | |
222 | * 2) its after the last_rx delta | |
223 | * 3) our rx_dropped count has gone up | |
224 | */ | |
225 | if ((new_stat->dev == napi->dev) && | |
226 | (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) && | |
227 | (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) { | |
228 | trace_drop_common(NULL, NULL); | |
229 | new_stat->last_drop_val = napi->dev->stats.rx_dropped; | |
230 | new_stat->last_rx = jiffies; | |
231 | break; | |
232 | } | |
233 | } | |
234 | rcu_read_unlock(); | |
235 | } | |
236 | ||
237 | static int set_all_monitor_traces(int state) | |
238 | { | |
239 | int rc = 0; | |
240 | struct dm_hw_stat_delta *new_stat = NULL; | |
241 | struct dm_hw_stat_delta *temp; | |
242 | ||
243 | mutex_lock(&trace_state_mutex); | |
244 | ||
245 | if (state == trace_state) { | |
246 | rc = -EAGAIN; | |
247 | goto out_unlock; | |
248 | } | |
249 | ||
250 | switch (state) { | |
251 | case TRACE_ON: | |
252 | if (!try_module_get(THIS_MODULE)) { | |
253 | rc = -ENODEV; | |
254 | break; | |
255 | } | |
256 | ||
257 | rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL); | |
258 | rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL); | |
259 | break; | |
260 | ||
261 | case TRACE_OFF: | |
262 | rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL); | |
263 | rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL); | |
264 | ||
265 | tracepoint_synchronize_unregister(); | |
266 | ||
267 | /* | |
268 | * Clean the device list | |
269 | */ | |
270 | list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) { | |
271 | if (new_stat->dev == NULL) { | |
272 | list_del_rcu(&new_stat->list); | |
273 | kfree_rcu(new_stat, rcu); | |
274 | } | |
275 | } | |
276 | ||
277 | module_put(THIS_MODULE); | |
278 | ||
279 | break; | |
280 | default: | |
281 | rc = 1; | |
282 | break; | |
283 | } | |
284 | ||
285 | if (!rc) | |
286 | trace_state = state; | |
287 | else | |
288 | rc = -EINPROGRESS; | |
289 | ||
290 | out_unlock: | |
291 | mutex_unlock(&trace_state_mutex); | |
292 | ||
293 | return rc; | |
294 | } | |
295 | ||
296 | ||
297 | static int net_dm_cmd_config(struct sk_buff *skb, | |
298 | struct genl_info *info) | |
299 | { | |
300 | return -ENOTSUPP; | |
301 | } | |
302 | ||
303 | static int net_dm_cmd_trace(struct sk_buff *skb, | |
304 | struct genl_info *info) | |
305 | { | |
306 | switch (info->genlhdr->cmd) { | |
307 | case NET_DM_CMD_START: | |
308 | return set_all_monitor_traces(TRACE_ON); | |
309 | case NET_DM_CMD_STOP: | |
310 | return set_all_monitor_traces(TRACE_OFF); | |
311 | } | |
312 | ||
313 | return -ENOTSUPP; | |
314 | } | |
315 | ||
316 | static int dropmon_net_event(struct notifier_block *ev_block, | |
317 | unsigned long event, void *ptr) | |
318 | { | |
319 | struct net_device *dev = netdev_notifier_info_to_dev(ptr); | |
320 | struct dm_hw_stat_delta *new_stat = NULL; | |
321 | struct dm_hw_stat_delta *tmp; | |
322 | ||
323 | switch (event) { | |
324 | case NETDEV_REGISTER: | |
325 | new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL); | |
326 | ||
327 | if (!new_stat) | |
328 | goto out; | |
329 | ||
330 | new_stat->dev = dev; | |
331 | new_stat->last_rx = jiffies; | |
332 | mutex_lock(&trace_state_mutex); | |
333 | list_add_rcu(&new_stat->list, &hw_stats_list); | |
334 | mutex_unlock(&trace_state_mutex); | |
335 | break; | |
336 | case NETDEV_UNREGISTER: | |
337 | mutex_lock(&trace_state_mutex); | |
338 | list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) { | |
339 | if (new_stat->dev == dev) { | |
340 | new_stat->dev = NULL; | |
341 | if (trace_state == TRACE_OFF) { | |
342 | list_del_rcu(&new_stat->list); | |
343 | kfree_rcu(new_stat, rcu); | |
344 | break; | |
345 | } | |
346 | } | |
347 | } | |
348 | mutex_unlock(&trace_state_mutex); | |
349 | break; | |
350 | } | |
351 | out: | |
352 | return NOTIFY_DONE; | |
353 | } | |
354 | ||
355 | static const struct genl_ops dropmon_ops[] = { | |
356 | { | |
357 | .cmd = NET_DM_CMD_CONFIG, | |
358 | .doit = net_dm_cmd_config, | |
359 | }, | |
360 | { | |
361 | .cmd = NET_DM_CMD_START, | |
362 | .doit = net_dm_cmd_trace, | |
363 | }, | |
364 | { | |
365 | .cmd = NET_DM_CMD_STOP, | |
366 | .doit = net_dm_cmd_trace, | |
367 | }, | |
368 | }; | |
369 | ||
370 | static struct genl_family net_drop_monitor_family __ro_after_init = { | |
371 | .hdrsize = 0, | |
372 | .name = "NET_DM", | |
373 | .version = 2, | |
374 | .module = THIS_MODULE, | |
375 | .ops = dropmon_ops, | |
376 | .n_ops = ARRAY_SIZE(dropmon_ops), | |
377 | .mcgrps = dropmon_mcgrps, | |
378 | .n_mcgrps = ARRAY_SIZE(dropmon_mcgrps), | |
379 | }; | |
380 | ||
381 | static struct notifier_block dropmon_net_notifier = { | |
382 | .notifier_call = dropmon_net_event | |
383 | }; | |
384 | ||
385 | static int __init init_net_drop_monitor(void) | |
386 | { | |
387 | struct per_cpu_dm_data *data; | |
388 | int cpu, rc; | |
389 | ||
390 | pr_info("Initializing network drop monitor service\n"); | |
391 | ||
392 | if (sizeof(void *) > 8) { | |
393 | pr_err("Unable to store program counters on this arch, Drop monitor failed\n"); | |
394 | return -ENOSPC; | |
395 | } | |
396 | ||
397 | rc = genl_register_family(&net_drop_monitor_family); | |
398 | if (rc) { | |
399 | pr_err("Could not create drop monitor netlink family\n"); | |
400 | return rc; | |
401 | } | |
402 | WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT); | |
403 | ||
404 | rc = register_netdevice_notifier(&dropmon_net_notifier); | |
405 | if (rc < 0) { | |
406 | pr_crit("Failed to register netdevice notifier\n"); | |
407 | goto out_unreg; | |
408 | } | |
409 | ||
410 | rc = 0; | |
411 | ||
412 | for_each_possible_cpu(cpu) { | |
413 | data = &per_cpu(dm_cpu_data, cpu); | |
414 | INIT_WORK(&data->dm_alert_work, send_dm_alert); | |
415 | init_timer(&data->send_timer); | |
416 | data->send_timer.data = (unsigned long)data; | |
417 | data->send_timer.function = sched_send_work; | |
418 | spin_lock_init(&data->lock); | |
419 | reset_per_cpu_data(data); | |
420 | } | |
421 | ||
422 | ||
423 | goto out; | |
424 | ||
425 | out_unreg: | |
426 | genl_unregister_family(&net_drop_monitor_family); | |
427 | out: | |
428 | return rc; | |
429 | } | |
430 | ||
431 | static void exit_net_drop_monitor(void) | |
432 | { | |
433 | struct per_cpu_dm_data *data; | |
434 | int cpu; | |
435 | ||
436 | BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier)); | |
437 | ||
438 | /* | |
439 | * Because of the module_get/put we do in the trace state change path | |
440 | * we are guarnateed not to have any current users when we get here | |
441 | * all we need to do is make sure that we don't have any running timers | |
442 | * or pending schedule calls | |
443 | */ | |
444 | ||
445 | for_each_possible_cpu(cpu) { | |
446 | data = &per_cpu(dm_cpu_data, cpu); | |
447 | del_timer_sync(&data->send_timer); | |
448 | cancel_work_sync(&data->dm_alert_work); | |
449 | /* | |
450 | * At this point, we should have exclusive access | |
451 | * to this struct and can free the skb inside it | |
452 | */ | |
453 | kfree_skb(data->skb); | |
454 | } | |
455 | ||
456 | BUG_ON(genl_unregister_family(&net_drop_monitor_family)); | |
457 | } | |
458 | ||
459 | module_init(init_net_drop_monitor); | |
460 | module_exit(exit_net_drop_monitor); | |
461 | ||
462 | MODULE_LICENSE("GPL v2"); | |
463 | MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>"); | |
464 | MODULE_ALIAS_GENL_FAMILY("NET_DM"); |