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 <linux/slab.h>
25 #include <net/genetlink.h>
26 #include <net/netevent.h>
28 #include <trace/events/skb.h>
29 #include <trace/events/napi.h>
31 #include <asm/unaligned.h>
36 static void send_dm_alert(struct work_struct *unused);
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 {
48 struct work_struct dm_alert_work;
49 struct sk_buff __rcu *skb;
50 atomic_t dm_hit_count;
51 struct timer_list send_timer;
55 struct dm_hw_stat_delta {
56 struct net_device *dev;
57 unsigned long last_rx;
58 struct list_head list;
60 unsigned long last_drop_val;
63 static struct genl_family net_drop_monitor_family = {
64 .id = GENL_ID_GENERATE,
68 .maxattr = NET_DM_CMD_MAX,
71 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
73 static int dm_hit_limit = 64;
74 static int dm_delay = 1;
75 static unsigned long dm_hw_check_delta = 2*HZ;
76 static LIST_HEAD(hw_stats_list);
78 static void reset_per_cpu_data(struct per_cpu_dm_data *data)
81 struct net_dm_alert_msg *msg;
84 struct sk_buff *oskb = rcu_dereference_protected(data->skb, 1);
86 al = sizeof(struct net_dm_alert_msg);
87 al += dm_hit_limit * sizeof(struct net_dm_drop_point);
88 al += sizeof(struct nlattr);
90 skb = genlmsg_new(al, GFP_KERNEL);
93 genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
95 nla = nla_reserve(skb, NLA_UNSPEC,
96 sizeof(struct net_dm_alert_msg));
100 schedule_work_on(data->cpu, &data->dm_alert_work);
103 * Don't need to lock this, since we are guaranteed to only
104 * run this on a single cpu at a time.
105 * Note also that we only update data->skb if the old and new skb
106 * pointers don't match. This ensures that we don't continually call
107 * synchornize_rcu if we repeatedly fail to alloc a new netlink message.
110 rcu_assign_pointer(data->skb, skb);
114 atomic_set(&data->dm_hit_count, dm_hit_limit);
119 static void send_dm_alert(struct work_struct *unused)
122 struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
124 WARN_ON_ONCE(data->cpu != smp_processor_id());
127 * Grab the skb we're about to send
129 skb = rcu_dereference_protected(data->skb, 1);
132 * Replace it with a new one
134 reset_per_cpu_data(data);
140 genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);
142 put_cpu_var(dm_cpu_data);
146 * This is the timer function to delay the sending of an alert
147 * in the event that more drops will arrive during the
148 * hysteresis period. Note that it operates under the timer interrupt
149 * so we don't need to disable preemption here
151 static void sched_send_work(unsigned long unused)
153 struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
155 schedule_work_on(smp_processor_id(), &data->dm_alert_work);
157 put_cpu_var(dm_cpu_data);
160 static void trace_drop_common(struct sk_buff *skb, void *location)
162 struct net_dm_alert_msg *msg;
163 struct nlmsghdr *nlh;
166 struct sk_buff *dskb;
167 struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
171 dskb = rcu_dereference(data->skb);
176 if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) {
178 * we're already at zero, discard this hit
183 nlh = (struct nlmsghdr *)dskb->data;
184 nla = genlmsg_data(nlmsg_data(nlh));
186 for (i = 0; i < msg->entries; i++) {
187 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
188 msg->points[i].count++;
189 atomic_inc(&data->dm_hit_count);
195 * We need to create a new entry
197 __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point));
198 nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
199 memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
200 msg->points[msg->entries].count = 1;
203 if (!timer_pending(&data->send_timer)) {
204 data->send_timer.expires = jiffies + dm_delay * HZ;
205 add_timer_on(&data->send_timer, smp_processor_id());
210 put_cpu_var(dm_cpu_data);
214 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
216 trace_drop_common(skb, location);
219 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi)
221 struct dm_hw_stat_delta *new_stat;
224 * Don't check napi structures with no associated device
230 list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
232 * only add a note to our monitor buffer if:
233 * 1) this is the dev we received on
234 * 2) its after the last_rx delta
235 * 3) our rx_dropped count has gone up
237 if ((new_stat->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 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
265 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL);
268 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
269 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
271 tracepoint_synchronize_unregister();
274 * Clean the device list
276 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
277 if (new_stat->dev == NULL) {
278 list_del_rcu(&new_stat->list);
279 kfree_rcu(new_stat, rcu);
294 mutex_unlock(&trace_state_mutex);
300 static int net_dm_cmd_config(struct sk_buff *skb,
301 struct genl_info *info)
306 static int net_dm_cmd_trace(struct sk_buff *skb,
307 struct genl_info *info)
309 switch (info->genlhdr->cmd) {
310 case NET_DM_CMD_START:
311 return set_all_monitor_traces(TRACE_ON);
313 case NET_DM_CMD_STOP:
314 return set_all_monitor_traces(TRACE_OFF);
321 static int dropmon_net_event(struct notifier_block *ev_block,
322 unsigned long event, void *ptr)
324 struct net_device *dev = ptr;
325 struct dm_hw_stat_delta *new_stat = NULL;
326 struct dm_hw_stat_delta *tmp;
329 case NETDEV_REGISTER:
330 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
336 new_stat->last_rx = jiffies;
337 mutex_lock(&trace_state_mutex);
338 list_add_rcu(&new_stat->list, &hw_stats_list);
339 mutex_unlock(&trace_state_mutex);
341 case NETDEV_UNREGISTER:
342 mutex_lock(&trace_state_mutex);
343 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
344 if (new_stat->dev == dev) {
345 new_stat->dev = NULL;
346 if (trace_state == TRACE_OFF) {
347 list_del_rcu(&new_stat->list);
348 kfree_rcu(new_stat, rcu);
353 mutex_unlock(&trace_state_mutex);
360 static struct genl_ops dropmon_ops[] = {
362 .cmd = NET_DM_CMD_CONFIG,
363 .doit = net_dm_cmd_config,
366 .cmd = NET_DM_CMD_START,
367 .doit = net_dm_cmd_trace,
370 .cmd = NET_DM_CMD_STOP,
371 .doit = net_dm_cmd_trace,
375 static struct notifier_block dropmon_net_notifier = {
376 .notifier_call = dropmon_net_event
379 static int __init init_net_drop_monitor(void)
381 struct per_cpu_dm_data *data;
384 printk(KERN_INFO "Initializing network drop monitor service\n");
386 if (sizeof(void *) > 8) {
387 printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n");
391 rc = genl_register_family_with_ops(&net_drop_monitor_family,
393 ARRAY_SIZE(dropmon_ops));
395 printk(KERN_ERR "Could not create drop monitor netlink family\n");
399 rc = register_netdevice_notifier(&dropmon_net_notifier);
401 printk(KERN_CRIT "Failed to register netdevice notifier\n");
407 for_each_present_cpu(cpu) {
408 data = &per_cpu(dm_cpu_data, cpu);
410 INIT_WORK(&data->dm_alert_work, send_dm_alert);
411 init_timer(&data->send_timer);
412 data->send_timer.data = cpu;
413 data->send_timer.function = sched_send_work;
414 reset_per_cpu_data(data);
421 genl_unregister_family(&net_drop_monitor_family);
426 late_initcall(init_net_drop_monitor);