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;
64 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
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);
71 static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
74 struct net_dm_alert_msg *msg;
79 al = sizeof(struct net_dm_alert_msg);
80 al += dm_hit_limit * sizeof(struct net_dm_drop_point);
81 al += sizeof(struct nlattr);
83 skb = genlmsg_new(al, GFP_KERNEL);
86 genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
88 nla = nla_reserve(skb, NLA_UNSPEC,
89 sizeof(struct net_dm_alert_msg));
93 mod_timer(&data->send_timer, jiffies + HZ / 10);
96 spin_lock_irqsave(&data->lock, flags);
98 spin_unlock_irqrestore(&data->lock, flags);
103 static const struct genl_multicast_group dropmon_mcgrps[] = {
104 { .name = "events", },
107 static void send_dm_alert(struct work_struct *work)
110 struct per_cpu_dm_data *data;
112 data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
114 skb = reset_per_cpu_data(data);
117 genlmsg_multicast(&net_drop_monitor_family, skb, 0,
122 * This is the timer function to delay the sending of an alert
123 * in the event that more drops will arrive during the
126 static void sched_send_work(unsigned long _data)
128 struct per_cpu_dm_data *data = (struct per_cpu_dm_data *)_data;
130 schedule_work(&data->dm_alert_work);
133 static void trace_drop_common(struct sk_buff *skb, void *location)
135 struct net_dm_alert_msg *msg;
136 struct nlmsghdr *nlh;
139 struct sk_buff *dskb;
140 struct per_cpu_dm_data *data;
143 local_irq_save(flags);
144 data = this_cpu_ptr(&dm_cpu_data);
145 spin_lock(&data->lock);
151 nlh = (struct nlmsghdr *)dskb->data;
152 nla = genlmsg_data(nlmsg_data(nlh));
154 for (i = 0; i < msg->entries; i++) {
155 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
156 msg->points[i].count++;
160 if (msg->entries == dm_hit_limit)
163 * We need to create a new entry
165 __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point));
166 nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
167 memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
168 msg->points[msg->entries].count = 1;
171 if (!timer_pending(&data->send_timer)) {
172 data->send_timer.expires = jiffies + dm_delay * HZ;
173 add_timer(&data->send_timer);
177 spin_unlock_irqrestore(&data->lock, flags);
180 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
182 trace_drop_common(skb, location);
185 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi,
186 int work, int budget)
188 struct dm_hw_stat_delta *new_stat;
191 * Don't check napi structures with no associated device
197 list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
199 * only add a note to our monitor buffer if:
200 * 1) this is the dev we received on
201 * 2) its after the last_rx delta
202 * 3) our rx_dropped count has gone up
204 if ((new_stat->dev == napi->dev) &&
205 (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) &&
206 (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) {
207 trace_drop_common(NULL, NULL);
208 new_stat->last_drop_val = napi->dev->stats.rx_dropped;
209 new_stat->last_rx = jiffies;
216 static int set_all_monitor_traces(int state)
219 struct dm_hw_stat_delta *new_stat = NULL;
220 struct dm_hw_stat_delta *temp;
222 mutex_lock(&trace_state_mutex);
224 if (state == trace_state) {
231 if (!try_module_get(THIS_MODULE)) {
236 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
237 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL);
241 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
242 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
244 tracepoint_synchronize_unregister();
247 * Clean the device list
249 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
250 if (new_stat->dev == NULL) {
251 list_del_rcu(&new_stat->list);
252 kfree_rcu(new_stat, rcu);
256 module_put(THIS_MODULE);
270 mutex_unlock(&trace_state_mutex);
276 static int net_dm_cmd_config(struct sk_buff *skb,
277 struct genl_info *info)
282 static int net_dm_cmd_trace(struct sk_buff *skb,
283 struct genl_info *info)
285 switch (info->genlhdr->cmd) {
286 case NET_DM_CMD_START:
287 return set_all_monitor_traces(TRACE_ON);
288 case NET_DM_CMD_STOP:
289 return set_all_monitor_traces(TRACE_OFF);
295 static int dropmon_net_event(struct notifier_block *ev_block,
296 unsigned long event, void *ptr)
298 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
299 struct dm_hw_stat_delta *new_stat = NULL;
300 struct dm_hw_stat_delta *tmp;
303 case NETDEV_REGISTER:
304 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
310 new_stat->last_rx = jiffies;
311 mutex_lock(&trace_state_mutex);
312 list_add_rcu(&new_stat->list, &hw_stats_list);
313 mutex_unlock(&trace_state_mutex);
315 case NETDEV_UNREGISTER:
316 mutex_lock(&trace_state_mutex);
317 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
318 if (new_stat->dev == dev) {
319 new_stat->dev = NULL;
320 if (trace_state == TRACE_OFF) {
321 list_del_rcu(&new_stat->list);
322 kfree_rcu(new_stat, rcu);
327 mutex_unlock(&trace_state_mutex);
334 static const struct genl_ops dropmon_ops[] = {
336 .cmd = NET_DM_CMD_CONFIG,
337 .doit = net_dm_cmd_config,
340 .cmd = NET_DM_CMD_START,
341 .doit = net_dm_cmd_trace,
344 .cmd = NET_DM_CMD_STOP,
345 .doit = net_dm_cmd_trace,
349 static struct genl_family net_drop_monitor_family __ro_after_init = {
353 .module = THIS_MODULE,
355 .n_ops = ARRAY_SIZE(dropmon_ops),
356 .mcgrps = dropmon_mcgrps,
357 .n_mcgrps = ARRAY_SIZE(dropmon_mcgrps),
360 static struct notifier_block dropmon_net_notifier = {
361 .notifier_call = dropmon_net_event
364 static int __init init_net_drop_monitor(void)
366 struct per_cpu_dm_data *data;
369 pr_info("Initializing network drop monitor service\n");
371 if (sizeof(void *) > 8) {
372 pr_err("Unable to store program counters on this arch, Drop monitor failed\n");
376 rc = genl_register_family(&net_drop_monitor_family);
378 pr_err("Could not create drop monitor netlink family\n");
381 WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT);
383 rc = register_netdevice_notifier(&dropmon_net_notifier);
385 pr_crit("Failed to register netdevice notifier\n");
391 for_each_possible_cpu(cpu) {
392 data = &per_cpu(dm_cpu_data, cpu);
393 INIT_WORK(&data->dm_alert_work, send_dm_alert);
394 init_timer(&data->send_timer);
395 data->send_timer.data = (unsigned long)data;
396 data->send_timer.function = sched_send_work;
397 spin_lock_init(&data->lock);
398 reset_per_cpu_data(data);
405 genl_unregister_family(&net_drop_monitor_family);
410 static void exit_net_drop_monitor(void)
412 struct per_cpu_dm_data *data;
415 BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier));
418 * Because of the module_get/put we do in the trace state change path
419 * we are guarnateed not to have any current users when we get here
420 * all we need to do is make sure that we don't have any running timers
421 * or pending schedule calls
424 for_each_possible_cpu(cpu) {
425 data = &per_cpu(dm_cpu_data, cpu);
426 del_timer_sync(&data->send_timer);
427 cancel_work_sync(&data->dm_alert_work);
429 * At this point, we should have exclusive access
430 * to this struct and can free the skb inside it
432 kfree_skb(data->skb);
435 BUG_ON(genl_unregister_family(&net_drop_monitor_family));
438 module_init(init_net_drop_monitor);
439 module_exit(exit_net_drop_monitor);
441 MODULE_LICENSE("GPL v2");
442 MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
443 MODULE_ALIAS_GENL_FAMILY("NET_DM");