From: Florian Westphal <fw@xxxxxxxxx>
Add garbage collection worker.
Move the rbnode reclaim logic from search tree to insert tree
to avoid race condition.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Yi-Hung Wei <yihung.wei@xxxxxxxxx>
---
include/net/netfilter/nf_conntrack_count.h | 14 ++-
net/netfilter/nf_conncount.c | 163 +++++++++++++++++++++--------
net/netfilter/nft_connlimit.c | 2 +-
3 files changed, 132 insertions(+), 47 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack_count.h b/include/net/netfilter/nf_conntrack_count.h
index af0c1c95eccd..4b2b2baf8ab4 100644
--- a/include/net/netfilter/nf_conntrack_count.h
+++ b/include/net/netfilter/nf_conntrack_count.h
@@ -5,10 +5,17 @@
struct nf_conncount_data;
+enum nf_conncount_list_add {
+ NF_CONNCOUNT_ADDED, /* list add was ok */
+ NF_CONNCOUNT_ERR, /* -ENOMEM, must drop skb */
+ NF_CONNCOUNT_SKIP, /* list is already reclaimed by gc */
+};
+
struct nf_conncount_list {
spinlock_t list_lock;
struct list_head head; /* connections with the same filtering key */
unsigned int count; /* length of list */
+ bool dead;
};
struct nf_conncount_data *nf_conncount_init(struct net *net, unsigned int family,
@@ -29,9 +36,10 @@ void nf_conncount_lookup(struct net *net, struct nf_conncount_list *list,
void nf_conncount_list_init(struct nf_conncount_list *list);
-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);
bool nf_conncount_gc_list(struct net *net,
struct nf_conncount_list *list);
diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c
index 760ba24db735..7e93487e5856 100644
--- a/net/netfilter/nf_conncount.c
+++ b/net/netfilter/nf_conncount.c
@@ -62,6 +62,10 @@ 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;
@@ -82,25 +86,32 @@ 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;
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++;
spin_unlock(&list->list_lock);
- return true;
+ return NF_CONNCOUNT_ADDED;
}
EXPORT_SYMBOL_GPL(nf_conncount_add);
@@ -192,6 +203,7 @@ 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);
@@ -250,23 +262,39 @@ static void tree_nodes_free(struct rb_root *root,
while (gc_count) {
rbconn = gc_nodes[--gc_count];
- rb_erase(&rbconn->node, root);
- call_rcu(&rbconn->rcu_head, __tree_nodes_free);
+ 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]);
@@ -284,16 +312,44 @@ 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)
@@ -327,19 +383,16 @@ 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 *parent;
struct nf_conncount_rb *rbconn;
- unsigned int gc_count, hash;
- bool no_gc = false;
+ unsigned int hash;
u8 keylen = data->keylen;
hash = jhash2(key, data->keylen, conncount_rnd) % CONNCOUNT_SLOTS;
root = &data->root[hash];
- restart:
- gc_count = 0;
parent = rcu_dereference_raw(root->rb_node);
while (parent) {
int diff;
@@ -357,44 +410,65 @@ count_tree(struct net *net,
nf_conncount_lookup(net, &rbconn->list, tuple, zone,
&addit);
- spin_lock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
- tree_nodes_free(root, gc_nodes, gc_count);
- spin_unlock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
-
if (!addit)
return rbconn->list.count;
- if (!nf_conncount_add(&rbconn->list, tuple, zone))
+ ret = nf_conncount_add(&rbconn->list, tuple, zone);
+ if (ret == NF_CONNCOUNT_ERR) {
return 0; /* hotdrop */
-
- return rbconn->list.count;
+ } 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 (no_gc || gc_count >= ARRAY_SIZE(gc_nodes))
- continue;
+ if (!tuple)
+ return 0;
- if (nf_conncount_gc_list(net, &rbconn->list))
+ return insert_tree(net, data, root, hash, key, keylen, tuple, zone);
+}
+
+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];
+
+ 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;
- spin_lock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
tree_nodes_free(root, gc_nodes, gc_count);
- spin_unlock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
- /* 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;
}
- if (!tuple)
- return 0;
+ clear_bit(tree, data->pending_trees);
+
+ next_tree = (tree + 1) % CONNCOUNT_SLOTS;
+ next_tree = find_next_bit(data->pending_trees, next_tree, CONNCOUNT_SLOTS);
+
+ if (next_tree < CONNCOUNT_SLOTS) {
+ data->gc_tree = next_tree;
+ schedule_work(work);
+ }
- return insert_tree(root, hash, key, keylen, tuple, zone);
+ spin_unlock_bh(&nf_conncount_locks[tree]);
}
/* Count and return number of conntrack entries in 'net' with particular 'key'.
@@ -438,6 +512,8 @@ 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;
}
@@ -473,6 +549,7 @@ 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)
diff --git a/net/netfilter/nft_connlimit.c b/net/netfilter/nft_connlimit.c
index 3dbc737915da..b90d96ba4a12 100644
--- a/net/netfilter/nft_connlimit.c
+++ b/net/netfilter/nft_connlimit.c
@@ -51,7 +51,7 @@ static inline void nft_connlimit_do_eval(struct nft_connlimit *priv,
if (!addit)
goto out;
- if (!nf_conncount_add(&priv->list, tuple_ptr, zone)) {
+ if (nf_conncount_add(&priv->list, tuple_ptr, zone) == NF_CONNCOUNT_ERR) {
regs->verdict.code = NF_DROP;
return;
}
--
2.7.4
--
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