Initial import

1 files changed, 778 insertions, 0 deletions

diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
new file mode 100644
index 000000000..4613df8c8
--- /dev/null
+++ b/net/openvswitch/flow_table.c
@@ -0,0 +1,778 @@
+/*
+ * Copyright (c) 2007-2014 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.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA
+ */
+
+#include "flow.h"
+#include "datapath.h"
+#include <linux/uaccess.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/if_ether.h>
+#include <linux/if_vlan.h>
+#include <net/llc_pdu.h>
+#include <linux/kernel.h>
+#include <linux/jhash.h>
+#include <linux/jiffies.h>
+#include <linux/llc.h>
+#include <linux/module.h>
+#include <linux/in.h>
+#include <linux/rcupdate.h>
+#include <linux/if_arp.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/sctp.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/icmp.h>
+#include <linux/icmpv6.h>
+#include <linux/rculist.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <net/ndisc.h>
+
+#define TBL_MIN_BUCKETS		1024
+#define REHASH_INTERVAL		(10 * 60 * HZ)
+
+static struct kmem_cache *flow_cache;
+struct kmem_cache *flow_stats_cache __read_mostly;
+
+static u16 range_n_bytes(const struct sw_flow_key_range *range)
+{
+	return range->end - range->start;
+}
+
+void ovs_flow_mask_key(struct sw_flow_key *dst, const struct sw_flow_key *src,
+		       const struct sw_flow_mask *mask)
+{
+	const long *m = (const long *)((const u8 *)&mask->key +
+				mask->range.start);
+	const long *s = (const long *)((const u8 *)src +
+				mask->range.start);
+	long *d = (long *)((u8 *)dst + mask->range.start);
+	int i;
+
+	/* The memory outside of the 'mask->range' are not set since
+	 * further operations on 'dst' only uses contents within
+	 * 'mask->range'.
+	 */
+	for (i = 0; i < range_n_bytes(&mask->range); i += sizeof(long))
+		*d++ = *s++ & *m++;
+}
+
+struct sw_flow *ovs_flow_alloc(void)
+{
+	struct sw_flow *flow;
+	struct flow_stats *stats;
+	int node;
+
+	flow = kmem_cache_alloc(flow_cache, GFP_KERNEL);
+	if (!flow)
+		return ERR_PTR(-ENOMEM);
+
+	flow->sf_acts = NULL;
+	flow->mask = NULL;
+	flow->id.unmasked_key = NULL;
+	flow->id.ufid_len = 0;
+	flow->stats_last_writer = NUMA_NO_NODE;
+
+	/* Initialize the default stat node. */
+	stats = kmem_cache_alloc_node(flow_stats_cache,
+				      GFP_KERNEL | __GFP_ZERO, 0);
+	if (!stats)
+		goto err;
+
+	spin_lock_init(&stats->lock);
+
+	RCU_INIT_POINTER(flow->stats[0], stats);
+
+	for_each_node(node)
+		if (node != 0)
+			RCU_INIT_POINTER(flow->stats[node], NULL);
+
+	return flow;
+err:
+	kmem_cache_free(flow_cache, flow);
+	return ERR_PTR(-ENOMEM);
+}
+
+int ovs_flow_tbl_count(const struct flow_table *table)
+{
+	return table->count;
+}
+
+static struct flex_array *alloc_buckets(unsigned int n_buckets)
+{
+	struct flex_array *buckets;
+	int i, err;
+
+	buckets = flex_array_alloc(sizeof(struct hlist_head),
+				   n_buckets, GFP_KERNEL);
+	if (!buckets)
+		return NULL;
+
+	err = flex_array_prealloc(buckets, 0, n_buckets, GFP_KERNEL);
+	if (err) {
+		flex_array_free(buckets);
+		return NULL;
+	}
+
+	for (i = 0; i < n_buckets; i++)
+		INIT_HLIST_HEAD((struct hlist_head *)
+					flex_array_get(buckets, i));
+
+	return buckets;
+}
+
+static void flow_free(struct sw_flow *flow)
+{
+	int node;
+
+	if (ovs_identifier_is_key(&flow->id))
+		kfree(flow->id.unmasked_key);
+	kfree((struct sw_flow_actions __force *)flow->sf_acts);
+	for_each_node(node)
+		if (flow->stats[node])
+			kmem_cache_free(flow_stats_cache,
+					(struct flow_stats __force *)flow->stats[node]);
+	kmem_cache_free(flow_cache, flow);
+}
+
+static void rcu_free_flow_callback(struct rcu_head *rcu)
+{
+	struct sw_flow *flow = container_of(rcu, struct sw_flow, rcu);
+
+	flow_free(flow);
+}
+
+void ovs_flow_free(struct sw_flow *flow, bool deferred)
+{
+	if (!flow)
+		return;
+
+	if (deferred)
+		call_rcu(&flow->rcu, rcu_free_flow_callback);
+	else
+		flow_free(flow);
+}
+
+static void free_buckets(struct flex_array *buckets)
+{
+	flex_array_free(buckets);
+}
+
+
+static void __table_instance_destroy(struct table_instance *ti)
+{
+	free_buckets(ti->buckets);
+	kfree(ti);
+}
+
+static struct table_instance *table_instance_alloc(int new_size)
+{
+	struct table_instance *ti = kmalloc(sizeof(*ti), GFP_KERNEL);
+
+	if (!ti)
+		return NULL;
+
+	ti->buckets = alloc_buckets(new_size);
+
+	if (!ti->buckets) {
+		kfree(ti);
+		return NULL;
+	}
+	ti->n_buckets = new_size;
+	ti->node_ver = 0;
+	ti->keep_flows = false;
+	get_random_bytes(&ti->hash_seed, sizeof(u32));
+
+	return ti;
+}
+
+int ovs_flow_tbl_init(struct flow_table *table)
+{
+	struct table_instance *ti, *ufid_ti;
+
+	ti = table_instance_alloc(TBL_MIN_BUCKETS);
+
+	if (!ti)
+		return -ENOMEM;
+
+	ufid_ti = table_instance_alloc(TBL_MIN_BUCKETS);
+	if (!ufid_ti)
+		goto free_ti;
+
+	rcu_assign_pointer(table->ti, ti);
+	rcu_assign_pointer(table->ufid_ti, ufid_ti);
+	INIT_LIST_HEAD(&table->mask_list);
+	table->last_rehash = jiffies;
+	table->count = 0;
+	table->ufid_count = 0;
+	return 0;
+
+free_ti:
+	__table_instance_destroy(ti);
+	return -ENOMEM;
+}
+
+static void flow_tbl_destroy_rcu_cb(struct rcu_head *rcu)
+{
+	struct table_instance *ti = container_of(rcu, struct table_instance, rcu);
+
+	__table_instance_destroy(ti);
+}
+
+static void table_instance_destroy(struct table_instance *ti,
+				   struct table_instance *ufid_ti,
+				   bool deferred)
+{
+	int i;
+
+	if (!ti)
+		return;
+
+	BUG_ON(!ufid_ti);
+	if (ti->keep_flows)
+		goto skip_flows;
+
+	for (i = 0; i < ti->n_buckets; i++) {
+		struct sw_flow *flow;
+		struct hlist_head *head = flex_array_get(ti->buckets, i);
+		struct hlist_node *n;
+		int ver = ti->node_ver;
+		int ufid_ver = ufid_ti->node_ver;
+
+		hlist_for_each_entry_safe(flow, n, head, flow_table.node[ver]) {
+			hlist_del_rcu(&flow->flow_table.node[ver]);
+			if (ovs_identifier_is_ufid(&flow->id))
+				hlist_del_rcu(&flow->ufid_table.node[ufid_ver]);
+			ovs_flow_free(flow, deferred);
+		}
+	}
+
+skip_flows:
+	if (deferred) {
+		call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
+		call_rcu(&ufid_ti->rcu, flow_tbl_destroy_rcu_cb);
+	} else {
+		__table_instance_destroy(ti);
+		__table_instance_destroy(ufid_ti);
+	}
+}
+
+/* No need for locking this function is called from RCU callback or
+ * error path.
+ */
+void ovs_flow_tbl_destroy(struct flow_table *table)
+{
+	struct table_instance *ti = rcu_dereference_raw(table->ti);
+	struct table_instance *ufid_ti = rcu_dereference_raw(table->ufid_ti);
+
+	table_instance_destroy(ti, ufid_ti, false);
+}
+
+struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *ti,
+				       u32 *bucket, u32 *last)
+{
+	struct sw_flow *flow;
+	struct hlist_head *head;
+	int ver;
+	int i;
+
+	ver = ti->node_ver;
+	while (*bucket < ti->n_buckets) {
+		i = 0;
+		head = flex_array_get(ti->buckets, *bucket);
+		hlist_for_each_entry_rcu(flow, head, flow_table.node[ver]) {
+			if (i < *last) {
+				i++;
+				continue;
+			}
+			*last = i + 1;
+			return flow;
+		}
+		(*bucket)++;
+		*last = 0;
+	}
+
+	return NULL;
+}
+
+static struct hlist_head *find_bucket(struct table_instance *ti, u32 hash)
+{
+	hash = jhash_1word(hash, ti->hash_seed);
+	return flex_array_get(ti->buckets,
+				(hash & (ti->n_buckets - 1)));
+}
+
+static void table_instance_insert(struct table_instance *ti,
+				  struct sw_flow *flow)
+{
+	struct hlist_head *head;
+
+	head = find_bucket(ti, flow->flow_table.hash);
+	hlist_add_head_rcu(&flow->flow_table.node[ti->node_ver], head);
+}
+
+static void ufid_table_instance_insert(struct table_instance *ti,
+				       struct sw_flow *flow)
+{
+	struct hlist_head *head;
+
+	head = find_bucket(ti, flow->ufid_table.hash);
+	hlist_add_head_rcu(&flow->ufid_table.node[ti->node_ver], head);
+}
+
+static void flow_table_copy_flows(struct table_instance *old,
+				  struct table_instance *new, bool ufid)
+{
+	int old_ver;
+	int i;
+
+	old_ver = old->node_ver;
+	new->node_ver = !old_ver;
+
+	/* Insert in new table. */
+	for (i = 0; i < old->n_buckets; i++) {
+		struct sw_flow *flow;
+		struct hlist_head *head;
+
+		head = flex_array_get(old->buckets, i);
+
+		if (ufid)
+			hlist_for_each_entry(flow, head,
+					     ufid_table.node[old_ver])
+				ufid_table_instance_insert(new, flow);
+		else
+			hlist_for_each_entry(flow, head,
+					     flow_table.node[old_ver])
+				table_instance_insert(new, flow);
+	}
+
+	old->keep_flows = true;
+}
+
+static struct table_instance *table_instance_rehash(struct table_instance *ti,
+						    int n_buckets, bool ufid)
+{
+	struct table_instance *new_ti;
+
+	new_ti = table_instance_alloc(n_buckets);
+	if (!new_ti)
+		return NULL;
+
+	flow_table_copy_flows(ti, new_ti, ufid);
+
+	return new_ti;
+}
+
+int ovs_flow_tbl_flush(struct flow_table *flow_table)
+{
+	struct table_instance *old_ti, *new_ti;
+	struct table_instance *old_ufid_ti, *new_ufid_ti;
+
+	new_ti = table_instance_alloc(TBL_MIN_BUCKETS);
+	if (!new_ti)
+		return -ENOMEM;
+	new_ufid_ti = table_instance_alloc(TBL_MIN_BUCKETS);
+	if (!new_ufid_ti)
+		goto err_free_ti;
+
+	old_ti = ovsl_dereference(flow_table->ti);
+	old_ufid_ti = ovsl_dereference(flow_table->ufid_ti);
+
+	rcu_assign_pointer(flow_table->ti, new_ti);
+	rcu_assign_pointer(flow_table->ufid_ti, new_ufid_ti);
+	flow_table->last_rehash = jiffies;
+	flow_table->count = 0;
+	flow_table->ufid_count = 0;
+
+	table_instance_destroy(old_ti, old_ufid_ti, true);
+	return 0;
+
+err_free_ti:
+	__table_instance_destroy(new_ti);
+	return -ENOMEM;
+}
+
+static u32 flow_hash(const struct sw_flow_key *key,
+		     const struct sw_flow_key_range *range)
+{
+	int key_start = range->start;
+	int key_end = range->end;
+	const u32 *hash_key = (const u32 *)((const u8 *)key + key_start);
+	int hash_u32s = (key_end - key_start) >> 2;
+
+	/* Make sure number of hash bytes are multiple of u32. */
+	BUILD_BUG_ON(sizeof(long) % sizeof(u32));
+
+	return jhash2(hash_key, hash_u32s, 0);
+}
+
+static int flow_key_start(const struct sw_flow_key *key)
+{
+	if (key->tun_key.ipv4_dst)
+		return 0;
+	else
+		return rounddown(offsetof(struct sw_flow_key, phy),
+					  sizeof(long));
+}
+
+static bool cmp_key(const struct sw_flow_key *key1,
+		    const struct sw_flow_key *key2,
+		    int key_start, int key_end)
+{
+	const long *cp1 = (const long *)((const u8 *)key1 + key_start);
+	const long *cp2 = (const long *)((const u8 *)key2 + key_start);
+	long diffs = 0;
+	int i;
+
+	for (i = key_start; i < key_end;  i += sizeof(long))
+		diffs |= *cp1++ ^ *cp2++;
+
+	return diffs == 0;
+}
+
+static bool flow_cmp_masked_key(const struct sw_flow *flow,
+				const struct sw_flow_key *key,
+				const struct sw_flow_key_range *range)
+{
+	return cmp_key(&flow->key, key, range->start, range->end);
+}
+
+static bool ovs_flow_cmp_unmasked_key(const struct sw_flow *flow,
+				      const struct sw_flow_match *match)
+{
+	struct sw_flow_key *key = match->key;
+	int key_start = flow_key_start(key);
+	int key_end = match->range.end;
+
+	BUG_ON(ovs_identifier_is_ufid(&flow->id));
+	return cmp_key(flow->id.unmasked_key, key, key_start, key_end);
+}
+
+static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
+					  const struct sw_flow_key *unmasked,
+					  const struct sw_flow_mask *mask)
+{
+	struct sw_flow *flow;
+	struct hlist_head *head;
+	u32 hash;
+	struct sw_flow_key masked_key;
+
+	ovs_flow_mask_key(&masked_key, unmasked, mask);
+	hash = flow_hash(&masked_key, &mask->range);
+	head = find_bucket(ti, hash);
+	hlist_for_each_entry_rcu(flow, head, flow_table.node[ti->node_ver]) {
+		if (flow->mask == mask && flow->flow_table.hash == hash &&
+		    flow_cmp_masked_key(flow, &masked_key, &mask->range))
+			return flow;
+	}
+	return NULL;
+}
+
+struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
+				    const struct sw_flow_key *key,
+				    u32 *n_mask_hit)
+{
+	struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
+	struct sw_flow_mask *mask;
+	struct sw_flow *flow;
+
+	*n_mask_hit = 0;
+	list_for_each_entry_rcu(mask, &tbl->mask_list, list) {
+		(*n_mask_hit)++;
+		flow = masked_flow_lookup(ti, key, mask);
+		if (flow)  /* Found */
+			return flow;
+	}
+	return NULL;
+}
+
+struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *tbl,
+				    const struct sw_flow_key *key)
+{
+	u32 __always_unused n_mask_hit;
+
+	return ovs_flow_tbl_lookup_stats(tbl, key, &n_mask_hit);
+}
+
+struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,
+					  const struct sw_flow_match *match)
+{
+	struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
+	struct sw_flow_mask *mask;
+	struct sw_flow *flow;
+
+	/* Always called under ovs-mutex. */
+	list_for_each_entry(mask, &tbl->mask_list, list) {
+		flow = masked_flow_lookup(ti, match->key, mask);
+		if (flow && ovs_identifier_is_key(&flow->id) &&
+		    ovs_flow_cmp_unmasked_key(flow, match))
+			return flow;
+	}
+	return NULL;
+}
+
+static u32 ufid_hash(const struct sw_flow_id *sfid)
+{
+	return jhash(sfid->ufid, sfid->ufid_len, 0);
+}
+
+static bool ovs_flow_cmp_ufid(const struct sw_flow *flow,
+			      const struct sw_flow_id *sfid)
+{
+	if (flow->id.ufid_len != sfid->ufid_len)
+		return false;
+
+	return !memcmp(flow->id.ufid, sfid->ufid, sfid->ufid_len);
+}
+
+bool ovs_flow_cmp(const struct sw_flow *flow, const struct sw_flow_match *match)
+{
+	if (ovs_identifier_is_ufid(&flow->id))
+		return flow_cmp_masked_key(flow, match->key, &match->range);
+
+	return ovs_flow_cmp_unmasked_key(flow, match);
+}
+
+struct sw_flow *ovs_flow_tbl_lookup_ufid(struct flow_table *tbl,
+					 const struct sw_flow_id *ufid)
+{
+	struct table_instance *ti = rcu_dereference_ovsl(tbl->ufid_ti);
+	struct sw_flow *flow;
+	struct hlist_head *head;
+	u32 hash;
+
+	hash = ufid_hash(ufid);
+	head = find_bucket(ti, hash);
+	hlist_for_each_entry_rcu(flow, head, ufid_table.node[ti->node_ver]) {
+		if (flow->ufid_table.hash == hash &&
+		    ovs_flow_cmp_ufid(flow, ufid))
+			return flow;
+	}
+	return NULL;
+}
+
+int ovs_flow_tbl_num_masks(const struct flow_table *table)
+{
+	struct sw_flow_mask *mask;
+	int num = 0;
+
+	list_for_each_entry(mask, &table->mask_list, list)
+		num++;
+
+	return num;
+}
+
+static struct table_instance *table_instance_expand(struct table_instance *ti,
+						    bool ufid)
+{
+	return table_instance_rehash(ti, ti->n_buckets * 2, ufid);
+}
+
+/* Remove 'mask' from the mask list, if it is not needed any more. */
+static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
+{
+	if (mask) {
+		/* ovs-lock is required to protect mask-refcount and
+		 * mask list.
+		 */
+		ASSERT_OVSL();
+		BUG_ON(!mask->ref_count);
+		mask->ref_count--;
+
+		if (!mask->ref_count) {
+			list_del_rcu(&mask->list);
+			kfree_rcu(mask, rcu);
+		}
+	}
+}
+
+/* Must be called with OVS mutex held. */
+void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow)
+{
+	struct table_instance *ti = ovsl_dereference(table->ti);
+	struct table_instance *ufid_ti = ovsl_dereference(table->ufid_ti);
+
+	BUG_ON(table->count == 0);
+	hlist_del_rcu(&flow->flow_table.node[ti->node_ver]);
+	table->count--;
+	if (ovs_identifier_is_ufid(&flow->id)) {
+		hlist_del_rcu(&flow->ufid_table.node[ufid_ti->node_ver]);
+		table->ufid_count--;
+	}
+
+	/* RCU delete the mask. 'flow->mask' is not NULLed, as it should be
+	 * accessible as long as the RCU read lock is held.
+	 */
+	flow_mask_remove(table, flow->mask);
+}
+
+static struct sw_flow_mask *mask_alloc(void)
+{
+	struct sw_flow_mask *mask;
+
+	mask = kmalloc(sizeof(*mask), GFP_KERNEL);
+	if (mask)
+		mask->ref_count = 1;
+
+	return mask;
+}
+
+static bool mask_equal(const struct sw_flow_mask *a,
+		       const struct sw_flow_mask *b)
+{
+	const u8 *a_ = (const u8 *)&a->key + a->range.start;
+	const u8 *b_ = (const u8 *)&b->key + b->range.start;
+
+	return  (a->range.end == b->range.end)
+		&& (a->range.start == b->range.start)
+		&& (memcmp(a_, b_, range_n_bytes(&a->range)) == 0);
+}
+
+static struct sw_flow_mask *flow_mask_find(const struct flow_table *tbl,
+					   const struct sw_flow_mask *mask)
+{
+	struct list_head *ml;
+
+	list_for_each(ml, &tbl->mask_list) {
+		struct sw_flow_mask *m;
+		m = container_of(ml, struct sw_flow_mask, list);
+		if (mask_equal(mask, m))
+			return m;
+	}
+
+	return NULL;
+}
+
+/* Add 'mask' into the mask list, if it is not already there. */
+static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow,
+			    const struct sw_flow_mask *new)
+{
+	struct sw_flow_mask *mask;
+	mask = flow_mask_find(tbl, new);
+	if (!mask) {
+		/* Allocate a new mask if none exsits. */
+		mask = mask_alloc();
+		if (!mask)
+			return -ENOMEM;
+		mask->key = new->key;
+		mask->range = new->range;
+		list_add_rcu(&mask->list, &tbl->mask_list);
+	} else {
+		BUG_ON(!mask->ref_count);
+		mask->ref_count++;
+	}
+
+	flow->mask = mask;
+	return 0;
+}
+
+/* Must be called with OVS mutex held. */
+static void flow_key_insert(struct flow_table *table, struct sw_flow *flow)
+{
+	struct table_instance *new_ti = NULL;
+	struct table_instance *ti;
+
+	flow->flow_table.hash = flow_hash(&flow->key, &flow->mask->range);
+	ti = ovsl_dereference(table->ti);
+	table_instance_insert(ti, flow);
+	table->count++;
+
+	/* Expand table, if necessary, to make room. */
+	if (table->count > ti->n_buckets)
+		new_ti = table_instance_expand(ti, false);
+	else if (time_after(jiffies, table->last_rehash + REHASH_INTERVAL))
+		new_ti = table_instance_rehash(ti, ti->n_buckets, false);
+
+	if (new_ti) {
+		rcu_assign_pointer(table->ti, new_ti);
+		call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
+		table->last_rehash = jiffies;
+	}
+}
+
+/* Must be called with OVS mutex held. */
+static void flow_ufid_insert(struct flow_table *table, struct sw_flow *flow)
+{
+	struct table_instance *ti;
+
+	flow->ufid_table.hash = ufid_hash(&flow->id);
+	ti = ovsl_dereference(table->ufid_ti);
+	ufid_table_instance_insert(ti, flow);
+	table->ufid_count++;
+
+	/* Expand table, if necessary, to make room. */
+	if (table->ufid_count > ti->n_buckets) {
+		struct table_instance *new_ti;
+
+		new_ti = table_instance_expand(ti, true);
+		if (new_ti) {
+			rcu_assign_pointer(table->ufid_ti, new_ti);
+			call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
+		}
+	}
+}
+
+/* Must be called with OVS mutex held. */
+int ovs_flow_tbl_insert(struct flow_table *table, struct sw_flow *flow,
+			const struct sw_flow_mask *mask)
+{
+	int err;
+
+	err = flow_mask_insert(table, flow, mask);
+	if (err)
+		return err;
+	flow_key_insert(table, flow);
+	if (ovs_identifier_is_ufid(&flow->id))
+		flow_ufid_insert(table, flow);
+
+	return 0;
+}
+
+/* Initializes the flow module.
+ * Returns zero if successful or a negative error code. */
+int ovs_flow_init(void)
+{
+	BUILD_BUG_ON(__alignof__(struct sw_flow_key) % __alignof__(long));
+	BUILD_BUG_ON(sizeof(struct sw_flow_key) % sizeof(long));
+
+	flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow)
+				       + (num_possible_nodes()
+					  * sizeof(struct flow_stats *)),
+				       0, 0, NULL);
+	if (flow_cache == NULL)
+		return -ENOMEM;
+
+	flow_stats_cache
+		= kmem_cache_create("sw_flow_stats", sizeof(struct flow_stats),
+				    0, SLAB_HWCACHE_ALIGN, NULL);
+	if (flow_stats_cache == NULL) {
+		kmem_cache_destroy(flow_cache);
+		flow_cache = NULL;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/* Uninitializes the flow module. */
+void ovs_flow_exit(void)
+{
+	kmem_cache_destroy(flow_stats_cache);
+	kmem_cache_destroy(flow_cache);
+}