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