Commit 4ea7e386 authored by Neil Horman's avatar Neil Horman Committed by David S. Miller
Browse files

dropmon: add ability to detect when hardware dropsrxpackets 



Patch to add the ability to detect drops in hardware interfaces via dropwatch.
Adds a tracepoint to net_rx_action to signal everytime a napi instance is
polled.  The dropmon code then periodically checks to see if the rx_frames
counter has changed, and if so, adds a drop notification to the netlink
protocol, using the reserved all-0's vector to indicate the drop location was in
hardware, rather than somewhere in the code.

Signed-off-by: default avatarNeil Horman <nhorman@tuxdriver.com>

 include/linux/net_dropmon.h |    8 ++
 include/trace/napi.h        |   11 +++
 net/core/dev.c              |    5 +
 net/core/drop_monitor.c     |  124 ++++++++++++++++++++++++++++++++++++++++++--
 net/core/net-traces.c       |    4 +
 net/core/netpoll.c          |    2
 6 files changed, 149 insertions(+), 5 deletions(-)
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d95ed927

include/linux/net_dropmon.h

+8 −0
Original line number Diff line number Diff line
@@ -2,12 +2,20 @@ 
#define __NET_DROPMON_H



#include <linux/netlink.h>

#include <linux/types.h>



struct net_dm_drop_point {

	__u8 pc[8];

	__u32 count;

};



#define is_drop_point_hw(x) do {\

	int ____i, ____j;\

	for (____i = 0; ____i < 8; i ____i++)\

		____j |= x[____i];\

	____j;\

} while (0)



#define NET_DM_CFG_VERSION  0

#define NET_DM_CFG_ALERT_COUNT  1

#define NET_DM_CFG_ALERT_DELAY 2

include/trace/napi.h

0 → 100644
+11 −0
Original line number Diff line number Diff line 
#ifndef _TRACE_NAPI_H_

#define _TRACE_NAPI_H_



#include <linux/netdevice.h>

#include <linux/tracepoint.h>



DECLARE_TRACE(napi_poll,

	TP_PROTO(struct napi_struct *napi),

	TP_ARGS(napi));



#endif

net/core/dev.c

+4 −1
Original line number Diff line number Diff line
@@ -126,6 +126,7 @@ 
#include <linux/in.h>

#include <linux/jhash.h>

#include <linux/random.h>

#include <trace/napi.h>



#include "net-sysfs.h"
@@ -2771,8 +2772,10 @@ static void net_rx_action(struct softirq_action *h) 
		 * accidently calling ->poll() when NAPI is not scheduled.

		 */

		work = 0;

		if (test_bit(NAPI_STATE_SCHED, &n->state))

		if (test_bit(NAPI_STATE_SCHED, &n->state)) {

			work = n->poll(n, weight);

			trace_napi_poll(n);

		}



		WARN_ON_ONCE(work > weight);

net/core/drop_monitor.c

+120 −4
Original line number Diff line number Diff line
@@ -22,8 +22,10 @@ 
#include <linux/timer.h>

#include <linux/bitops.h>

#include <net/genetlink.h>

#include <net/netevent.h>



#include <trace/skb.h>

#include <trace/napi.h>



#include <asm/unaligned.h>
@@ -38,7 +40,8 @@ static void send_dm_alert(struct work_struct *unused); 
 * and the work handle that will send up

 * netlink alerts

 */

struct sock *dm_sock;

static int trace_state = TRACE_OFF;

static spinlock_t trace_state_lock = SPIN_LOCK_UNLOCKED;



struct per_cpu_dm_data {

	struct work_struct dm_alert_work;
@@ -47,6 +50,13 @@ struct per_cpu_dm_data { 
	struct timer_list send_timer;

};



struct dm_hw_stat_delta {

	struct net_device *dev;

	struct list_head list;

	struct rcu_head rcu;

	unsigned long last_drop_val;

};



static struct genl_family net_drop_monitor_family = {

	.id             = GENL_ID_GENERATE,

	.hdrsize        = 0,
@@ -59,7 +69,8 @@ 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 void reset_per_cpu_data(struct per_cpu_dm_data *data)

{
@@ -115,7 +126,7 @@ static void sched_send_work(unsigned long unused) 
	schedule_work(&data->dm_alert_work);

}



static void trace_kfree_skb_hit(struct sk_buff *skb, void *location)

static void trace_drop_common(struct sk_buff *skb, void *location)

{

	struct net_dm_alert_msg *msg;

	struct nlmsghdr *nlh;
@@ -159,24 +170,80 @@ out: 
	return;

}



static void trace_kfree_skb_hit(struct sk_buff *skb, void *location)

{

	trace_drop_common(skb, location);

}



static void trace_napi_poll_hit(struct napi_struct *napi)

{

	struct dm_hw_stat_delta *new_stat;



	/*

	 * Ratelimit our check time to dm_hw_check_delta jiffies

	 */

	if (!time_after(jiffies, napi->dev->last_rx + dm_hw_check_delta))

		return;



	rcu_read_lock();

	list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {

		if ((new_stat->dev == napi->dev)  &&

		    (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;

			break;

		}

	}

	rcu_read_unlock();

}





static void free_dm_hw_stat(struct rcu_head *head)

{

	struct dm_hw_stat_delta *n;

	n = container_of(head, struct dm_hw_stat_delta, rcu);

	kfree(n);

}



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;



	spin_lock(&trace_state_lock);



	switch (state) {

	case TRACE_ON:

		rc |= register_trace_kfree_skb(trace_kfree_skb_hit);

		rc |= register_trace_napi_poll(trace_napi_poll_hit);

		break;

	case TRACE_OFF:

		rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit);

		rc |= unregister_trace_napi_poll(trace_napi_poll_hit);



		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);

				call_rcu(&new_stat->rcu, free_dm_hw_stat);

			}

		}

		break;

	default:

		rc = 1;

		break;

	}



	if (!rc)

		trace_state = state;



	spin_unlock(&trace_state_lock);



	if (rc)

		return -EINPROGRESS;

	return rc;
@@ -204,6 +271,44 @@ static int net_dm_cmd_trace(struct sk_buff *skb, 
	return -ENOTSUPP;

}



static int dropmon_net_event(struct notifier_block *ev_block,

			unsigned long event, void *ptr)

{

	struct net_device *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;

		INIT_RCU_HEAD(&new_stat->rcu);

		spin_lock(&trace_state_lock);

		list_add_rcu(&new_stat->list, &hw_stats_list);

		spin_unlock(&trace_state_lock);

		break;

	case NETDEV_UNREGISTER:

		spin_lock(&trace_state_lock);

		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);

					call_rcu(&new_stat->rcu, free_dm_hw_stat);

					break;

				}

			}

		}

		spin_unlock(&trace_state_lock);

		break;

	}

out:

	return NOTIFY_DONE;

}



static struct genl_ops dropmon_ops[] = {

	{
@@ -220,6 +325,10 @@ static struct genl_ops dropmon_ops[] = { 
	},

};



static struct notifier_block dropmon_net_notifier = {

	.notifier_call = dropmon_net_event

};



static int __init init_net_drop_monitor(void)

{

	int cpu;
@@ -243,12 +352,18 @@ static int __init init_net_drop_monitor(void) 
		ret = genl_register_ops(&net_drop_monitor_family,

					&dropmon_ops[i]);

		if (ret) {

			printk(KERN_CRIT "failed to register operation %d\n",

			printk(KERN_CRIT "Failed to register operation %d\n",

				dropmon_ops[i].cmd);

			goto out_unreg;

		}

	}



	rc = register_netdevice_notifier(&dropmon_net_notifier);

	if (rc < 0) {

		printk(KERN_CRIT "Failed to register netdevice notifier\n");

		goto out_unreg;

	}



	rc = 0;



	for_each_present_cpu(cpu) {
@@ -259,6 +374,7 @@ static int __init init_net_drop_monitor(void) 
		data->send_timer.data = cpu;

		data->send_timer.function = sched_send_work;

	}



	goto out;



out_unreg:

net/core/net-traces.c

+4 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/netlink.h>

#include <linux/net_dropmon.h>

#include <trace/skb.h>

#include <trace/napi.h>



#include <asm/unaligned.h>

#include <asm/bitops.h>
@@ -27,3 +28,6 @@ 


DEFINE_TRACE(kfree_skb);

EXPORT_TRACEPOINT_SYMBOL_GPL(kfree_skb);



DEFINE_TRACE(napi_poll);

EXPORT_TRACEPOINT_SYMBOL_GPL(napi_poll);

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