cregit-Linux how code gets into the kernel

Release 4.11 net/core/drop_monitor.c

Directory: net/core
/*
 * 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;
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman13952.06%457.14%


Reiter Wolfgang10037.45%228.57%


Eric Dumazet2810.49%114.29%


Total267100.00%7100.00%




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);
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman4577.59%350.00%


Eric Dumazet915.52%116.67%


Johannes Berg46.90%233.33%


Total58100.00%6100.00%



/*
 * 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(unsigned long _data)
{
	struct per_cpu_dm_data *data = (struct per_cpu_dm_data *)_data;

	schedule_work(&data->dm_alert_work);
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman2273.33%150.00%


Eric Dumazet826.67%150.00%


Total30100.00%2100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman24785.76%466.67%


Eric Dumazet3913.54%116.67%


Christoph Lameter20.69%116.67%


Total288100.00%6100.00%






static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
{
	trace_drop_common(skb, location);
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman2284.62%150.00%


Steven Rostedt415.38%150.00%


Total26100.00%2100.00%






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();
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman10689.08%240.00%


Jesper Dangaard Brouer65.04%120.00%


Steven Rostedt43.36%120.00%


Xiao Guangrong32.52%120.00%


Total119100.00%5100.00%






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;
}



Contributors
PersonTokensPropCommitsCommitProp
Neil Horman18294.79%571.43%


Steven Rostedt84.17%114.29%


Lai Jiangshan21.04%114.29%


Total192100.00%7100.00%






static int net_dm_cmd_config(struct sk_buff *skb,
			struct genl_info *info)
{
	return -ENOTSUPP;
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman20100.00%1100.00%


Total20100.00%1100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman48100.00%1100.00%


Total48100.00%1100.00%






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) {
				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;
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman17597.22%360.00%


Jiri Pirko31.67%120.00%


Lai Jiangshan21.11%120.00%


Total180100.00%5100.00%




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,
        },
	{
		.cmd = NET_DM_CMD_STOP,
		.doit = net_dm_cmd_trace,
        },
};


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);
		init_timer(&data->send_timer);
		data->send_timer.data = (unsigned long)data;
		data->send_timer.function = sched_send_work;
		spin_lock_init(&data->lock);
		reset_per_cpu_data(data);
	}


	goto out;

out_unreg:
	genl_unregister_family(&net_drop_monitor_family);
out:
	return rc;
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman14879.14%650.00%


Eric Dumazet136.95%18.33%


Johannes Berg126.42%325.00%


Changli Gao105.35%18.33%


Joe Perches42.14%18.33%


Total187100.00%12100.00%






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));
}


Contributors
PersonTokensPropCommitsCommitProp
Neil Horman75100.00%1100.00%


Total75100.00%1100.00%




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");

Overall Contributors
PersonTokensPropCommitsCommitProp
Neil Horman147980.73%1133.33%


Eric Dumazet1035.62%13.03%


Reiter Wolfgang1005.46%26.06%


Johannes Berg864.69%618.18%


Steven Rostedt170.93%26.06%


Joe Perches110.60%13.03%


Changli Gao100.55%13.03%


Jesper Dangaard Brouer60.33%13.03%


Lai Jiangshan40.22%13.03%


Tejun Heo30.16%13.03%


Xiao Guangrong30.16%13.03%


Jiri Pirko30.16%13.03%


Thomas Gleixner30.16%13.03%


Christoph Lameter20.11%13.03%


David S. Miller10.05%13.03%


Stephen Hemminger10.05%13.03%


Total1832100.00%33100.00%


Directory: net/core



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