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
 211 static void free_dm_hw_stat(struct rcu_head *head)
 212 {
 213         struct dm_hw_stat_delta *n;
 214         n = container_of(head, struct dm_hw_stat_delta, rcu);
 215         kfree(n);
 216 }
 217
 218 static int set_all_monitor_traces(int state)
 219 {
 220         int rc = 0;
 221         struct dm_hw_stat_delta *new_stat = NULL;
 222         struct dm_hw_stat_delta *temp;
 223
 224         spin_lock(&trace_state_lock);
 225
 226         if (state == trace_state) {
 227                 rc = -EAGAIN;
 228                 goto out_unlock;
 229         }
 230
 231         switch (state) {
 232         case TRACE_ON:
 233                 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
 234                 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL);
 235                 break;
 236         case TRACE_OFF:
 237                 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
 238                 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
 239
 240                 tracepoint_synchronize_unregister();
 241
 242                 /*
 243                  * Clean the device list
 244                  */
 245                 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
 246                         if (new_stat->dev == NULL) {
 247                                 list_del_rcu(&new_stat->list);
 248                                 call_rcu(&new_stat->rcu, free_dm_hw_stat);
 249                         }
 250                 }
 251                 break;
 252         default:
 253                 rc = 1;
 254                 break;
 255         }
 256
 257         if (!rc)
 258                 trace_state = state;
 259         else
 260                 rc = -EINPROGRESS;
 261
 262 out_unlock:
 263         spin_unlock(&trace_state_lock);
 264
 265         return rc;
 266 }
 267
 268
 269 static int net_dm_cmd_config(struct sk_buff *skb,
 270                         struct genl_info *info)
 271 {
 272         return -ENOTSUPP;
 273 }
 274
 275 static int net_dm_cmd_trace(struct sk_buff *skb,
 276                         struct genl_info *info)
 277 {
 278         switch (info->genlhdr->cmd) {
 279         case NET_DM_CMD_START:
 280                 return set_all_monitor_traces(TRACE_ON);
 281                 break;
 282         case NET_DM_CMD_STOP:
 283                 return set_all_monitor_traces(TRACE_OFF);
 284                 break;
 285         }
 286
 287         return -ENOTSUPP;
 288 }
 289
 290 static int dropmon_net_event(struct notifier_block *ev_block,
 291                         unsigned long event, void *ptr)
 292 {
 293         struct net_device *dev = ptr;
 294         struct dm_hw_stat_delta *new_stat = NULL;
 295         struct dm_hw_stat_delta *tmp;
 296
 297         switch (event) {
 298         case NETDEV_REGISTER:
 299                 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
 300
 301                 if (!new_stat)
 302                         goto out;
 303
 304                 new_stat->dev = dev;
 305                 new_stat->last_rx = jiffies;
 306                 spin_lock(&trace_state_lock);
 307                 list_add_rcu(&new_stat->list, &hw_stats_list);
 308                 spin_unlock(&trace_state_lock);
 309                 break;
 310         case NETDEV_UNREGISTER:
 311                 spin_lock(&trace_state_lock);
 312                 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
 313                         if (new_stat->dev == dev) {
 314                                 new_stat->dev = NULL;
 315                                 if (trace_state == TRACE_OFF) {
 316                                         list_del_rcu(&new_stat->list);
 317                                         call_rcu(&new_stat->rcu, free_dm_hw_stat);
 318                                         break;
 319                                 }
 320                         }
 321                 }
 322                 spin_unlock(&trace_state_lock);
 323                 break;
 324         }
 325 out:
 326         return NOTIFY_DONE;
 327 }
 328
 329 static struct genl_ops dropmon_ops[] = {
 330         {
 331                 .cmd = NET_DM_CMD_CONFIG,
 332                 .doit = net_dm_cmd_config,
 333         },
 334         {
 335                 .cmd = NET_DM_CMD_START,
 336                 .doit = net_dm_cmd_trace,
 337         },
 338         {
 339                 .cmd = NET_DM_CMD_STOP,
 340                 .doit = net_dm_cmd_trace,
 341         },
 342 };
 343
 344 static struct notifier_block dropmon_net_notifier = {
 345         .notifier_call = dropmon_net_event
 346 };
 347
 348 static int __init init_net_drop_monitor(void)
 349 {
 350         struct per_cpu_dm_data *data;
 351         int cpu, rc;
 352
 353         printk(KERN_INFO "Initializing network drop monitor service\n");
 354
 355         if (sizeof(void *) > 8) {
 356                 printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n");
 357                 return -ENOSPC;
 358         }
 359
 360         rc = genl_register_family_with_ops(&net_drop_monitor_family,
 361                                            dropmon_ops,
 362                                            ARRAY_SIZE(dropmon_ops));
 363         if (rc) {
 364                 printk(KERN_ERR "Could not create drop monitor netlink family\n");
 365                 return rc;
 366         }
 367
 368         rc = register_netdevice_notifier(&dropmon_net_notifier);
 369         if (rc < 0) {
 370                 printk(KERN_CRIT "Failed to register netdevice notifier\n");
 371                 goto out_unreg;
 372         }
 373
 374         rc = 0;
 375
 376         for_each_present_cpu(cpu) {
 377                 data = &per_cpu(dm_cpu_data, cpu);
 378                 reset_per_cpu_data(data);
 379                 INIT_WORK(&data->dm_alert_work, send_dm_alert);
 380                 init_timer(&data->send_timer);
 381                 data->send_timer.data = cpu;
 382                 data->send_timer.function = sched_send_work;
 383         }
 384
 385         goto out;
 386
 387 out_unreg:
 388         genl_unregister_family(&net_drop_monitor_family);
 389 out:
 390         return rc;
 391 }
 392
 393 late_initcall(init_net_drop_monitor);