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 switch (state) { 227 case TRACE_ON: 228 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL); 229 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL); 230 break; 231 case TRACE_OFF: 232 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL); 233 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL); 234 235 tracepoint_synchronize_unregister(); 236 237 /* 238 * Clean the device list 239 */ 240 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) { 241 if (new_stat->dev == NULL) { 242 list_del_rcu(&new_stat->list); 243 call_rcu(&new_stat->rcu, free_dm_hw_stat); 244 } 245 } 246 break; 247 default: 248 rc = 1; 249 break; 250 } 251 252 if (!rc) 253 trace_state = state; 254 255 spin_unlock(&trace_state_lock); 256 257 if (rc) 258 return -EINPROGRESS; 259 return rc; 260 } 261 262 263 static int net_dm_cmd_config(struct sk_buff *skb, 264 struct genl_info *info) 265 { 266 return -ENOTSUPP; 267 } 268 269 static int net_dm_cmd_trace(struct sk_buff *skb, 270 struct genl_info *info) 271 { 272 switch (info->genlhdr->cmd) { 273 case NET_DM_CMD_START: 274 return set_all_monitor_traces(TRACE_ON); 275 break; 276 case NET_DM_CMD_STOP: 277 return set_all_monitor_traces(TRACE_OFF); 278 break; 279 } 280 281 return -ENOTSUPP; 282 } 283 284 static int dropmon_net_event(struct notifier_block *ev_block, 285 unsigned long event, void *ptr) 286 { 287 struct net_device *dev = ptr; 288 struct dm_hw_stat_delta *new_stat = NULL; 289 struct dm_hw_stat_delta *tmp; 290 291 switch (event) { 292 case NETDEV_REGISTER: 293 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL); 294 295 if (!new_stat) 296 goto out; 297 298 new_stat->dev = dev; 299 new_stat->last_rx = jiffies; 300 spin_lock(&trace_state_lock); 301 list_add_rcu(&new_stat->list, &hw_stats_list); 302 spin_unlock(&trace_state_lock); 303 break; 304 case NETDEV_UNREGISTER: 305 spin_lock(&trace_state_lock); 306 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) { 307 if (new_stat->dev == dev) { 308 new_stat->dev = NULL; 309 if (trace_state == TRACE_OFF) { 310 list_del_rcu(&new_stat->list); 311 call_rcu(&new_stat->rcu, free_dm_hw_stat); 312 break; 313 } 314 } 315 } 316 spin_unlock(&trace_state_lock); 317 break; 318 } 319 out: 320 return NOTIFY_DONE; 321 } 322 323 static struct genl_ops dropmon_ops[] = { 324 { 325 .cmd = NET_DM_CMD_CONFIG, 326 .doit = net_dm_cmd_config, 327 }, 328 { 329 .cmd = NET_DM_CMD_START, 330 .doit = net_dm_cmd_trace, 331 }, 332 { 333 .cmd = NET_DM_CMD_STOP, 334 .doit = net_dm_cmd_trace, 335 }, 336 }; 337 338 static struct notifier_block dropmon_net_notifier = { 339 .notifier_call = dropmon_net_event 340 }; 341 342 static int __init init_net_drop_monitor(void) 343 { 344 int cpu; 345 int rc, i, ret; 346 struct per_cpu_dm_data *data; 347 printk(KERN_INFO "Initalizing network drop monitor service\n"); 348 349 if (sizeof(void *) > 8) { 350 printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n"); 351 return -ENOSPC; 352 } 353 354 if (genl_register_family(&net_drop_monitor_family) < 0) { 355 printk(KERN_ERR "Could not create drop monitor netlink family\n"); 356 return -EFAULT; 357 } 358 359 rc = -EFAULT; 360 361 for (i = 0; i < ARRAY_SIZE(dropmon_ops); i++) { 362 ret = genl_register_ops(&net_drop_monitor_family, 363 &dropmon_ops[i]); 364 if (ret) { 365 printk(KERN_CRIT "Failed to register operation %d\n", 366 dropmon_ops[i].cmd); 367 goto out_unreg; 368 } 369 } 370 371 rc = register_netdevice_notifier(&dropmon_net_notifier); 372 if (rc < 0) { 373 printk(KERN_CRIT "Failed to register netdevice notifier\n"); 374 goto out_unreg; 375 } 376 377 rc = 0; 378 379 for_each_present_cpu(cpu) { 380 data = &per_cpu(dm_cpu_data, cpu); 381 reset_per_cpu_data(data); 382 INIT_WORK(&data->dm_alert_work, send_dm_alert); 383 init_timer(&data->send_timer); 384 data->send_timer.data = cpu; 385 data->send_timer.function = sched_send_work; 386 } 387 388 goto out; 389 390 out_unreg: 391 genl_unregister_family(&net_drop_monitor_family); 392 out: 393 return rc; 394 } 395 396 late_initcall(init_net_drop_monitor); 397