| /* |
| * Monitoring code for network dropped packet alerts |
| * |
| * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com> |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/netdevice.h> |
| #include <linux/etherdevice.h> |
| #include <linux/string.h> |
| #include <linux/if_arp.h> |
| #include <linux/inetdevice.h> |
| #include <linux/inet.h> |
| #include <linux/interrupt.h> |
| #include <linux/netpoll.h> |
| #include <linux/sched.h> |
| #include <linux/delay.h> |
| #include <linux/types.h> |
| #include <linux/workqueue.h> |
| #include <linux/netlink.h> |
| #include <linux/net_dropmon.h> |
| #include <linux/percpu.h> |
| #include <linux/timer.h> |
| #include <linux/bitops.h> |
| #include <linux/slab.h> |
| #include <linux/module.h> |
| #include <net/genetlink.h> |
| #include <net/netevent.h> |
| |
| #include <trace/events/skb.h> |
| #include <trace/events/napi.h> |
| |
| #include <asm/unaligned.h> |
| |
| #define TRACE_ON 1 |
| #define TRACE_OFF 0 |
| |
| /* |
| * Globals, our netlink socket pointer |
| * and the work handle that will send up |
| * netlink alerts |
| */ |
| static int trace_state = TRACE_OFF; |
| static DEFINE_MUTEX(trace_state_mutex); |
| |
| struct per_cpu_dm_data { |
| spinlock_t lock; |
| struct sk_buff *skb; |
| struct work_struct dm_alert_work; |
| struct timer_list send_timer; |
| }; |
| |
| struct dm_hw_stat_delta { |
| struct net_device *dev; |
| unsigned long last_rx; |
| struct list_head list; |
| struct rcu_head rcu; |
| unsigned long last_drop_val; |
| }; |
| |
| static struct genl_family net_drop_monitor_family; |
| |
| static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data); |
| |
| static int dm_hit_limit = 64; |
| static int dm_delay = 1; |
| static unsigned long dm_hw_check_delta = 2*HZ; |
| static LIST_HEAD(hw_stats_list); |
| |
| static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data) |
| { |
| size_t al; |
| struct net_dm_alert_msg *msg; |
| struct nlattr *nla; |
| struct sk_buff *skb; |
| unsigned long flags; |
| void *msg_header; |
| |
| al = sizeof(struct net_dm_alert_msg); |
| al += dm_hit_limit * sizeof(struct net_dm_drop_point); |
| al += sizeof(struct nlattr); |
| |
| skb = genlmsg_new(al, GFP_KERNEL); |
| |
| if (!skb) |
| goto err; |
| |
| msg_header = genlmsg_put(skb, 0, 0, &net_drop_monitor_family, |
| 0, NET_DM_CMD_ALERT); |
| if (!msg_header) { |
| nlmsg_free(skb); |
| skb = NULL; |
| goto err; |
| } |
| nla = nla_reserve(skb, NLA_UNSPEC, |
| sizeof(struct net_dm_alert_msg)); |
| if (!nla) { |
| nlmsg_free(skb); |
| skb = NULL; |
| goto err; |
| } |
| msg = nla_data(nla); |
| memset(msg, 0, al); |
| goto out; |
| |
| err: |
| mod_timer(&data->send_timer, jiffies + HZ / 10); |
| out: |
| spin_lock_irqsave(&data->lock, flags); |
| swap(data->skb, skb); |
| spin_unlock_irqrestore(&data->lock, flags); |
| |
| if (skb) { |
| struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data; |
| struct genlmsghdr *gnlh = (struct genlmsghdr *)nlmsg_data(nlh); |
| |
| genlmsg_end(skb, genlmsg_data(gnlh)); |
| } |
| |
| return skb; |
| } |
| |
| static const struct genl_multicast_group dropmon_mcgrps[] = { |
| { .name = "events", .cap_sys_admin = 1 }, |
| }; |
| |
| static void send_dm_alert(struct work_struct *work) |
| { |
| struct sk_buff *skb; |
| struct per_cpu_dm_data *data; |
| |
| data = container_of(work, struct per_cpu_dm_data, dm_alert_work); |
| |
| skb = reset_per_cpu_data(data); |
| |
| if (skb) |
| genlmsg_multicast(&net_drop_monitor_family, skb, 0, |
| 0, GFP_KERNEL); |
| } |
| |
| /* |
| * This is the timer function to delay the sending of an alert |
| * in the event that more drops will arrive during the |
| * hysteresis period. |
| */ |
| static void sched_send_work(struct timer_list *t) |
| { |
| struct per_cpu_dm_data *data = from_timer(data, t, send_timer); |
| |
| schedule_work(&data->dm_alert_work); |
| } |
| |
| static void trace_drop_common(struct sk_buff *skb, void *location) |
| { |
| struct net_dm_alert_msg *msg; |
| struct net_dm_drop_point *point; |
| struct nlmsghdr *nlh; |
| struct nlattr *nla; |
| int i; |
| struct sk_buff *dskb; |
| struct per_cpu_dm_data *data; |
| unsigned long flags; |
| |
| local_irq_save(flags); |
| data = this_cpu_ptr(&dm_cpu_data); |
| spin_lock(&data->lock); |
| dskb = data->skb; |
| |
| if (!dskb) |
| goto out; |
| |
| nlh = (struct nlmsghdr *)dskb->data; |
| nla = genlmsg_data(nlmsg_data(nlh)); |
| msg = nla_data(nla); |
| point = msg->points; |
| for (i = 0; i < msg->entries; i++) { |
| if (!memcmp(&location, &point->pc, sizeof(void *))) { |
| point->count++; |
| goto out; |
| } |
| point++; |
| } |
| if (msg->entries == dm_hit_limit) |
| goto out; |
| /* |
| * We need to create a new entry |
| */ |
| __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point)); |
| nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point)); |
| memcpy(point->pc, &location, sizeof(void *)); |
| point->count = 1; |
| msg->entries++; |
| |
| if (!timer_pending(&data->send_timer)) { |
| data->send_timer.expires = jiffies + dm_delay * HZ; |
| add_timer(&data->send_timer); |
| } |
| |
| out: |
| spin_unlock_irqrestore(&data->lock, flags); |
| } |
| |
| static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location) |
| { |
| trace_drop_common(skb, location); |
| } |
| |
| static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi, |
| int work, int budget) |
| { |
| struct dm_hw_stat_delta *new_stat; |
| |
| /* |
| * Don't check napi structures with no associated device |
| */ |
| if (!napi->dev) |
| return; |
| |
| rcu_read_lock(); |
| list_for_each_entry_rcu(new_stat, &hw_stats_list, list) { |
| struct net_device *dev; |
| |
| /* |
| * only add a note to our monitor buffer if: |
| * 1) this is the dev we received on |
| * 2) its after the last_rx delta |
| * 3) our rx_dropped count has gone up |
| */ |
| /* Paired with WRITE_ONCE() in dropmon_net_event() */ |
| dev = READ_ONCE(new_stat->dev); |
| if ((dev == napi->dev) && |
| (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) && |
| (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) { |
| trace_drop_common(NULL, NULL); |
| new_stat->last_drop_val = napi->dev->stats.rx_dropped; |
| new_stat->last_rx = jiffies; |
| break; |
| } |
| } |
| rcu_read_unlock(); |
| } |
| |
| static int set_all_monitor_traces(int state) |
| { |
| int rc = 0; |
| struct dm_hw_stat_delta *new_stat = NULL; |
| struct dm_hw_stat_delta *temp; |
| |
| mutex_lock(&trace_state_mutex); |
| |
| if (state == trace_state) { |
| rc = -EAGAIN; |
| goto out_unlock; |
| } |
| |
| switch (state) { |
| case TRACE_ON: |
| if (!try_module_get(THIS_MODULE)) { |
| rc = -ENODEV; |
| break; |
| } |
| |
| rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL); |
| rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL); |
| break; |
| |
| case TRACE_OFF: |
| rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL); |
| rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL); |
| |
| tracepoint_synchronize_unregister(); |
| |
| /* |
| * Clean the device list |
| */ |
| list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) { |
| if (new_stat->dev == NULL) { |
| list_del_rcu(&new_stat->list); |
| kfree_rcu(new_stat, rcu); |
| } |
| } |
| |
| module_put(THIS_MODULE); |
| |
| break; |
| default: |
| rc = 1; |
| break; |
| } |
| |
| if (!rc) |
| trace_state = state; |
| else |
| rc = -EINPROGRESS; |
| |
| out_unlock: |
| mutex_unlock(&trace_state_mutex); |
| |
| return rc; |
| } |
| |
| |
| static int net_dm_cmd_config(struct sk_buff *skb, |
| struct genl_info *info) |
| { |
| return -ENOTSUPP; |
| } |
| |
| static int net_dm_cmd_trace(struct sk_buff *skb, |
| struct genl_info *info) |
| { |
| switch (info->genlhdr->cmd) { |
| case NET_DM_CMD_START: |
| return set_all_monitor_traces(TRACE_ON); |
| case NET_DM_CMD_STOP: |
| return set_all_monitor_traces(TRACE_OFF); |
| } |
| |
| return -ENOTSUPP; |
| } |
| |
| static int dropmon_net_event(struct notifier_block *ev_block, |
| unsigned long event, void *ptr) |
| { |
| struct net_device *dev = netdev_notifier_info_to_dev(ptr); |
| struct dm_hw_stat_delta *new_stat = NULL; |
| struct dm_hw_stat_delta *tmp; |
| |
| switch (event) { |
| case NETDEV_REGISTER: |
| new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL); |
| |
| if (!new_stat) |
| goto out; |
| |
| new_stat->dev = dev; |
| new_stat->last_rx = jiffies; |
| mutex_lock(&trace_state_mutex); |
| list_add_rcu(&new_stat->list, &hw_stats_list); |
| mutex_unlock(&trace_state_mutex); |
| break; |
| case NETDEV_UNREGISTER: |
| mutex_lock(&trace_state_mutex); |
| list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) { |
| if (new_stat->dev == dev) { |
| |
| /* Paired with READ_ONCE() in trace_napi_poll_hit() */ |
| WRITE_ONCE(new_stat->dev, NULL); |
| |
| if (trace_state == TRACE_OFF) { |
| list_del_rcu(&new_stat->list); |
| kfree_rcu(new_stat, rcu); |
| break; |
| } |
| } |
| } |
| mutex_unlock(&trace_state_mutex); |
| break; |
| } |
| out: |
| return NOTIFY_DONE; |
| } |
| |
| static const struct genl_ops dropmon_ops[] = { |
| { |
| .cmd = NET_DM_CMD_CONFIG, |
| .doit = net_dm_cmd_config, |
| }, |
| { |
| .cmd = NET_DM_CMD_START, |
| .doit = net_dm_cmd_trace, |
| .flags = GENL_ADMIN_PERM, |
| }, |
| { |
| .cmd = NET_DM_CMD_STOP, |
| .doit = net_dm_cmd_trace, |
| .flags = GENL_ADMIN_PERM, |
| }, |
| }; |
| |
| static struct genl_family net_drop_monitor_family __ro_after_init = { |
| .hdrsize = 0, |
| .name = "NET_DM", |
| .version = 2, |
| .module = THIS_MODULE, |
| .ops = dropmon_ops, |
| .n_ops = ARRAY_SIZE(dropmon_ops), |
| .mcgrps = dropmon_mcgrps, |
| .n_mcgrps = ARRAY_SIZE(dropmon_mcgrps), |
| }; |
| |
| static struct notifier_block dropmon_net_notifier = { |
| .notifier_call = dropmon_net_event |
| }; |
| |
| static int __init init_net_drop_monitor(void) |
| { |
| struct per_cpu_dm_data *data; |
| int cpu, rc; |
| |
| pr_info("Initializing network drop monitor service\n"); |
| |
| if (sizeof(void *) > 8) { |
| pr_err("Unable to store program counters on this arch, Drop monitor failed\n"); |
| return -ENOSPC; |
| } |
| |
| rc = genl_register_family(&net_drop_monitor_family); |
| if (rc) { |
| pr_err("Could not create drop monitor netlink family\n"); |
| return rc; |
| } |
| WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT); |
| |
| rc = register_netdevice_notifier(&dropmon_net_notifier); |
| if (rc < 0) { |
| pr_crit("Failed to register netdevice notifier\n"); |
| goto out_unreg; |
| } |
| |
| rc = 0; |
| |
| for_each_possible_cpu(cpu) { |
| data = &per_cpu(dm_cpu_data, cpu); |
| INIT_WORK(&data->dm_alert_work, send_dm_alert); |
| timer_setup(&data->send_timer, sched_send_work, 0); |
| spin_lock_init(&data->lock); |
| reset_per_cpu_data(data); |
| } |
| |
| |
| goto out; |
| |
| out_unreg: |
| genl_unregister_family(&net_drop_monitor_family); |
| out: |
| return rc; |
| } |
| |
| static void exit_net_drop_monitor(void) |
| { |
| struct per_cpu_dm_data *data; |
| int cpu; |
| |
| BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier)); |
| |
| /* |
| * Because of the module_get/put we do in the trace state change path |
| * we are guarnateed not to have any current users when we get here |
| * all we need to do is make sure that we don't have any running timers |
| * or pending schedule calls |
| */ |
| |
| for_each_possible_cpu(cpu) { |
| data = &per_cpu(dm_cpu_data, cpu); |
| del_timer_sync(&data->send_timer); |
| cancel_work_sync(&data->dm_alert_work); |
| /* |
| * At this point, we should have exclusive access |
| * to this struct and can free the skb inside it |
| */ |
| kfree_skb(data->skb); |
| } |
| |
| BUG_ON(genl_unregister_family(&net_drop_monitor_family)); |
| } |
| |
| module_init(init_net_drop_monitor); |
| module_exit(exit_net_drop_monitor); |
| |
| MODULE_LICENSE("GPL v2"); |
| MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>"); |
| MODULE_ALIAS_GENL_FAMILY("NET_DM"); |