2 * Monitoring code for network dropped packet alerts
4 * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
7 #include <linux/netdevice.h>
8 #include <linux/etherdevice.h>
9 #include <linux/string.h>
10 #include <linux/if_arp.h>
11 #include <linux/inetdevice.h>
12 #include <linux/inet.h>
13 #include <linux/interrupt.h>
14 #include <linux/netpoll.h>
15 #include <linux/sched.h>
16 #include <linux/delay.h>
17 #include <linux/types.h>
18 #include <linux/workqueue.h>
19 #include <linux/netlink.h>
20 #include <linux/net_dropmon.h>
21 #include <linux/percpu.h>
22 #include <linux/timer.h>
23 #include <linux/bitops.h>
24 #include <net/genetlink.h>
25 #include <net/netevent.h>
27 #include <trace/events/skb.h>
28 #include <trace/events/napi.h>
30 #include <asm/unaligned.h>
35 static void send_dm_alert(struct work_struct *unused);
39 * Globals, our netlink socket pointer
40 * and the work handle that will send up
43 static int trace_state = TRACE_OFF;
44 static spinlock_t trace_state_lock = SPIN_LOCK_UNLOCKED;
46 struct per_cpu_dm_data {
47 struct work_struct dm_alert_work;
49 atomic_t dm_hit_count;
50 struct timer_list send_timer;
53 struct dm_hw_stat_delta {
54 struct net_device *dev;
55 unsigned long last_rx;
56 struct list_head list;
58 unsigned long last_drop_val;
61 static struct genl_family net_drop_monitor_family = {
62 .id = GENL_ID_GENERATE,
66 .maxattr = NET_DM_CMD_MAX,
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 void reset_per_cpu_data(struct per_cpu_dm_data *data)
79 struct net_dm_alert_msg *msg;
82 al = sizeof(struct net_dm_alert_msg);
83 al += dm_hit_limit * sizeof(struct net_dm_drop_point);
84 al += sizeof(struct nlattr);
86 data->skb = genlmsg_new(al, GFP_KERNEL);
87 genlmsg_put(data->skb, 0, 0, &net_drop_monitor_family,
89 nla = nla_reserve(data->skb, NLA_UNSPEC, sizeof(struct net_dm_alert_msg));
92 atomic_set(&data->dm_hit_count, dm_hit_limit);
95 static void send_dm_alert(struct work_struct *unused)
98 struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
101 * Grab the skb we're about to send
106 * Replace it with a new one
108 reset_per_cpu_data(data);
113 genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);
118 * This is the timer function to delay the sending of an alert
119 * in the event that more drops will arrive during the
120 * hysteresis period. Note that it operates under the timer interrupt
121 * so we don't need to disable preemption here
123 static void sched_send_work(unsigned long unused)
125 struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
127 schedule_work(&data->dm_alert_work);
130 static void trace_drop_common(struct sk_buff *skb, void *location)
132 struct net_dm_alert_msg *msg;
133 struct nlmsghdr *nlh;
136 struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
139 if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) {
141 * we're already at zero, discard this hit
146 nlh = (struct nlmsghdr *)data->skb->data;
147 nla = genlmsg_data(nlmsg_data(nlh));
149 for (i = 0; i < msg->entries; i++) {
150 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
151 msg->points[i].count++;
157 * We need to create a new entry
159 __nla_reserve_nohdr(data->skb, sizeof(struct net_dm_drop_point));
160 nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
161 memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
162 msg->points[msg->entries].count = 1;
165 if (!timer_pending(&data->send_timer)) {
166 data->send_timer.expires = jiffies + dm_delay * HZ;
167 add_timer_on(&data->send_timer, smp_processor_id());
174 static void trace_kfree_skb_hit(struct sk_buff *skb, void *location)
176 trace_drop_common(skb, location);
179 static void trace_napi_poll_hit(struct napi_struct *napi)
181 struct dm_hw_stat_delta *new_stat;
184 * Don't check napi structures with no associated device
190 list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
192 * only add a note to our monitor buffer if:
193 * 1) this is the dev we received on
194 * 2) its after the last_rx delta
195 * 3) our rx_dropped count has gone up
197 if ((new_stat->dev == napi->dev) &&
198 (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) &&
199 (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) {
200 trace_drop_common(NULL, NULL);
201 new_stat->last_drop_val = napi->dev->stats.rx_dropped;
202 new_stat->last_rx = jiffies;
210 static void free_dm_hw_stat(struct rcu_head *head)
212 struct dm_hw_stat_delta *n;
213 n = container_of(head, struct dm_hw_stat_delta, rcu);
217 static int set_all_monitor_traces(int state)
220 struct dm_hw_stat_delta *new_stat = NULL;
221 struct dm_hw_stat_delta *temp;
223 spin_lock(&trace_state_lock);
227 rc |= register_trace_kfree_skb(trace_kfree_skb_hit);
228 rc |= register_trace_napi_poll(trace_napi_poll_hit);
231 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit);
232 rc |= unregister_trace_napi_poll(trace_napi_poll_hit);
234 tracepoint_synchronize_unregister();
237 * Clean the device list
239 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
240 if (new_stat->dev == NULL) {
241 list_del_rcu(&new_stat->list);
242 call_rcu(&new_stat->rcu, free_dm_hw_stat);
254 spin_unlock(&trace_state_lock);
262 static int net_dm_cmd_config(struct sk_buff *skb,
263 struct genl_info *info)
268 static int net_dm_cmd_trace(struct sk_buff *skb,
269 struct genl_info *info)
271 switch (info->genlhdr->cmd) {
272 case NET_DM_CMD_START:
273 return set_all_monitor_traces(TRACE_ON);
275 case NET_DM_CMD_STOP:
276 return set_all_monitor_traces(TRACE_OFF);
283 static int dropmon_net_event(struct notifier_block *ev_block,
284 unsigned long event, void *ptr)
286 struct net_device *dev = ptr;
287 struct dm_hw_stat_delta *new_stat = NULL;
288 struct dm_hw_stat_delta *tmp;
291 case NETDEV_REGISTER:
292 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
298 new_stat->last_rx = jiffies;
299 INIT_RCU_HEAD(&new_stat->rcu);
300 spin_lock(&trace_state_lock);
301 list_add_rcu(&new_stat->list, &hw_stats_list);
302 spin_unlock(&trace_state_lock);
304 case NETDEV_UNREGISTER:
305 spin_lock(&trace_state_lock);
306 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
307 if (new_stat->dev == dev) {
308 new_stat->dev = NULL;
309 if (trace_state == TRACE_OFF) {
310 list_del_rcu(&new_stat->list);
311 call_rcu(&new_stat->rcu, free_dm_hw_stat);
316 spin_unlock(&trace_state_lock);
323 static struct genl_ops dropmon_ops[] = {
325 .cmd = NET_DM_CMD_CONFIG,
326 .doit = net_dm_cmd_config,
329 .cmd = NET_DM_CMD_START,
330 .doit = net_dm_cmd_trace,
333 .cmd = NET_DM_CMD_STOP,
334 .doit = net_dm_cmd_trace,
338 static struct notifier_block dropmon_net_notifier = {
339 .notifier_call = dropmon_net_event
342 static int __init init_net_drop_monitor(void)
346 struct per_cpu_dm_data *data;
347 printk(KERN_INFO "Initalizing network drop monitor service\n");
349 if (sizeof(void *) > 8) {
350 printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n");
354 if (genl_register_family(&net_drop_monitor_family) < 0) {
355 printk(KERN_ERR "Could not create drop monitor netlink family\n");
361 for (i = 0; i < ARRAY_SIZE(dropmon_ops); i++) {
362 ret = genl_register_ops(&net_drop_monitor_family,
365 printk(KERN_CRIT "Failed to register operation %d\n",
371 rc = register_netdevice_notifier(&dropmon_net_notifier);
373 printk(KERN_CRIT "Failed to register netdevice notifier\n");
379 for_each_present_cpu(cpu) {
380 data = &per_cpu(dm_cpu_data, cpu);
381 reset_per_cpu_data(data);
382 INIT_WORK(&data->dm_alert_work, send_dm_alert);
383 init_timer(&data->send_timer);
384 data->send_timer.data = cpu;
385 data->send_timer.function = sched_send_work;
391 genl_unregister_family(&net_drop_monitor_family);
396 late_initcall(init_net_drop_monitor);