1 files changed, 215 insertions, 46 deletions

diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
index 3d3f8fce10a5..3b1ad876d6b0 100644
--- a/net/netfilter/nft_hash.c
+++ b/net/netfilter/nft_hash.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
+ * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -14,21 +14,34 @@
 #include <linux/list.h>
 #include <linux/jhash.h>
 #include <linux/netlink.h>
+#include <linux/vmalloc.h>
 #include <linux/netfilter.h>
 #include <linux/netfilter/nf_tables.h>
 #include <net/netfilter/nf_tables.h>
 
+#define NFT_HASH_MIN_SIZE	4
+
 struct nft_hash {
-	struct hlist_head	*hash;
-	unsigned int		hsize;
+	struct nft_hash_table __rcu	*tbl;
+};
+
+struct nft_hash_table {
+	unsigned int			size;
+	unsigned int			elements;
+	struct nft_hash_elem __rcu	*buckets[];
 };
 
 struct nft_hash_elem {
-	struct hlist_node	hnode;
-	struct nft_data		key;
-	struct nft_data		data[];
+	struct nft_hash_elem __rcu	*next;
+	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;
 
@@ -38,7 +51,7 @@ static unsigned int nft_hash_data(const struct nft_data *data,
 	unsigned int h;
 
 	h = jhash(data->data, len, nft_hash_rnd);
-	return ((u64)h * hsize) >> 32;
+	return h & (hsize - 1);
 }
 
 static bool nft_hash_lookup(const struct nft_set *set,
@@ -46,11 +59,12 @@ static bool nft_hash_lookup(const struct nft_set *set,
 			    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 nft_hash_elem *he;
 	unsigned int h;
 
-	h = nft_hash_data(key, priv->hsize, set->klen);
-	hlist_for_each_entry(he, &priv->hash[h], hnode) {
+	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)
@@ -60,19 +74,148 @@ static bool nft_hash_lookup(const struct nft_set *set,
 	return false;
 }
 
-static void nft_hash_elem_destroy(const struct nft_set *set,
-				  struct nft_hash_elem *he)
+static void nft_hash_tbl_free(const struct nft_hash_table *tbl)
 {
-	nft_data_uninit(&he->key, NFT_DATA_VALUE);
-	if (set->flags & NFT_SET_MAP)
-		nft_data_uninit(he->data, set->dtype);
-	kfree(he);
+	if (is_vmalloc_addr(tbl))
+		vfree(tbl);
+	else
+		kfree(tbl);
+}
+
+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;
+		}
+	}
+	ntbl->elements = tbl->elements;
+
+	/* 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]);
+	}
+	ntbl->elements = tbl->elements;
+
+	/* Publish new table */
+	rcu_assign_pointer(priv->tbl, ntbl);
+	synchronize_rcu();
+
+	nft_hash_tbl_free(tbl);
+	return 0;
 }
 
 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 nft_hash_elem *he;
 	unsigned int size, h;
 
@@ -91,33 +234,66 @@ 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, priv->hsize, set->klen);
-	hlist_add_head_rcu(&he->hnode, &priv->hash[h]);
+	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);
+	tbl->elements++;
+
+	/* Expand table when exceeding 75% load */
+	if (tbl->elements > tbl->size / 4 * 3)
+		nft_hash_tbl_expand(set, priv);
+
 	return 0;
 }
 
+static void nft_hash_elem_destroy(const struct nft_set *set,
+				  struct nft_hash_elem *he)
+{
+	nft_data_uninit(&he->key, NFT_DATA_VALUE);
+	if (set->flags & NFT_SET_MAP)
+		nft_data_uninit(he->data, set->dtype);
+	kfree(he);
+}
+
 static void nft_hash_remove(const struct nft_set *set,
 			    const struct nft_set_elem *elem)
 {
-	struct nft_hash_elem *he = elem->cookie;
+	struct nft_hash *priv = nft_set_priv(set);
+	struct nft_hash_table *tbl = nft_dereference(priv->tbl);
+	struct nft_hash_elem *he, __rcu **pprev;
 
-	hlist_del_rcu(&he->hnode);
+	pprev = elem->cookie;
+	he = nft_dereference((*pprev));
+
+	RCU_INIT_POINTER(*pprev, he->next);
+	synchronize_rcu();
 	kfree(he);
+	tbl->elements--;
+
+	/* Shrink table beneath 30% load */
+	if (tbl->elements < 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;
 	struct nft_hash_elem *he;
 	unsigned int h;
 
-	h = nft_hash_data(&elem->key, priv->hsize, set->klen);
-	hlist_for_each_entry(he, &priv->hash[h], hnode) {
-		if (nft_data_cmp(&he->key, &elem->key, set->klen))
+	h = nft_hash_data(&elem->key, tbl->size, set->klen);
+	pprev = &tbl->buckets[h];
+	nft_hash_for_each_entry(he, tbl->buckets[h]) {
+		if (nft_data_cmp(&he->key, &elem->key, set->klen)) {
+			pprev = &he->next;
 			continue;
+		}
 
-		elem->cookie = he;
-		elem->flags  = 0;
+		elem->cookie = (void *)pprev;
+		elem->flags = 0;
 		if (set->flags & NFT_SET_MAP)
 			nft_data_copy(&elem->data, he->data);
 		return 0;
@@ -129,12 +305,13 @@ 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 nft_hash_elem *he;
 	struct nft_set_elem elem;
 	unsigned int i;
 
-	for (i = 0; i < priv->hsize; i++) {
-		hlist_for_each_entry(he, &priv->hash[i], hnode) {
+	for (i = 0; i < tbl->size; i++) {
+		nft_hash_for_each_entry(he, tbl->buckets[i]) {
 			if (iter->count < iter->skip)
 				goto cont;
 
@@ -161,43 +338,35 @@ static int nft_hash_init(const struct nft_set *set,
 			 const struct nlattr * const tb[])
 {
 	struct nft_hash *priv = nft_set_priv(set);
-	unsigned int cnt, i;
+	struct nft_hash_table *tbl;
 
 	if (unlikely(!nft_hash_rnd_initted)) {
 		get_random_bytes(&nft_hash_rnd, 4);
 		nft_hash_rnd_initted = true;
 	}
 
-	/* Aim for a load factor of 0.75 */
-	// FIXME: temporarily broken until we have set descriptions
-	cnt = 100;
-	cnt = cnt * 4 / 3;
-
-	priv->hash = kcalloc(cnt, sizeof(struct hlist_head), GFP_KERNEL);
-	if (priv->hash == NULL)
+	tbl = nft_hash_tbl_alloc(NFT_HASH_MIN_SIZE);
+	if (tbl == NULL)
 		return -ENOMEM;
-	priv->hsize = cnt;
-
-	for (i = 0; i < cnt; i++)
-		INIT_HLIST_HEAD(&priv->hash[i]);
-
+	RCU_INIT_POINTER(priv->tbl, tbl);
 	return 0;
 }
 
 static void nft_hash_destroy(const struct nft_set *set)
 {
 	const struct nft_hash *priv = nft_set_priv(set);
-	const struct hlist_node *next;
-	struct nft_hash_elem *elem;
+	const struct nft_hash_table *tbl = nft_dereference(priv->tbl);
+	struct nft_hash_elem *he, *next;
 	unsigned int i;
 
-	for (i = 0; i < priv->hsize; i++) {
-		hlist_for_each_entry_safe(elem, next, &priv->hash[i], hnode) {
-			hlist_del(&elem->hnode);
-			nft_hash_elem_destroy(set, elem);
+	for (i = 0; i < tbl->size; i++) {
+		for (he = nft_dereference(tbl->buckets[i]); he != NULL;
+		     he = next) {
+			next = nft_dereference(he->next);
+			nft_hash_elem_destroy(set, he);
 		}
 	}
-	kfree(priv->hash);
+	kfree(tbl);
 }
 
 static struct nft_set_ops nft_hash_ops __read_mostly = {