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;
84 al = sizeof(struct net_dm_alert_msg);
85 al += dm_hit_limit * sizeof(struct net_dm_drop_point);
86 al += sizeof(struct nlattr);
88 skb = genlmsg_new(al, GFP_KERNEL);
91 genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
93 nla = nla_reserve(skb, NLA_UNSPEC,
94 sizeof(struct net_dm_alert_msg));
98 mod_timer(&data->send_timer, jiffies + HZ / 10);
101 spin_lock_irqsave(&data->lock, flags);
102 swap(data->skb, skb);
103 spin_unlock_irqrestore(&data->lock, flags);
108 static struct genl_multicast_group dropmon_mcgrps[] = {
109 { .name = "events", },
112 static void send_dm_alert(struct work_struct *work)
115 struct per_cpu_dm_data *data;
117 data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
119 skb = reset_per_cpu_data(data);
122 genlmsg_multicast(&net_drop_monitor_family, skb, 0,
127 * This is the timer function to delay the sending of an alert
128 * in the event that more drops will arrive during the
131 static void sched_send_work(unsigned long _data)
133 struct per_cpu_dm_data *data = (struct per_cpu_dm_data *)_data;
135 schedule_work(&data->dm_alert_work);
138 static void trace_drop_common(struct sk_buff *skb, void *location)
140 struct net_dm_alert_msg *msg;
141 struct nlmsghdr *nlh;
144 struct sk_buff *dskb;
145 struct per_cpu_dm_data *data;
148 local_irq_save(flags);
149 data = this_cpu_ptr(&dm_cpu_data);
150 spin_lock(&data->lock);
156 nlh = (struct nlmsghdr *)dskb->data;
157 nla = genlmsg_data(nlmsg_data(nlh));
159 for (i = 0; i < msg->entries; i++) {
160 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
161 msg->points[i].count++;
165 if (msg->entries == dm_hit_limit)
168 * We need to create a new entry
170 __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point));
171 nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
172 memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
173 msg->points[msg->entries].count = 1;
176 if (!timer_pending(&data->send_timer)) {
177 data->send_timer.expires = jiffies + dm_delay * HZ;
178 add_timer(&data->send_timer);
182 spin_unlock_irqrestore(&data->lock, flags);
185 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
187 trace_drop_common(skb, location);
190 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi,
191 int work, int budget)
193 struct dm_hw_stat_delta *new_stat;
196 * Don't check napi structures with no associated device
202 list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
204 * only add a note to our monitor buffer if:
205 * 1) this is the dev we received on
206 * 2) its after the last_rx delta
207 * 3) our rx_dropped count has gone up
209 if ((new_stat->dev == napi->dev) &&
210 (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) &&
211 (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) {
212 trace_drop_common(NULL, NULL);
213 new_stat->last_drop_val = napi->dev->stats.rx_dropped;
214 new_stat->last_rx = jiffies;
221 static int set_all_monitor_traces(int state)
224 struct dm_hw_stat_delta *new_stat = NULL;
225 struct dm_hw_stat_delta *temp;
227 mutex_lock(&trace_state_mutex);
229 if (state == trace_state) {
236 if (!try_module_get(THIS_MODULE)) {
241 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
242 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL);
246 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
247 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
249 tracepoint_synchronize_unregister();
252 * Clean the device list
254 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
255 if (new_stat->dev == NULL) {
256 list_del_rcu(&new_stat->list);
257 kfree_rcu(new_stat, rcu);
261 module_put(THIS_MODULE);
275 mutex_unlock(&trace_state_mutex);
281 static int net_dm_cmd_config(struct sk_buff *skb,
282 struct genl_info *info)
287 static int net_dm_cmd_trace(struct sk_buff *skb,
288 struct genl_info *info)
290 switch (info->genlhdr->cmd) {
291 case NET_DM_CMD_START:
292 return set_all_monitor_traces(TRACE_ON);
293 case NET_DM_CMD_STOP:
294 return set_all_monitor_traces(TRACE_OFF);
300 static int dropmon_net_event(struct notifier_block *ev_block,
301 unsigned long event, void *ptr)
303 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
304 struct dm_hw_stat_delta *new_stat = NULL;
305 struct dm_hw_stat_delta *tmp;
308 case NETDEV_REGISTER:
309 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
315 new_stat->last_rx = jiffies;
316 mutex_lock(&trace_state_mutex);
317 list_add_rcu(&new_stat->list, &hw_stats_list);
318 mutex_unlock(&trace_state_mutex);
320 case NETDEV_UNREGISTER:
321 mutex_lock(&trace_state_mutex);
322 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
323 if (new_stat->dev == dev) {
324 new_stat->dev = NULL;
325 if (trace_state == TRACE_OFF) {
326 list_del_rcu(&new_stat->list);
327 kfree_rcu(new_stat, rcu);
332 mutex_unlock(&trace_state_mutex);
339 static const struct genl_ops dropmon_ops[] = {
341 .cmd = NET_DM_CMD_CONFIG,
342 .doit = net_dm_cmd_config,
345 .cmd = NET_DM_CMD_START,
346 .doit = net_dm_cmd_trace,
349 .cmd = NET_DM_CMD_STOP,
350 .doit = net_dm_cmd_trace,
354 static struct notifier_block dropmon_net_notifier = {
355 .notifier_call = dropmon_net_event
358 static int __init init_net_drop_monitor(void)
360 struct per_cpu_dm_data *data;
363 pr_info("Initializing network drop monitor service\n");
365 if (sizeof(void *) > 8) {
366 pr_err("Unable to store program counters on this arch, Drop monitor failed\n");
370 rc = genl_register_family_with_ops_groups(&net_drop_monitor_family,
371 dropmon_ops, dropmon_mcgrps);
373 pr_err("Could not create drop monitor netlink family\n");
376 WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT);
378 rc = register_netdevice_notifier(&dropmon_net_notifier);
380 pr_crit("Failed to register netdevice notifier\n");
386 for_each_possible_cpu(cpu) {
387 data = &per_cpu(dm_cpu_data, cpu);
388 INIT_WORK(&data->dm_alert_work, send_dm_alert);
389 init_timer(&data->send_timer);
390 data->send_timer.data = (unsigned long)data;
391 data->send_timer.function = sched_send_work;
392 spin_lock_init(&data->lock);
393 reset_per_cpu_data(data);
400 genl_unregister_family(&net_drop_monitor_family);
405 static void exit_net_drop_monitor(void)
407 struct per_cpu_dm_data *data;
410 BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier));
413 * Because of the module_get/put we do in the trace state change path
414 * we are guarnateed not to have any current users when we get here
415 * all we need to do is make sure that we don't have any running timers
416 * or pending schedule calls
419 for_each_possible_cpu(cpu) {
420 data = &per_cpu(dm_cpu_data, cpu);
421 del_timer_sync(&data->send_timer);
422 cancel_work_sync(&data->dm_alert_work);
424 * At this point, we should have exclusive access
425 * to this struct and can free the skb inside it
427 kfree_skb(data->skb);
430 BUG_ON(genl_unregister_family(&net_drop_monitor_family));
433 module_init(init_net_drop_monitor);
434 module_exit(exit_net_drop_monitor);
436 MODULE_LICENSE("GPL v2");
437 MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
438 MODULE_ALIAS_GENL_FAMILY("NET_DM");