2 * Monitoring code for network dropped packet alerts
4 * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
31 #include <trace/events/skb.h>
32 #include <trace/events/napi.h>
34 #include <asm/unaligned.h>
40 * Globals, our netlink socket pointer
41 * and the work handle that will send up
44 static int trace_state = TRACE_OFF;
45 static DEFINE_MUTEX(trace_state_mutex);
47 struct per_cpu_dm_data {
50 struct work_struct dm_alert_work;
51 struct timer_list send_timer;
54 struct dm_hw_stat_delta {
55 struct net_device *dev;
56 unsigned long last_rx;
57 struct list_head list;
59 unsigned long last_drop_val;
62 static struct genl_family net_drop_monitor_family = {
63 .id = GENL_ID_GENERATE,
69 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
71 static int dm_hit_limit = 64;
72 static int dm_delay = 1;
73 static unsigned long dm_hw_check_delta = 2*HZ;
74 static LIST_HEAD(hw_stats_list);
76 static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
79 struct net_dm_alert_msg *msg;
85 al = sizeof(struct net_dm_alert_msg);
86 al += dm_hit_limit * sizeof(struct net_dm_drop_point);
87 al += sizeof(struct nlattr);
89 skb = genlmsg_new(al, GFP_KERNEL);
94 msg_header = genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
101 nla = nla_reserve(skb, NLA_UNSPEC,
102 sizeof(struct net_dm_alert_msg));
113 mod_timer(&data->send_timer, jiffies + HZ / 10);
115 spin_lock_irqsave(&data->lock, flags);
116 swap(data->skb, skb);
117 spin_unlock_irqrestore(&data->lock, flags);
120 struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data;
121 struct genlmsghdr *gnlh = (struct genlmsghdr *)nlmsg_data(nlh);
123 genlmsg_end(skb, genlmsg_data(gnlh));
129 static const struct genl_multicast_group dropmon_mcgrps[] = {
130 { .name = "events", },
133 static void send_dm_alert(struct work_struct *work)
136 struct per_cpu_dm_data *data;
138 data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
140 skb = reset_per_cpu_data(data);
143 genlmsg_multicast(&net_drop_monitor_family, skb, 0,
148 * This is the timer function to delay the sending of an alert
149 * in the event that more drops will arrive during the
152 static void sched_send_work(unsigned long _data)
154 struct per_cpu_dm_data *data = (struct per_cpu_dm_data *)_data;
156 schedule_work(&data->dm_alert_work);
159 static void trace_drop_common(struct sk_buff *skb, void *location)
161 struct net_dm_alert_msg *msg;
162 struct net_dm_drop_point *point;
163 struct nlmsghdr *nlh;
166 struct sk_buff *dskb;
167 struct per_cpu_dm_data *data;
170 local_irq_save(flags);
171 data = this_cpu_ptr(&dm_cpu_data);
172 spin_lock(&data->lock);
178 nlh = (struct nlmsghdr *)dskb->data;
179 nla = genlmsg_data(nlmsg_data(nlh));
182 for (i = 0; i < msg->entries; i++) {
183 if (!memcmp(&location, &point->pc, sizeof(void *))) {
189 if (msg->entries == dm_hit_limit)
192 * We need to create a new entry
194 __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point));
195 nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
196 memcpy(point->pc, &location, sizeof(void *));
200 if (!timer_pending(&data->send_timer)) {
201 data->send_timer.expires = jiffies + dm_delay * HZ;
202 add_timer(&data->send_timer);
206 spin_unlock_irqrestore(&data->lock, flags);
209 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
211 trace_drop_common(skb, location);
214 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi,
215 int work, int budget)
217 struct dm_hw_stat_delta *new_stat;
220 * Don't check napi structures with no associated device
226 list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
227 struct net_device *dev;
230 * only add a note to our monitor buffer if:
231 * 1) this is the dev we received on
232 * 2) its after the last_rx delta
233 * 3) our rx_dropped count has gone up
235 /* Paired with WRITE_ONCE() in dropmon_net_event() */
236 dev = READ_ONCE(new_stat->dev);
237 if ((dev == napi->dev) &&
238 (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) &&
239 (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) {
240 trace_drop_common(NULL, NULL);
241 new_stat->last_drop_val = napi->dev->stats.rx_dropped;
242 new_stat->last_rx = jiffies;
249 static int set_all_monitor_traces(int state)
252 struct dm_hw_stat_delta *new_stat = NULL;
253 struct dm_hw_stat_delta *temp;
255 mutex_lock(&trace_state_mutex);
257 if (state == trace_state) {
264 if (!try_module_get(THIS_MODULE)) {
269 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
270 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL);
274 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
275 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
277 tracepoint_synchronize_unregister();
280 * Clean the device list
282 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
283 if (new_stat->dev == NULL) {
284 list_del_rcu(&new_stat->list);
285 kfree_rcu(new_stat, rcu);
289 module_put(THIS_MODULE);
303 mutex_unlock(&trace_state_mutex);
309 static int net_dm_cmd_config(struct sk_buff *skb,
310 struct genl_info *info)
315 static int net_dm_cmd_trace(struct sk_buff *skb,
316 struct genl_info *info)
318 switch (info->genlhdr->cmd) {
319 case NET_DM_CMD_START:
320 return set_all_monitor_traces(TRACE_ON);
321 case NET_DM_CMD_STOP:
322 return set_all_monitor_traces(TRACE_OFF);
328 static int dropmon_net_event(struct notifier_block *ev_block,
329 unsigned long event, void *ptr)
331 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
332 struct dm_hw_stat_delta *new_stat = NULL;
333 struct dm_hw_stat_delta *tmp;
336 case NETDEV_REGISTER:
337 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
343 new_stat->last_rx = jiffies;
344 mutex_lock(&trace_state_mutex);
345 list_add_rcu(&new_stat->list, &hw_stats_list);
346 mutex_unlock(&trace_state_mutex);
348 case NETDEV_UNREGISTER:
349 mutex_lock(&trace_state_mutex);
350 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
351 if (new_stat->dev == dev) {
353 /* Paired with READ_ONCE() in trace_napi_poll_hit() */
354 WRITE_ONCE(new_stat->dev, NULL);
356 if (trace_state == TRACE_OFF) {
357 list_del_rcu(&new_stat->list);
358 kfree_rcu(new_stat, rcu);
363 mutex_unlock(&trace_state_mutex);
370 static const struct genl_ops dropmon_ops[] = {
372 .cmd = NET_DM_CMD_CONFIG,
373 .doit = net_dm_cmd_config,
376 .cmd = NET_DM_CMD_START,
377 .doit = net_dm_cmd_trace,
380 .cmd = NET_DM_CMD_STOP,
381 .doit = net_dm_cmd_trace,
385 static struct notifier_block dropmon_net_notifier = {
386 .notifier_call = dropmon_net_event
389 static int __init init_net_drop_monitor(void)
391 struct per_cpu_dm_data *data;
394 pr_info("Initializing network drop monitor service\n");
396 if (sizeof(void *) > 8) {
397 pr_err("Unable to store program counters on this arch, Drop monitor failed\n");
401 rc = genl_register_family_with_ops_groups(&net_drop_monitor_family,
402 dropmon_ops, dropmon_mcgrps);
404 pr_err("Could not create drop monitor netlink family\n");
407 WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT);
409 rc = register_netdevice_notifier(&dropmon_net_notifier);
411 pr_crit("Failed to register netdevice notifier\n");
417 for_each_possible_cpu(cpu) {
418 data = &per_cpu(dm_cpu_data, cpu);
419 INIT_WORK(&data->dm_alert_work, send_dm_alert);
420 init_timer(&data->send_timer);
421 data->send_timer.data = (unsigned long)data;
422 data->send_timer.function = sched_send_work;
423 spin_lock_init(&data->lock);
424 reset_per_cpu_data(data);
431 genl_unregister_family(&net_drop_monitor_family);
436 static void exit_net_drop_monitor(void)
438 struct per_cpu_dm_data *data;
441 BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier));
444 * Because of the module_get/put we do in the trace state change path
445 * we are guarnateed not to have any current users when we get here
446 * all we need to do is make sure that we don't have any running timers
447 * or pending schedule calls
450 for_each_possible_cpu(cpu) {
451 data = &per_cpu(dm_cpu_data, cpu);
452 del_timer_sync(&data->send_timer);
453 cancel_work_sync(&data->dm_alert_work);
455 * At this point, we should have exclusive access
456 * to this struct and can free the skb inside it
458 kfree_skb(data->skb);
461 BUG_ON(genl_unregister_family(&net_drop_monitor_family));
464 module_init(init_net_drop_monitor);
465 module_exit(exit_net_drop_monitor);
467 MODULE_LICENSE("GPL v2");
468 MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
469 MODULE_ALIAS_GENL_FAMILY("NET_DM");