netfilter: nf_conncount: Move locking into count_tree()

This patch is originally from Florian Westphal.

This is a preparation patch to allow lockless traversal
of the tree via RCU.

Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c
index 7dfd9d5e6a3edccc57d20525909c7259158bae3c..d1a4fd1c0f8116f89e66b624486587db29875a2d 100644 (file)
--- a/net/netfilter/nf_conncount.c
+++ b/net/netfilter/nf_conncount.c
@@ -262,18 +262,26 @@ static void tree_nodes_free(struct rb_root *root,
 }
 
 static unsigned int
-count_tree(struct net *net, struct rb_root *root,
-          const u32 *key, u8 keylen,
+count_tree(struct net *net,
+          struct nf_conncount_data *data,
+          const u32 *key,
           const struct nf_conntrack_tuple *tuple,
           const struct nf_conntrack_zone *zone)
 {
        struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES];
+       struct rb_root *root;
        struct rb_node **rbnode, *parent;
        struct nf_conncount_rb *rbconn;
        struct nf_conncount_tuple *conn;
-       unsigned int gc_count;
+       unsigned int gc_count, hash;
        bool no_gc = false;
+       unsigned int count = 0;
+       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;
@@ -292,20 +300,20 @@ count_tree(struct net *net, struct rb_root *root,
                        rbnode = &((*rbnode)->rb_right);
                } else {
                        /* same source network -> be counted! */
-                       unsigned int count;
-
                        nf_conncount_lookup(net, &rbconn->list, tuple, zone,
                                            &addit);
                        count = rbconn->list.count;
 
                        tree_nodes_free(root, gc_nodes, gc_count);
                        if (!addit)
-                               return count;
+                               goto out_unlock;
 
                        if (!nf_conncount_add(&rbconn->list, tuple, zone))
-                               return 0; /* hotdrop */
+                               count = 0; /* hotdrop */
+                               goto out_unlock;
 
-                       return count + 1;
+                       count++;
+                       goto out_unlock;
                }
 
                if (no_gc || gc_count >= ARRAY_SIZE(gc_nodes))
@@ -328,18 +336,18 @@ count_tree(struct net *net, struct rb_root *root,
                goto restart;
        }
 
+       count = 0;
        if (!tuple)
-               return 0;
-
+               goto out_unlock;
        /* no match, need to insert new node */
        rbconn = kmem_cache_alloc(conncount_rb_cachep, GFP_ATOMIC);
        if (rbconn == NULL)
-               return 0;
+               goto out_unlock;
 
        conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
        if (conn == NULL) {
                kmem_cache_free(conncount_rb_cachep, rbconn);
-               return 0;
+               goto out_unlock;
        }
 
        conn->tuple = *tuple;
@@ -348,10 +356,13 @@ count_tree(struct net *net, struct rb_root *root,
 
        nf_conncount_list_init(&rbconn->list);
        list_add(&conn->node, &rbconn->list.head);
+       count = 1;
 
        rb_link_node(&rbconn->node, parent, rbnode);
        rb_insert_color(&rbconn->node, root);
-       return 1;
+out_unlock:
+       spin_unlock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
+       return count;
 }
 
 /* Count and return number of conntrack entries in 'net' with particular 'key'.
@@ -363,20 +374,7 @@ unsigned int nf_conncount_count(struct net *net,
                                const struct nf_conntrack_tuple *tuple,
                                const struct nf_conntrack_zone *zone)
 {
-       struct rb_root *root;
-       int count;
-       u32 hash;
-
-       hash = jhash2(key, data->keylen, conncount_rnd) % CONNCOUNT_SLOTS;
-       root = &data->root[hash];
-
-       spin_lock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
-
-       count = count_tree(net, root, key, data->keylen, tuple, zone);
-
-       spin_unlock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
-
-       return count;
+       return count_tree(net, data, key, tuple, zone);
 }
 EXPORT_SYMBOL_GPL(nf_conncount_count);