/*
* Monitoring code for network dropped packet alerts
*
* Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
*/
#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 <net/genetlink.h>
#include <trace/skb.h>
#include <asm/unaligned.h>
#define TRACE_ON 1
#define TRACE_OFF 0
static void send_dm_alert(struct work_struct *unused);
/*
* Globals, our netlink socket pointer
* and the work handle that will send up
* netlink alerts
*/
struct sock *dm_sock;
struct per_cpu_dm_data {
struct work_struct dm_alert_work;
struct sk_buff *skb;
atomic_t dm_hit_count;
struct timer_list send_timer;
};
static struct genl_family net_drop_monitor_family = {
.id = GENL_ID_GENERATE,
.hdrsize = 0,
.name = "NET_DM",
.version = 1,
.maxattr = NET_DM_CMD_MAX,
};
static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
static int dm_hit_limit = 64;
static int dm_delay = 1;
static void reset_per_cpu_data(struct per_cpu_dm_data *data)
{
size_t al;
struct net_dm_alert_msg *msg;
al = sizeof(struct net_dm_alert_msg);
al += dm_hit_limit * sizeof(struct net_dm_drop_point);
data->skb = genlmsg_new(al, GFP_KERNEL);
genlmsg_put(data->skb, 0, 0, &net_drop_monitor_family,
0, NET_DM_CMD_ALERT);
msg = __nla_reserve_nohdr(data->skb, sizeof(struct net_dm_alert_msg));
memset(msg, 0, al);
atomic_set(&data->dm_hit_count, dm_hit_limit);
}
static void send_dm_alert(struct work_struct *unused)
{
struct sk_buff *skb;
struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
/*
* Grab the skb we're about to send
*/
skb = data->skb;
/*
* Replace it with a new one
*/
reset_per_cpu_data(data);
/*
* Ship it!
*/
genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, 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. Note that it operates under the timer interrupt
* so we don't need to disable preemption here
*/
static void sched_send_work(unsigned long unused)
{
struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
schedule_work(&data->dm_alert_work);
}
static void trace_kfree_skb_hit(struct sk_buff *skb, void *location)
{
struct net_dm_alert_msg *msg;
struct nlmsghdr *nlh;
int i;
struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) {
/*
* we're already at zero, discard this hit
*/
goto out;
}
nlh = (struct nlmsghdr *)data->skb->data;
msg = genlmsg_data(nlmsg_data(nlh));
for (i = 0; i < msg->entries; i++) {
if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
msg->points[i].count++;
goto out;
}
}
/*
* We need to create a new entry
*/
__nla_reserve_nohdr(data->skb, 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_on(&data->send_timer, smp_processor_id());
}
out:
return;
}
static int set_all_monitor_traces(int state)
{
int rc = 0;
switch (state) {
case TRACE_ON:
rc |= register_trace_kfree_skb(trace_kfree_skb_hit);
break;
case TRACE_OFF:
rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit);
tracepoint_synchronize_unregister();
break;
default:
rc = 1;
break;
}
if (rc)
return -EINPROGRESS;
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);
break;
case NET_DM_CMD_STOP:
return set_all_monitor_traces(TRACE_OFF);
break;
}
return -ENOTSUPP;
}
static 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,
},
{
.cmd = NET_DM_CMD_STOP,
.doit = net_dm_cmd_trace,
},
};
static int __init init_net_drop_monitor(void)
{
int cpu;
int rc, i, ret;
struct per_cpu_dm_data *data;
printk(KERN_INFO "Initalizing network drop monitor service\n");
if (sizeof(void *) > 8) {
printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n");
return -ENOSPC;
}
if (genl_register_family(&net_drop_monitor_family) < 0) {
printk(KERN_ERR "Could not create drop monitor netlink family\n");
return -EFAULT;
}
rc = -EFAULT;
for (i = 0; i < ARRAY_SIZE(dropmon_ops); i++) {
ret = genl_register_ops(&net_drop_monitor_family,
&dropmon_ops[i]);
if (ret) {
printk(KERN_CRIT "failed to register operation %d\n",
dropmon_ops[i].cmd);
goto out_unreg;
}
}
rc = 0;
for_each_present_cpu(cpu) {
data = &per_cpu(dm_cpu_data, cpu);
reset_per_cpu_data(data);
INIT_WORK(&data->dm_alert_work, send_dm_alert);
init_timer(&data->send_timer);
data->send_timer.data = cpu;
data->send_timer.function = sched_send_work;
}
goto out;
out_unreg:
genl_unregister_family(&net_drop_monitor_family);
out:
return rc;
}
late_initcall(init_net_drop_monitor);
