linux/net/core/drop_monitor.c
Ido Schimmel ca30707dee drop_monitor: Add packet alert mode
So far drop monitor supported only one alert mode in which a summary of
locations in which packets were recently dropped was sent to user space.

This alert mode is sufficient in order to understand that packets were
dropped, but lacks information to perform a more detailed analysis.

Add a new alert mode in which the dropped packet itself is passed to
user space along with metadata: The drop location (as program counter
and resolved symbol), ingress netdevice and drop timestamp. More
metadata can be added in the future.

To avoid performing expensive operations in the context in which
kfree_skb() is invoked (can be hard IRQ), the dropped skb is cloned and
queued on per-CPU skb drop list. Then, in process context the netlink
message is allocated, prepared and finally sent to user space.

The per-CPU skb drop list is limited to 1000 skbs to prevent exhausting
the system's memory. Subsequent patches will make this limit
configurable and also add a counter that indicates how many skbs were
tail dropped.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-08-11 10:53:30 -07:00

829 lines
19 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* 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;
/* net_dm_mutex
*
* An overall lock guarding every operation coming from userspace.
* It also guards the global 'hw_stats_list' list.
*/
static DEFINE_MUTEX(net_dm_mutex);
struct per_cpu_dm_data {
spinlock_t lock; /* Protects 'skb' and 'send_timer' */
struct sk_buff *skb;
struct sk_buff_head drop_queue;
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 enum net_dm_alert_mode net_dm_alert_mode = NET_DM_ALERT_MODE_SUMMARY;
struct net_dm_alert_ops {
void (*kfree_skb_probe)(void *ignore, struct sk_buff *skb,
void *location);
void (*napi_poll_probe)(void *ignore, struct napi_struct *napi,
int work, int budget);
void (*work_item_func)(struct work_struct *work);
};
struct net_dm_skb_cb {
void *pc;
};
#define NET_DM_SKB_CB(__skb) ((struct net_dm_skb_cb *)&((__skb)->cb[0]))
#define NET_DM_QUEUE_LEN 1000
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", },
};
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 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);
for (i = 0; i < msg->entries; i++) {
if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
msg->points[i].count++;
goto out;
}
}
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(msg->points[msg->entries].pc, &location, sizeof(void *));
msg->points[msg->entries].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) {
/*
* 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
*/
if ((new_stat->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 const struct net_dm_alert_ops net_dm_alert_summary_ops = {
.kfree_skb_probe = trace_kfree_skb_hit,
.napi_poll_probe = trace_napi_poll_hit,
.work_item_func = send_dm_alert,
};
static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
struct sk_buff *skb,
void *location)
{
ktime_t tstamp = ktime_get_real();
struct per_cpu_dm_data *data;
struct sk_buff *nskb;
unsigned long flags;
nskb = skb_clone(skb, GFP_ATOMIC);
if (!nskb)
return;
NET_DM_SKB_CB(nskb)->pc = location;
/* Override the timestamp because we care about the time when the
* packet was dropped.
*/
nskb->tstamp = tstamp;
data = this_cpu_ptr(&dm_cpu_data);
spin_lock_irqsave(&data->drop_queue.lock, flags);
if (skb_queue_len(&data->drop_queue) < NET_DM_QUEUE_LEN)
__skb_queue_tail(&data->drop_queue, nskb);
else
goto unlock_free;
spin_unlock_irqrestore(&data->drop_queue.lock, flags);
schedule_work(&data->dm_alert_work);
return;
unlock_free:
spin_unlock_irqrestore(&data->drop_queue.lock, flags);
consume_skb(nskb);
}
static void net_dm_packet_trace_napi_poll_hit(void *ignore,
struct napi_struct *napi,
int work, int budget)
{
}
static size_t net_dm_in_port_size(void)
{
/* NET_DM_ATTR_IN_PORT nest */
return nla_total_size(0) +
/* NET_DM_ATTR_PORT_NETDEV_IFINDEX */
nla_total_size(sizeof(u32));
}
#define NET_DM_MAX_SYMBOL_LEN 40
static size_t net_dm_packet_report_size(size_t payload_len)
{
size_t size;
size = nlmsg_msg_size(GENL_HDRLEN + net_drop_monitor_family.hdrsize);
return NLMSG_ALIGN(size) +
/* NET_DM_ATTR_PC */
nla_total_size(sizeof(u64)) +
/* NET_DM_ATTR_SYMBOL */
nla_total_size(NET_DM_MAX_SYMBOL_LEN + 1) +
/* NET_DM_ATTR_IN_PORT */
net_dm_in_port_size() +
/* NET_DM_ATTR_TIMESTAMP */
nla_total_size(sizeof(struct timespec)) +
/* NET_DM_ATTR_PROTO */
nla_total_size(sizeof(u16)) +
/* NET_DM_ATTR_PAYLOAD */
nla_total_size(payload_len);
}
static int net_dm_packet_report_in_port_put(struct sk_buff *msg, int ifindex)
{
struct nlattr *attr;
attr = nla_nest_start(msg, NET_DM_ATTR_IN_PORT);
if (!attr)
return -EMSGSIZE;
if (ifindex &&
nla_put_u32(msg, NET_DM_ATTR_PORT_NETDEV_IFINDEX, ifindex))
goto nla_put_failure;
nla_nest_end(msg, attr);
return 0;
nla_put_failure:
nla_nest_cancel(msg, attr);
return -EMSGSIZE;
}
static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
size_t payload_len)
{
u64 pc = (u64)(uintptr_t) NET_DM_SKB_CB(skb)->pc;
char buf[NET_DM_MAX_SYMBOL_LEN];
struct nlattr *attr;
struct timespec ts;
void *hdr;
int rc;
hdr = genlmsg_put(msg, 0, 0, &net_drop_monitor_family, 0,
NET_DM_CMD_PACKET_ALERT);
if (!hdr)
return -EMSGSIZE;
if (nla_put_u64_64bit(msg, NET_DM_ATTR_PC, pc, NET_DM_ATTR_PAD))
goto nla_put_failure;
snprintf(buf, sizeof(buf), "%pS", NET_DM_SKB_CB(skb)->pc);
if (nla_put_string(msg, NET_DM_ATTR_SYMBOL, buf))
goto nla_put_failure;
rc = net_dm_packet_report_in_port_put(msg, skb->skb_iif);
if (rc)
goto nla_put_failure;
if (ktime_to_timespec_cond(skb->tstamp, &ts) &&
nla_put(msg, NET_DM_ATTR_TIMESTAMP, sizeof(ts), &ts))
goto nla_put_failure;
if (!payload_len)
goto out;
if (nla_put_u16(msg, NET_DM_ATTR_PROTO, be16_to_cpu(skb->protocol)))
goto nla_put_failure;
attr = skb_put(msg, nla_total_size(payload_len));
attr->nla_type = NET_DM_ATTR_PAYLOAD;
attr->nla_len = nla_attr_size(payload_len);
if (skb_copy_bits(skb, 0, nla_data(attr), payload_len))
goto nla_put_failure;
out:
genlmsg_end(msg, hdr);
return 0;
nla_put_failure:
genlmsg_cancel(msg, hdr);
return -EMSGSIZE;
}
#define NET_DM_MAX_PACKET_SIZE (0xffff - NLA_HDRLEN - NLA_ALIGNTO)
static void net_dm_packet_report(struct sk_buff *skb)
{
struct sk_buff *msg;
size_t payload_len;
int rc;
/* Make sure we start copying the packet from the MAC header */
if (skb->data > skb_mac_header(skb))
skb_push(skb, skb->data - skb_mac_header(skb));
else
skb_pull(skb, skb_mac_header(skb) - skb->data);
/* Ensure packet fits inside a single netlink attribute */
payload_len = min_t(size_t, skb->len, NET_DM_MAX_PACKET_SIZE);
msg = nlmsg_new(net_dm_packet_report_size(payload_len), GFP_KERNEL);
if (!msg)
goto out;
rc = net_dm_packet_report_fill(msg, skb, payload_len);
if (rc) {
nlmsg_free(msg);
goto out;
}
genlmsg_multicast(&net_drop_monitor_family, msg, 0, 0, GFP_KERNEL);
out:
consume_skb(skb);
}
static void net_dm_packet_work(struct work_struct *work)
{
struct per_cpu_dm_data *data;
struct sk_buff_head list;
struct sk_buff *skb;
unsigned long flags;
data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
__skb_queue_head_init(&list);
spin_lock_irqsave(&data->drop_queue.lock, flags);
skb_queue_splice_tail_init(&data->drop_queue, &list);
spin_unlock_irqrestore(&data->drop_queue.lock, flags);
while ((skb = __skb_dequeue(&list)))
net_dm_packet_report(skb);
}
static const struct net_dm_alert_ops net_dm_alert_packet_ops = {
.kfree_skb_probe = net_dm_packet_trace_kfree_skb_hit,
.napi_poll_probe = net_dm_packet_trace_napi_poll_hit,
.work_item_func = net_dm_packet_work,
};
static const struct net_dm_alert_ops *net_dm_alert_ops_arr[] = {
[NET_DM_ALERT_MODE_SUMMARY] = &net_dm_alert_summary_ops,
[NET_DM_ALERT_MODE_PACKET] = &net_dm_alert_packet_ops,
};
static int net_dm_trace_on_set(struct netlink_ext_ack *extack)
{
const struct net_dm_alert_ops *ops;
int cpu, rc;
ops = net_dm_alert_ops_arr[net_dm_alert_mode];
if (!try_module_get(THIS_MODULE)) {
NL_SET_ERR_MSG_MOD(extack, "Failed to take reference on module");
return -ENODEV;
}
for_each_possible_cpu(cpu) {
struct per_cpu_dm_data *data = &per_cpu(dm_cpu_data, cpu);
struct sk_buff *skb;
INIT_WORK(&data->dm_alert_work, ops->work_item_func);
timer_setup(&data->send_timer, sched_send_work, 0);
/* Allocate a new per-CPU skb for the summary alert message and
* free the old one which might contain stale data from
* previous tracing.
*/
skb = reset_per_cpu_data(data);
consume_skb(skb);
}
rc = register_trace_kfree_skb(ops->kfree_skb_probe, NULL);
if (rc) {
NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to kfree_skb() tracepoint");
goto err_module_put;
}
rc = register_trace_napi_poll(ops->napi_poll_probe, NULL);
if (rc) {
NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to napi_poll() tracepoint");
goto err_unregister_trace;
}
return 0;
err_unregister_trace:
unregister_trace_kfree_skb(ops->kfree_skb_probe, NULL);
err_module_put:
module_put(THIS_MODULE);
return rc;
}
static void net_dm_trace_off_set(void)
{
struct dm_hw_stat_delta *new_stat, *temp;
const struct net_dm_alert_ops *ops;
int cpu;
ops = net_dm_alert_ops_arr[net_dm_alert_mode];
unregister_trace_napi_poll(ops->napi_poll_probe, NULL);
unregister_trace_kfree_skb(ops->kfree_skb_probe, NULL);
tracepoint_synchronize_unregister();
/* Make sure we do not send notifications to user space after request
* to stop tracing returns.
*/
for_each_possible_cpu(cpu) {
struct per_cpu_dm_data *data = &per_cpu(dm_cpu_data, cpu);
struct sk_buff *skb;
del_timer_sync(&data->send_timer);
cancel_work_sync(&data->dm_alert_work);
while ((skb = __skb_dequeue(&data->drop_queue)))
consume_skb(skb);
}
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);
}
static int set_all_monitor_traces(int state, struct netlink_ext_ack *extack)
{
int rc = 0;
if (state == trace_state) {
NL_SET_ERR_MSG_MOD(extack, "Trace state already set to requested state");
return -EAGAIN;
}
switch (state) {
case TRACE_ON:
rc = net_dm_trace_on_set(extack);
break;
case TRACE_OFF:
net_dm_trace_off_set();
break;
default:
rc = 1;
break;
}
if (!rc)
trace_state = state;
else
rc = -EINPROGRESS;
return rc;
}
static int net_dm_alert_mode_get_from_info(struct genl_info *info,
enum net_dm_alert_mode *p_alert_mode)
{
u8 val;
val = nla_get_u8(info->attrs[NET_DM_ATTR_ALERT_MODE]);
switch (val) {
case NET_DM_ALERT_MODE_SUMMARY: /* fall-through */
case NET_DM_ALERT_MODE_PACKET:
*p_alert_mode = val;
break;
default:
return -EINVAL;
}
return 0;
}
static int net_dm_alert_mode_set(struct genl_info *info)
{
struct netlink_ext_ack *extack = info->extack;
enum net_dm_alert_mode alert_mode;
int rc;
if (!info->attrs[NET_DM_ATTR_ALERT_MODE])
return 0;
rc = net_dm_alert_mode_get_from_info(info, &alert_mode);
if (rc) {
NL_SET_ERR_MSG_MOD(extack, "Invalid alert mode");
return -EINVAL;
}
net_dm_alert_mode = alert_mode;
return 0;
}
static int net_dm_cmd_config(struct sk_buff *skb,
struct genl_info *info)
{
struct netlink_ext_ack *extack = info->extack;
int rc;
if (trace_state == TRACE_ON) {
NL_SET_ERR_MSG_MOD(extack, "Cannot configure drop monitor while tracing is on");
return -EBUSY;
}
rc = net_dm_alert_mode_set(info);
if (rc)
return rc;
return 0;
}
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, info->extack);
case NET_DM_CMD_STOP:
return set_all_monitor_traces(TRACE_OFF, info->extack);
}
return -EOPNOTSUPP;
}
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(&net_dm_mutex);
list_add_rcu(&new_stat->list, &hw_stats_list);
mutex_unlock(&net_dm_mutex);
break;
case NETDEV_UNREGISTER:
mutex_lock(&net_dm_mutex);
list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
if (new_stat->dev == dev) {
new_stat->dev = NULL;
if (trace_state == TRACE_OFF) {
list_del_rcu(&new_stat->list);
kfree_rcu(new_stat, rcu);
break;
}
}
}
mutex_unlock(&net_dm_mutex);
break;
}
out:
return NOTIFY_DONE;
}
static const struct nla_policy net_dm_nl_policy[NET_DM_ATTR_MAX + 1] = {
[NET_DM_ATTR_UNSPEC] = { .strict_start_type = NET_DM_ATTR_UNSPEC + 1 },
[NET_DM_ATTR_ALERT_MODE] = { .type = NLA_U8 },
};
static const struct genl_ops dropmon_ops[] = {
{
.cmd = NET_DM_CMD_CONFIG,
.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
.doit = net_dm_cmd_config,
.flags = GENL_ADMIN_PERM,
},
{
.cmd = NET_DM_CMD_START,
.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
.doit = net_dm_cmd_trace,
},
{
.cmd = NET_DM_CMD_STOP,
.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
.doit = net_dm_cmd_trace,
},
};
static int net_dm_nl_pre_doit(const struct genl_ops *ops,
struct sk_buff *skb, struct genl_info *info)
{
mutex_lock(&net_dm_mutex);
return 0;
}
static void net_dm_nl_post_doit(const struct genl_ops *ops,
struct sk_buff *skb, struct genl_info *info)
{
mutex_unlock(&net_dm_mutex);
}
static struct genl_family net_drop_monitor_family __ro_after_init = {
.hdrsize = 0,
.name = "NET_DM",
.version = 2,
.maxattr = NET_DM_ATTR_MAX,
.policy = net_dm_nl_policy,
.pre_doit = net_dm_nl_pre_doit,
.post_doit = net_dm_nl_post_doit,
.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);
spin_lock_init(&data->lock);
skb_queue_head_init(&data->drop_queue);
}
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
*/
for_each_possible_cpu(cpu) {
data = &per_cpu(dm_cpu_data, cpu);
/*
* At this point, we should have exclusive access
* to this struct and can free the skb inside it
*/
kfree_skb(data->skb);
WARN_ON(!skb_queue_empty(&data->drop_queue));
}
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");