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TOMOYO Linux Cross Reference
Linux/net/core/drop_monitor.c

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  1 /*
  2  * Monitoring code for network dropped packet alerts
  3  *
  4  * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
  5  */
  6 
  7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  8 
  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>
 30 
 31 #include <trace/events/skb.h>
 32 #include <trace/events/napi.h>
 33 
 34 #include <asm/unaligned.h>
 35 
 36 #define TRACE_ON 1
 37 #define TRACE_OFF 0
 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_MUTEX(trace_state_mutex);
 46 
 47 struct per_cpu_dm_data {
 48         spinlock_t              lock;
 49         struct sk_buff          *skb;
 50         struct work_struct      dm_alert_work;
 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 struct sk_buff *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         struct sk_buff *skb;
 83         unsigned long flags;
 84 
 85         al = sizeof(struct net_dm_alert_msg);
 86         al += dm_hit_limit * sizeof(struct net_dm_drop_point);
 87         al += sizeof(struct nlattr);
 88 
 89         skb = genlmsg_new(al, GFP_KERNEL);
 90 
 91         if (skb) {
 92                 genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
 93                                 0, NET_DM_CMD_ALERT);
 94                 nla = nla_reserve(skb, NLA_UNSPEC,
 95                                   sizeof(struct net_dm_alert_msg));
 96                 msg = nla_data(nla);
 97                 memset(msg, 0, al);
 98         } else {
 99                 mod_timer(&data->send_timer, jiffies + HZ / 10);
100         }
101 
102         spin_lock_irqsave(&data->lock, flags);
103         swap(data->skb, skb);
104         spin_unlock_irqrestore(&data->lock, flags);
105 
106         return skb;
107 }
108 
109 static void send_dm_alert(struct work_struct *work)
110 {
111         struct sk_buff *skb;
112         struct per_cpu_dm_data *data;
113 
114         data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
115 
116         skb = reset_per_cpu_data(data);
117 
118         if (skb)
119                 genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);
120 }
121 
122 /*
123  * This is the timer function to delay the sending of an alert
124  * in the event that more drops will arrive during the
125  * hysteresis period.
126  */
127 static void sched_send_work(unsigned long _data)
128 {
129         struct per_cpu_dm_data *data = (struct per_cpu_dm_data *)_data;
130 
131         schedule_work(&data->dm_alert_work);
132 }
133 
134 static void trace_drop_common(struct sk_buff *skb, void *location)
135 {
136         struct net_dm_alert_msg *msg;
137         struct nlmsghdr *nlh;
138         struct nlattr *nla;
139         int i;
140         struct sk_buff *dskb;
141         struct per_cpu_dm_data *data;
142         unsigned long flags;
143 
144         local_irq_save(flags);
145         data = &__get_cpu_var(dm_cpu_data);
146         spin_lock(&data->lock);
147         dskb = data->skb;
148 
149         if (!dskb)
150                 goto out;
151 
152         nlh = (struct nlmsghdr *)dskb->data;
153         nla = genlmsg_data(nlmsg_data(nlh));
154         msg = nla_data(nla);
155         for (i = 0; i < msg->entries; i++) {
156                 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
157                         msg->points[i].count++;
158                         goto out;
159                 }
160         }
161         if (msg->entries == dm_hit_limit)
162                 goto out;
163         /*
164          * We need to create a new entry
165          */
166         __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point));
167         nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
168         memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
169         msg->points[msg->entries].count = 1;
170         msg->entries++;
171 
172         if (!timer_pending(&data->send_timer)) {
173                 data->send_timer.expires = jiffies + dm_delay * HZ;
174                 add_timer(&data->send_timer);
175         }
176 
177 out:
178         spin_unlock_irqrestore(&data->lock, flags);
179 }
180 
181 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
182 {
183         trace_drop_common(skb, location);
184 }
185 
186 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi)
187 {
188         struct dm_hw_stat_delta *new_stat;
189 
190         /*
191          * Don't check napi structures with no associated device
192          */
193         if (!napi->dev)
194                 return;
195 
196         rcu_read_lock();
197         list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
198                 /*
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
203                  */
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;
210                         break;
211                 }
212         }
213         rcu_read_unlock();
214 }
215 
216 static int set_all_monitor_traces(int state)
217 {
218         int rc = 0;
219         struct dm_hw_stat_delta *new_stat = NULL;
220         struct dm_hw_stat_delta *temp;
221 
222         mutex_lock(&trace_state_mutex);
223 
224         if (state == trace_state) {
225                 rc = -EAGAIN;
226                 goto out_unlock;
227         }
228 
229         switch (state) {
230         case TRACE_ON:
231                 if (!try_module_get(THIS_MODULE)) {
232                         rc = -ENODEV;
233                         break;
234                 }
235 
236                 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
237                 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL);
238                 break;
239 
240         case TRACE_OFF:
241                 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
242                 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
243 
244                 tracepoint_synchronize_unregister();
245 
246                 /*
247                  * Clean the device list
248                  */
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);
253                         }
254                 }
255 
256                 module_put(THIS_MODULE);
257 
258                 break;
259         default:
260                 rc = 1;
261                 break;
262         }
263 
264         if (!rc)
265                 trace_state = state;
266         else
267                 rc = -EINPROGRESS;
268 
269 out_unlock:
270         mutex_unlock(&trace_state_mutex);
271 
272         return rc;
273 }
274 
275 
276 static int net_dm_cmd_config(struct sk_buff *skb,
277                         struct genl_info *info)
278 {
279         return -ENOTSUPP;
280 }
281 
282 static int net_dm_cmd_trace(struct sk_buff *skb,
283                         struct genl_info *info)
284 {
285         switch (info->genlhdr->cmd) {
286         case NET_DM_CMD_START:
287                 return set_all_monitor_traces(TRACE_ON);
288                 break;
289         case NET_DM_CMD_STOP:
290                 return set_all_monitor_traces(TRACE_OFF);
291                 break;
292         }
293 
294         return -ENOTSUPP;
295 }
296 
297 static int dropmon_net_event(struct notifier_block *ev_block,
298                              unsigned long event, void *ptr)
299 {
300         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
301         struct dm_hw_stat_delta *new_stat = NULL;
302         struct dm_hw_stat_delta *tmp;
303 
304         switch (event) {
305         case NETDEV_REGISTER:
306                 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
307 
308                 if (!new_stat)
309                         goto out;
310 
311                 new_stat->dev = dev;
312                 new_stat->last_rx = jiffies;
313                 mutex_lock(&trace_state_mutex);
314                 list_add_rcu(&new_stat->list, &hw_stats_list);
315                 mutex_unlock(&trace_state_mutex);
316                 break;
317         case NETDEV_UNREGISTER:
318                 mutex_lock(&trace_state_mutex);
319                 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
320                         if (new_stat->dev == dev) {
321                                 new_stat->dev = NULL;
322                                 if (trace_state == TRACE_OFF) {
323                                         list_del_rcu(&new_stat->list);
324                                         kfree_rcu(new_stat, rcu);
325                                         break;
326                                 }
327                         }
328                 }
329                 mutex_unlock(&trace_state_mutex);
330                 break;
331         }
332 out:
333         return NOTIFY_DONE;
334 }
335 
336 static struct genl_ops dropmon_ops[] = {
337         {
338                 .cmd = NET_DM_CMD_CONFIG,
339                 .doit = net_dm_cmd_config,
340         },
341         {
342                 .cmd = NET_DM_CMD_START,
343                 .doit = net_dm_cmd_trace,
344         },
345         {
346                 .cmd = NET_DM_CMD_STOP,
347                 .doit = net_dm_cmd_trace,
348         },
349 };
350 
351 static struct notifier_block dropmon_net_notifier = {
352         .notifier_call = dropmon_net_event
353 };
354 
355 static int __init init_net_drop_monitor(void)
356 {
357         struct per_cpu_dm_data *data;
358         int cpu, rc;
359 
360         pr_info("Initializing network drop monitor service\n");
361 
362         if (sizeof(void *) > 8) {
363                 pr_err("Unable to store program counters on this arch, Drop monitor failed\n");
364                 return -ENOSPC;
365         }
366 
367         rc = genl_register_family_with_ops(&net_drop_monitor_family,
368                                            dropmon_ops,
369                                            ARRAY_SIZE(dropmon_ops));
370         if (rc) {
371                 pr_err("Could not create drop monitor netlink family\n");
372                 return rc;
373         }
374 
375         rc = register_netdevice_notifier(&dropmon_net_notifier);
376         if (rc < 0) {
377                 pr_crit("Failed to register netdevice notifier\n");
378                 goto out_unreg;
379         }
380 
381         rc = 0;
382 
383         for_each_possible_cpu(cpu) {
384                 data = &per_cpu(dm_cpu_data, cpu);
385                 INIT_WORK(&data->dm_alert_work, send_dm_alert);
386                 init_timer(&data->send_timer);
387                 data->send_timer.data = (unsigned long)data;
388                 data->send_timer.function = sched_send_work;
389                 spin_lock_init(&data->lock);
390                 reset_per_cpu_data(data);
391         }
392 
393 
394         goto out;
395 
396 out_unreg:
397         genl_unregister_family(&net_drop_monitor_family);
398 out:
399         return rc;
400 }
401 
402 static void exit_net_drop_monitor(void)
403 {
404         struct per_cpu_dm_data *data;
405         int cpu;
406 
407         BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier));
408 
409         /*
410          * Because of the module_get/put we do in the trace state change path
411          * we are guarnateed not to have any current users when we get here
412          * all we need to do is make sure that we don't have any running timers
413          * or pending schedule calls
414          */
415 
416         for_each_possible_cpu(cpu) {
417                 data = &per_cpu(dm_cpu_data, cpu);
418                 del_timer_sync(&data->send_timer);
419                 cancel_work_sync(&data->dm_alert_work);
420                 /*
421                  * At this point, we should have exclusive access
422                  * to this struct and can free the skb inside it
423                  */
424                 kfree_skb(data->skb);
425         }
426 
427         BUG_ON(genl_unregister_family(&net_drop_monitor_family));
428 }
429 
430 module_init(init_net_drop_monitor);
431 module_exit(exit_net_drop_monitor);
432 
433 MODULE_LICENSE("GPL v2");
434 MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
435 MODULE_ALIAS_GENL_FAMILY("NET_DM");
436 

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