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 }; 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 struct sk_buff *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 struct sk_buff *skb; 82 unsigned long flags; 83 84 al = sizeof(struct net_dm_alert_msg); 85 al += dm_hit_limit * sizeof(struct net_dm_drop_point); 86 al += sizeof(struct nlattr); 87 88 skb = genlmsg_new(al, GFP_KERNEL); 89 90 if (skb) { 91 genlmsg_put(skb, 0, 0, &net_drop_monitor_family, 92 0, NET_DM_CMD_ALERT); 93 nla = nla_reserve(skb, NLA_UNSPEC, 94 sizeof(struct net_dm_alert_msg)); 95 msg = nla_data(nla); 96 memset(msg, 0, al); 97 } else { 98 mod_timer(&data->send_timer, jiffies + HZ / 10); 99 } 100 101 spin_lock_irqsave(&data->lock, flags); 102 swap(data->skb, skb); 103 spin_unlock_irqrestore(&data->lock, flags); 104 105 return skb; 106 } 107 108 static const struct genl_multicast_group dropmon_mcgrps[] = { 109 { .name = "events", }, 110 }; 111 112 static void send_dm_alert(struct work_struct *work) 113 { 114 struct sk_buff *skb; 115 struct per_cpu_dm_data *data; 116 117 data = container_of(work, struct per_cpu_dm_data, dm_alert_work); 118 119 skb = reset_per_cpu_data(data); 120 121 if (skb) 122 genlmsg_multicast(&net_drop_monitor_family, skb, 0, 123 0, GFP_KERNEL); 124 } 125 126 /* 127 * This is the timer function to delay the sending of an alert 128 * in the event that more drops will arrive during the 129 * hysteresis period. 130 */ 131 static void sched_send_work(unsigned long _data) 132 { 133 struct per_cpu_dm_data *data = (struct per_cpu_dm_data *)_data; 134 135 schedule_work(&data->dm_alert_work); 136 } 137 138 static void trace_drop_common(struct sk_buff *skb, void *location) 139 { 140 struct net_dm_alert_msg *msg; 141 struct nlmsghdr *nlh; 142 struct nlattr *nla; 143 int i; 144 struct sk_buff *dskb; 145 struct per_cpu_dm_data *data; 146 unsigned long flags; 147 148 local_irq_save(flags); 149 data = this_cpu_ptr(&dm_cpu_data); 150 spin_lock(&data->lock); 151 dskb = data->skb; 152 153 if (!dskb) 154 goto out; 155 156 nlh = (struct nlmsghdr *)dskb->data; 157 nla = genlmsg_data(nlmsg_data(nlh)); 158 msg = nla_data(nla); 159 for (i = 0; i < msg->entries; i++) { 160 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) { 161 msg->points[i].count++; 162 goto out; 163 } 164 } 165 if (msg->entries == dm_hit_limit) 166 goto out; 167 /* 168 * We need to create a new entry 169 */ 170 __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point)); 171 nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point)); 172 memcpy(msg->points[msg->entries].pc, &location, sizeof(void *)); 173 msg->points[msg->entries].count = 1; 174 msg->entries++; 175 176 if (!timer_pending(&data->send_timer)) { 177 data->send_timer.expires = jiffies + dm_delay * HZ; 178 add_timer(&data->send_timer); 179 } 180 181 out: 182 spin_unlock_irqrestore(&data->lock, flags); 183 } 184 185 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location) 186 { 187 trace_drop_common(skb, location); 188 } 189 190 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi, 191 int work, int budget) 192 { 193 struct dm_hw_stat_delta *new_stat; 194 195 /* 196 * Don't check napi structures with no associated device 197 */ 198 if (!napi->dev) 199 return; 200 201 rcu_read_lock(); 202 list_for_each_entry_rcu(new_stat, &hw_stats_list, list) { 203 /* 204 * only add a note to our monitor buffer if: 205 * 1) this is the dev we received on 206 * 2) its after the last_rx delta 207 * 3) our rx_dropped count has gone up 208 */ 209 if ((new_stat->dev == napi->dev) && 210 (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) && 211 (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) { 212 trace_drop_common(NULL, NULL); 213 new_stat->last_drop_val = napi->dev->stats.rx_dropped; 214 new_stat->last_rx = jiffies; 215 break; 216 } 217 } 218 rcu_read_unlock(); 219 } 220 221 static int set_all_monitor_traces(int state) 222 { 223 int rc = 0; 224 struct dm_hw_stat_delta *new_stat = NULL; 225 struct dm_hw_stat_delta *temp; 226 227 mutex_lock(&trace_state_mutex); 228 229 if (state == trace_state) { 230 rc = -EAGAIN; 231 goto out_unlock; 232 } 233 234 switch (state) { 235 case TRACE_ON: 236 if (!try_module_get(THIS_MODULE)) { 237 rc = -ENODEV; 238 break; 239 } 240 241 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL); 242 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL); 243 break; 244 245 case TRACE_OFF: 246 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL); 247 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL); 248 249 tracepoint_synchronize_unregister(); 250 251 /* 252 * Clean the device list 253 */ 254 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) { 255 if (new_stat->dev == NULL) { 256 list_del_rcu(&new_stat->list); 257 kfree_rcu(new_stat, rcu); 258 } 259 } 260 261 module_put(THIS_MODULE); 262 263 break; 264 default: 265 rc = 1; 266 break; 267 } 268 269 if (!rc) 270 trace_state = state; 271 else 272 rc = -EINPROGRESS; 273 274 out_unlock: 275 mutex_unlock(&trace_state_mutex); 276 277 return rc; 278 } 279 280 281 static int net_dm_cmd_config(struct sk_buff *skb, 282 struct genl_info *info) 283 { 284 return -ENOTSUPP; 285 } 286 287 static int net_dm_cmd_trace(struct sk_buff *skb, 288 struct genl_info *info) 289 { 290 switch (info->genlhdr->cmd) { 291 case NET_DM_CMD_START: 292 return set_all_monitor_traces(TRACE_ON); 293 case NET_DM_CMD_STOP: 294 return set_all_monitor_traces(TRACE_OFF); 295 } 296 297 return -ENOTSUPP; 298 } 299 300 static int dropmon_net_event(struct notifier_block *ev_block, 301 unsigned long event, void *ptr) 302 { 303 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 304 struct dm_hw_stat_delta *new_stat = NULL; 305 struct dm_hw_stat_delta *tmp; 306 307 switch (event) { 308 case NETDEV_REGISTER: 309 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL); 310 311 if (!new_stat) 312 goto out; 313 314 new_stat->dev = dev; 315 new_stat->last_rx = jiffies; 316 mutex_lock(&trace_state_mutex); 317 list_add_rcu(&new_stat->list, &hw_stats_list); 318 mutex_unlock(&trace_state_mutex); 319 break; 320 case NETDEV_UNREGISTER: 321 mutex_lock(&trace_state_mutex); 322 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) { 323 if (new_stat->dev == dev) { 324 new_stat->dev = NULL; 325 if (trace_state == TRACE_OFF) { 326 list_del_rcu(&new_stat->list); 327 kfree_rcu(new_stat, rcu); 328 break; 329 } 330 } 331 } 332 mutex_unlock(&trace_state_mutex); 333 break; 334 } 335 out: 336 return NOTIFY_DONE; 337 } 338 339 static const struct genl_ops dropmon_ops[] = { 340 { 341 .cmd = NET_DM_CMD_CONFIG, 342 .doit = net_dm_cmd_config, 343 }, 344 { 345 .cmd = NET_DM_CMD_START, 346 .doit = net_dm_cmd_trace, 347 }, 348 { 349 .cmd = NET_DM_CMD_STOP, 350 .doit = net_dm_cmd_trace, 351 }, 352 }; 353 354 static struct notifier_block dropmon_net_notifier = { 355 .notifier_call = dropmon_net_event 356 }; 357 358 static int __init init_net_drop_monitor(void) 359 { 360 struct per_cpu_dm_data *data; 361 int cpu, rc; 362 363 pr_info("Initializing network drop monitor service\n"); 364 365 if (sizeof(void *) > 8) { 366 pr_err("Unable to store program counters on this arch, Drop monitor failed\n"); 367 return -ENOSPC; 368 } 369 370 rc = genl_register_family_with_ops_groups(&net_drop_monitor_family, 371 dropmon_ops, dropmon_mcgrps); 372 if (rc) { 373 pr_err("Could not create drop monitor netlink family\n"); 374 return rc; 375 } 376 WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT); 377 378 rc = register_netdevice_notifier(&dropmon_net_notifier); 379 if (rc < 0) { 380 pr_crit("Failed to register netdevice notifier\n"); 381 goto out_unreg; 382 } 383 384 rc = 0; 385 386 for_each_possible_cpu(cpu) { 387 data = &per_cpu(dm_cpu_data, cpu); 388 INIT_WORK(&data->dm_alert_work, send_dm_alert); 389 init_timer(&data->send_timer); 390 data->send_timer.data = (unsigned long)data; 391 data->send_timer.function = sched_send_work; 392 spin_lock_init(&data->lock); 393 reset_per_cpu_data(data); 394 } 395 396 397 goto out; 398 399 out_unreg: 400 genl_unregister_family(&net_drop_monitor_family); 401 out: 402 return rc; 403 } 404 405 static void exit_net_drop_monitor(void) 406 { 407 struct per_cpu_dm_data *data; 408 int cpu; 409 410 BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier)); 411 412 /* 413 * Because of the module_get/put we do in the trace state change path 414 * we are guarnateed not to have any current users when we get here 415 * all we need to do is make sure that we don't have any running timers 416 * or pending schedule calls 417 */ 418 419 for_each_possible_cpu(cpu) { 420 data = &per_cpu(dm_cpu_data, cpu); 421 del_timer_sync(&data->send_timer); 422 cancel_work_sync(&data->dm_alert_work); 423 /* 424 * At this point, we should have exclusive access 425 * to this struct and can free the skb inside it 426 */ 427 kfree_skb(data->skb); 428 } 429 430 BUG_ON(genl_unregister_family(&net_drop_monitor_family)); 431 } 432 433 module_init(init_net_drop_monitor); 434 module_exit(exit_net_drop_monitor); 435 436 MODULE_LICENSE("GPL v2"); 437 MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>"); 438 MODULE_ALIAS_GENL_FAMILY("NET_DM"); 439