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 <net/genetlink.h>
  25 #include <net/netevent.h>
  26
  27 #include <trace/events/skb.h>
  28 #include <trace/events/napi.h>
  29
  30 #include <asm/unaligned.h>
  31
  32 #define TRACE_ON 1
  33 #define TRACE_OFF 0
  34
  35 static void send_dm_alert(struct work_struct *unused);
  36
  37
  38 /*
  39  * Globals, our netlink socket pointer
  40  * and the work handle that will send up
  41  * netlink alerts
  42  */
  43 static int trace_state = TRACE_OFF;
  44 static DEFINE_SPINLOCK(trace_state_lock);
  45
  46 struct per_cpu_dm_data {
  47         struct work_struct dm_alert_work;
  48         struct sk_buff *skb;
  49         atomic_t dm_hit_count;
  50         struct timer_list send_timer;
  51 };
  52
  53 struct dm_hw_stat_delta {
  54         struct net_device *dev;
  55         unsigned long last_rx;
  56         struct list_head list;
  57         struct rcu_head rcu;
  58         unsigned long last_drop_val;
  59 };
  60
  61 static struct genl_family net_drop_monitor_family = {
  62         .id             = GENL_ID_GENERATE,
  63         .hdrsize        = 0,
  64         .name           = "NET_DM",
  65         .version        = 2,
  66         .maxattr        = NET_DM_CMD_MAX,
  67 };
  68
  69 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
  70
  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);
  75
  76 static void reset_per_cpu_data(struct per_cpu_dm_data *data)
  77 {
  78         size_t al;
  79         struct net_dm_alert_msg *msg;
  80         struct nlattr *nla;
  81
  82         al = sizeof(struct net_dm_alert_msg);
  83         al += dm_hit_limit * sizeof(struct net_dm_drop_point);
  84         al += sizeof(struct nlattr);
  85
  86         data->skb = genlmsg_new(al, GFP_KERNEL);
  87         genlmsg_put(data->skb, 0, 0, &net_drop_monitor_family,
  88                         0, NET_DM_CMD_ALERT);
  89         nla = nla_reserve(data->skb, NLA_UNSPEC, sizeof(struct net_dm_alert_msg));
  90         msg = nla_data(nla);
  91         memset(msg, 0, al);
  92         atomic_set(&data->dm_hit_count, dm_hit_limit);
  93 }
  94
  95 static void send_dm_alert(struct work_struct *unused)
  96 {
  97         struct sk_buff *skb;
  98         struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
  99
 100         /*
 101          * Grab the skb we're about to send
 102          */
 103         skb = data->skb;
 104
 105         /*
 106          * Replace it with a new one
 107          */
 108         reset_per_cpu_data(data);
 109
 110         /*
 111          * Ship it!
 112          */
 113         genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);
 114
 115 }
 116
 117 /*
 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
 122  */
 123 static void sched_send_work(unsigned long unused)
 124 {
 125         struct per_cpu_dm_data *data =  &__get_cpu_var(dm_cpu_data);
 126
 127         schedule_work(&data->dm_alert_work);
 128 }
 129
 130 static void trace_drop_common(struct sk_buff *skb, void *location)
 131 {
 132         struct net_dm_alert_msg *msg;
 133         struct nlmsghdr *nlh;
 134         struct nlattr *nla;
 135         int i;
 136         struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
 137
 138
 139         if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) {
 140                 /*
 141                  * we're already at zero, discard this hit
 142                  */
 143                 goto out;
 144         }
 145
 146         nlh = (struct nlmsghdr *)data->skb->data;
 147         nla = genlmsg_data(nlmsg_data(nlh));
 148         msg = nla_data(nla);
 149         for (i = 0; i < msg->entries; i++) {
 150                 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
 151                         msg->points[i].count++;
 152                         goto out;
 153                 }
 154         }
 155
 156         /*
 157          * We need to create a new entry
 158          */
 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;
 163         msg->entries++;
 164
 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());
 168         }
 169
 170 out:
 171         return;
 172 }
 173
 174 static void trace_kfree_skb_hit(struct sk_buff *skb, void *location)
 175 {
 176         trace_drop_common(skb, location);
 177 }
 178
 179 static void trace_napi_poll_hit(struct napi_struct *napi)
 180 {
 181         struct dm_hw_stat_delta *new_stat;
 182
 183         /*
 184          * Don't check napi structures with no associated device
 185          */
 186         if (!napi->dev)
 187                 return;
 188
 189         rcu_read_lock();
 190         list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
 191                 /*
 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
 196                  */
 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;
 203                         break;
 204                 }
 205         }
 206         rcu_read_unlock();
 207 }
 208
 209
 210 static void free_dm_hw_stat(struct rcu_head *head)
 211 {
 212         struct dm_hw_stat_delta *n;
 213         n = container_of(head, struct dm_hw_stat_delta, rcu);
 214         kfree(n);
 215 }
 216
 217 static int set_all_monitor_traces(int state)
 218 {
 219         int rc = 0;
 220         struct dm_hw_stat_delta *new_stat = NULL;
 221         struct dm_hw_stat_delta *temp;
 222
 223         spin_lock(&trace_state_lock);
 224
 225         switch (state) {
 226         case TRACE_ON:
 227                 rc |= register_trace_kfree_skb(trace_kfree_skb_hit);
 228                 rc |= register_trace_napi_poll(trace_napi_poll_hit);
 229                 break;
 230         case TRACE_OFF:
 231                 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit);
 232                 rc |= unregister_trace_napi_poll(trace_napi_poll_hit);
 233
 234                 tracepoint_synchronize_unregister();
 235
 236                 /*
 237                  * Clean the device list
 238                  */
 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);
 243                         }
 244                 }
 245                 break;
 246         default:
 247                 rc = 1;
 248                 break;
 249         }
 250
 251         if (!rc)
 252                 trace_state = state;
 253
 254         spin_unlock(&trace_state_lock);
 255
 256         if (rc)
 257                 return -EINPROGRESS;
 258         return rc;
 259 }
 260
 261
 262 static int net_dm_cmd_config(struct sk_buff *skb,
 263                         struct genl_info *info)
 264 {
 265         return -ENOTSUPP;
 266 }
 267
 268 static int net_dm_cmd_trace(struct sk_buff *skb,
 269                         struct genl_info *info)
 270 {
 271         switch (info->genlhdr->cmd) {
 272         case NET_DM_CMD_START:
 273                 return set_all_monitor_traces(TRACE_ON);
 274                 break;
 275         case NET_DM_CMD_STOP:
 276                 return set_all_monitor_traces(TRACE_OFF);
 277                 break;
 278         }
 279
 280         return -ENOTSUPP;
 281 }
 282
 283 static int dropmon_net_event(struct notifier_block *ev_block,
 284                         unsigned long event, void *ptr)
 285 {
 286         struct net_device *dev = ptr;
 287         struct dm_hw_stat_delta *new_stat = NULL;
 288         struct dm_hw_stat_delta *tmp;
 289
 290         switch (event) {
 291         case NETDEV_REGISTER:
 292                 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
 293
 294                 if (!new_stat)
 295                         goto out;
 296
 297                 new_stat->dev = dev;
 298                 new_stat->last_rx = jiffies;
 299                 spin_lock(&trace_state_lock);
 300                 list_add_rcu(&new_stat->list, &hw_stats_list);
 301                 spin_unlock(&trace_state_lock);
 302                 break;
 303         case NETDEV_UNREGISTER:
 304                 spin_lock(&trace_state_lock);
 305                 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
 306                         if (new_stat->dev == dev) {
 307                                 new_stat->dev = NULL;
 308                                 if (trace_state == TRACE_OFF) {
 309                                         list_del_rcu(&new_stat->list);
 310                                         call_rcu(&new_stat->rcu, free_dm_hw_stat);
 311                                         break;
 312                                 }
 313                         }
 314                 }
 315                 spin_unlock(&trace_state_lock);
 316                 break;
 317         }
 318 out:
 319         return NOTIFY_DONE;
 320 }
 321
 322 static struct genl_ops dropmon_ops[] = {
 323         {
 324                 .cmd = NET_DM_CMD_CONFIG,
 325                 .doit = net_dm_cmd_config,
 326         },
 327         {
 328                 .cmd = NET_DM_CMD_START,
 329                 .doit = net_dm_cmd_trace,
 330         },
 331         {
 332                 .cmd = NET_DM_CMD_STOP,
 333                 .doit = net_dm_cmd_trace,
 334         },
 335 };
 336
 337 static struct notifier_block dropmon_net_notifier = {
 338         .notifier_call = dropmon_net_event
 339 };
 340
 341 static int __init init_net_drop_monitor(void)
 342 {
 343         int cpu;
 344         int rc, i, ret;
 345         struct per_cpu_dm_data *data;
 346         printk(KERN_INFO "Initalizing network drop monitor service\n");
 347
 348         if (sizeof(void *) > 8) {
 349                 printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n");
 350                 return -ENOSPC;
 351         }
 352
 353         if (genl_register_family(&net_drop_monitor_family) < 0) {
 354                 printk(KERN_ERR "Could not create drop monitor netlink family\n");
 355                 return -EFAULT;
 356         }
 357
 358         rc = -EFAULT;
 359
 360         for (i = 0; i < ARRAY_SIZE(dropmon_ops); i++) {
 361                 ret = genl_register_ops(&net_drop_monitor_family,
 362                                         &dropmon_ops[i]);
 363                 if (ret) {
 364                         printk(KERN_CRIT "Failed to register operation %d\n",
 365                                 dropmon_ops[i].cmd);
 366                         goto out_unreg;
 367                 }
 368         }
 369
 370         rc = register_netdevice_notifier(&dropmon_net_notifier);
 371         if (rc < 0) {
 372                 printk(KERN_CRIT "Failed to register netdevice notifier\n");
 373                 goto out_unreg;
 374         }
 375
 376         rc = 0;
 377
 378         for_each_present_cpu(cpu) {
 379                 data = &per_cpu(dm_cpu_data, cpu);
 380                 reset_per_cpu_data(data);
 381                 INIT_WORK(&data->dm_alert_work, send_dm_alert);
 382                 init_timer(&data->send_timer);
 383                 data->send_timer.data = cpu;
 384                 data->send_timer.function = sched_send_work;
 385         }
 386
 387         goto out;
 388
 389 out_unreg:
 390         genl_unregister_family(&net_drop_monitor_family);
 391 out:
 392         return rc;
 393 }
 394
 395 late_initcall(init_net_drop_monitor);