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Commit | Line | Data |
---|---|---|
9a8afc8d NH |
1 | /* |
2 | * Monitoring code for network dropped packet alerts | |
3 | * | |
4 | * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com> | |
5 | */ | |
6 | ||
e005d193 JP |
7 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
8 | ||
9a8afc8d NH |
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> | |
5a0e3ad6 | 26 | #include <linux/slab.h> |
cad456d5 | 27 | #include <linux/module.h> |
9a8afc8d | 28 | #include <net/genetlink.h> |
4ea7e386 | 29 | #include <net/netevent.h> |
9a8afc8d | 30 | |
ad8d75ff | 31 | #include <trace/events/skb.h> |
9cbc1cb8 | 32 | #include <trace/events/napi.h> |
9a8afc8d NH |
33 | |
34 | #include <asm/unaligned.h> | |
35 | ||
36 | #define TRACE_ON 1 | |
37 | #define TRACE_OFF 0 | |
38 | ||
39 | static void send_dm_alert(struct work_struct *unused); | |
40 | ||
41 | ||
42 | /* | |
43 | * Globals, our netlink socket pointer | |
44 | * and the work handle that will send up | |
45 | * netlink alerts | |
46 | */ | |
4ea7e386 | 47 | static int trace_state = TRACE_OFF; |
cde2e9a6 | 48 | static DEFINE_MUTEX(trace_state_mutex); |
9a8afc8d NH |
49 | |
50 | struct per_cpu_dm_data { | |
51 | struct work_struct dm_alert_work; | |
3885ca78 | 52 | struct sk_buff __rcu *skb; |
9a8afc8d NH |
53 | atomic_t dm_hit_count; |
54 | struct timer_list send_timer; | |
4fdcfa12 | 55 | int cpu; |
9a8afc8d NH |
56 | }; |
57 | ||
4ea7e386 NH |
58 | struct dm_hw_stat_delta { |
59 | struct net_device *dev; | |
5848cc09 | 60 | unsigned long last_rx; |
4ea7e386 NH |
61 | struct list_head list; |
62 | struct rcu_head rcu; | |
63 | unsigned long last_drop_val; | |
64 | }; | |
65 | ||
9a8afc8d NH |
66 | static struct genl_family net_drop_monitor_family = { |
67 | .id = GENL_ID_GENERATE, | |
68 | .hdrsize = 0, | |
69 | .name = "NET_DM", | |
683703a2 | 70 | .version = 2, |
9a8afc8d NH |
71 | .maxattr = NET_DM_CMD_MAX, |
72 | }; | |
73 | ||
74 | static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data); | |
75 | ||
76 | static int dm_hit_limit = 64; | |
77 | static int dm_delay = 1; | |
4ea7e386 NH |
78 | static unsigned long dm_hw_check_delta = 2*HZ; |
79 | static LIST_HEAD(hw_stats_list); | |
9a8afc8d NH |
80 | |
81 | static void reset_per_cpu_data(struct per_cpu_dm_data *data) | |
82 | { | |
83 | size_t al; | |
84 | struct net_dm_alert_msg *msg; | |
683703a2 | 85 | struct nlattr *nla; |
3885ca78 NH |
86 | struct sk_buff *skb; |
87 | struct sk_buff *oskb = rcu_dereference_protected(data->skb, 1); | |
9a8afc8d NH |
88 | |
89 | al = sizeof(struct net_dm_alert_msg); | |
90 | al += dm_hit_limit * sizeof(struct net_dm_drop_point); | |
683703a2 NH |
91 | al += sizeof(struct nlattr); |
92 | ||
3885ca78 NH |
93 | skb = genlmsg_new(al, GFP_KERNEL); |
94 | ||
95 | if (skb) { | |
96 | genlmsg_put(skb, 0, 0, &net_drop_monitor_family, | |
97 | 0, NET_DM_CMD_ALERT); | |
98 | nla = nla_reserve(skb, NLA_UNSPEC, | |
99 | sizeof(struct net_dm_alert_msg)); | |
100 | msg = nla_data(nla); | |
101 | memset(msg, 0, al); | |
4fdcfa12 NH |
102 | } else |
103 | schedule_work_on(data->cpu, &data->dm_alert_work); | |
3885ca78 NH |
104 | |
105 | /* | |
106 | * Don't need to lock this, since we are guaranteed to only | |
107 | * run this on a single cpu at a time. | |
108 | * Note also that we only update data->skb if the old and new skb | |
109 | * pointers don't match. This ensures that we don't continually call | |
110 | * synchornize_rcu if we repeatedly fail to alloc a new netlink message. | |
111 | */ | |
112 | if (skb != oskb) { | |
113 | rcu_assign_pointer(data->skb, skb); | |
114 | ||
115 | synchronize_rcu(); | |
116 | ||
117 | atomic_set(&data->dm_hit_count, dm_hit_limit); | |
118 | } | |
119 | ||
9a8afc8d NH |
120 | } |
121 | ||
122 | static void send_dm_alert(struct work_struct *unused) | |
123 | { | |
124 | struct sk_buff *skb; | |
3885ca78 | 125 | struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data); |
9a8afc8d | 126 | |
4fdcfa12 NH |
127 | WARN_ON_ONCE(data->cpu != smp_processor_id()); |
128 | ||
9a8afc8d NH |
129 | /* |
130 | * Grab the skb we're about to send | |
131 | */ | |
3885ca78 | 132 | skb = rcu_dereference_protected(data->skb, 1); |
9a8afc8d NH |
133 | |
134 | /* | |
135 | * Replace it with a new one | |
136 | */ | |
137 | reset_per_cpu_data(data); | |
138 | ||
139 | /* | |
140 | * Ship it! | |
141 | */ | |
3885ca78 NH |
142 | if (skb) |
143 | genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL); | |
9a8afc8d | 144 | |
3885ca78 | 145 | put_cpu_var(dm_cpu_data); |
9a8afc8d NH |
146 | } |
147 | ||
148 | /* | |
149 | * This is the timer function to delay the sending of an alert | |
150 | * in the event that more drops will arrive during the | |
151 | * hysteresis period. Note that it operates under the timer interrupt | |
152 | * so we don't need to disable preemption here | |
153 | */ | |
154 | static void sched_send_work(unsigned long unused) | |
155 | { | |
3885ca78 NH |
156 | struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data); |
157 | ||
158 | schedule_work_on(smp_processor_id(), &data->dm_alert_work); | |
9a8afc8d | 159 | |
3885ca78 | 160 | put_cpu_var(dm_cpu_data); |
9a8afc8d NH |
161 | } |
162 | ||
4ea7e386 | 163 | static void trace_drop_common(struct sk_buff *skb, void *location) |
9a8afc8d NH |
164 | { |
165 | struct net_dm_alert_msg *msg; | |
166 | struct nlmsghdr *nlh; | |
683703a2 | 167 | struct nlattr *nla; |
9a8afc8d | 168 | int i; |
3885ca78 NH |
169 | struct sk_buff *dskb; |
170 | struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data); | |
9a8afc8d NH |
171 | |
172 | ||
3885ca78 NH |
173 | rcu_read_lock(); |
174 | dskb = rcu_dereference(data->skb); | |
175 | ||
176 | if (!dskb) | |
177 | goto out; | |
178 | ||
9a8afc8d NH |
179 | if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) { |
180 | /* | |
181 | * we're already at zero, discard this hit | |
182 | */ | |
183 | goto out; | |
184 | } | |
185 | ||
3885ca78 | 186 | nlh = (struct nlmsghdr *)dskb->data; |
683703a2 NH |
187 | nla = genlmsg_data(nlmsg_data(nlh)); |
188 | msg = nla_data(nla); | |
9a8afc8d NH |
189 | for (i = 0; i < msg->entries; i++) { |
190 | if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) { | |
191 | msg->points[i].count++; | |
bbe362be | 192 | atomic_inc(&data->dm_hit_count); |
9a8afc8d NH |
193 | goto out; |
194 | } | |
195 | } | |
196 | ||
197 | /* | |
198 | * We need to create a new entry | |
199 | */ | |
3885ca78 | 200 | __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point)); |
683703a2 | 201 | nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point)); |
9a8afc8d NH |
202 | memcpy(msg->points[msg->entries].pc, &location, sizeof(void *)); |
203 | msg->points[msg->entries].count = 1; | |
204 | msg->entries++; | |
205 | ||
206 | if (!timer_pending(&data->send_timer)) { | |
207 | data->send_timer.expires = jiffies + dm_delay * HZ; | |
208 | add_timer_on(&data->send_timer, smp_processor_id()); | |
209 | } | |
210 | ||
211 | out: | |
3885ca78 NH |
212 | rcu_read_unlock(); |
213 | put_cpu_var(dm_cpu_data); | |
9a8afc8d NH |
214 | return; |
215 | } | |
216 | ||
38516ab5 | 217 | static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location) |
4ea7e386 NH |
218 | { |
219 | trace_drop_common(skb, location); | |
220 | } | |
221 | ||
38516ab5 | 222 | static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi) |
4ea7e386 NH |
223 | { |
224 | struct dm_hw_stat_delta *new_stat; | |
225 | ||
226 | /* | |
5848cc09 | 227 | * Don't check napi structures with no associated device |
4ea7e386 | 228 | */ |
5848cc09 | 229 | if (!napi->dev) |
4ea7e386 NH |
230 | return; |
231 | ||
232 | rcu_read_lock(); | |
233 | list_for_each_entry_rcu(new_stat, &hw_stats_list, list) { | |
5848cc09 NH |
234 | /* |
235 | * only add a note to our monitor buffer if: | |
236 | * 1) this is the dev we received on | |
237 | * 2) its after the last_rx delta | |
238 | * 3) our rx_dropped count has gone up | |
239 | */ | |
4ea7e386 | 240 | if ((new_stat->dev == napi->dev) && |
5848cc09 | 241 | (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) && |
4ea7e386 NH |
242 | (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) { |
243 | trace_drop_common(NULL, NULL); | |
244 | new_stat->last_drop_val = napi->dev->stats.rx_dropped; | |
5848cc09 | 245 | new_stat->last_rx = jiffies; |
4ea7e386 NH |
246 | break; |
247 | } | |
248 | } | |
249 | rcu_read_unlock(); | |
250 | } | |
251 | ||
9a8afc8d NH |
252 | static int set_all_monitor_traces(int state) |
253 | { | |
254 | int rc = 0; | |
4ea7e386 NH |
255 | struct dm_hw_stat_delta *new_stat = NULL; |
256 | struct dm_hw_stat_delta *temp; | |
257 | ||
cde2e9a6 | 258 | mutex_lock(&trace_state_mutex); |
9a8afc8d | 259 | |
4b706372 NH |
260 | if (state == trace_state) { |
261 | rc = -EAGAIN; | |
262 | goto out_unlock; | |
263 | } | |
264 | ||
9a8afc8d NH |
265 | switch (state) { |
266 | case TRACE_ON: | |
cad456d5 NH |
267 | if (!try_module_get(THIS_MODULE)) { |
268 | rc = -ENODEV; | |
269 | break; | |
270 | } | |
271 | ||
38516ab5 SR |
272 | rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL); |
273 | rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL); | |
9a8afc8d | 274 | break; |
cad456d5 | 275 | |
9a8afc8d | 276 | case TRACE_OFF: |
38516ab5 SR |
277 | rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL); |
278 | rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL); | |
9a8afc8d NH |
279 | |
280 | tracepoint_synchronize_unregister(); | |
4ea7e386 NH |
281 | |
282 | /* | |
283 | * Clean the device list | |
284 | */ | |
285 | list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) { | |
286 | if (new_stat->dev == NULL) { | |
287 | list_del_rcu(&new_stat->list); | |
fa81c0e1 | 288 | kfree_rcu(new_stat, rcu); |
4ea7e386 NH |
289 | } |
290 | } | |
cad456d5 NH |
291 | |
292 | module_put(THIS_MODULE); | |
293 | ||
9a8afc8d NH |
294 | break; |
295 | default: | |
296 | rc = 1; | |
297 | break; | |
298 | } | |
299 | ||
4ea7e386 NH |
300 | if (!rc) |
301 | trace_state = state; | |
4b706372 NH |
302 | else |
303 | rc = -EINPROGRESS; | |
4ea7e386 | 304 | |
4b706372 | 305 | out_unlock: |
cde2e9a6 | 306 | mutex_unlock(&trace_state_mutex); |
4ea7e386 | 307 | |
9a8afc8d NH |
308 | return rc; |
309 | } | |
310 | ||
311 | ||
312 | static int net_dm_cmd_config(struct sk_buff *skb, | |
313 | struct genl_info *info) | |
314 | { | |
315 | return -ENOTSUPP; | |
316 | } | |
317 | ||
318 | static int net_dm_cmd_trace(struct sk_buff *skb, | |
319 | struct genl_info *info) | |
320 | { | |
321 | switch (info->genlhdr->cmd) { | |
322 | case NET_DM_CMD_START: | |
323 | return set_all_monitor_traces(TRACE_ON); | |
324 | break; | |
325 | case NET_DM_CMD_STOP: | |
326 | return set_all_monitor_traces(TRACE_OFF); | |
327 | break; | |
328 | } | |
329 | ||
330 | return -ENOTSUPP; | |
331 | } | |
332 | ||
4ea7e386 NH |
333 | static int dropmon_net_event(struct notifier_block *ev_block, |
334 | unsigned long event, void *ptr) | |
335 | { | |
336 | struct net_device *dev = ptr; | |
337 | struct dm_hw_stat_delta *new_stat = NULL; | |
338 | struct dm_hw_stat_delta *tmp; | |
339 | ||
340 | switch (event) { | |
341 | case NETDEV_REGISTER: | |
342 | new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL); | |
343 | ||
344 | if (!new_stat) | |
345 | goto out; | |
346 | ||
347 | new_stat->dev = dev; | |
5848cc09 | 348 | new_stat->last_rx = jiffies; |
cde2e9a6 | 349 | mutex_lock(&trace_state_mutex); |
4ea7e386 | 350 | list_add_rcu(&new_stat->list, &hw_stats_list); |
cde2e9a6 | 351 | mutex_unlock(&trace_state_mutex); |
4ea7e386 NH |
352 | break; |
353 | case NETDEV_UNREGISTER: | |
cde2e9a6 | 354 | mutex_lock(&trace_state_mutex); |
4ea7e386 NH |
355 | list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) { |
356 | if (new_stat->dev == dev) { | |
357 | new_stat->dev = NULL; | |
358 | if (trace_state == TRACE_OFF) { | |
359 | list_del_rcu(&new_stat->list); | |
fa81c0e1 | 360 | kfree_rcu(new_stat, rcu); |
4ea7e386 NH |
361 | break; |
362 | } | |
363 | } | |
364 | } | |
cde2e9a6 | 365 | mutex_unlock(&trace_state_mutex); |
4ea7e386 NH |
366 | break; |
367 | } | |
368 | out: | |
369 | return NOTIFY_DONE; | |
370 | } | |
9a8afc8d NH |
371 | |
372 | static struct genl_ops dropmon_ops[] = { | |
373 | { | |
374 | .cmd = NET_DM_CMD_CONFIG, | |
375 | .doit = net_dm_cmd_config, | |
376 | }, | |
377 | { | |
378 | .cmd = NET_DM_CMD_START, | |
379 | .doit = net_dm_cmd_trace, | |
380 | }, | |
381 | { | |
382 | .cmd = NET_DM_CMD_STOP, | |
383 | .doit = net_dm_cmd_trace, | |
384 | }, | |
385 | }; | |
386 | ||
4ea7e386 NH |
387 | static struct notifier_block dropmon_net_notifier = { |
388 | .notifier_call = dropmon_net_event | |
389 | }; | |
390 | ||
9a8afc8d NH |
391 | static int __init init_net_drop_monitor(void) |
392 | { | |
9a8afc8d | 393 | struct per_cpu_dm_data *data; |
a256be70 CG |
394 | int cpu, rc; |
395 | ||
e005d193 | 396 | pr_info("Initializing network drop monitor service\n"); |
9a8afc8d NH |
397 | |
398 | if (sizeof(void *) > 8) { | |
e005d193 | 399 | pr_err("Unable to store program counters on this arch, Drop monitor failed\n"); |
9a8afc8d NH |
400 | return -ENOSPC; |
401 | } | |
402 | ||
a256be70 CG |
403 | rc = genl_register_family_with_ops(&net_drop_monitor_family, |
404 | dropmon_ops, | |
405 | ARRAY_SIZE(dropmon_ops)); | |
406 | if (rc) { | |
e005d193 | 407 | pr_err("Could not create drop monitor netlink family\n"); |
a256be70 | 408 | return rc; |
9a8afc8d NH |
409 | } |
410 | ||
4ea7e386 NH |
411 | rc = register_netdevice_notifier(&dropmon_net_notifier); |
412 | if (rc < 0) { | |
e005d193 | 413 | pr_crit("Failed to register netdevice notifier\n"); |
4ea7e386 NH |
414 | goto out_unreg; |
415 | } | |
416 | ||
9a8afc8d NH |
417 | rc = 0; |
418 | ||
cad456d5 | 419 | for_each_possible_cpu(cpu) { |
9a8afc8d | 420 | data = &per_cpu(dm_cpu_data, cpu); |
4fdcfa12 | 421 | data->cpu = cpu; |
9a8afc8d NH |
422 | INIT_WORK(&data->dm_alert_work, send_dm_alert); |
423 | init_timer(&data->send_timer); | |
424 | data->send_timer.data = cpu; | |
425 | data->send_timer.function = sched_send_work; | |
4fdcfa12 | 426 | reset_per_cpu_data(data); |
9a8afc8d | 427 | } |
4ea7e386 | 428 | |
3885ca78 | 429 | |
9a8afc8d NH |
430 | goto out; |
431 | ||
432 | out_unreg: | |
433 | genl_unregister_family(&net_drop_monitor_family); | |
434 | out: | |
435 | return rc; | |
436 | } | |
437 | ||
cad456d5 NH |
438 | static void exit_net_drop_monitor(void) |
439 | { | |
440 | struct per_cpu_dm_data *data; | |
441 | int cpu; | |
442 | ||
443 | BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier)); | |
444 | ||
445 | /* | |
446 | * Because of the module_get/put we do in the trace state change path | |
447 | * we are guarnateed not to have any current users when we get here | |
448 | * all we need to do is make sure that we don't have any running timers | |
449 | * or pending schedule calls | |
450 | */ | |
451 | ||
452 | for_each_possible_cpu(cpu) { | |
453 | data = &per_cpu(dm_cpu_data, cpu); | |
454 | del_timer_sync(&data->send_timer); | |
455 | cancel_work_sync(&data->dm_alert_work); | |
456 | /* | |
457 | * At this point, we should have exclusive access | |
458 | * to this struct and can free the skb inside it | |
459 | */ | |
460 | kfree_skb(data->skb); | |
461 | } | |
462 | ||
463 | BUG_ON(genl_unregister_family(&net_drop_monitor_family)); | |
464 | } | |
465 | ||
466 | module_init(init_net_drop_monitor); | |
467 | module_exit(exit_net_drop_monitor); | |
468 | ||
469 | MODULE_LICENSE("GPL v2"); | |
470 | MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>"); |