Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1783 insertions, 0 deletions

diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
new file mode 100644
index 000000000..7742ee689
--- /dev/null
+++ b/net/core/drop_monitor.c
@@ -0,0 +1,1783 @@
+// 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 <net/flow_offload.h>
+#include <net/devlink.h>
+
+#include <trace/events/skb.h>
+#include <trace/events/napi.h>
+#include <trace/events/devlink.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 bool monitor_hw;
+
+/* 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 net_dm_stats {
+	u64 dropped;
+	struct u64_stats_sync syncp;
+};
+
+#define NET_DM_MAX_HW_TRAP_NAME_LEN 40
+
+struct net_dm_hw_entry {
+	char trap_name[NET_DM_MAX_HW_TRAP_NAME_LEN];
+	u32 count;
+};
+
+struct net_dm_hw_entries {
+	u32 num_entries;
+	struct net_dm_hw_entry entries[];
+};
+
+struct per_cpu_dm_data {
+	spinlock_t		lock;	/* Protects 'skb', 'hw_entries' and
+					 * 'send_timer'
+					 */
+	union {
+		struct sk_buff			*skb;
+		struct net_dm_hw_entries	*hw_entries;
+	};
+	struct sk_buff_head	drop_queue;
+	struct work_struct	dm_alert_work;
+	struct timer_list	send_timer;
+	struct net_dm_stats	stats;
+};
+
+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 DEFINE_PER_CPU(struct per_cpu_dm_data, dm_hw_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;
+static u32 net_dm_trunc_len;
+static u32 net_dm_queue_len = 1000;
+
+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);
+	void (*hw_work_item_func)(struct work_struct *work);
+	void (*hw_trap_probe)(void *ignore, const struct devlink *devlink,
+			      struct sk_buff *skb,
+			      const struct devlink_trap_metadata *metadata);
+};
+
+struct net_dm_skb_cb {
+	union {
+		struct devlink_trap_metadata *hw_metadata;
+		void *pc;
+	};
+};
+
+#define NET_DM_SKB_CB(__skb) ((struct net_dm_skb_cb *)&((__skb)->cb[0]))
+
+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", .cap_sys_admin = 1 },
+};
+
+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 net_dm_drop_point *point;
+	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);
+	point = msg->points;
+	for (i = 0; i < msg->entries; i++) {
+		if (!memcmp(&location, &point->pc, sizeof(void *))) {
+			point->count++;
+			goto out;
+		}
+		point++;
+	}
+	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(point->pc, &location, sizeof(void *));
+	point->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) {
+		struct net_device *dev;
+
+		/*
+		 * 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
+		 */
+		/* Paired with WRITE_ONCE() in dropmon_net_event() */
+		dev = READ_ONCE(new_stat->dev);
+		if ((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 struct net_dm_hw_entries *
+net_dm_hw_reset_per_cpu_data(struct per_cpu_dm_data *hw_data)
+{
+	struct net_dm_hw_entries *hw_entries;
+	unsigned long flags;
+
+	hw_entries = kzalloc(struct_size(hw_entries, entries, dm_hit_limit),
+			     GFP_KERNEL);
+	if (!hw_entries) {
+		/* If the memory allocation failed, we try to perform another
+		 * allocation in 1/10 second. Otherwise, the probe function
+		 * will constantly bail out.
+		 */
+		mod_timer(&hw_data->send_timer, jiffies + HZ / 10);
+	}
+
+	spin_lock_irqsave(&hw_data->lock, flags);
+	swap(hw_data->hw_entries, hw_entries);
+	spin_unlock_irqrestore(&hw_data->lock, flags);
+
+	return hw_entries;
+}
+
+static int net_dm_hw_entry_put(struct sk_buff *msg,
+			       const struct net_dm_hw_entry *hw_entry)
+{
+	struct nlattr *attr;
+
+	attr = nla_nest_start(msg, NET_DM_ATTR_HW_ENTRY);
+	if (!attr)
+		return -EMSGSIZE;
+
+	if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_NAME, hw_entry->trap_name))
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, NET_DM_ATTR_HW_TRAP_COUNT, hw_entry->count))
+		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_hw_entries_put(struct sk_buff *msg,
+				 const struct net_dm_hw_entries *hw_entries)
+{
+	struct nlattr *attr;
+	int i;
+
+	attr = nla_nest_start(msg, NET_DM_ATTR_HW_ENTRIES);
+	if (!attr)
+		return -EMSGSIZE;
+
+	for (i = 0; i < hw_entries->num_entries; i++) {
+		int rc;
+
+		rc = net_dm_hw_entry_put(msg, &hw_entries->entries[i]);
+		if (rc)
+			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_hw_summary_report_fill(struct sk_buff *msg,
+			      const struct net_dm_hw_entries *hw_entries)
+{
+	struct net_dm_alert_msg anc_hdr = { 0 };
+	void *hdr;
+	int rc;
+
+	hdr = genlmsg_put(msg, 0, 0, &net_drop_monitor_family, 0,
+			  NET_DM_CMD_ALERT);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	/* We need to put the ancillary header in order not to break user
+	 * space.
+	 */
+	if (nla_put(msg, NLA_UNSPEC, sizeof(anc_hdr), &anc_hdr))
+		goto nla_put_failure;
+
+	rc = net_dm_hw_entries_put(msg, hw_entries);
+	if (rc)
+		goto nla_put_failure;
+
+	genlmsg_end(msg, hdr);
+
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
+static void net_dm_hw_summary_work(struct work_struct *work)
+{
+	struct net_dm_hw_entries *hw_entries;
+	struct per_cpu_dm_data *hw_data;
+	struct sk_buff *msg;
+	int rc;
+
+	hw_data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
+
+	hw_entries = net_dm_hw_reset_per_cpu_data(hw_data);
+	if (!hw_entries)
+		return;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		goto out;
+
+	rc = net_dm_hw_summary_report_fill(msg, hw_entries);
+	if (rc) {
+		nlmsg_free(msg);
+		goto out;
+	}
+
+	genlmsg_multicast(&net_drop_monitor_family, msg, 0, 0, GFP_KERNEL);
+
+out:
+	kfree(hw_entries);
+}
+
+static void
+net_dm_hw_trap_summary_probe(void *ignore, const struct devlink *devlink,
+			     struct sk_buff *skb,
+			     const struct devlink_trap_metadata *metadata)
+{
+	struct net_dm_hw_entries *hw_entries;
+	struct net_dm_hw_entry *hw_entry;
+	struct per_cpu_dm_data *hw_data;
+	unsigned long flags;
+	int i;
+
+	if (metadata->trap_type == DEVLINK_TRAP_TYPE_CONTROL)
+		return;
+
+	hw_data = this_cpu_ptr(&dm_hw_cpu_data);
+	spin_lock_irqsave(&hw_data->lock, flags);
+	hw_entries = hw_data->hw_entries;
+
+	if (!hw_entries)
+		goto out;
+
+	for (i = 0; i < hw_entries->num_entries; i++) {
+		hw_entry = &hw_entries->entries[i];
+		if (!strncmp(hw_entry->trap_name, metadata->trap_name,
+			     NET_DM_MAX_HW_TRAP_NAME_LEN - 1)) {
+			hw_entry->count++;
+			goto out;
+		}
+	}
+	if (WARN_ON_ONCE(hw_entries->num_entries == dm_hit_limit))
+		goto out;
+
+	hw_entry = &hw_entries->entries[hw_entries->num_entries];
+	strlcpy(hw_entry->trap_name, metadata->trap_name,
+		NET_DM_MAX_HW_TRAP_NAME_LEN - 1);
+	hw_entry->count = 1;
+	hw_entries->num_entries++;
+
+	if (!timer_pending(&hw_data->send_timer)) {
+		hw_data->send_timer.expires = jiffies + dm_delay * HZ;
+		add_timer(&hw_data->send_timer);
+	}
+
+out:
+	spin_unlock_irqrestore(&hw_data->lock, flags);
+}
+
+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,
+	.hw_work_item_func	= net_dm_hw_summary_work,
+	.hw_trap_probe		= net_dm_hw_trap_summary_probe,
+};
+
+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;
+
+	if (!skb_mac_header_was_set(skb))
+		return;
+
+	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);
+	u64_stats_update_begin(&data->stats.syncp);
+	data->stats.dropped++;
+	u64_stats_update_end(&data->stats.syncp);
+	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)) +
+	       /* NET_DM_ATTR_PORT_NETDEV_NAME */
+	       nla_total_size(IFNAMSIZ + 1);
+}
+
+#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_ORIGIN */
+	       nla_total_size(sizeof(u16)) +
+	       /* 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(u64)) +
+	       /* NET_DM_ATTR_ORIG_LEN */
+	       nla_total_size(sizeof(u32)) +
+	       /* 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,
+					    const char *name)
+{
+	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;
+
+	if (name && nla_put_string(msg, NET_DM_ATTR_PORT_NETDEV_NAME, name))
+		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;
+	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_u16(msg, NET_DM_ATTR_ORIGIN, NET_DM_ORIGIN_SW))
+		goto nla_put_failure;
+
+	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, NULL);
+	if (rc)
+		goto nla_put_failure;
+
+	if (nla_put_u64_64bit(msg, NET_DM_ATTR_TIMESTAMP,
+			      ktime_to_ns(skb->tstamp), NET_DM_ATTR_PAD))
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, NET_DM_ATTR_ORIG_LEN, skb->len))
+		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);
+	if (net_dm_trunc_len)
+		payload_len = min_t(size_t, net_dm_trunc_len, payload_len);
+
+	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 size_t
+net_dm_flow_action_cookie_size(const struct devlink_trap_metadata *hw_metadata)
+{
+	return hw_metadata->fa_cookie ?
+	       nla_total_size(hw_metadata->fa_cookie->cookie_len) : 0;
+}
+
+static size_t
+net_dm_hw_packet_report_size(size_t payload_len,
+			     const struct devlink_trap_metadata *hw_metadata)
+{
+	size_t size;
+
+	size = nlmsg_msg_size(GENL_HDRLEN + net_drop_monitor_family.hdrsize);
+
+	return NLMSG_ALIGN(size) +
+	       /* NET_DM_ATTR_ORIGIN */
+	       nla_total_size(sizeof(u16)) +
+	       /* NET_DM_ATTR_HW_TRAP_GROUP_NAME */
+	       nla_total_size(strlen(hw_metadata->trap_group_name) + 1) +
+	       /* NET_DM_ATTR_HW_TRAP_NAME */
+	       nla_total_size(strlen(hw_metadata->trap_name) + 1) +
+	       /* NET_DM_ATTR_IN_PORT */
+	       net_dm_in_port_size() +
+	       /* NET_DM_ATTR_FLOW_ACTION_COOKIE */
+	       net_dm_flow_action_cookie_size(hw_metadata) +
+	       /* NET_DM_ATTR_TIMESTAMP */
+	       nla_total_size(sizeof(u64)) +
+	       /* NET_DM_ATTR_ORIG_LEN */
+	       nla_total_size(sizeof(u32)) +
+	       /* NET_DM_ATTR_PROTO */
+	       nla_total_size(sizeof(u16)) +
+	       /* NET_DM_ATTR_PAYLOAD */
+	       nla_total_size(payload_len);
+}
+
+static int net_dm_hw_packet_report_fill(struct sk_buff *msg,
+					struct sk_buff *skb, size_t payload_len)
+{
+	struct devlink_trap_metadata *hw_metadata;
+	struct nlattr *attr;
+	void *hdr;
+
+	hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
+
+	hdr = genlmsg_put(msg, 0, 0, &net_drop_monitor_family, 0,
+			  NET_DM_CMD_PACKET_ALERT);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (nla_put_u16(msg, NET_DM_ATTR_ORIGIN, NET_DM_ORIGIN_HW))
+		goto nla_put_failure;
+
+	if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_GROUP_NAME,
+			   hw_metadata->trap_group_name))
+		goto nla_put_failure;
+
+	if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_NAME,
+			   hw_metadata->trap_name))
+		goto nla_put_failure;
+
+	if (hw_metadata->input_dev) {
+		struct net_device *dev = hw_metadata->input_dev;
+		int rc;
+
+		rc = net_dm_packet_report_in_port_put(msg, dev->ifindex,
+						      dev->name);
+		if (rc)
+			goto nla_put_failure;
+	}
+
+	if (hw_metadata->fa_cookie &&
+	    nla_put(msg, NET_DM_ATTR_FLOW_ACTION_COOKIE,
+		    hw_metadata->fa_cookie->cookie_len,
+		    hw_metadata->fa_cookie->cookie))
+		goto nla_put_failure;
+
+	if (nla_put_u64_64bit(msg, NET_DM_ATTR_TIMESTAMP,
+			      ktime_to_ns(skb->tstamp), NET_DM_ATTR_PAD))
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, NET_DM_ATTR_ORIG_LEN, skb->len))
+		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;
+}
+
+static struct devlink_trap_metadata *
+net_dm_hw_metadata_copy(const struct devlink_trap_metadata *metadata)
+{
+	const struct flow_action_cookie *fa_cookie;
+	struct devlink_trap_metadata *hw_metadata;
+	const char *trap_group_name;
+	const char *trap_name;
+
+	hw_metadata = kzalloc(sizeof(*hw_metadata), GFP_ATOMIC);
+	if (!hw_metadata)
+		return NULL;
+
+	trap_group_name = kstrdup(metadata->trap_group_name, GFP_ATOMIC);
+	if (!trap_group_name)
+		goto free_hw_metadata;
+	hw_metadata->trap_group_name = trap_group_name;
+
+	trap_name = kstrdup(metadata->trap_name, GFP_ATOMIC);
+	if (!trap_name)
+		goto free_trap_group;
+	hw_metadata->trap_name = trap_name;
+
+	if (metadata->fa_cookie) {
+		size_t cookie_size = sizeof(*fa_cookie) +
+				     metadata->fa_cookie->cookie_len;
+
+		fa_cookie = kmemdup(metadata->fa_cookie, cookie_size,
+				    GFP_ATOMIC);
+		if (!fa_cookie)
+			goto free_trap_name;
+		hw_metadata->fa_cookie = fa_cookie;
+	}
+
+	hw_metadata->input_dev = metadata->input_dev;
+	if (hw_metadata->input_dev)
+		dev_hold(hw_metadata->input_dev);
+
+	return hw_metadata;
+
+free_trap_name:
+	kfree(trap_name);
+free_trap_group:
+	kfree(trap_group_name);
+free_hw_metadata:
+	kfree(hw_metadata);
+	return NULL;
+}
+
+static void
+net_dm_hw_metadata_free(const struct devlink_trap_metadata *hw_metadata)
+{
+	if (hw_metadata->input_dev)
+		dev_put(hw_metadata->input_dev);
+	kfree(hw_metadata->fa_cookie);
+	kfree(hw_metadata->trap_name);
+	kfree(hw_metadata->trap_group_name);
+	kfree(hw_metadata);
+}
+
+static void net_dm_hw_packet_report(struct sk_buff *skb)
+{
+	struct devlink_trap_metadata *hw_metadata;
+	struct sk_buff *msg;
+	size_t payload_len;
+	int rc;
+
+	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);
+
+	payload_len = min_t(size_t, skb->len, NET_DM_MAX_PACKET_SIZE);
+	if (net_dm_trunc_len)
+		payload_len = min_t(size_t, net_dm_trunc_len, payload_len);
+
+	hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
+	msg = nlmsg_new(net_dm_hw_packet_report_size(payload_len, hw_metadata),
+			GFP_KERNEL);
+	if (!msg)
+		goto out;
+
+	rc = net_dm_hw_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:
+	net_dm_hw_metadata_free(NET_DM_SKB_CB(skb)->hw_metadata);
+	consume_skb(skb);
+}
+
+static void net_dm_hw_packet_work(struct work_struct *work)
+{
+	struct per_cpu_dm_data *hw_data;
+	struct sk_buff_head list;
+	struct sk_buff *skb;
+	unsigned long flags;
+
+	hw_data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
+
+	__skb_queue_head_init(&list);
+
+	spin_lock_irqsave(&hw_data->drop_queue.lock, flags);
+	skb_queue_splice_tail_init(&hw_data->drop_queue, &list);
+	spin_unlock_irqrestore(&hw_data->drop_queue.lock, flags);
+
+	while ((skb = __skb_dequeue(&list)))
+		net_dm_hw_packet_report(skb);
+}
+
+static void
+net_dm_hw_trap_packet_probe(void *ignore, const struct devlink *devlink,
+			    struct sk_buff *skb,
+			    const struct devlink_trap_metadata *metadata)
+{
+	struct devlink_trap_metadata *n_hw_metadata;
+	ktime_t tstamp = ktime_get_real();
+	struct per_cpu_dm_data *hw_data;
+	struct sk_buff *nskb;
+	unsigned long flags;
+
+	if (metadata->trap_type == DEVLINK_TRAP_TYPE_CONTROL)
+		return;
+
+	if (!skb_mac_header_was_set(skb))
+		return;
+
+	nskb = skb_clone(skb, GFP_ATOMIC);
+	if (!nskb)
+		return;
+
+	n_hw_metadata = net_dm_hw_metadata_copy(metadata);
+	if (!n_hw_metadata)
+		goto free;
+
+	NET_DM_SKB_CB(nskb)->hw_metadata = n_hw_metadata;
+	nskb->tstamp = tstamp;
+
+	hw_data = this_cpu_ptr(&dm_hw_cpu_data);
+
+	spin_lock_irqsave(&hw_data->drop_queue.lock, flags);
+	if (skb_queue_len(&hw_data->drop_queue) < net_dm_queue_len)
+		__skb_queue_tail(&hw_data->drop_queue, nskb);
+	else
+		goto unlock_free;
+	spin_unlock_irqrestore(&hw_data->drop_queue.lock, flags);
+
+	schedule_work(&hw_data->dm_alert_work);
+
+	return;
+
+unlock_free:
+	spin_unlock_irqrestore(&hw_data->drop_queue.lock, flags);
+	u64_stats_update_begin(&hw_data->stats.syncp);
+	hw_data->stats.dropped++;
+	u64_stats_update_end(&hw_data->stats.syncp);
+	net_dm_hw_metadata_free(n_hw_metadata);
+free:
+	consume_skb(nskb);
+}
+
+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,
+	.hw_work_item_func	= net_dm_hw_packet_work,
+	.hw_trap_probe		= net_dm_hw_trap_packet_probe,
+};
+
+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,
+};
+
+#if IS_ENABLED(CONFIG_NET_DEVLINK)
+static int net_dm_hw_probe_register(const struct net_dm_alert_ops *ops)
+{
+	return register_trace_devlink_trap_report(ops->hw_trap_probe, NULL);
+}
+
+static void net_dm_hw_probe_unregister(const struct net_dm_alert_ops *ops)
+{
+	unregister_trace_devlink_trap_report(ops->hw_trap_probe, NULL);
+	tracepoint_synchronize_unregister();
+}
+#else
+static int net_dm_hw_probe_register(const struct net_dm_alert_ops *ops)
+{
+	return -EOPNOTSUPP;
+}
+
+static void net_dm_hw_probe_unregister(const struct net_dm_alert_ops *ops)
+{
+}
+#endif
+
+static int net_dm_hw_monitor_start(struct netlink_ext_ack *extack)
+{
+	const struct net_dm_alert_ops *ops;
+	int cpu, rc;
+
+	if (monitor_hw) {
+		NL_SET_ERR_MSG_MOD(extack, "Hardware monitoring already enabled");
+		return -EAGAIN;
+	}
+
+	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 *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+		struct net_dm_hw_entries *hw_entries;
+
+		INIT_WORK(&hw_data->dm_alert_work, ops->hw_work_item_func);
+		timer_setup(&hw_data->send_timer, sched_send_work, 0);
+		hw_entries = net_dm_hw_reset_per_cpu_data(hw_data);
+		kfree(hw_entries);
+	}
+
+	rc = net_dm_hw_probe_register(ops);
+	if (rc) {
+		NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to devlink_trap_probe() tracepoint");
+		goto err_module_put;
+	}
+
+	monitor_hw = true;
+
+	return 0;
+
+err_module_put:
+	for_each_possible_cpu(cpu) {
+		struct per_cpu_dm_data *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+		struct sk_buff *skb;
+
+		del_timer_sync(&hw_data->send_timer);
+		cancel_work_sync(&hw_data->dm_alert_work);
+		while ((skb = __skb_dequeue(&hw_data->drop_queue))) {
+			struct devlink_trap_metadata *hw_metadata;
+
+			hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
+			net_dm_hw_metadata_free(hw_metadata);
+			consume_skb(skb);
+		}
+	}
+	module_put(THIS_MODULE);
+	return rc;
+}
+
+static void net_dm_hw_monitor_stop(struct netlink_ext_ack *extack)
+{
+	const struct net_dm_alert_ops *ops;
+	int cpu;
+
+	if (!monitor_hw) {
+		NL_SET_ERR_MSG_MOD(extack, "Hardware monitoring already disabled");
+		return;
+	}
+
+	ops = net_dm_alert_ops_arr[net_dm_alert_mode];
+
+	monitor_hw = false;
+
+	net_dm_hw_probe_unregister(ops);
+
+	for_each_possible_cpu(cpu) {
+		struct per_cpu_dm_data *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+		struct sk_buff *skb;
+
+		del_timer_sync(&hw_data->send_timer);
+		cancel_work_sync(&hw_data->dm_alert_work);
+		while ((skb = __skb_dequeue(&hw_data->drop_queue))) {
+			struct devlink_trap_metadata *hw_metadata;
+
+			hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
+			net_dm_hw_metadata_free(hw_metadata);
+			consume_skb(skb);
+		}
+	}
+
+	module_put(THIS_MODULE);
+}
+
+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:
+	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);
+	}
+	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 bool net_dm_is_monitoring(void)
+{
+	return trace_state == TRACE_ON || monitor_hw;
+}
+
+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:
+	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 void net_dm_trunc_len_set(struct genl_info *info)
+{
+	if (!info->attrs[NET_DM_ATTR_TRUNC_LEN])
+		return;
+
+	net_dm_trunc_len = nla_get_u32(info->attrs[NET_DM_ATTR_TRUNC_LEN]);
+}
+
+static void net_dm_queue_len_set(struct genl_info *info)
+{
+	if (!info->attrs[NET_DM_ATTR_QUEUE_LEN])
+		return;
+
+	net_dm_queue_len = nla_get_u32(info->attrs[NET_DM_ATTR_QUEUE_LEN]);
+}
+
+static int net_dm_cmd_config(struct sk_buff *skb,
+			struct genl_info *info)
+{
+	struct netlink_ext_ack *extack = info->extack;
+	int rc;
+
+	if (net_dm_is_monitoring()) {
+		NL_SET_ERR_MSG_MOD(extack, "Cannot configure drop monitor during monitoring");
+		return -EBUSY;
+	}
+
+	rc = net_dm_alert_mode_set(info);
+	if (rc)
+		return rc;
+
+	net_dm_trunc_len_set(info);
+
+	net_dm_queue_len_set(info);
+
+	return 0;
+}
+
+static int net_dm_monitor_start(bool set_sw, bool set_hw,
+				struct netlink_ext_ack *extack)
+{
+	bool sw_set = false;
+	int rc;
+
+	if (set_sw) {
+		rc = set_all_monitor_traces(TRACE_ON, extack);
+		if (rc)
+			return rc;
+		sw_set = true;
+	}
+
+	if (set_hw) {
+		rc = net_dm_hw_monitor_start(extack);
+		if (rc)
+			goto err_monitor_hw;
+	}
+
+	return 0;
+
+err_monitor_hw:
+	if (sw_set)
+		set_all_monitor_traces(TRACE_OFF, extack);
+	return rc;
+}
+
+static void net_dm_monitor_stop(bool set_sw, bool set_hw,
+				struct netlink_ext_ack *extack)
+{
+	if (set_hw)
+		net_dm_hw_monitor_stop(extack);
+	if (set_sw)
+		set_all_monitor_traces(TRACE_OFF, extack);
+}
+
+static int net_dm_cmd_trace(struct sk_buff *skb,
+			struct genl_info *info)
+{
+	bool set_sw = !!info->attrs[NET_DM_ATTR_SW_DROPS];
+	bool set_hw = !!info->attrs[NET_DM_ATTR_HW_DROPS];
+	struct netlink_ext_ack *extack = info->extack;
+
+	/* To maintain backward compatibility, we start / stop monitoring of
+	 * software drops if no flag is specified.
+	 */
+	if (!set_sw && !set_hw)
+		set_sw = true;
+
+	switch (info->genlhdr->cmd) {
+	case NET_DM_CMD_START:
+		return net_dm_monitor_start(set_sw, set_hw, extack);
+	case NET_DM_CMD_STOP:
+		net_dm_monitor_stop(set_sw, set_hw, extack);
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static int net_dm_config_fill(struct sk_buff *msg, struct genl_info *info)
+{
+	void *hdr;
+
+	hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
+			  &net_drop_monitor_family, 0, NET_DM_CMD_CONFIG_NEW);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (nla_put_u8(msg, NET_DM_ATTR_ALERT_MODE, net_dm_alert_mode))
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, NET_DM_ATTR_TRUNC_LEN, net_dm_trunc_len))
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, NET_DM_ATTR_QUEUE_LEN, net_dm_queue_len))
+		goto nla_put_failure;
+
+	genlmsg_end(msg, hdr);
+
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
+static int net_dm_cmd_config_get(struct sk_buff *skb, struct genl_info *info)
+{
+	struct sk_buff *msg;
+	int rc;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	rc = net_dm_config_fill(msg, info);
+	if (rc)
+		goto free_msg;
+
+	return genlmsg_reply(msg, info);
+
+free_msg:
+	nlmsg_free(msg);
+	return rc;
+}
+
+static void net_dm_stats_read(struct net_dm_stats *stats)
+{
+	int cpu;
+
+	memset(stats, 0, sizeof(*stats));
+	for_each_possible_cpu(cpu) {
+		struct per_cpu_dm_data *data = &per_cpu(dm_cpu_data, cpu);
+		struct net_dm_stats *cpu_stats = &data->stats;
+		unsigned int start;
+		u64 dropped;
+
+		do {
+			start = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
+			dropped = cpu_stats->dropped;
+		} while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, start));
+
+		stats->dropped += dropped;
+	}
+}
+
+static int net_dm_stats_put(struct sk_buff *msg)
+{
+	struct net_dm_stats stats;
+	struct nlattr *attr;
+
+	net_dm_stats_read(&stats);
+
+	attr = nla_nest_start(msg, NET_DM_ATTR_STATS);
+	if (!attr)
+		return -EMSGSIZE;
+
+	if (nla_put_u64_64bit(msg, NET_DM_ATTR_STATS_DROPPED,
+			      stats.dropped, NET_DM_ATTR_PAD))
+		goto nla_put_failure;
+
+	nla_nest_end(msg, attr);
+
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(msg, attr);
+	return -EMSGSIZE;
+}
+
+static void net_dm_hw_stats_read(struct net_dm_stats *stats)
+{
+	int cpu;
+
+	memset(stats, 0, sizeof(*stats));
+	for_each_possible_cpu(cpu) {
+		struct per_cpu_dm_data *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+		struct net_dm_stats *cpu_stats = &hw_data->stats;
+		unsigned int start;
+		u64 dropped;
+
+		do {
+			start = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
+			dropped = cpu_stats->dropped;
+		} while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, start));
+
+		stats->dropped += dropped;
+	}
+}
+
+static int net_dm_hw_stats_put(struct sk_buff *msg)
+{
+	struct net_dm_stats stats;
+	struct nlattr *attr;
+
+	net_dm_hw_stats_read(&stats);
+
+	attr = nla_nest_start(msg, NET_DM_ATTR_HW_STATS);
+	if (!attr)
+		return -EMSGSIZE;
+
+	if (nla_put_u64_64bit(msg, NET_DM_ATTR_STATS_DROPPED,
+			      stats.dropped, NET_DM_ATTR_PAD))
+		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_stats_fill(struct sk_buff *msg, struct genl_info *info)
+{
+	void *hdr;
+	int rc;
+
+	hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
+			  &net_drop_monitor_family, 0, NET_DM_CMD_STATS_NEW);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	rc = net_dm_stats_put(msg);
+	if (rc)
+		goto nla_put_failure;
+
+	rc = net_dm_hw_stats_put(msg);
+	if (rc)
+		goto nla_put_failure;
+
+	genlmsg_end(msg, hdr);
+
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
+static int net_dm_cmd_stats_get(struct sk_buff *skb, struct genl_info *info)
+{
+	struct sk_buff *msg;
+	int rc;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	rc = net_dm_stats_fill(msg, info);
+	if (rc)
+		goto free_msg;
+
+	return genlmsg_reply(msg, info);
+
+free_msg:
+	nlmsg_free(msg);
+	return rc;
+}
+
+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) {
+
+				/* Paired with READ_ONCE() in trace_napi_poll_hit() */
+				WRITE_ONCE(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 },
+	[NET_DM_ATTR_TRUNC_LEN] = { .type = NLA_U32 },
+	[NET_DM_ATTR_QUEUE_LEN] = { .type = NLA_U32 },
+	[NET_DM_ATTR_SW_DROPS]	= {. type = NLA_FLAG },
+	[NET_DM_ATTR_HW_DROPS]	= {. type = NLA_FLAG },
+};
+
+static const struct genl_small_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,
+		.flags = GENL_ADMIN_PERM,
+	},
+	{
+		.cmd = NET_DM_CMD_STOP,
+		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.doit = net_dm_cmd_trace,
+		.flags = GENL_ADMIN_PERM,
+	},
+	{
+		.cmd = NET_DM_CMD_CONFIG_GET,
+		.doit = net_dm_cmd_config_get,
+	},
+	{
+		.cmd = NET_DM_CMD_STATS_GET,
+		.doit = net_dm_cmd_stats_get,
+	},
+};
+
+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,
+	.small_ops	= dropmon_ops,
+	.n_small_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 void __net_dm_cpu_data_init(struct per_cpu_dm_data *data)
+{
+	spin_lock_init(&data->lock);
+	skb_queue_head_init(&data->drop_queue);
+	u64_stats_init(&data->stats.syncp);
+}
+
+static void __net_dm_cpu_data_fini(struct per_cpu_dm_data *data)
+{
+	WARN_ON(!skb_queue_empty(&data->drop_queue));
+}
+
+static void net_dm_cpu_data_init(int cpu)
+{
+	struct per_cpu_dm_data *data;
+
+	data = &per_cpu(dm_cpu_data, cpu);
+	__net_dm_cpu_data_init(data);
+}
+
+static void net_dm_cpu_data_fini(int cpu)
+{
+	struct per_cpu_dm_data *data;
+
+	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.
+	 */
+	consume_skb(data->skb);
+	__net_dm_cpu_data_fini(data);
+}
+
+static void net_dm_hw_cpu_data_init(int cpu)
+{
+	struct per_cpu_dm_data *hw_data;
+
+	hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+	__net_dm_cpu_data_init(hw_data);
+}
+
+static void net_dm_hw_cpu_data_fini(int cpu)
+{
+	struct per_cpu_dm_data *hw_data;
+
+	hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+	kfree(hw_data->hw_entries);
+	__net_dm_cpu_data_fini(hw_data);
+}
+
+static int __init init_net_drop_monitor(void)
+{
+	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) {
+		net_dm_cpu_data_init(cpu);
+		net_dm_hw_cpu_data_init(cpu);
+	}
+
+	goto out;
+
+out_unreg:
+	genl_unregister_family(&net_drop_monitor_family);
+out:
+	return rc;
+}
+
+static void exit_net_drop_monitor(void)
+{
+	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) {
+		net_dm_hw_cpu_data_fini(cpu);
+		net_dm_cpu_data_fini(cpu);
+	}
+
+	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");
+MODULE_DESCRIPTION("Monitoring code for network dropped packet alerts");