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 64 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data); 65 66 static int dm_hit_limit = 64; 67 static int dm_delay = 1; 68 static unsigned long dm_hw_check_delta = 2*HZ; 69 static LIST_HEAD(hw_stats_list); 70 71 static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data) 72 { 73 size_t al; 74 struct net_dm_alert_msg *msg; 75 struct nlattr *nla; 76 struct sk_buff *skb; 77 unsigned long flags; 78 79 al = sizeof(struct net_dm_alert_msg); 80 al += dm_hit_limit * sizeof(struct net_dm_drop_point); 81 al += sizeof(struct nlattr); 82 83 skb = genlmsg_new(al, GFP_KERNEL); 84 85 if (skb) { 86 genlmsg_put(skb, 0, 0, &net_drop_monitor_family, 87 0, NET_DM_CMD_ALERT); 88 nla = nla_reserve(skb, NLA_UNSPEC, 89 sizeof(struct net_dm_alert_msg)); 90 msg = nla_data(nla); 91 memset(msg, 0, al); 92 } else { 93 mod_timer(&data->send_timer, jiffies + HZ / 10); 94 } 95 96 spin_lock_irqsave(&data->lock, flags); 97 swap(data->skb, skb); 98 spin_unlock_irqrestore(&data->lock, flags); 99 100 return skb; 101 } 102 103 static const struct genl_multicast_group dropmon_mcgrps[] = { 104 { .name = "events", }, 105 }; 106 107 static void send_dm_alert(struct work_struct *work) 108 { 109 struct sk_buff *skb; 110 struct per_cpu_dm_data *data; 111 112 data = container_of(work, struct per_cpu_dm_data, dm_alert_work); 113 114 skb = reset_per_cpu_data(data); 115 116 if (skb) 117 genlmsg_multicast(&net_drop_monitor_family, skb, 0, 118 0, GFP_KERNEL); 119 } 120 121 /* 122 * This is the timer function to delay the sending of an alert 123 * in the event that more drops will arrive during the 124 * hysteresis period. 125 */ 126 static void sched_send_work(unsigned long _data) 127 { 128 struct per_cpu_dm_data *data = (struct per_cpu_dm_data *)_data; 129 130 schedule_work(&data->dm_alert_work); 131 } 132 133 static void trace_drop_common(struct sk_buff *skb, void *location) 134 { 135 struct net_dm_alert_msg *msg; 136 struct nlmsghdr *nlh; 137 struct nlattr *nla; 138 int i; 139 struct sk_buff *dskb; 140 struct per_cpu_dm_data *data; 141 unsigned long flags; 142 143 local_irq_save(flags); 144 data = this_cpu_ptr(&dm_cpu_data); 145 spin_lock(&data->lock); 146 dskb = data->skb; 147 148 if (!dskb) 149 goto out; 150 151 nlh = (struct nlmsghdr *)dskb->data; 152 nla = genlmsg_data(nlmsg_data(nlh)); 153 msg = nla_data(nla); 154 for (i = 0; i < msg->entries; i++) { 155 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) { 156 msg->points[i].count++; 157 goto out; 158 } 159 } 160 if (msg->entries == dm_hit_limit) 161 goto out; 162 /* 163 * We need to create a new entry 164 */ 165 __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point)); 166 nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point)); 167 memcpy(msg->points[msg->entries].pc, &location, sizeof(void *)); 168 msg->points[msg->entries].count = 1; 169 msg->entries++; 170 171 if (!timer_pending(&data->send_timer)) { 172 data->send_timer.expires = jiffies + dm_delay * HZ; 173 add_timer(&data->send_timer); 174 } 175 176 out: 177 spin_unlock_irqrestore(&data->lock, flags); 178 } 179 180 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location) 181 { 182 trace_drop_common(skb, location); 183 } 184 185 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi, 186 int work, int budget) 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 case NET_DM_CMD_STOP: 289 return set_all_monitor_traces(TRACE_OFF); 290 } 291 292 return -ENOTSUPP; 293 } 294 295 static int dropmon_net_event(struct notifier_block *ev_block, 296 unsigned long event, void *ptr) 297 { 298 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 299 struct dm_hw_stat_delta *new_stat = NULL; 300 struct dm_hw_stat_delta *tmp; 301 302 switch (event) { 303 case NETDEV_REGISTER: 304 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL); 305 306 if (!new_stat) 307 goto out; 308 309 new_stat->dev = dev; 310 new_stat->last_rx = jiffies; 311 mutex_lock(&trace_state_mutex); 312 list_add_rcu(&new_stat->list, &hw_stats_list); 313 mutex_unlock(&trace_state_mutex); 314 break; 315 case NETDEV_UNREGISTER: 316 mutex_lock(&trace_state_mutex); 317 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) { 318 if (new_stat->dev == dev) { 319 new_stat->dev = NULL; 320 if (trace_state == TRACE_OFF) { 321 list_del_rcu(&new_stat->list); 322 kfree_rcu(new_stat, rcu); 323 break; 324 } 325 } 326 } 327 mutex_unlock(&trace_state_mutex); 328 break; 329 } 330 out: 331 return NOTIFY_DONE; 332 } 333 334 static const struct genl_ops dropmon_ops[] = { 335 { 336 .cmd = NET_DM_CMD_CONFIG, 337 .doit = net_dm_cmd_config, 338 }, 339 { 340 .cmd = NET_DM_CMD_START, 341 .doit = net_dm_cmd_trace, 342 }, 343 { 344 .cmd = NET_DM_CMD_STOP, 345 .doit = net_dm_cmd_trace, 346 }, 347 }; 348 349 static struct genl_family net_drop_monitor_family __ro_after_init = { 350 .hdrsize = 0, 351 .name = "NET_DM", 352 .version = 2, 353 .module = THIS_MODULE, 354 .ops = dropmon_ops, 355 .n_ops = ARRAY_SIZE(dropmon_ops), 356 .mcgrps = dropmon_mcgrps, 357 .n_mcgrps = ARRAY_SIZE(dropmon_mcgrps), 358 }; 359 360 static struct notifier_block dropmon_net_notifier = { 361 .notifier_call = dropmon_net_event 362 }; 363 364 static int __init init_net_drop_monitor(void) 365 { 366 struct per_cpu_dm_data *data; 367 int cpu, rc; 368 369 pr_info("Initializing network drop monitor service\n"); 370 371 if (sizeof(void *) > 8) { 372 pr_err("Unable to store program counters on this arch, Drop monitor failed\n"); 373 return -ENOSPC; 374 } 375 376 rc = genl_register_family(&net_drop_monitor_family); 377 if (rc) { 378 pr_err("Could not create drop monitor netlink family\n"); 379 return rc; 380 } 381 WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT); 382 383 rc = register_netdevice_notifier(&dropmon_net_notifier); 384 if (rc < 0) { 385 pr_crit("Failed to register netdevice notifier\n"); 386 goto out_unreg; 387 } 388 389 rc = 0; 390 391 for_each_possible_cpu(cpu) { 392 data = &per_cpu(dm_cpu_data, cpu); 393 INIT_WORK(&data->dm_alert_work, send_dm_alert); 394 init_timer(&data->send_timer); 395 data->send_timer.data = (unsigned long)data; 396 data->send_timer.function = sched_send_work; 397 spin_lock_init(&data->lock); 398 reset_per_cpu_data(data); 399 } 400 401 402 goto out; 403 404 out_unreg: 405 genl_unregister_family(&net_drop_monitor_family); 406 out: 407 return rc; 408 } 409 410 static void exit_net_drop_monitor(void) 411 { 412 struct per_cpu_dm_data *data; 413 int cpu; 414 415 BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier)); 416 417 /* 418 * Because of the module_get/put we do in the trace state change path 419 * we are guarnateed not to have any current users when we get here 420 * all we need to do is make sure that we don't have any running timers 421 * or pending schedule calls 422 */ 423 424 for_each_possible_cpu(cpu) { 425 data = &per_cpu(dm_cpu_data, cpu); 426 del_timer_sync(&data->send_timer); 427 cancel_work_sync(&data->dm_alert_work); 428 /* 429 * At this point, we should have exclusive access 430 * to this struct and can free the skb inside it 431 */ 432 kfree_skb(data->skb); 433 } 434 435 BUG_ON(genl_unregister_family(&net_drop_monitor_family)); 436 } 437 438 module_init(init_net_drop_monitor); 439 module_exit(exit_net_drop_monitor); 440 441 MODULE_LICENSE("GPL v2"); 442 MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>"); 443 MODULE_ALIAS_GENL_FAMILY("NET_DM"); 444