Adding upstream version 6.1.76.upstream/6.1.76upstream

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

1 files changed, 1222 insertions, 0 deletions

diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
new file mode 100644
index 000000000..d4a2db0b2
--- /dev/null
+++ b/net/openvswitch/flow_table.c
@@ -0,0 +1,1222 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2007-2014 Nicira, Inc.
+ */
+
+#include "flow.h"
+#include "datapath.h"
+#include "flow_netlink.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/cpumask.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 <linux/sort.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <net/ndisc.h>
+
+#define TBL_MIN_BUCKETS		1024
+#define MASK_ARRAY_SIZE_MIN	16
+#define REHASH_INTERVAL		(10 * 60 * HZ)
+
+#define MC_DEFAULT_HASH_ENTRIES	256
+#define MC_HASH_SHIFT		8
+#define MC_HASH_SEGS		((sizeof(uint32_t) * 8) / MC_HASH_SHIFT)
+
+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,
+		       bool full, const struct sw_flow_mask *mask)
+{
+	int start = full ? 0 : mask->range.start;
+	int len = full ? sizeof *dst : range_n_bytes(&mask->range);
+	const long *m = (const long *)((const u8 *)&mask->key + start);
+	const long *s = (const long *)((const u8 *)src + start);
+	long *d = (long *)((u8 *)dst + start);
+	int i;
+
+	/* If 'full' is true then all of 'dst' is fully initialized. Otherwise,
+	 * if 'full' is false the memory outside of the 'mask->range' is left
+	 * uninitialized. This can be used as an optimization when further
+	 * operations on 'dst' only use contents within 'mask->range'.
+	 */
+	for (i = 0; i < len; i += sizeof(long))
+		*d++ = *s++ & *m++;
+}
+
+struct sw_flow *ovs_flow_alloc(void)
+{
+	struct sw_flow *flow;
+	struct sw_flow_stats *stats;
+
+	flow = kmem_cache_zalloc(flow_cache, GFP_KERNEL);
+	if (!flow)
+		return ERR_PTR(-ENOMEM);
+
+	flow->stats_last_writer = -1;
+
+	/* Initialize the default stat node. */
+	stats = kmem_cache_alloc_node(flow_stats_cache,
+				      GFP_KERNEL | __GFP_ZERO,
+				      node_online(0) ? 0 : NUMA_NO_NODE);
+	if (!stats)
+		goto err;
+
+	spin_lock_init(&stats->lock);
+
+	RCU_INIT_POINTER(flow->stats[0], stats);
+
+	cpumask_set_cpu(0, &flow->cpu_used_mask);
+
+	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 void flow_free(struct sw_flow *flow)
+{
+	int cpu;
+
+	if (ovs_identifier_is_key(&flow->id))
+		kfree(flow->id.unmasked_key);
+	if (flow->sf_acts)
+		ovs_nla_free_flow_actions((struct sw_flow_actions __force *)
+					  flow->sf_acts);
+	/* We open code this to make sure cpu 0 is always considered */
+	for (cpu = 0; cpu < nr_cpu_ids;
+	     cpu = cpumask_next(cpu, &flow->cpu_used_mask)) {
+		if (flow->stats[cpu])
+			kmem_cache_free(flow_stats_cache,
+					(struct sw_flow_stats __force *)flow->stats[cpu]);
+	}
+
+	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 __table_instance_destroy(struct table_instance *ti)
+{
+	kvfree(ti->buckets);
+	kfree(ti);
+}
+
+static struct table_instance *table_instance_alloc(int new_size)
+{
+	struct table_instance *ti = kmalloc(sizeof(*ti), GFP_KERNEL);
+	int i;
+
+	if (!ti)
+		return NULL;
+
+	ti->buckets = kvmalloc_array(new_size, sizeof(struct hlist_head),
+				     GFP_KERNEL);
+	if (!ti->buckets) {
+		kfree(ti);
+		return NULL;
+	}
+
+	for (i = 0; i < new_size; i++)
+		INIT_HLIST_HEAD(&ti->buckets[i]);
+
+	ti->n_buckets = new_size;
+	ti->node_ver = 0;
+	get_random_bytes(&ti->hash_seed, sizeof(u32));
+
+	return ti;
+}
+
+static void __mask_array_destroy(struct mask_array *ma)
+{
+	free_percpu(ma->masks_usage_stats);
+	kfree(ma);
+}
+
+static void mask_array_rcu_cb(struct rcu_head *rcu)
+{
+	struct mask_array *ma = container_of(rcu, struct mask_array, rcu);
+
+	__mask_array_destroy(ma);
+}
+
+static void tbl_mask_array_reset_counters(struct mask_array *ma)
+{
+	int i, cpu;
+
+	/* As the per CPU counters are not atomic we can not go ahead and
+	 * reset them from another CPU. To be able to still have an approximate
+	 * zero based counter we store the value at reset, and subtract it
+	 * later when processing.
+	 */
+	for (i = 0; i < ma->max; i++) {
+		ma->masks_usage_zero_cntr[i] = 0;
+
+		for_each_possible_cpu(cpu) {
+			struct mask_array_stats *stats;
+			unsigned int start;
+			u64 counter;
+
+			stats = per_cpu_ptr(ma->masks_usage_stats, cpu);
+			do {
+				start = u64_stats_fetch_begin_irq(&stats->syncp);
+				counter = stats->usage_cntrs[i];
+			} while (u64_stats_fetch_retry_irq(&stats->syncp, start));
+
+			ma->masks_usage_zero_cntr[i] += counter;
+		}
+	}
+}
+
+static struct mask_array *tbl_mask_array_alloc(int size)
+{
+	struct mask_array *new;
+
+	size = max(MASK_ARRAY_SIZE_MIN, size);
+	new = kzalloc(sizeof(struct mask_array) +
+		      sizeof(struct sw_flow_mask *) * size +
+		      sizeof(u64) * size, GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	new->masks_usage_zero_cntr = (u64 *)((u8 *)new +
+					     sizeof(struct mask_array) +
+					     sizeof(struct sw_flow_mask *) *
+					     size);
+
+	new->masks_usage_stats = __alloc_percpu(sizeof(struct mask_array_stats) +
+						sizeof(u64) * size,
+						__alignof__(u64));
+	if (!new->masks_usage_stats) {
+		kfree(new);
+		return NULL;
+	}
+
+	new->count = 0;
+	new->max = size;
+
+	return new;
+}
+
+static int tbl_mask_array_realloc(struct flow_table *tbl, int size)
+{
+	struct mask_array *old;
+	struct mask_array *new;
+
+	new = tbl_mask_array_alloc(size);
+	if (!new)
+		return -ENOMEM;
+
+	old = ovsl_dereference(tbl->mask_array);
+	if (old) {
+		int i;
+
+		for (i = 0; i < old->max; i++) {
+			if (ovsl_dereference(old->masks[i]))
+				new->masks[new->count++] = old->masks[i];
+		}
+		call_rcu(&old->rcu, mask_array_rcu_cb);
+	}
+
+	rcu_assign_pointer(tbl->mask_array, new);
+
+	return 0;
+}
+
+static int tbl_mask_array_add_mask(struct flow_table *tbl,
+				   struct sw_flow_mask *new)
+{
+	struct mask_array *ma = ovsl_dereference(tbl->mask_array);
+	int err, ma_count = READ_ONCE(ma->count);
+
+	if (ma_count >= ma->max) {
+		err = tbl_mask_array_realloc(tbl, ma->max +
+						  MASK_ARRAY_SIZE_MIN);
+		if (err)
+			return err;
+
+		ma = ovsl_dereference(tbl->mask_array);
+	} else {
+		/* On every add or delete we need to reset the counters so
+		 * every new mask gets a fair chance of being prioritized.
+		 */
+		tbl_mask_array_reset_counters(ma);
+	}
+
+	BUG_ON(ovsl_dereference(ma->masks[ma_count]));
+
+	rcu_assign_pointer(ma->masks[ma_count], new);
+	WRITE_ONCE(ma->count, ma_count + 1);
+
+	return 0;
+}
+
+static void tbl_mask_array_del_mask(struct flow_table *tbl,
+				    struct sw_flow_mask *mask)
+{
+	struct mask_array *ma = ovsl_dereference(tbl->mask_array);
+	int i, ma_count = READ_ONCE(ma->count);
+
+	/* Remove the deleted mask pointers from the array */
+	for (i = 0; i < ma_count; i++) {
+		if (mask == ovsl_dereference(ma->masks[i]))
+			goto found;
+	}
+
+	BUG();
+	return;
+
+found:
+	WRITE_ONCE(ma->count, ma_count - 1);
+
+	rcu_assign_pointer(ma->masks[i], ma->masks[ma_count - 1]);
+	RCU_INIT_POINTER(ma->masks[ma_count - 1], NULL);
+
+	kfree_rcu(mask, rcu);
+
+	/* Shrink the mask array if necessary. */
+	if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) &&
+	    ma_count <= (ma->max / 3))
+		tbl_mask_array_realloc(tbl, ma->max / 2);
+	else
+		tbl_mask_array_reset_counters(ma);
+
+}
+
+/* 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)
+			tbl_mask_array_del_mask(tbl, mask);
+	}
+}
+
+static void __mask_cache_destroy(struct mask_cache *mc)
+{
+	free_percpu(mc->mask_cache);
+	kfree(mc);
+}
+
+static void mask_cache_rcu_cb(struct rcu_head *rcu)
+{
+	struct mask_cache *mc = container_of(rcu, struct mask_cache, rcu);
+
+	__mask_cache_destroy(mc);
+}
+
+static struct mask_cache *tbl_mask_cache_alloc(u32 size)
+{
+	struct mask_cache_entry __percpu *cache = NULL;
+	struct mask_cache *new;
+
+	/* Only allow size to be 0, or a power of 2, and does not exceed
+	 * percpu allocation size.
+	 */
+	if ((!is_power_of_2(size) && size != 0) ||
+	    (size * sizeof(struct mask_cache_entry)) > PCPU_MIN_UNIT_SIZE)
+		return NULL;
+
+	new = kzalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	new->cache_size = size;
+	if (new->cache_size > 0) {
+		cache = __alloc_percpu(array_size(sizeof(struct mask_cache_entry),
+						  new->cache_size),
+				       __alignof__(struct mask_cache_entry));
+		if (!cache) {
+			kfree(new);
+			return NULL;
+		}
+	}
+
+	new->mask_cache = cache;
+	return new;
+}
+int ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32 size)
+{
+	struct mask_cache *mc = rcu_dereference_ovsl(table->mask_cache);
+	struct mask_cache *new;
+
+	if (size == mc->cache_size)
+		return 0;
+
+	if ((!is_power_of_2(size) && size != 0) ||
+	    (size * sizeof(struct mask_cache_entry)) > PCPU_MIN_UNIT_SIZE)
+		return -EINVAL;
+
+	new = tbl_mask_cache_alloc(size);
+	if (!new)
+		return -ENOMEM;
+
+	rcu_assign_pointer(table->mask_cache, new);
+	call_rcu(&mc->rcu, mask_cache_rcu_cb);
+
+	return 0;
+}
+
+int ovs_flow_tbl_init(struct flow_table *table)
+{
+	struct table_instance *ti, *ufid_ti;
+	struct mask_cache *mc;
+	struct mask_array *ma;
+
+	mc = tbl_mask_cache_alloc(MC_DEFAULT_HASH_ENTRIES);
+	if (!mc)
+		return -ENOMEM;
+
+	ma = tbl_mask_array_alloc(MASK_ARRAY_SIZE_MIN);
+	if (!ma)
+		goto free_mask_cache;
+
+	ti = table_instance_alloc(TBL_MIN_BUCKETS);
+	if (!ti)
+		goto free_mask_array;
+
+	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);
+	rcu_assign_pointer(table->mask_array, ma);
+	rcu_assign_pointer(table->mask_cache, mc);
+	table->last_rehash = jiffies;
+	table->count = 0;
+	table->ufid_count = 0;
+	return 0;
+
+free_ti:
+	__table_instance_destroy(ti);
+free_mask_array:
+	__mask_array_destroy(ma);
+free_mask_cache:
+	__mask_cache_destroy(mc);
+	return -ENOMEM;
+}
+
+static void flow_tbl_destroy_rcu_cb(struct rcu_head *rcu)
+{
+	struct table_instance *ti;
+
+	ti = container_of(rcu, struct table_instance, rcu);
+	__table_instance_destroy(ti);
+}
+
+static void table_instance_flow_free(struct flow_table *table,
+				     struct table_instance *ti,
+				     struct table_instance *ufid_ti,
+				     struct sw_flow *flow)
+{
+	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--;
+	}
+
+	flow_mask_remove(table, flow->mask);
+}
+
+/* Must be called with OVS mutex held. */
+void table_instance_flow_flush(struct flow_table *table,
+			       struct table_instance *ti,
+			       struct table_instance *ufid_ti)
+{
+	int i;
+
+	for (i = 0; i < ti->n_buckets; i++) {
+		struct hlist_head *head = &ti->buckets[i];
+		struct hlist_node *n;
+		struct sw_flow *flow;
+
+		hlist_for_each_entry_safe(flow, n, head,
+					  flow_table.node[ti->node_ver]) {
+
+			table_instance_flow_free(table, ti, ufid_ti,
+						 flow);
+			ovs_flow_free(flow, true);
+		}
+	}
+
+	if (WARN_ON(table->count != 0 ||
+		    table->ufid_count != 0)) {
+		table->count = 0;
+		table->ufid_count = 0;
+	}
+}
+
+static void table_instance_destroy(struct table_instance *ti,
+				   struct table_instance *ufid_ti)
+{
+	call_rcu(&ti->rcu, flow_tbl_destroy_rcu_cb);
+	call_rcu(&ufid_ti->rcu, flow_tbl_destroy_rcu_cb);
+}
+
+/* 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);
+	struct mask_cache *mc = rcu_dereference_raw(table->mask_cache);
+	struct mask_array *ma = rcu_dereference_raw(table->mask_array);
+
+	call_rcu(&mc->rcu, mask_cache_rcu_cb);
+	call_rcu(&ma->rcu, mask_array_rcu_cb);
+	table_instance_destroy(ti, ufid_ti);
+}
+
+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 = &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 &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 = &old->buckets[i];
+
+		if (ufid)
+			hlist_for_each_entry_rcu(flow, head,
+						 ufid_table.node[old_ver],
+						 lockdep_ovsl_is_held())
+				ufid_table_instance_insert(new, flow);
+		else
+			hlist_for_each_entry_rcu(flow, head,
+						 flow_table.node[old_ver],
+						 lockdep_ovsl_is_held())
+				table_instance_insert(new, flow);
+	}
+}
+
+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;
+
+	table_instance_flow_flush(flow_table, old_ti, old_ufid_ti);
+	table_instance_destroy(old_ti, old_ufid_ti);
+	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)
+{
+	const u32 *hash_key = (const u32 *)((const u8 *)key + range->start);
+
+	/* Make sure number of hash bytes are multiple of u32. */
+	int hash_u32s = range_n_bytes(range) >> 2;
+
+	return jhash2(hash_key, hash_u32s, 0);
+}
+
+static int flow_key_start(const struct sw_flow_key *key)
+{
+	if (key->tun_proto)
+		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);
+	int i;
+
+	for (i = key_start; i < key_end; i += sizeof(long))
+		if (*cp1++ ^ *cp2++)
+			return false;
+
+	return true;
+}
+
+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,
+					  u32 *n_mask_hit)
+{
+	struct sw_flow *flow;
+	struct hlist_head *head;
+	u32 hash;
+	struct sw_flow_key masked_key;
+
+	ovs_flow_mask_key(&masked_key, unmasked, false, mask);
+	hash = flow_hash(&masked_key, &mask->range);
+	head = find_bucket(ti, hash);
+	(*n_mask_hit)++;
+
+	hlist_for_each_entry_rcu(flow, head, flow_table.node[ti->node_ver],
+				 lockdep_ovsl_is_held()) {
+		if (flow->mask == mask && flow->flow_table.hash == hash &&
+		    flow_cmp_masked_key(flow, &masked_key, &mask->range))
+			return flow;
+	}
+	return NULL;
+}
+
+/* Flow lookup does full lookup on flow table. It starts with
+ * mask from index passed in *index.
+ * This function MUST be called with BH disabled due to the use
+ * of CPU specific variables.
+ */
+static struct sw_flow *flow_lookup(struct flow_table *tbl,
+				   struct table_instance *ti,
+				   struct mask_array *ma,
+				   const struct sw_flow_key *key,
+				   u32 *n_mask_hit,
+				   u32 *n_cache_hit,
+				   u32 *index)
+{
+	struct mask_array_stats *stats = this_cpu_ptr(ma->masks_usage_stats);
+	struct sw_flow *flow;
+	struct sw_flow_mask *mask;
+	int i;
+
+	if (likely(*index < ma->max)) {
+		mask = rcu_dereference_ovsl(ma->masks[*index]);
+		if (mask) {
+			flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
+			if (flow) {
+				u64_stats_update_begin(&stats->syncp);
+				stats->usage_cntrs[*index]++;
+				u64_stats_update_end(&stats->syncp);
+				(*n_cache_hit)++;
+				return flow;
+			}
+		}
+	}
+
+	for (i = 0; i < ma->max; i++)  {
+
+		if (i == *index)
+			continue;
+
+		mask = rcu_dereference_ovsl(ma->masks[i]);
+		if (unlikely(!mask))
+			break;
+
+		flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
+		if (flow) { /* Found */
+			*index = i;
+			u64_stats_update_begin(&stats->syncp);
+			stats->usage_cntrs[*index]++;
+			u64_stats_update_end(&stats->syncp);
+			return flow;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * mask_cache maps flow to probable mask. This cache is not tightly
+ * coupled cache, It means updates to  mask list can result in inconsistent
+ * cache entry in mask cache.
+ * This is per cpu cache and is divided in MC_HASH_SEGS segments.
+ * In case of a hash collision the entry is hashed in next segment.
+ * */
+struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
+					  const struct sw_flow_key *key,
+					  u32 skb_hash,
+					  u32 *n_mask_hit,
+					  u32 *n_cache_hit)
+{
+	struct mask_cache *mc = rcu_dereference(tbl->mask_cache);
+	struct mask_array *ma = rcu_dereference(tbl->mask_array);
+	struct table_instance *ti = rcu_dereference(tbl->ti);
+	struct mask_cache_entry *entries, *ce;
+	struct sw_flow *flow;
+	u32 hash;
+	int seg;
+
+	*n_mask_hit = 0;
+	*n_cache_hit = 0;
+	if (unlikely(!skb_hash || mc->cache_size == 0)) {
+		u32 mask_index = 0;
+		u32 cache = 0;
+
+		return flow_lookup(tbl, ti, ma, key, n_mask_hit, &cache,
+				   &mask_index);
+	}
+
+	/* Pre and post recirulation flows usually have the same skb_hash
+	 * value. To avoid hash collisions, rehash the 'skb_hash' with
+	 * 'recirc_id'.  */
+	if (key->recirc_id)
+		skb_hash = jhash_1word(skb_hash, key->recirc_id);
+
+	ce = NULL;
+	hash = skb_hash;
+	entries = this_cpu_ptr(mc->mask_cache);
+
+	/* Find the cache entry 'ce' to operate on. */
+	for (seg = 0; seg < MC_HASH_SEGS; seg++) {
+		int index = hash & (mc->cache_size - 1);
+		struct mask_cache_entry *e;
+
+		e = &entries[index];
+		if (e->skb_hash == skb_hash) {
+			flow = flow_lookup(tbl, ti, ma, key, n_mask_hit,
+					   n_cache_hit, &e->mask_index);
+			if (!flow)
+				e->skb_hash = 0;
+			return flow;
+		}
+
+		if (!ce || e->skb_hash < ce->skb_hash)
+			ce = e;  /* A better replacement cache candidate. */
+
+		hash >>= MC_HASH_SHIFT;
+	}
+
+	/* Cache miss, do full lookup. */
+	flow = flow_lookup(tbl, ti, ma, key, n_mask_hit, n_cache_hit,
+			   &ce->mask_index);
+	if (flow)
+		ce->skb_hash = skb_hash;
+
+	*n_cache_hit = 0;
+	return flow;
+}
+
+struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *tbl,
+				    const struct sw_flow_key *key)
+{
+	struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
+	struct mask_array *ma = rcu_dereference_ovsl(tbl->mask_array);
+	u32 __always_unused n_mask_hit;
+	u32 __always_unused n_cache_hit;
+	struct sw_flow *flow;
+	u32 index = 0;
+
+	/* This function gets called trough the netlink interface and therefore
+	 * is preemptible. However, flow_lookup() function needs to be called
+	 * with BH disabled due to CPU specific variables.
+	 */
+	local_bh_disable();
+	flow = flow_lookup(tbl, ti, ma, key, &n_mask_hit, &n_cache_hit, &index);
+	local_bh_enable();
+	return flow;
+}
+
+struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,
+					  const struct sw_flow_match *match)
+{
+	struct mask_array *ma = ovsl_dereference(tbl->mask_array);
+	int i;
+
+	/* Always called under ovs-mutex. */
+	for (i = 0; i < ma->max; i++) {
+		struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
+		u32 __always_unused n_mask_hit;
+		struct sw_flow_mask *mask;
+		struct sw_flow *flow;
+
+		mask = ovsl_dereference(ma->masks[i]);
+		if (!mask)
+			continue;
+
+		flow = masked_flow_lookup(ti, match->key, mask, &n_mask_hit);
+		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],
+				 lockdep_ovsl_is_held()) {
+		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 mask_array *ma = rcu_dereference_ovsl(table->mask_array);
+	return READ_ONCE(ma->count);
+}
+
+u32 ovs_flow_tbl_masks_cache_size(const struct flow_table *table)
+{
+	struct mask_cache *mc = rcu_dereference_ovsl(table->mask_cache);
+
+	return READ_ONCE(mc->cache_size);
+}
+
+static struct table_instance *table_instance_expand(struct table_instance *ti,
+						    bool ufid)
+{
+	return table_instance_rehash(ti, ti->n_buckets * 2, ufid);
+}
+
+/* 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);
+	table_instance_flow_free(table, ti, ufid_ti, flow);
+}
+
+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 mask_array *ma;
+	int i;
+
+	ma = ovsl_dereference(tbl->mask_array);
+	for (i = 0; i < ma->max; i++) {
+		struct sw_flow_mask *t;
+		t = ovsl_dereference(ma->masks[i]);
+
+		if (t && mask_equal(mask, t))
+			return t;
+	}
+
+	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;
+
+		/* Add mask to mask-list. */
+		if (tbl_mask_array_add_mask(tbl, mask)) {
+			kfree(mask);
+			return -ENOMEM;
+		}
+	} 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;
+}
+
+static int compare_mask_and_count(const void *a, const void *b)
+{
+	const struct mask_count *mc_a = a;
+	const struct mask_count *mc_b = b;
+
+	return (s64)mc_b->counter - (s64)mc_a->counter;
+}
+
+/* Must be called with OVS mutex held. */
+void ovs_flow_masks_rebalance(struct flow_table *table)
+{
+	struct mask_array *ma = rcu_dereference_ovsl(table->mask_array);
+	struct mask_count *masks_and_count;
+	struct mask_array *new;
+	int masks_entries = 0;
+	int i;
+
+	/* Build array of all current entries with use counters. */
+	masks_and_count = kmalloc_array(ma->max, sizeof(*masks_and_count),
+					GFP_KERNEL);
+	if (!masks_and_count)
+		return;
+
+	for (i = 0; i < ma->max; i++) {
+		struct sw_flow_mask *mask;
+		int cpu;
+
+		mask = rcu_dereference_ovsl(ma->masks[i]);
+		if (unlikely(!mask))
+			break;
+
+		masks_and_count[i].index = i;
+		masks_and_count[i].counter = 0;
+
+		for_each_possible_cpu(cpu) {
+			struct mask_array_stats *stats;
+			unsigned int start;
+			u64 counter;
+
+			stats = per_cpu_ptr(ma->masks_usage_stats, cpu);
+			do {
+				start = u64_stats_fetch_begin_irq(&stats->syncp);
+				counter = stats->usage_cntrs[i];
+			} while (u64_stats_fetch_retry_irq(&stats->syncp,
+							   start));
+
+			masks_and_count[i].counter += counter;
+		}
+
+		/* Subtract the zero count value. */
+		masks_and_count[i].counter -= ma->masks_usage_zero_cntr[i];
+
+		/* Rather than calling tbl_mask_array_reset_counters()
+		 * below when no change is needed, do it inline here.
+		 */
+		ma->masks_usage_zero_cntr[i] += masks_and_count[i].counter;
+	}
+
+	if (i == 0)
+		goto free_mask_entries;
+
+	/* Sort the entries */
+	masks_entries = i;
+	sort(masks_and_count, masks_entries, sizeof(*masks_and_count),
+	     compare_mask_and_count, NULL);
+
+	/* If the order is the same, nothing to do... */
+	for (i = 0; i < masks_entries; i++) {
+		if (i != masks_and_count[i].index)
+			break;
+	}
+	if (i == masks_entries)
+		goto free_mask_entries;
+
+	/* Rebuilt the new list in order of usage. */
+	new = tbl_mask_array_alloc(ma->max);
+	if (!new)
+		goto free_mask_entries;
+
+	for (i = 0; i < masks_entries; i++) {
+		int index = masks_and_count[i].index;
+
+		if (ovsl_dereference(ma->masks[index]))
+			new->masks[new->count++] = ma->masks[index];
+	}
+
+	rcu_assign_pointer(table->mask_array, new);
+	call_rcu(&ma->rcu, mask_array_rcu_cb);
+
+free_mask_entries:
+	kfree(masks_and_count);
+}
+
+/* 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)
+				       + (nr_cpu_ids
+					  * sizeof(struct sw_flow_stats *)),
+				       0, 0, NULL);
+	if (flow_cache == NULL)
+		return -ENOMEM;
+
+	flow_stats_cache
+		= kmem_cache_create("sw_flow_stats", sizeof(struct sw_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);
+}