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Commit cfe4a9dd authored by Thomas Graf's avatar Thomas Graf Committed by David S. Miller
Browse files

nftables: Convert nft_hash to use generic rhashtable 



The sizing of the hash table and the practice of requiring a lookup
to retrieve the pprev to be stored in the element cookie before the
deletion of an entry is left intact.

Signed-off-by: default avatarThomas Graf <tgraf@suug.ch>
Acked-by: default avatarPatrick McHardy <kaber@trash.net>
Reviewed-by: default avatarNikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e341694e

net/netfilter/nft_hash.c

+55 −236
Original line number Diff line number Diff line
@@ -15,209 +15,40 @@ 
#include <linux/log2.h>

#include <linux/jhash.h>

#include <linux/netlink.h>

#include <linux/vmalloc.h>

#include <linux/rhashtable.h>

#include <linux/netfilter.h>

#include <linux/netfilter/nf_tables.h>

#include <net/netfilter/nf_tables.h>



#define NFT_HASH_MIN_SIZE	4UL



struct nft_hash {

	struct nft_hash_table __rcu	*tbl;

};



struct nft_hash_table {

	unsigned int			size;

	struct nft_hash_elem __rcu	*buckets[];

};

/* We target a hash table size of 4, element hint is 75% of final size */

#define NFT_HASH_ELEMENT_HINT 3



struct nft_hash_elem {

	struct nft_hash_elem __rcu	*next;

	struct rhash_head		node;

	struct nft_data			key;

	struct nft_data			data[];

};



#define nft_hash_for_each_entry(i, head) \

	for (i = nft_dereference(head); i != NULL; i = nft_dereference(i->next))

#define nft_hash_for_each_entry_rcu(i, head) \

	for (i = rcu_dereference(head); i != NULL; i = rcu_dereference(i->next))



static u32 nft_hash_rnd __read_mostly;

static bool nft_hash_rnd_initted __read_mostly;



static unsigned int nft_hash_data(const struct nft_data *data,

				  unsigned int hsize, unsigned int len)

{

	unsigned int h;



	h = jhash(data->data, len, nft_hash_rnd);

	return h & (hsize - 1);

}



static bool nft_hash_lookup(const struct nft_set *set,

			    const struct nft_data *key,

			    struct nft_data *data)

{

	const struct nft_hash *priv = nft_set_priv(set);

	const struct nft_hash_table *tbl = rcu_dereference(priv->tbl);

	const struct rhashtable *priv = nft_set_priv(set);

	const struct nft_hash_elem *he;

	unsigned int h;



	h = nft_hash_data(key, tbl->size, set->klen);

	nft_hash_for_each_entry_rcu(he, tbl->buckets[h]) {

		if (nft_data_cmp(&he->key, key, set->klen))

			continue;

		if (set->flags & NFT_SET_MAP)

	he = rhashtable_lookup(priv, key);

	if (he && set->flags & NFT_SET_MAP)

		nft_data_copy(data, he->data);

		return true;

	}

	return false;

}



static void nft_hash_tbl_free(const struct nft_hash_table *tbl)

{

	kvfree(tbl);

}



static unsigned int nft_hash_tbl_size(unsigned int nelem)

{

	return max(roundup_pow_of_two(nelem * 4 / 3), NFT_HASH_MIN_SIZE);

}



static struct nft_hash_table *nft_hash_tbl_alloc(unsigned int nbuckets)

{

	struct nft_hash_table *tbl;

	size_t size;



	size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);

	tbl = kzalloc(size, GFP_KERNEL | __GFP_REPEAT | __GFP_NOWARN);

	if (tbl == NULL)

		tbl = vzalloc(size);

	if (tbl == NULL)

		return NULL;

	tbl->size = nbuckets;



	return tbl;

}



static void nft_hash_chain_unzip(const struct nft_set *set,

				 const struct nft_hash_table *ntbl,

				 struct nft_hash_table *tbl, unsigned int n)

{

	struct nft_hash_elem *he, *last, *next;

	unsigned int h;



	he = nft_dereference(tbl->buckets[n]);

	if (he == NULL)

		return;

	h = nft_hash_data(&he->key, ntbl->size, set->klen);



	/* Find last element of first chain hashing to bucket h */

	last = he;

	nft_hash_for_each_entry(he, he->next) {

		if (nft_hash_data(&he->key, ntbl->size, set->klen) != h)

			break;

		last = he;

	}



	/* Unlink first chain from the old table */

	RCU_INIT_POINTER(tbl->buckets[n], last->next);



	/* If end of chain reached, done */

	if (he == NULL)

		return;



	/* Find first element of second chain hashing to bucket h */

	next = NULL;

	nft_hash_for_each_entry(he, he->next) {

		if (nft_hash_data(&he->key, ntbl->size, set->klen) != h)

			continue;

		next = he;

		break;

	}



	/* Link the two chains */

	RCU_INIT_POINTER(last->next, next);

}



static int nft_hash_tbl_expand(const struct nft_set *set, struct nft_hash *priv)

{

	struct nft_hash_table *tbl = nft_dereference(priv->tbl), *ntbl;

	struct nft_hash_elem *he;

	unsigned int i, h;

	bool complete;



	ntbl = nft_hash_tbl_alloc(tbl->size * 2);

	if (ntbl == NULL)

		return -ENOMEM;



	/* Link new table's buckets to first element in the old table

	 * hashing to the new bucket.

	 */

	for (i = 0; i < ntbl->size; i++) {

		h = i < tbl->size ? i : i - tbl->size;

		nft_hash_for_each_entry(he, tbl->buckets[h]) {

			if (nft_hash_data(&he->key, ntbl->size, set->klen) != i)

				continue;

			RCU_INIT_POINTER(ntbl->buckets[i], he);

			break;

		}

	}



	/* Publish new table */

	rcu_assign_pointer(priv->tbl, ntbl);



	/* Unzip interleaved hash chains */

	do {

		/* Wait for readers to use new table/unzipped chains */

		synchronize_rcu();



		complete = true;

		for (i = 0; i < tbl->size; i++) {

			nft_hash_chain_unzip(set, ntbl, tbl, i);

			if (tbl->buckets[i] != NULL)

				complete = false;

		}

	} while (!complete);



	nft_hash_tbl_free(tbl);

	return 0;

}



static int nft_hash_tbl_shrink(const struct nft_set *set, struct nft_hash *priv)

{

	struct nft_hash_table *tbl = nft_dereference(priv->tbl), *ntbl;

	struct nft_hash_elem __rcu **pprev;

	unsigned int i;



	ntbl = nft_hash_tbl_alloc(tbl->size / 2);

	if (ntbl == NULL)

		return -ENOMEM;



	for (i = 0; i < ntbl->size; i++) {

		ntbl->buckets[i] = tbl->buckets[i];



		for (pprev = &ntbl->buckets[i]; *pprev != NULL;

		     pprev = &nft_dereference(*pprev)->next)

			;

		RCU_INIT_POINTER(*pprev, tbl->buckets[i + ntbl->size]);

	}



	/* Publish new table */

	rcu_assign_pointer(priv->tbl, ntbl);

	synchronize_rcu();



	nft_hash_tbl_free(tbl);

	return 0;

	return !!he;

}



static int nft_hash_insert(const struct nft_set *set,

			   const struct nft_set_elem *elem)

{

	struct nft_hash *priv = nft_set_priv(set);

	struct nft_hash_table *tbl = nft_dereference(priv->tbl);

	struct rhashtable *priv = nft_set_priv(set);

	struct nft_hash_elem *he;

	unsigned int size, h;

	unsigned int size;



	if (elem->flags != 0)

		return -EINVAL;
@@ -234,13 +65,7 @@ static int nft_hash_insert(const struct nft_set *set, 
	if (set->flags & NFT_SET_MAP)

		nft_data_copy(he->data, &elem->data);



	h = nft_hash_data(&he->key, tbl->size, set->klen);

	RCU_INIT_POINTER(he->next, tbl->buckets[h]);

	rcu_assign_pointer(tbl->buckets[h], he);



	/* Expand table when exceeding 75% load */

	if (set->nelems + 1 > tbl->size / 4 * 3)

		nft_hash_tbl_expand(set, priv);

	rhashtable_insert(priv, &he->node, GFP_KERNEL);



	return 0;

}
@@ -257,36 +82,31 @@ static void nft_hash_elem_destroy(const struct nft_set *set, 
static void nft_hash_remove(const struct nft_set *set,

			    const struct nft_set_elem *elem)

{

	struct nft_hash *priv = nft_set_priv(set);

	struct nft_hash_table *tbl = nft_dereference(priv->tbl);

	struct nft_hash_elem *he, __rcu **pprev;

	struct rhashtable *priv = nft_set_priv(set);

	struct rhash_head *he, __rcu **pprev;



	pprev = elem->cookie;

	he = nft_dereference((*pprev));

	he = rht_dereference((*pprev), priv);



	rhashtable_remove_pprev(priv, he, pprev, GFP_KERNEL);



	RCU_INIT_POINTER(*pprev, he->next);

	synchronize_rcu();

	kfree(he);



	/* Shrink table beneath 30% load */

	if (set->nelems - 1 < tbl->size * 3 / 10 &&

	    tbl->size > NFT_HASH_MIN_SIZE)

		nft_hash_tbl_shrink(set, priv);

}



static int nft_hash_get(const struct nft_set *set, struct nft_set_elem *elem)

{

	const struct nft_hash *priv = nft_set_priv(set);

	const struct nft_hash_table *tbl = nft_dereference(priv->tbl);

	struct nft_hash_elem __rcu * const *pprev;

	const struct rhashtable *priv = nft_set_priv(set);

	const struct bucket_table *tbl = rht_dereference_rcu(priv->tbl, priv);

	struct rhash_head __rcu * const *pprev;

	struct nft_hash_elem *he;

	unsigned int h;

	u32 h;



	h = nft_hash_data(&elem->key, tbl->size, set->klen);

	h = rhashtable_hashfn(priv, &elem->key, set->klen);

	pprev = &tbl->buckets[h];

	nft_hash_for_each_entry(he, tbl->buckets[h]) {

	rht_for_each_entry_rcu(he, tbl->buckets[h], node) {

		if (nft_data_cmp(&he->key, &elem->key, set->klen)) {

			pprev = &he->next;

			pprev = &he->node.next;

			continue;

		}
@@ -302,14 +122,15 @@ static int nft_hash_get(const struct nft_set *set, struct nft_set_elem *elem) 
static void nft_hash_walk(const struct nft_ctx *ctx, const struct nft_set *set,

			  struct nft_set_iter *iter)

{

	const struct nft_hash *priv = nft_set_priv(set);

	const struct nft_hash_table *tbl = nft_dereference(priv->tbl);

	const struct rhashtable *priv = nft_set_priv(set);

	const struct bucket_table *tbl;

	const struct nft_hash_elem *he;

	struct nft_set_elem elem;

	unsigned int i;



	tbl = rht_dereference_rcu(priv->tbl, priv);

	for (i = 0; i < tbl->size; i++) {

		nft_hash_for_each_entry(he, tbl->buckets[i]) {

		rht_for_each_entry_rcu(he, tbl->buckets[i], node) {

			if (iter->count < iter->skip)

				goto cont;
@@ -329,48 +150,46 @@ static void nft_hash_walk(const struct nft_ctx *ctx, const struct nft_set *set, 


static unsigned int nft_hash_privsize(const struct nlattr * const nla[])

{

	return sizeof(struct nft_hash);

	return sizeof(struct rhashtable);

}



static int lockdep_nfnl_lock_is_held(void)

{

	return lockdep_nfnl_is_held(NFNL_SUBSYS_NFTABLES);

}



static int nft_hash_init(const struct nft_set *set,

			 const struct nft_set_desc *desc,

			 const struct nlattr * const tb[])

{

	struct nft_hash *priv = nft_set_priv(set);

	struct nft_hash_table *tbl;

	unsigned int size;

	struct rhashtable *priv = nft_set_priv(set);

	struct rhashtable_params params = {

		.nelem_hint = desc->size ? : NFT_HASH_ELEMENT_HINT,

		.head_offset = offsetof(struct nft_hash_elem, node),

		.key_offset = offsetof(struct nft_hash_elem, key),

		.key_len = set->klen,

		.hashfn = jhash,

		.grow_decision = rht_grow_above_75,

		.shrink_decision = rht_shrink_below_30,

		.mutex_is_held = lockdep_nfnl_lock_is_held,

	};



	if (unlikely(!nft_hash_rnd_initted)) {

		get_random_bytes(&nft_hash_rnd, 4);

		nft_hash_rnd_initted = true;

	}



	size = NFT_HASH_MIN_SIZE;

	if (desc->size)

		size = nft_hash_tbl_size(desc->size);



	tbl = nft_hash_tbl_alloc(size);

	if (tbl == NULL)

		return -ENOMEM;

	RCU_INIT_POINTER(priv->tbl, tbl);

	return 0;

	return rhashtable_init(priv, &params);

}



static void nft_hash_destroy(const struct nft_set *set)

{

	const struct nft_hash *priv = nft_set_priv(set);

	const struct nft_hash_table *tbl = nft_dereference(priv->tbl);

	const struct rhashtable *priv = nft_set_priv(set);

	const struct bucket_table *tbl;

	struct nft_hash_elem *he, *next;

	unsigned int i;



	for (i = 0; i < tbl->size; i++) {

		for (he = nft_dereference(tbl->buckets[i]); he != NULL;

		     he = next) {

			next = nft_dereference(he->next);

	tbl = rht_dereference(priv->tbl, priv);

	for (i = 0; i < tbl->size; i++)

		rht_for_each_entry_safe(he, next, tbl->buckets[i], priv, node)

			nft_hash_elem_destroy(set, he);

		}

	}

	kfree(tbl);



	rhashtable_destroy(priv);

}



static bool nft_hash_estimate(const struct nft_set_desc *desc, u32 features,
@@ -383,8 +202,8 @@ static bool nft_hash_estimate(const struct nft_set_desc *desc, u32 features, 
		esize += FIELD_SIZEOF(struct nft_hash_elem, data[0]);



	if (desc->size) {

		est->size = sizeof(struct nft_hash) +

			    nft_hash_tbl_size(desc->size) *

		est->size = sizeof(struct rhashtable) +

			    roundup_pow_of_two(desc->size * 4 / 3) *

			    sizeof(struct nft_hash_elem *) +

			    desc->size * esize;

	} else {