net/openvswitch/meter.c - kernel/msm-4.19 - Gitiles

 /*
  * Copyright (c) 2017 Nicira, Inc.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of version 2 of the GNU General Public
  * License as published by the Free Software Foundation.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/if.h>
 #include <linux/skbuff.h>
 #include <linux/ip.h>
 #include <linux/kernel.h>
 #include <linux/openvswitch.h>
 #include <linux/netlink.h>
 #include <linux/rculist.h>

 #include <net/netlink.h>
 #include <net/genetlink.h>

 #include "datapath.h"
 #include "meter.h"

 #define METER_HASH_BUCKETS 1024

 static const struct nla_policy meter_policy[OVS_METER_ATTR_MAX + 1] = {
 	[OVS_METER_ATTR_ID] = { .type = NLA_U32, },
 	[OVS_METER_ATTR_KBPS] = { .type = NLA_FLAG },
 	[OVS_METER_ATTR_STATS] = { .len = sizeof(struct ovs_flow_stats) },
 	[OVS_METER_ATTR_BANDS] = { .type = NLA_NESTED },
 	[OVS_METER_ATTR_USED] = { .type = NLA_U64 },
 	[OVS_METER_ATTR_CLEAR] = { .type = NLA_FLAG },
 	[OVS_METER_ATTR_MAX_METERS] = { .type = NLA_U32 },
 	[OVS_METER_ATTR_MAX_BANDS] = { .type = NLA_U32 },
 };

 static const struct nla_policy band_policy[OVS_BAND_ATTR_MAX + 1] = {
 	[OVS_BAND_ATTR_TYPE] = { .type = NLA_U32, },
 	[OVS_BAND_ATTR_RATE] = { .type = NLA_U32, },
 	[OVS_BAND_ATTR_BURST] = { .type = NLA_U32, },
 	[OVS_BAND_ATTR_STATS] = { .len = sizeof(struct ovs_flow_stats) },
 };

 static void ovs_meter_free(struct dp_meter *meter)
 {
 	if (!meter)
 		return;

 	kfree_rcu(meter, rcu);
 }

 static struct hlist_head *meter_hash_bucket(const struct datapath *dp,
 					    u32 meter_id)
 {
 	return &dp->meters[meter_id & (METER_HASH_BUCKETS - 1)];
 }

 /* Call with ovs_mutex or RCU read lock. */
 static struct dp_meter *lookup_meter(const struct datapath *dp,
 				     u32 meter_id)
 {
 	struct dp_meter *meter;
 	struct hlist_head *head;

 	head = meter_hash_bucket(dp, meter_id);
 	hlist_for_each_entry_rcu(meter, head, dp_hash_node) {
 		if (meter->id == meter_id)
 			return meter;
 	}
 	return NULL;
 }

 static void attach_meter(struct datapath *dp, struct dp_meter *meter)
 {
 	struct hlist_head *head = meter_hash_bucket(dp, meter->id);

 	hlist_add_head_rcu(&meter->dp_hash_node, head);
 }

 static void detach_meter(struct dp_meter *meter)
 {
 	ASSERT_OVSL();
 	if (meter)
 		hlist_del_rcu(&meter->dp_hash_node);
 }

 static struct sk_buff *
 ovs_meter_cmd_reply_start(struct genl_info *info, u8 cmd,
 			  struct ovs_header **ovs_reply_header)
 {
 	struct sk_buff *skb;
 	struct ovs_header *ovs_header = info->userhdr;

 	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 	if (!skb)
 		return ERR_PTR(-ENOMEM);

 	*ovs_reply_header = genlmsg_put(skb, info->snd_portid,
 					info->snd_seq,
 					&dp_meter_genl_family, 0, cmd);
 	if (!*ovs_reply_header) {
 		nlmsg_free(skb);
 		return ERR_PTR(-EMSGSIZE);
 	}
 	(*ovs_reply_header)->dp_ifindex = ovs_header->dp_ifindex;

 	return skb;
 }

 static int ovs_meter_cmd_reply_stats(struct sk_buff *reply, u32 meter_id,
 				     struct dp_meter *meter)
 {
 	struct nlattr *nla;
 	struct dp_meter_band *band;
 	u16 i;

 	if (nla_put_u32(reply, OVS_METER_ATTR_ID, meter_id))
 		goto error;

 	if (!meter)
 		return 0;

 	if (nla_put(reply, OVS_METER_ATTR_STATS,
 		    sizeof(struct ovs_flow_stats), &meter->stats) ||
 	    nla_put_u64_64bit(reply, OVS_METER_ATTR_USED, meter->used,
 			      OVS_METER_ATTR_PAD))
 		goto error;

 	nla = nla_nest_start(reply, OVS_METER_ATTR_BANDS);
 	if (!nla)
 		goto error;

 	band = meter->bands;

 	for (i = 0; i < meter->n_bands; ++i, ++band) {
 		struct nlattr *band_nla;

 		band_nla = nla_nest_start(reply, OVS_BAND_ATTR_UNSPEC);
 		if (!band_nla || nla_put(reply, OVS_BAND_ATTR_STATS,
 					 sizeof(struct ovs_flow_stats),
 					 &band->stats))
 			goto error;
 		nla_nest_end(reply, band_nla);
 	}
 	nla_nest_end(reply, nla);

 	return 0;
 error:
 	return -EMSGSIZE;
 }

 static int ovs_meter_cmd_features(struct sk_buff *skb, struct genl_info *info)
 {
 	struct sk_buff *reply;
 	struct ovs_header *ovs_reply_header;
 	struct nlattr *nla, *band_nla;
 	int err;

 	reply = ovs_meter_cmd_reply_start(info, OVS_METER_CMD_FEATURES,
 					  &ovs_reply_header);
 	if (IS_ERR(reply))
 		return PTR_ERR(reply);

 	if (nla_put_u32(reply, OVS_METER_ATTR_MAX_METERS, U32_MAX) ||
 	    nla_put_u32(reply, OVS_METER_ATTR_MAX_BANDS, DP_MAX_BANDS))
 		goto nla_put_failure;

 	nla = nla_nest_start(reply, OVS_METER_ATTR_BANDS);
 	if (!nla)
 		goto nla_put_failure;

 	band_nla = nla_nest_start(reply, OVS_BAND_ATTR_UNSPEC);
 	if (!band_nla)
 		goto nla_put_failure;
 	/* Currently only DROP band type is supported. */
 	if (nla_put_u32(reply, OVS_BAND_ATTR_TYPE, OVS_METER_BAND_TYPE_DROP))
 		goto nla_put_failure;
 	nla_nest_end(reply, band_nla);
 	nla_nest_end(reply, nla);

 	genlmsg_end(reply, ovs_reply_header);
 	return genlmsg_reply(reply, info);

 nla_put_failure:
 	nlmsg_free(reply);
 	err = -EMSGSIZE;
 	return err;
 }

 static struct dp_meter *dp_meter_create(struct nlattr **a)
 {
 	struct nlattr *nla;
 	int rem;
 	u16 n_bands = 0;
 	struct dp_meter *meter;
 	struct dp_meter_band *band;
 	int err;

 	/* Validate attributes, count the bands. */
 	if (!a[OVS_METER_ATTR_BANDS])
 		return ERR_PTR(-EINVAL);

 	nla_for_each_nested(nla, a[OVS_METER_ATTR_BANDS], rem)
 		if (++n_bands > DP_MAX_BANDS)
 			return ERR_PTR(-EINVAL);

 	/* Allocate and set up the meter before locking anything. */
 	meter = kzalloc(n_bands * sizeof(struct dp_meter_band) +
 			sizeof(*meter), GFP_KERNEL);
 	if (!meter)
 		return ERR_PTR(-ENOMEM);

 	meter->used = div_u64(ktime_get_ns(), 1000 * 1000);
 	meter->kbps = a[OVS_METER_ATTR_KBPS] ? 1 : 0;
 	meter->keep_stats = !a[OVS_METER_ATTR_CLEAR];
 	spin_lock_init(&meter->lock);
 	if (meter->keep_stats && a[OVS_METER_ATTR_STATS]) {
 		meter->stats = *(struct ovs_flow_stats *)
 			nla_data(a[OVS_METER_ATTR_STATS]);
 	}
 	meter->n_bands = n_bands;

 	/* Set up meter bands. */
 	band = meter->bands;
 	nla_for_each_nested(nla, a[OVS_METER_ATTR_BANDS], rem) {
 		struct nlattr *attr[OVS_BAND_ATTR_MAX + 1];
 		u32 band_max_delta_t;

 		err = nla_parse((struct nlattr **)&attr, OVS_BAND_ATTR_MAX,
 				nla_data(nla), nla_len(nla), band_policy,
 				NULL);
 		if (err)
 			goto exit_free_meter;

 		if (!attr[OVS_BAND_ATTR_TYPE] ||
 		    !attr[OVS_BAND_ATTR_RATE] ||
 		    !attr[OVS_BAND_ATTR_BURST]) {
 			err = -EINVAL;
 			goto exit_free_meter;
 		}

 		band->type = nla_get_u32(attr[OVS_BAND_ATTR_TYPE]);
 		band->rate = nla_get_u32(attr[OVS_BAND_ATTR_RATE]);
 		band->burst_size = nla_get_u32(attr[OVS_BAND_ATTR_BURST]);
 		/* Figure out max delta_t that is enough to fill any bucket.
 		 * Keep max_delta_t size to the bucket units:
 		 * pkts => 1/1000 packets, kilobits => bits.
 		 */
 		band_max_delta_t = (band->burst_size + band->rate) * 1000;
 		/* Start with a full bucket. */
 		band->bucket = band_max_delta_t;
 		if (band_max_delta_t > meter->max_delta_t)
 			meter->max_delta_t = band_max_delta_t;
 		band++;
 	}

 	return meter;

 exit_free_meter:
 	kfree(meter);
 	return ERR_PTR(err);
 }

 static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
 {
 	struct nlattr **a = info->attrs;
 	struct dp_meter *meter, *old_meter;
 	struct sk_buff *reply;
 	struct ovs_header *ovs_reply_header;
 	struct ovs_header *ovs_header = info->userhdr;
 	struct datapath *dp;
 	int err;
 	u32 meter_id;
 	bool failed;

 	meter = dp_meter_create(a);
 	if (IS_ERR_OR_NULL(meter))
 		return PTR_ERR(meter);

 	reply = ovs_meter_cmd_reply_start(info, OVS_METER_CMD_SET,
 					  &ovs_reply_header);
 	if (IS_ERR(reply)) {
 		err = PTR_ERR(reply);
 		goto exit_free_meter;
 	}

 	ovs_lock();
 	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
 	if (!dp) {
 		err = -ENODEV;
 		goto exit_unlock;
 	}

 	if (!a[OVS_METER_ATTR_ID]) {
 		err = -ENODEV;
 		goto exit_unlock;
 	}

 	meter_id = nla_get_u32(a[OVS_METER_ATTR_ID]);

 	/* Cannot fail after this. */
 	old_meter = lookup_meter(dp, meter_id);
 	detach_meter(old_meter);
 	attach_meter(dp, meter);
 	ovs_unlock();

 	/* Build response with the meter_id and stats from
 	 * the old meter, if any.
 	 */
 	failed = nla_put_u32(reply, OVS_METER_ATTR_ID, meter_id);
 	WARN_ON(failed);
 	if (old_meter) {
 		spin_lock_bh(&old_meter->lock);
 		if (old_meter->keep_stats) {
 			err = ovs_meter_cmd_reply_stats(reply, meter_id,
 							old_meter);
 			WARN_ON(err);
 		}
 		spin_unlock_bh(&old_meter->lock);
 		ovs_meter_free(old_meter);
 	}

 	genlmsg_end(reply, ovs_reply_header);
 	return genlmsg_reply(reply, info);

 exit_unlock:
 	ovs_unlock();
 	nlmsg_free(reply);
 exit_free_meter:
 	kfree(meter);
 	return err;
 }

 static int ovs_meter_cmd_get(struct sk_buff *skb, struct genl_info *info)
 {
 	struct nlattr **a = info->attrs;
 	u32 meter_id;
 	struct ovs_header *ovs_header = info->userhdr;
 	struct ovs_header *ovs_reply_header;
 	struct datapath *dp;
 	int err;
 	struct sk_buff *reply;
 	struct dp_meter *meter;

 	if (!a[OVS_METER_ATTR_ID])
 		return -EINVAL;

 	meter_id = nla_get_u32(a[OVS_METER_ATTR_ID]);

 	reply = ovs_meter_cmd_reply_start(info, OVS_METER_CMD_GET,
 					  &ovs_reply_header);
 	if (IS_ERR(reply))
 		return PTR_ERR(reply);

 	ovs_lock();

 	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
 	if (!dp) {
 		err = -ENODEV;
 		goto exit_unlock;
 	}

 	/* Locate meter, copy stats. */
 	meter = lookup_meter(dp, meter_id);
 	if (!meter) {
 		err = -ENOENT;
 		goto exit_unlock;
 	}

 	spin_lock_bh(&meter->lock);
 	err = ovs_meter_cmd_reply_stats(reply, meter_id, meter);
 	spin_unlock_bh(&meter->lock);
 	if (err)
 		goto exit_unlock;

 	ovs_unlock();

 	genlmsg_end(reply, ovs_reply_header);
 	return genlmsg_reply(reply, info);

 exit_unlock:
 	ovs_unlock();
 	nlmsg_free(reply);
 	return err;
 }

 static int ovs_meter_cmd_del(struct sk_buff *skb, struct genl_info *info)
 {
 	struct nlattr **a = info->attrs;
 	u32 meter_id;
 	struct ovs_header *ovs_header = info->userhdr;
 	struct ovs_header *ovs_reply_header;
 	struct datapath *dp;
 	int err;
 	struct sk_buff *reply;
 	struct dp_meter *old_meter;

 	if (!a[OVS_METER_ATTR_ID])
 		return -EINVAL;
 	meter_id = nla_get_u32(a[OVS_METER_ATTR_ID]);

 	reply = ovs_meter_cmd_reply_start(info, OVS_METER_CMD_DEL,
 					  &ovs_reply_header);
 	if (IS_ERR(reply))
 		return PTR_ERR(reply);

 	ovs_lock();

 	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
 	if (!dp) {
 		err = -ENODEV;
 		goto exit_unlock;
 	}

 	old_meter = lookup_meter(dp, meter_id);
 	if (old_meter) {
 		spin_lock_bh(&old_meter->lock);
 		err = ovs_meter_cmd_reply_stats(reply, meter_id, old_meter);
 		WARN_ON(err);
 		spin_unlock_bh(&old_meter->lock);
 		detach_meter(old_meter);
 	}
 	ovs_unlock();
 	ovs_meter_free(old_meter);
 	genlmsg_end(reply, ovs_reply_header);
 	return genlmsg_reply(reply, info);

 exit_unlock:
 	ovs_unlock();
 	nlmsg_free(reply);
 	return err;
 }

 /* Meter action execution.
  *
  * Return true 'meter_id' drop band is triggered. The 'skb' should be
  * dropped by the caller'.
  */
 bool ovs_meter_execute(struct datapath *dp, struct sk_buff *skb,
 		       struct sw_flow_key *key, u32 meter_id)
 {
 	struct dp_meter *meter;
 	struct dp_meter_band *band;
 	long long int now_ms = div_u64(ktime_get_ns(), 1000 * 1000);
 	long long int long_delta_ms;
 	u32 delta_ms;
 	u32 cost;
 	int i, band_exceeded_max = -1;
 	u32 band_exceeded_rate = 0;

 	meter = lookup_meter(dp, meter_id);
 	/* Do not drop the packet when there is no meter. */
 	if (!meter)
 		return false;

 	/* Lock the meter while using it. */
 	spin_lock(&meter->lock);

 	long_delta_ms = (now_ms - meter->used); /* ms */

 	/* Make sure delta_ms will not be too large, so that bucket will not
 	 * wrap around below.
 	 */
 	delta_ms = (long_delta_ms > (long long int)meter->max_delta_t)
 		   ? meter->max_delta_t : (u32)long_delta_ms;

 	/* Update meter statistics.
 	 */
 	meter->used = now_ms;
 	meter->stats.n_packets += 1;
 	meter->stats.n_bytes += skb->len;

 	/* Bucket rate is either in kilobits per second, or in packets per
 	 * second.  We maintain the bucket in the units of either bits or
 	 * 1/1000th of a packet, correspondingly.
 	 * Then, when rate is multiplied with milliseconds, we get the
 	 * bucket units:
 	 * msec * kbps = bits, and
 	 * msec * packets/sec = 1/1000 packets.
 	 *
 	 * 'cost' is the number of bucket units in this packet.
 	 */
 	cost = (meter->kbps) ? skb->len * 8 : 1000;

 	/* Update all bands and find the one hit with the highest rate. */
 	for (i = 0; i < meter->n_bands; ++i) {
 		long long int max_bucket_size;

 		band = &meter->bands[i];
 		max_bucket_size = (band->burst_size + band->rate) * 1000;

 		band->bucket += delta_ms * band->rate;
 		if (band->bucket > max_bucket_size)
 			band->bucket = max_bucket_size;

 		if (band->bucket >= cost) {
 			band->bucket -= cost;
 		} else if (band->rate > band_exceeded_rate) {
 			band_exceeded_rate = band->rate;
 			band_exceeded_max = i;
 		}
 	}

 	if (band_exceeded_max >= 0) {
 		/* Update band statistics. */
 		band = &meter->bands[band_exceeded_max];
 		band->stats.n_packets += 1;
 		band->stats.n_bytes += skb->len;

 		/* Drop band triggered, let the caller drop the 'skb'.  */
 		if (band->type == OVS_METER_BAND_TYPE_DROP) {
 			spin_unlock(&meter->lock);
 			return true;
 		}
 	}

 	spin_unlock(&meter->lock);
 	return false;
 }

 static struct genl_ops dp_meter_genl_ops[] = {
 	{ .cmd = OVS_METER_CMD_FEATURES,
 		.flags = 0,		  /* OK for unprivileged users. */
 		.policy = meter_policy,
 		.doit = ovs_meter_cmd_features
 	},
 	{ .cmd = OVS_METER_CMD_SET,
 		.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN
 					   *  privilege.
 					   */
 		.policy = meter_policy,
 		.doit = ovs_meter_cmd_set,
 	},
 	{ .cmd = OVS_METER_CMD_GET,
 		.flags = 0,		  /* OK for unprivileged users. */
 		.policy = meter_policy,
 		.doit = ovs_meter_cmd_get,
 	},
 	{ .cmd = OVS_METER_CMD_DEL,
 		.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN
 					   *  privilege.
 					   */
 		.policy = meter_policy,
 		.doit = ovs_meter_cmd_del
 	},
 };

 static const struct genl_multicast_group ovs_meter_multicast_group = {
 	.name = OVS_METER_MCGROUP,
 };

 struct genl_family dp_meter_genl_family __ro_after_init = {
 	.hdrsize = sizeof(struct ovs_header),
 	.name = OVS_METER_FAMILY,
 	.version = OVS_METER_VERSION,
 	.maxattr = OVS_METER_ATTR_MAX,
 	.netnsok = true,
 	.parallel_ops = true,
 	.ops = dp_meter_genl_ops,
 	.n_ops = ARRAY_SIZE(dp_meter_genl_ops),
 	.mcgrps = &ovs_meter_multicast_group,
 	.n_mcgrps = 1,
 	.module = THIS_MODULE,
 };

 int ovs_meters_init(struct datapath *dp)
 {
 	int i;

 	dp->meters = kmalloc_array(METER_HASH_BUCKETS,
 				   sizeof(struct hlist_head), GFP_KERNEL);

 	if (!dp->meters)
 		return -ENOMEM;

 	for (i = 0; i < METER_HASH_BUCKETS; i++)
 		INIT_HLIST_HEAD(&dp->meters[i]);

 	return 0;
 }

 void ovs_meters_exit(struct datapath *dp)
 {
 	int i;

 	for (i = 0; i < METER_HASH_BUCKETS; i++) {
 		struct hlist_head *head = &dp->meters[i];
 		struct dp_meter *meter;
 		struct hlist_node *n;

 		hlist_for_each_entry_safe(meter, n, head, dp_hash_node)
 			kfree(meter);
 	}

 	kfree(dp->meters);
 }
	/*
	* Copyright (c) 2017 Nicira, Inc.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of version 2 of the GNU General Public
	* License as published by the Free Software Foundation.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/if.h>
	#include <linux/skbuff.h>
	#include <linux/ip.h>
	#include <linux/kernel.h>
	#include <linux/openvswitch.h>
	#include <linux/netlink.h>
	#include <linux/rculist.h>

	#include <net/netlink.h>
	#include <net/genetlink.h>

	#include "datapath.h"
	#include "meter.h"

	#define METER_HASH_BUCKETS 1024

	static const struct nla_policy meter_policy[OVS_METER_ATTR_MAX + 1] = {
	[OVS_METER_ATTR_ID] = { .type = NLA_U32, },
	[OVS_METER_ATTR_KBPS] = { .type = NLA_FLAG },
	[OVS_METER_ATTR_STATS] = { .len = sizeof(struct ovs_flow_stats) },
	[OVS_METER_ATTR_BANDS] = { .type = NLA_NESTED },
	[OVS_METER_ATTR_USED] = { .type = NLA_U64 },
	[OVS_METER_ATTR_CLEAR] = { .type = NLA_FLAG },
	[OVS_METER_ATTR_MAX_METERS] = { .type = NLA_U32 },
	[OVS_METER_ATTR_MAX_BANDS] = { .type = NLA_U32 },
	};

	static const struct nla_policy band_policy[OVS_BAND_ATTR_MAX + 1] = {
	[OVS_BAND_ATTR_TYPE] = { .type = NLA_U32, },
	[OVS_BAND_ATTR_RATE] = { .type = NLA_U32, },
	[OVS_BAND_ATTR_BURST] = { .type = NLA_U32, },
	[OVS_BAND_ATTR_STATS] = { .len = sizeof(struct ovs_flow_stats) },
	};

	static void ovs_meter_free(struct dp_meter *meter)
	{
	if (!meter)
	return;

	kfree_rcu(meter, rcu);
	}

	static struct hlist_head meter_hash_bucket(const struct datapath dp,
	u32 meter_id)
	{
	return &dp->meters[meter_id & (METER_HASH_BUCKETS - 1)];
	}

	/* Call with ovs_mutex or RCU read lock. */
	static struct dp_meter lookup_meter(const struct datapath dp,
	u32 meter_id)
	{
	struct dp_meter *meter;
	struct hlist_head *head;

	head = meter_hash_bucket(dp, meter_id);
	hlist_for_each_entry_rcu(meter, head, dp_hash_node) {
	if (meter->id == meter_id)
	return meter;
	}
	return NULL;
	}

	static void attach_meter(struct datapath dp, struct dp_meter meter)
	{
	struct hlist_head *head = meter_hash_bucket(dp, meter->id);

	hlist_add_head_rcu(&meter->dp_hash_node, head);
	}

	static void detach_meter(struct dp_meter *meter)
	{
	ASSERT_OVSL();
	if (meter)
	hlist_del_rcu(&meter->dp_hash_node);
	}

	static struct sk_buff *
	ovs_meter_cmd_reply_start(struct genl_info *info, u8 cmd,
	struct ovs_header **ovs_reply_header)
	{
	struct sk_buff *skb;
	struct ovs_header *ovs_header = info->userhdr;

	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
	if (!skb)
	return ERR_PTR(-ENOMEM);

	*ovs_reply_header = genlmsg_put(skb, info->snd_portid,
	info->snd_seq,
	&dp_meter_genl_family, 0, cmd);
	if (!*ovs_reply_header) {
	nlmsg_free(skb);
	return ERR_PTR(-EMSGSIZE);
	}
	(*ovs_reply_header)->dp_ifindex = ovs_header->dp_ifindex;

	return skb;
	}

	static int ovs_meter_cmd_reply_stats(struct sk_buff *reply, u32 meter_id,
	struct dp_meter *meter)
	{
	struct nlattr *nla;
	struct dp_meter_band *band;
	u16 i;

	if (nla_put_u32(reply, OVS_METER_ATTR_ID, meter_id))
	goto error;

	if (!meter)
	return 0;

	if (nla_put(reply, OVS_METER_ATTR_STATS,
	sizeof(struct ovs_flow_stats), &meter->stats) \|\|
	nla_put_u64_64bit(reply, OVS_METER_ATTR_USED, meter->used,
	OVS_METER_ATTR_PAD))
	goto error;

	nla = nla_nest_start(reply, OVS_METER_ATTR_BANDS);
	if (!nla)
	goto error;

	band = meter->bands;

	for (i = 0; i < meter->n_bands; ++i, ++band) {
	struct nlattr *band_nla;

	band_nla = nla_nest_start(reply, OVS_BAND_ATTR_UNSPEC);
	if (!band_nla \|\| nla_put(reply, OVS_BAND_ATTR_STATS,
	sizeof(struct ovs_flow_stats),
	&band->stats))
	goto error;
	nla_nest_end(reply, band_nla);
	}
	nla_nest_end(reply, nla);

	return 0;
	error:
	return -EMSGSIZE;
	}

	static int ovs_meter_cmd_features(struct sk_buff skb, struct genl_info info)
	{
	struct sk_buff *reply;
	struct ovs_header *ovs_reply_header;
	struct nlattr nla, band_nla;
	int err;

	reply = ovs_meter_cmd_reply_start(info, OVS_METER_CMD_FEATURES,
	&ovs_reply_header);
	if (IS_ERR(reply))
	return PTR_ERR(reply);

	if (nla_put_u32(reply, OVS_METER_ATTR_MAX_METERS, U32_MAX) \|\|
	nla_put_u32(reply, OVS_METER_ATTR_MAX_BANDS, DP_MAX_BANDS))
	goto nla_put_failure;

	nla = nla_nest_start(reply, OVS_METER_ATTR_BANDS);
	if (!nla)
	goto nla_put_failure;

	band_nla = nla_nest_start(reply, OVS_BAND_ATTR_UNSPEC);
	if (!band_nla)
	goto nla_put_failure;
	/* Currently only DROP band type is supported. */
	if (nla_put_u32(reply, OVS_BAND_ATTR_TYPE, OVS_METER_BAND_TYPE_DROP))
	goto nla_put_failure;
	nla_nest_end(reply, band_nla);
	nla_nest_end(reply, nla);

	genlmsg_end(reply, ovs_reply_header);
	return genlmsg_reply(reply, info);

	nla_put_failure:
	nlmsg_free(reply);
	err = -EMSGSIZE;
	return err;
	}

	static struct dp_meter dp_meter_create(struct nlattr *a)
	{
	struct nlattr *nla;
	int rem;
	u16 n_bands = 0;
	struct dp_meter *meter;
	struct dp_meter_band *band;
	int err;

	/* Validate attributes, count the bands. */
	if (!a[OVS_METER_ATTR_BANDS])
	return ERR_PTR(-EINVAL);

	nla_for_each_nested(nla, a[OVS_METER_ATTR_BANDS], rem)
	if (++n_bands > DP_MAX_BANDS)
	return ERR_PTR(-EINVAL);

	/* Allocate and set up the meter before locking anything. */
	meter = kzalloc(n_bands * sizeof(struct dp_meter_band) +
	sizeof(*meter), GFP_KERNEL);
	if (!meter)
	return ERR_PTR(-ENOMEM);

	meter->used = div_u64(ktime_get_ns(), 1000 * 1000);
	meter->kbps = a[OVS_METER_ATTR_KBPS] ? 1 : 0;
	meter->keep_stats = !a[OVS_METER_ATTR_CLEAR];
	spin_lock_init(&meter->lock);
	if (meter->keep_stats && a[OVS_METER_ATTR_STATS]) {
	meter->stats = (struct ovs_flow_stats )
	nla_data(a[OVS_METER_ATTR_STATS]);
	}
	meter->n_bands = n_bands;

	/* Set up meter bands. */
	band = meter->bands;
	nla_for_each_nested(nla, a[OVS_METER_ATTR_BANDS], rem) {
	struct nlattr *attr[OVS_BAND_ATTR_MAX + 1];
	u32 band_max_delta_t;

	err = nla_parse((struct nlattr **)&attr, OVS_BAND_ATTR_MAX,
	nla_data(nla), nla_len(nla), band_policy,
	NULL);
	if (err)
	goto exit_free_meter;

	if (!attr[OVS_BAND_ATTR_TYPE] \|\|
	!attr[OVS_BAND_ATTR_RATE] \|\|
	!attr[OVS_BAND_ATTR_BURST]) {
	err = -EINVAL;
	goto exit_free_meter;
	}

	band->type = nla_get_u32(attr[OVS_BAND_ATTR_TYPE]);
	band->rate = nla_get_u32(attr[OVS_BAND_ATTR_RATE]);
	band->burst_size = nla_get_u32(attr[OVS_BAND_ATTR_BURST]);
	/* Figure out max delta_t that is enough to fill any bucket.
	* Keep max_delta_t size to the bucket units:
	* pkts => 1/1000 packets, kilobits => bits.
	*/
	band_max_delta_t = (band->burst_size + band->rate) * 1000;
	/* Start with a full bucket. */
	band->bucket = band_max_delta_t;
	if (band_max_delta_t > meter->max_delta_t)
	meter->max_delta_t = band_max_delta_t;
	band++;
	}

	return meter;

	exit_free_meter:
	kfree(meter);
	return ERR_PTR(err);
	}

	static int ovs_meter_cmd_set(struct sk_buff skb, struct genl_info info)
	{
	struct nlattr **a = info->attrs;
	struct dp_meter meter, old_meter;
	struct sk_buff *reply;
	struct ovs_header *ovs_reply_header;
	struct ovs_header *ovs_header = info->userhdr;
	struct datapath *dp;
	int err;
	u32 meter_id;
	bool failed;

	meter = dp_meter_create(a);
	if (IS_ERR_OR_NULL(meter))
	return PTR_ERR(meter);

	reply = ovs_meter_cmd_reply_start(info, OVS_METER_CMD_SET,
	&ovs_reply_header);
	if (IS_ERR(reply)) {
	err = PTR_ERR(reply);
	goto exit_free_meter;
	}

	ovs_lock();
	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
	if (!dp) {
	err = -ENODEV;
	goto exit_unlock;
	}

	if (!a[OVS_METER_ATTR_ID]) {
	err = -ENODEV;
	goto exit_unlock;
	}

	meter_id = nla_get_u32(a[OVS_METER_ATTR_ID]);

	/* Cannot fail after this. */
	old_meter = lookup_meter(dp, meter_id);
	detach_meter(old_meter);
	attach_meter(dp, meter);
	ovs_unlock();

	/* Build response with the meter_id and stats from
	* the old meter, if any.
	*/
	failed = nla_put_u32(reply, OVS_METER_ATTR_ID, meter_id);
	WARN_ON(failed);
	if (old_meter) {
	spin_lock_bh(&old_meter->lock);
	if (old_meter->keep_stats) {
	err = ovs_meter_cmd_reply_stats(reply, meter_id,
	old_meter);
	WARN_ON(err);
	}
	spin_unlock_bh(&old_meter->lock);
	ovs_meter_free(old_meter);
	}

	genlmsg_end(reply, ovs_reply_header);
	return genlmsg_reply(reply, info);

	exit_unlock:
	ovs_unlock();
	nlmsg_free(reply);
	exit_free_meter:
	kfree(meter);
	return err;
	}

	static int ovs_meter_cmd_get(struct sk_buff skb, struct genl_info info)
	{
	struct nlattr **a = info->attrs;
	u32 meter_id;
	struct ovs_header *ovs_header = info->userhdr;
	struct ovs_header *ovs_reply_header;
	struct datapath *dp;
	int err;
	struct sk_buff *reply;
	struct dp_meter *meter;

	if (!a[OVS_METER_ATTR_ID])
	return -EINVAL;

	meter_id = nla_get_u32(a[OVS_METER_ATTR_ID]);

	reply = ovs_meter_cmd_reply_start(info, OVS_METER_CMD_GET,
	&ovs_reply_header);
	if (IS_ERR(reply))
	return PTR_ERR(reply);

	ovs_lock();

	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
	if (!dp) {
	err = -ENODEV;
	goto exit_unlock;
	}

	/* Locate meter, copy stats. */
	meter = lookup_meter(dp, meter_id);
	if (!meter) {
	err = -ENOENT;
	goto exit_unlock;
	}

	spin_lock_bh(&meter->lock);
	err = ovs_meter_cmd_reply_stats(reply, meter_id, meter);
	spin_unlock_bh(&meter->lock);
	if (err)
	goto exit_unlock;

	ovs_unlock();

	genlmsg_end(reply, ovs_reply_header);
	return genlmsg_reply(reply, info);

	exit_unlock:
	ovs_unlock();
	nlmsg_free(reply);
	return err;
	}

	static int ovs_meter_cmd_del(struct sk_buff skb, struct genl_info info)
	{
	struct nlattr **a = info->attrs;
	u32 meter_id;
	struct ovs_header *ovs_header = info->userhdr;
	struct ovs_header *ovs_reply_header;
	struct datapath *dp;
	int err;
	struct sk_buff *reply;
	struct dp_meter *old_meter;

	if (!a[OVS_METER_ATTR_ID])
	return -EINVAL;
	meter_id = nla_get_u32(a[OVS_METER_ATTR_ID]);

	reply = ovs_meter_cmd_reply_start(info, OVS_METER_CMD_DEL,
	&ovs_reply_header);
	if (IS_ERR(reply))
	return PTR_ERR(reply);

	ovs_lock();

	dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
	if (!dp) {
	err = -ENODEV;
	goto exit_unlock;
	}

	old_meter = lookup_meter(dp, meter_id);
	if (old_meter) {
	spin_lock_bh(&old_meter->lock);
	err = ovs_meter_cmd_reply_stats(reply, meter_id, old_meter);
	WARN_ON(err);
	spin_unlock_bh(&old_meter->lock);
	detach_meter(old_meter);
	}
	ovs_unlock();
	ovs_meter_free(old_meter);
	genlmsg_end(reply, ovs_reply_header);
	return genlmsg_reply(reply, info);

	exit_unlock:
	ovs_unlock();
	nlmsg_free(reply);
	return err;
	}

	/* Meter action execution.
	*
	* Return true 'meter_id' drop band is triggered. The 'skb' should be
	* dropped by the caller'.
	*/
	bool ovs_meter_execute(struct datapath dp, struct sk_buff skb,
	struct sw_flow_key *key, u32 meter_id)
	{
	struct dp_meter *meter;
	struct dp_meter_band *band;
	long long int now_ms = div_u64(ktime_get_ns(), 1000 * 1000);
	long long int long_delta_ms;
	u32 delta_ms;
	u32 cost;
	int i, band_exceeded_max = -1;
	u32 band_exceeded_rate = 0;

	meter = lookup_meter(dp, meter_id);
	/* Do not drop the packet when there is no meter. */
	if (!meter)
	return false;

	/* Lock the meter while using it. */
	spin_lock(&meter->lock);

	long_delta_ms = (now_ms - meter->used); /* ms */

	/* Make sure delta_ms will not be too large, so that bucket will not
	* wrap around below.
	*/
	delta_ms = (long_delta_ms > (long long int)meter->max_delta_t)
	? meter->max_delta_t : (u32)long_delta_ms;

	/* Update meter statistics.
	*/
	meter->used = now_ms;
	meter->stats.n_packets += 1;
	meter->stats.n_bytes += skb->len;

	/* Bucket rate is either in kilobits per second, or in packets per
	* second. We maintain the bucket in the units of either bits or
	* 1/1000th of a packet, correspondingly.
	* Then, when rate is multiplied with milliseconds, we get the
	* bucket units:
	* msec * kbps = bits, and
	* msec * packets/sec = 1/1000 packets.
	*
	* 'cost' is the number of bucket units in this packet.
	*/
	cost = (meter->kbps) ? skb->len * 8 : 1000;

	/* Update all bands and find the one hit with the highest rate. */
	for (i = 0; i < meter->n_bands; ++i) {
	long long int max_bucket_size;

	band = &meter->bands[i];
	max_bucket_size = (band->burst_size + band->rate) * 1000;

	band->bucket += delta_ms * band->rate;
	if (band->bucket > max_bucket_size)
	band->bucket = max_bucket_size;

	if (band->bucket >= cost) {
	band->bucket -= cost;
	} else if (band->rate > band_exceeded_rate) {
	band_exceeded_rate = band->rate;
	band_exceeded_max = i;
	}
	}

	if (band_exceeded_max >= 0) {
	/* Update band statistics. */
	band = &meter->bands[band_exceeded_max];
	band->stats.n_packets += 1;
	band->stats.n_bytes += skb->len;

	/* Drop band triggered, let the caller drop the 'skb'. */
	if (band->type == OVS_METER_BAND_TYPE_DROP) {
	spin_unlock(&meter->lock);
	return true;
	}
	}

	spin_unlock(&meter->lock);
	return false;
	}

	static struct genl_ops dp_meter_genl_ops[] = {
	{ .cmd = OVS_METER_CMD_FEATURES,
	.flags = 0, /* OK for unprivileged users. */
	.policy = meter_policy,
	.doit = ovs_meter_cmd_features
	},
	{ .cmd = OVS_METER_CMD_SET,
	.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN
	* privilege.
	*/
	.policy = meter_policy,
	.doit = ovs_meter_cmd_set,
	},
	{ .cmd = OVS_METER_CMD_GET,
	.flags = 0, /* OK for unprivileged users. */
	.policy = meter_policy,
	.doit = ovs_meter_cmd_get,
	},
	{ .cmd = OVS_METER_CMD_DEL,
	.flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN
	* privilege.
	*/
	.policy = meter_policy,
	.doit = ovs_meter_cmd_del
	},
	};

	static const struct genl_multicast_group ovs_meter_multicast_group = {
	.name = OVS_METER_MCGROUP,
	};

	struct genl_family dp_meter_genl_family __ro_after_init = {
	.hdrsize = sizeof(struct ovs_header),
	.name = OVS_METER_FAMILY,
	.version = OVS_METER_VERSION,
	.maxattr = OVS_METER_ATTR_MAX,
	.netnsok = true,
	.parallel_ops = true,
	.ops = dp_meter_genl_ops,
	.n_ops = ARRAY_SIZE(dp_meter_genl_ops),
	.mcgrps = &ovs_meter_multicast_group,
	.n_mcgrps = 1,
	.module = THIS_MODULE,
	};

	int ovs_meters_init(struct datapath *dp)
	{
	int i;

	dp->meters = kmalloc_array(METER_HASH_BUCKETS,
	sizeof(struct hlist_head), GFP_KERNEL);

	if (!dp->meters)
	return -ENOMEM;

	for (i = 0; i < METER_HASH_BUCKETS; i++)
	INIT_HLIST_HEAD(&dp->meters[i]);

	return 0;
	}

	void ovs_meters_exit(struct datapath *dp)
	{
	int i;

	for (i = 0; i < METER_HASH_BUCKETS; i++) {
	struct hlist_head *head = &dp->meters[i];
	struct dp_meter *meter;
	struct hlist_node *n;

	hlist_for_each_entry_safe(meter, n, head, dp_hash_node)
	kfree(meter);
	}

	kfree(dp->meters);
	}