1 files changed, 385 insertions, 0 deletions
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
new file mode 100644
index 00000000..7f36b38e
--- /dev/null
+++ b/net/core/drop_monitor.c
@@ -0,0 +1,385 @@
+/*
+ * 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 <linux/slab.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
+
+static void send_dm_alert(struct work_struct *unused);
+
+
+/*
+ * Globals, our netlink socket pointer
+ * and the work handle that will send up
+ * netlink alerts
+ */
+static int trace_state = TRACE_OFF;
+static DEFINE_SPINLOCK(trace_state_lock);
+
+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;
+};
+
+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 = {
+	.id             = GENL_ID_GENERATE,
+	.hdrsize        = 0,
+	.name           = "NET_DM",
+	.version        = 2,
+	.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 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)
+{
+	size_t al;
+	struct net_dm_alert_msg *msg;
+	struct nlattr *nla;
+
+	al = sizeof(struct net_dm_alert_msg);
+	al += dm_hit_limit * sizeof(struct net_dm_drop_point);
+	al += sizeof(struct nlattr);
+
+	data->skb = genlmsg_new(al, GFP_KERNEL);
+	genlmsg_put(data->skb, 0, 0, &net_drop_monitor_family,
+			0, NET_DM_CMD_ALERT);
+	nla = nla_reserve(data->skb, NLA_UNSPEC, sizeof(struct net_dm_alert_msg));
+	msg = nla_data(nla);
+	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_drop_common(struct sk_buff *skb, void *location)
+{
+	struct net_dm_alert_msg *msg;
+	struct nlmsghdr *nlh;
+	struct nlattr *nla;
+	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;
+	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;
+		}
+	}
+
+	/*
+	 * We need to create a new entry
+	 */
+	__nla_reserve_nohdr(data->skb, 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_on(&data->send_timer, smp_processor_id());
+	}
+
+out:
+	return;
+}
+
+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)
+{
+	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 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);
+
+	if (state == trace_state) {
+		rc = -EAGAIN;
+		goto out_unlock;
+	}
+
+	switch (state) {
+	case TRACE_ON:
+		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);
+			}
+		}
+		break;
+	default:
+		rc = 1;
+		break;
+	}
+
+	if (!rc)
+		trace_state = state;
+	else
+		rc = -EINPROGRESS;
+
+out_unlock:
+	spin_unlock(&trace_state_lock);
+
+	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 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;
+		new_stat->last_rx = jiffies;
+		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);
+					kfree_rcu(new_stat, rcu);
+					break;
+				}
+			}
+		}
+		spin_unlock(&trace_state_lock);
+		break;
+	}
+out:
+	return NOTIFY_DONE;
+}
+
+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 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;
+
+	printk(KERN_INFO "Initializing 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;
+	}
+
+	rc = genl_register_family_with_ops(&net_drop_monitor_family,
+					   dropmon_ops,
+					   ARRAY_SIZE(dropmon_ops));
+	if (rc) {
+		printk(KERN_ERR "Could not create drop monitor netlink family\n");
+		return rc;
+	}
+
+	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) {
+		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);