1 files changed, 181 insertions, 72 deletions

diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c
index 3f14806b7271..02ca7df793f5 100644
--- a/net/netfilter/nf_conncount.c
+++ b/net/netfilter/nf_conncount.c
@@ -49,12 +49,14 @@ struct nf_conncount_tuple {
 	struct nf_conntrack_zone	zone;
 	int				cpu;
 	u32				jiffies32;
+	struct rcu_head			rcu_head;
 };
 
 struct nf_conncount_rb {
 	struct rb_node node;
 	struct nf_conncount_list list;
 	u32 key[MAX_KEYLEN];
+	struct rcu_head rcu_head;
 };
 
 static spinlock_t nf_conncount_locks[CONNCOUNT_LOCK_SLOTS] __cacheline_aligned_in_smp;
@@ -62,6 +64,10 @@ static spinlock_t nf_conncount_locks[CONNCOUNT_LOCK_SLOTS] __cacheline_aligned_i
 struct nf_conncount_data {
 	unsigned int keylen;
 	struct rb_root root[CONNCOUNT_SLOTS];
+	struct net *net;
+	struct work_struct gc_work;
+	unsigned long pending_trees[BITS_TO_LONGS(CONNCOUNT_SLOTS)];
+	unsigned int gc_tree;
 };
 
 static u_int32_t conncount_rnd __read_mostly;
@@ -82,42 +88,70 @@ static int key_diff(const u32 *a, const u32 *b, unsigned int klen)
 	return memcmp(a, b, klen * sizeof(u32));
 }
 
-bool nf_conncount_add(struct nf_conncount_list *list,
-		      const struct nf_conntrack_tuple *tuple,
-		      const struct nf_conntrack_zone *zone)
+enum nf_conncount_list_add
+nf_conncount_add(struct nf_conncount_list *list,
+		 const struct nf_conntrack_tuple *tuple,
+		 const struct nf_conntrack_zone *zone)
 {
 	struct nf_conncount_tuple *conn;
 
 	if (WARN_ON_ONCE(list->count > INT_MAX))
-		return false;
+		return NF_CONNCOUNT_ERR;
 
 	conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
 	if (conn == NULL)
-		return false;
+		return NF_CONNCOUNT_ERR;
+
 	conn->tuple = *tuple;
 	conn->zone = *zone;
 	conn->cpu = raw_smp_processor_id();
 	conn->jiffies32 = (u32)jiffies;
+	spin_lock(&list->list_lock);
+	if (list->dead == true) {
+		kmem_cache_free(conncount_conn_cachep, conn);
+		spin_unlock(&list->list_lock);
+		return NF_CONNCOUNT_SKIP;
+	}
 	list_add_tail(&conn->node, &list->head);
 	list->count++;
-	return true;
+	spin_unlock(&list->list_lock);
+	return NF_CONNCOUNT_ADDED;
 }
 EXPORT_SYMBOL_GPL(nf_conncount_add);
 
-static void conn_free(struct nf_conncount_list *list,
+static void __conn_free(struct rcu_head *h)
+{
+	struct nf_conncount_tuple *conn;
+
+	conn = container_of(h, struct nf_conncount_tuple, rcu_head);
+	kmem_cache_free(conncount_conn_cachep, conn);
+}
+
+static bool conn_free(struct nf_conncount_list *list,
 		      struct nf_conncount_tuple *conn)
 {
-	if (WARN_ON_ONCE(list->count == 0))
-		return;
+	bool free_entry = false;
+
+	spin_lock(&list->list_lock);
+
+	if (list->count == 0) {
+		spin_unlock(&list->list_lock);
+                return free_entry;
+	}
 
 	list->count--;
-	list_del(&conn->node);
-	kmem_cache_free(conncount_conn_cachep, conn);
+	list_del_rcu(&conn->node);
+	if (list->count == 0)
+		free_entry = true;
+
+	spin_unlock(&list->list_lock);
+	call_rcu(&conn->rcu_head, __conn_free);
+	return free_entry;
 }
 
 static const struct nf_conntrack_tuple_hash *
 find_or_evict(struct net *net, struct nf_conncount_list *list,
-	      struct nf_conncount_tuple *conn)
+	      struct nf_conncount_tuple *conn, bool *free_entry)
 {
 	const struct nf_conntrack_tuple_hash *found;
 	unsigned long a, b;
@@ -137,7 +171,7 @@ find_or_evict(struct net *net, struct nf_conncount_list *list,
 	 */
 	age = a - b;
 	if (conn->cpu == cpu || age >= 2) {
-		conn_free(list, conn);
+		*free_entry = conn_free(list, conn);
 		return ERR_PTR(-ENOENT);
 	}
 
@@ -154,6 +188,7 @@ void nf_conncount_lookup(struct net *net,
 	struct nf_conncount_tuple *conn, *conn_n;
 	struct nf_conn *found_ct;
 	unsigned int collect = 0;
+	bool free_entry = false;
 
 	/* best effort only */
 	*addit = tuple ? true : false;
@@ -163,7 +198,7 @@ void nf_conncount_lookup(struct net *net,
 		if (collect > CONNCOUNT_GC_MAX_NODES)
 			break;
 
-		found = find_or_evict(net, list, conn);
+		found = find_or_evict(net, list, conn, &free_entry);
 		if (IS_ERR(found)) {
 			/* Not found, but might be about to be confirmed */
 			if (PTR_ERR(found) == -EAGAIN) {
@@ -208,24 +243,31 @@ EXPORT_SYMBOL_GPL(nf_conncount_lookup);
 
 void nf_conncount_list_init(struct nf_conncount_list *list)
 {
+	spin_lock_init(&list->list_lock);
 	INIT_LIST_HEAD(&list->head);
 	list->count = 1;
+	list->dead = false;
 }
 EXPORT_SYMBOL_GPL(nf_conncount_list_init);
 
-void nf_conncount_gc_list(struct net *net,
+/* Return true if the list is empty */
+bool nf_conncount_gc_list(struct net *net,
 			  struct nf_conncount_list *list)
 {
 	const struct nf_conntrack_tuple_hash *found;
 	struct nf_conncount_tuple *conn, *conn_n;
 	struct nf_conn *found_ct;
 	unsigned int collected = 0;
+	bool free_entry = false;
 
 	list_for_each_entry_safe(conn, conn_n, &list->head, node) {
-		found = find_or_evict(net, list, conn);
+		found = find_or_evict(net, list, conn, &free_entry);
 		if (IS_ERR(found)) {
-			if (PTR_ERR(found) == -ENOENT)
+			if (PTR_ERR(found) == -ENOENT)  {
+				if (free_entry)
+					return true;
 				collected++;
+			}
 			continue;
 		}
 
@@ -236,18 +278,28 @@ void nf_conncount_gc_list(struct net *net,
 			 * closed already -> ditch it
 			 */
 			nf_ct_put(found_ct);
-			conn_free(list, conn);
+			if (conn_free(list, conn))
+				return true;
 			collected++;
 			continue;
 		}
 
 		nf_ct_put(found_ct);
 		if (collected > CONNCOUNT_GC_MAX_NODES)
-			return;
+			return false;
 	}
+	return false;
 }
 EXPORT_SYMBOL_GPL(nf_conncount_gc_list);
 
+static void __tree_nodes_free(struct rcu_head *h)
+{
+	struct nf_conncount_rb *rbconn;
+
+	rbconn = container_of(h, struct nf_conncount_rb, rcu_head);
+	kmem_cache_free(conncount_rb_cachep, rbconn);
+}
+
 static void tree_nodes_free(struct rb_root *root,
 			    struct nf_conncount_rb *gc_nodes[],
 			    unsigned int gc_count)
@@ -256,23 +308,39 @@ static void tree_nodes_free(struct rb_root *root,
 
 	while (gc_count) {
 		rbconn = gc_nodes[--gc_count];
-		rb_erase(&rbconn->node, root);
-		kmem_cache_free(conncount_rb_cachep, rbconn);
+		spin_lock(&rbconn->list.list_lock);
+		if (rbconn->list.count == 0 && rbconn->list.dead == false) {
+			rbconn->list.dead = true;
+			rb_erase(&rbconn->node, root);
+			call_rcu(&rbconn->rcu_head, __tree_nodes_free);
+		}
+		spin_unlock(&rbconn->list.list_lock);
 	}
 }
 
+static void schedule_gc_worker(struct nf_conncount_data *data, int tree)
+{
+	set_bit(tree, data->pending_trees);
+	schedule_work(&data->gc_work);
+}
+
 static unsigned int
-insert_tree(struct rb_root *root,
+insert_tree(struct net *net,
+	    struct nf_conncount_data *data,
+	    struct rb_root *root,
 	    unsigned int hash,
 	    const u32 *key,
 	    u8 keylen,
 	    const struct nf_conntrack_tuple *tuple,
 	    const struct nf_conntrack_zone *zone)
 {
+	enum nf_conncount_list_add ret;
+	struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES];
 	struct rb_node **rbnode, *parent;
 	struct nf_conncount_rb *rbconn;
 	struct nf_conncount_tuple *conn;
-	unsigned int count = 0;
+	unsigned int count = 0, gc_count = 0;
+	bool node_found = false;
 
 	spin_lock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
 
@@ -290,16 +358,44 @@ insert_tree(struct rb_root *root,
 			rbnode = &((*rbnode)->rb_right);
 		} else {
 			/* unlikely: other cpu added node already */
-			if (!nf_conncount_add(&rbconn->list, tuple, zone)) {
+			node_found = true;
+			ret = nf_conncount_add(&rbconn->list, tuple, zone);
+			if (ret == NF_CONNCOUNT_ERR) {
 				count = 0; /* hotdrop */
-				goto out_unlock;
+			} else if (ret == NF_CONNCOUNT_ADDED) {
+				count = rbconn->list.count;
+			} else {
+				/* NF_CONNCOUNT_SKIP, rbconn is already
+				 * reclaimed by gc, insert a new tree node
+				 */
+				node_found = false;
 			}
-
-			count = rbconn->list.count;
-			goto out_unlock;
+			break;
 		}
+
+		if (gc_count >= ARRAY_SIZE(gc_nodes))
+			continue;
+
+		if (nf_conncount_gc_list(net, &rbconn->list))
+			gc_nodes[gc_count++] = rbconn;
+	}
+
+	if (gc_count) {
+		tree_nodes_free(root, gc_nodes, gc_count);
+		/* tree_node_free before new allocation permits
+		 * allocator to re-use newly free'd object.
+		 *
+		 * This is a rare event; in most cases we will find
+		 * existing node to re-use. (or gc_count is 0).
+		 */
+
+		if (gc_count >= ARRAY_SIZE(gc_nodes))
+			schedule_gc_worker(data, hash);
 	}
 
+	if (node_found)
+		goto out_unlock;
+
 	/* expected case: match, insert new node */
 	rbconn = kmem_cache_alloc(conncount_rb_cachep, GFP_ATOMIC);
 	if (rbconn == NULL)
@@ -333,87 +429,97 @@ count_tree(struct net *net,
 	   const struct nf_conntrack_tuple *tuple,
 	   const struct nf_conntrack_zone *zone)
 {
-	struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES];
+	enum nf_conncount_list_add ret;
 	struct rb_root *root;
-	struct rb_node **rbnode, *parent;
+	struct rb_node *parent;
 	struct nf_conncount_rb *rbconn;
-	unsigned int gc_count, hash;
-	bool no_gc = false;
-	unsigned int count = 0;
+	unsigned int hash;
 	u8 keylen = data->keylen;
 
 	hash = jhash2(key, data->keylen, conncount_rnd) % CONNCOUNT_SLOTS;
 	root = &data->root[hash];
 
-	spin_lock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
- restart:
-	gc_count = 0;
-	parent = NULL;
-	rbnode = &(root->rb_node);
-	while (*rbnode) {
+	parent = rcu_dereference_raw(root->rb_node);
+	while (parent) {
 		int diff;
 		bool addit;
 
-		rbconn = rb_entry(*rbnode, struct nf_conncount_rb, node);
+		rbconn = rb_entry(parent, struct nf_conncount_rb, node);
 
-		parent = *rbnode;
 		diff = key_diff(key, rbconn->key, keylen);
 		if (diff < 0) {
-			rbnode = &((*rbnode)->rb_left);
+			parent = rcu_dereference_raw(parent->rb_left);
 		} else if (diff > 0) {
-			rbnode = &((*rbnode)->rb_right);
+			parent = rcu_dereference_raw(parent->rb_right);
 		} else {
 			/* same source network -> be counted! */
 			nf_conncount_lookup(net, &rbconn->list, tuple, zone,
 					    &addit);
-			count = rbconn->list.count;
 
-			tree_nodes_free(root, gc_nodes, gc_count);
 			if (!addit)
-				goto out_unlock;
+				return rbconn->list.count;
+
+			ret = nf_conncount_add(&rbconn->list, tuple, zone);
+			if (ret == NF_CONNCOUNT_ERR) {
+				return 0; /* hotdrop */
+			} else if (ret == NF_CONNCOUNT_ADDED) {
+				return rbconn->list.count;
+			} else {
+				/* NF_CONNCOUNT_SKIP, rbconn is already
+				 * reclaimed by gc, insert a new tree node
+				 */
+				break;
+			}
+		}
+	}
 
-			if (!nf_conncount_add(&rbconn->list, tuple, zone))
-				count = 0; /* hotdrop */
-				goto out_unlock;
+	if (!tuple)
+		return 0;
 
-			count++;
-			goto out_unlock;
-		}
+	return insert_tree(net, data, root, hash, key, keylen, tuple, zone);
+}
 
-		if (no_gc || gc_count >= ARRAY_SIZE(gc_nodes))
-			continue;
+static void tree_gc_worker(struct work_struct *work)
+{
+	struct nf_conncount_data *data = container_of(work, struct nf_conncount_data, gc_work);
+	struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES], *rbconn;
+	struct rb_root *root;
+	struct rb_node *node;
+	unsigned int tree, next_tree, gc_count = 0;
+
+	tree = data->gc_tree % CONNCOUNT_LOCK_SLOTS;
+	root = &data->root[tree];
 
-		nf_conncount_gc_list(net, &rbconn->list);
-		if (list_empty(&rbconn->list.head))
+	rcu_read_lock();
+	for (node = rb_first(root); node != NULL; node = rb_next(node)) {
+		rbconn = rb_entry(node, struct nf_conncount_rb, node);
+		if (nf_conncount_gc_list(data->net, &rbconn->list))
 			gc_nodes[gc_count++] = rbconn;
 	}
+	rcu_read_unlock();
+
+	spin_lock_bh(&nf_conncount_locks[tree]);
 
 	if (gc_count) {
-		no_gc = true;
 		tree_nodes_free(root, gc_nodes, gc_count);
-		/* tree_node_free before new allocation permits
-		 * allocator to re-use newly free'd object.
-		 *
-		 * This is a rare event; in most cases we will find
-		 * existing node to re-use. (or gc_count is 0).
-		 */
-		goto restart;
 	}
 
-	count = 0;
-	if (!tuple)
-		goto out_unlock;
+	clear_bit(tree, data->pending_trees);
 
-	spin_unlock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
-	return insert_tree(root, hash, key, keylen, tuple, zone);
+	next_tree = (tree + 1) % CONNCOUNT_SLOTS;
+	next_tree = find_next_bit(data->pending_trees, next_tree, CONNCOUNT_SLOTS);
 
-out_unlock:
-	spin_unlock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
-	return count;
+	if (next_tree < CONNCOUNT_SLOTS) {
+		data->gc_tree = next_tree;
+		schedule_work(work);
+	}
+
+	spin_unlock_bh(&nf_conncount_locks[tree]);
 }
 
 /* Count and return number of conntrack entries in 'net' with particular 'key'.
  * If 'tuple' is not null, insert it into the accounting data structure.
+ * Call with RCU read lock.
  */
 unsigned int nf_conncount_count(struct net *net,
 				struct nf_conncount_data *data,
@@ -452,6 +558,8 @@ struct nf_conncount_data *nf_conncount_init(struct net *net, unsigned int family
 		data->root[i] = RB_ROOT;
 
 	data->keylen = keylen / sizeof(u32);
+	data->net = net;
+	INIT_WORK(&data->gc_work, tree_gc_worker);
 
 	return data;
 }
@@ -487,6 +595,7 @@ void nf_conncount_destroy(struct net *net, unsigned int family,
 {
 	unsigned int i;
 
+	cancel_work_sync(&data->gc_work);
 	nf_ct_netns_put(net, family);
 
 	for (i = 0; i < ARRAY_SIZE(data->root); ++i)