Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wirel...
[linux-2.6.git] / net / core / drop_monitor.c
1 /*
2  * Monitoring code for network dropped packet alerts
3  *
4  * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
5  */
6
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>
27
28 #include <trace/events/skb.h>
29 #include <trace/events/napi.h>
30
31 #include <asm/unaligned.h>
32
33 #define TRACE_ON 1
34 #define TRACE_OFF 0
35
36 static void send_dm_alert(struct work_struct *unused);
37
38
39 /*
40  * Globals, our netlink socket pointer
41  * and the work handle that will send up
42  * netlink alerts
43  */
44 static int trace_state = TRACE_OFF;
45 static DEFINE_SPINLOCK(trace_state_lock);
46
47 struct per_cpu_dm_data {
48         struct work_struct dm_alert_work;
49         struct sk_buff *skb;
50         atomic_t dm_hit_count;
51         struct timer_list send_timer;
52 };
53
54 struct dm_hw_stat_delta {
55         struct net_device *dev;
56         unsigned long last_rx;
57         struct list_head list;
58         struct rcu_head rcu;
59         unsigned long last_drop_val;
60 };
61
62 static struct genl_family net_drop_monitor_family = {
63         .id             = GENL_ID_GENERATE,
64         .hdrsize        = 0,
65         .name           = "NET_DM",
66         .version        = 2,
67         .maxattr        = NET_DM_CMD_MAX,
68 };
69
70 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
71
72 static int dm_hit_limit = 64;
73 static int dm_delay = 1;
74 static unsigned long dm_hw_check_delta = 2*HZ;
75 static LIST_HEAD(hw_stats_list);
76
77 static void reset_per_cpu_data(struct per_cpu_dm_data *data)
78 {
79         size_t al;
80         struct net_dm_alert_msg *msg;
81         struct nlattr *nla;
82
83         al = sizeof(struct net_dm_alert_msg);
84         al += dm_hit_limit * sizeof(struct net_dm_drop_point);
85         al += sizeof(struct nlattr);
86
87         data->skb = genlmsg_new(al, GFP_KERNEL);
88         genlmsg_put(data->skb, 0, 0, &net_drop_monitor_family,
89                         0, NET_DM_CMD_ALERT);
90         nla = nla_reserve(data->skb, NLA_UNSPEC, sizeof(struct net_dm_alert_msg));
91         msg = nla_data(nla);
92         memset(msg, 0, al);
93         atomic_set(&data->dm_hit_count, dm_hit_limit);
94 }
95
96 static void send_dm_alert(struct work_struct *unused)
97 {
98         struct sk_buff *skb;
99         struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
100
101         /*
102          * Grab the skb we're about to send
103          */
104         skb = data->skb;
105
106         /*
107          * Replace it with a new one
108          */
109         reset_per_cpu_data(data);
110
111         /*
112          * Ship it!
113          */
114         genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);
115
116 }
117
118 /*
119  * This is the timer function to delay the sending of an alert
120  * in the event that more drops will arrive during the
121  * hysteresis period.  Note that it operates under the timer interrupt
122  * so we don't need to disable preemption here
123  */
124 static void sched_send_work(unsigned long unused)
125 {
126         struct per_cpu_dm_data *data =  &__get_cpu_var(dm_cpu_data);
127
128         schedule_work(&data->dm_alert_work);
129 }
130
131 static void trace_drop_common(struct sk_buff *skb, void *location)
132 {
133         struct net_dm_alert_msg *msg;
134         struct nlmsghdr *nlh;
135         struct nlattr *nla;
136         int i;
137         struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
138
139
140         if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) {
141                 /*
142                  * we're already at zero, discard this hit
143                  */
144                 goto out;
145         }
146
147         nlh = (struct nlmsghdr *)data->skb->data;
148         nla = genlmsg_data(nlmsg_data(nlh));
149         msg = nla_data(nla);
150         for (i = 0; i < msg->entries; i++) {
151                 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
152                         msg->points[i].count++;
153                         goto out;
154                 }
155         }
156
157         /*
158          * We need to create a new entry
159          */
160         __nla_reserve_nohdr(data->skb, sizeof(struct net_dm_drop_point));
161         nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
162         memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
163         msg->points[msg->entries].count = 1;
164         msg->entries++;
165
166         if (!timer_pending(&data->send_timer)) {
167                 data->send_timer.expires = jiffies + dm_delay * HZ;
168                 add_timer_on(&data->send_timer, smp_processor_id());
169         }
170
171 out:
172         return;
173 }
174
175 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
176 {
177         trace_drop_common(skb, location);
178 }
179
180 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi)
181 {
182         struct dm_hw_stat_delta *new_stat;
183
184         /*
185          * Don't check napi structures with no associated device
186          */
187         if (!napi->dev)
188                 return;
189
190         rcu_read_lock();
191         list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
192                 /*
193                  * only add a note to our monitor buffer if:
194                  * 1) this is the dev we received on
195                  * 2) its after the last_rx delta
196                  * 3) our rx_dropped count has gone up
197                  */
198                 if ((new_stat->dev == napi->dev)  &&
199                     (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) &&
200                     (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) {
201                         trace_drop_common(NULL, NULL);
202                         new_stat->last_drop_val = napi->dev->stats.rx_dropped;
203                         new_stat->last_rx = jiffies;
204                         break;
205                 }
206         }
207         rcu_read_unlock();
208 }
209
210 static int set_all_monitor_traces(int state)
211 {
212         int rc = 0;
213         struct dm_hw_stat_delta *new_stat = NULL;
214         struct dm_hw_stat_delta *temp;
215
216         spin_lock(&trace_state_lock);
217
218         if (state == trace_state) {
219                 rc = -EAGAIN;
220                 goto out_unlock;
221         }
222
223         switch (state) {
224         case TRACE_ON:
225                 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
226                 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL);
227                 break;
228         case TRACE_OFF:
229                 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
230                 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
231
232                 tracepoint_synchronize_unregister();
233
234                 /*
235                  * Clean the device list
236                  */
237                 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
238                         if (new_stat->dev == NULL) {
239                                 list_del_rcu(&new_stat->list);
240                                 kfree_rcu(new_stat, rcu);
241                         }
242                 }
243                 break;
244         default:
245                 rc = 1;
246                 break;
247         }
248
249         if (!rc)
250                 trace_state = state;
251         else
252                 rc = -EINPROGRESS;
253
254 out_unlock:
255         spin_unlock(&trace_state_lock);
256
257         return rc;
258 }
259
260
261 static int net_dm_cmd_config(struct sk_buff *skb,
262                         struct genl_info *info)
263 {
264         return -ENOTSUPP;
265 }
266
267 static int net_dm_cmd_trace(struct sk_buff *skb,
268                         struct genl_info *info)
269 {
270         switch (info->genlhdr->cmd) {
271         case NET_DM_CMD_START:
272                 return set_all_monitor_traces(TRACE_ON);
273                 break;
274         case NET_DM_CMD_STOP:
275                 return set_all_monitor_traces(TRACE_OFF);
276                 break;
277         }
278
279         return -ENOTSUPP;
280 }
281
282 static int dropmon_net_event(struct notifier_block *ev_block,
283                         unsigned long event, void *ptr)
284 {
285         struct net_device *dev = ptr;
286         struct dm_hw_stat_delta *new_stat = NULL;
287         struct dm_hw_stat_delta *tmp;
288
289         switch (event) {
290         case NETDEV_REGISTER:
291                 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
292
293                 if (!new_stat)
294                         goto out;
295
296                 new_stat->dev = dev;
297                 new_stat->last_rx = jiffies;
298                 spin_lock(&trace_state_lock);
299                 list_add_rcu(&new_stat->list, &hw_stats_list);
300                 spin_unlock(&trace_state_lock);
301                 break;
302         case NETDEV_UNREGISTER:
303                 spin_lock(&trace_state_lock);
304                 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
305                         if (new_stat->dev == dev) {
306                                 new_stat->dev = NULL;
307                                 if (trace_state == TRACE_OFF) {
308                                         list_del_rcu(&new_stat->list);
309                                         kfree_rcu(new_stat, rcu);
310                                         break;
311                                 }
312                         }
313                 }
314                 spin_unlock(&trace_state_lock);
315                 break;
316         }
317 out:
318         return NOTIFY_DONE;
319 }
320
321 static struct genl_ops dropmon_ops[] = {
322         {
323                 .cmd = NET_DM_CMD_CONFIG,
324                 .doit = net_dm_cmd_config,
325         },
326         {
327                 .cmd = NET_DM_CMD_START,
328                 .doit = net_dm_cmd_trace,
329         },
330         {
331                 .cmd = NET_DM_CMD_STOP,
332                 .doit = net_dm_cmd_trace,
333         },
334 };
335
336 static struct notifier_block dropmon_net_notifier = {
337         .notifier_call = dropmon_net_event
338 };
339
340 static int __init init_net_drop_monitor(void)
341 {
342         struct per_cpu_dm_data *data;
343         int cpu, rc;
344
345         printk(KERN_INFO "Initializing network drop monitor service\n");
346
347         if (sizeof(void *) > 8) {
348                 printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n");
349                 return -ENOSPC;
350         }
351
352         rc = genl_register_family_with_ops(&net_drop_monitor_family,
353                                            dropmon_ops,
354                                            ARRAY_SIZE(dropmon_ops));
355         if (rc) {
356                 printk(KERN_ERR "Could not create drop monitor netlink family\n");
357                 return rc;
358         }
359
360         rc = register_netdevice_notifier(&dropmon_net_notifier);
361         if (rc < 0) {
362                 printk(KERN_CRIT "Failed to register netdevice notifier\n");
363                 goto out_unreg;
364         }
365
366         rc = 0;
367
368         for_each_present_cpu(cpu) {
369                 data = &per_cpu(dm_cpu_data, cpu);
370                 reset_per_cpu_data(data);
371                 INIT_WORK(&data->dm_alert_work, send_dm_alert);
372                 init_timer(&data->send_timer);
373                 data->send_timer.data = cpu;
374                 data->send_timer.function = sched_send_work;
375         }
376
377         goto out;
378
379 out_unreg:
380         genl_unregister_family(&net_drop_monitor_family);
381 out:
382         return rc;
383 }
384
385 late_initcall(init_net_drop_monitor);