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authorPablo Neira Ayuso <pablo@netfilter.org>2018-12-28 01:24:48 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2018-12-29 02:45:22 +0100
commitc80f10bc973af2ace6b1414724eeff61eaa71837 (patch)
treedb8a8a15e3a8c50b8a8a5626e200bf955a0eea89 /net
parent2f971a8f425545da52ca0e6bee81f5b1ea0ccc5f (diff)
netfilter: nf_conncount: speculative garbage collection on empty lists
Instead of removing a empty list node that might be reintroduced soon thereafter, tentatively place the empty list node on the list passed to tree_nodes_free(), then re-check if the list is empty again before erasing it from the tree. [ Florian: rebase on top of pending nf_conncount fixes ] Fixes: 5c789e131cbb9 ("netfilter: nf_conncount: Add list lock and gc worker, and RCU for init tree search") Reviewed-by: Shawn Bohrer <sbohrer@cloudflare.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nf_conncount.c47
1 files changed, 15 insertions, 32 deletions
diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c
index d0fd195b19a8..f0b05dfebc6e 100644
--- a/net/netfilter/nf_conncount.c
+++ b/net/netfilter/nf_conncount.c
@@ -81,27 +81,20 @@ static int key_diff(const u32 *a, const u32 *b, unsigned int klen)
return memcmp(a, b, klen * sizeof(u32));
}
-static bool conn_free(struct nf_conncount_list *list,
+static void conn_free(struct nf_conncount_list *list,
struct nf_conncount_tuple *conn)
{
- bool free_entry = false;
-
lockdep_assert_held(&list->list_lock);
list->count--;
list_del(&conn->node);
- if (list->count == 0) {
- list->dead = true;
- free_entry = true;
- }
kmem_cache_free(conncount_conn_cachep, conn);
- 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, bool *free_entry)
+ struct nf_conncount_tuple *conn)
{
const struct nf_conntrack_tuple_hash *found;
unsigned long a, b;
@@ -121,7 +114,7 @@ find_or_evict(struct net *net, struct nf_conncount_list *list,
*/
age = a - b;
if (conn->cpu == cpu || age >= 2) {
- *free_entry = conn_free(list, conn);
+ conn_free(list, conn);
return ERR_PTR(-ENOENT);
}
@@ -137,14 +130,13 @@ static int __nf_conncount_add(struct net *net,
struct nf_conncount_tuple *conn, *conn_n;
struct nf_conn *found_ct;
unsigned int collect = 0;
- bool free_entry = false;
/* check the saved connections */
list_for_each_entry_safe(conn, conn_n, &list->head, node) {
if (collect > CONNCOUNT_GC_MAX_NODES)
break;
- found = find_or_evict(net, list, conn, &free_entry);
+ found = find_or_evict(net, list, conn);
if (IS_ERR(found)) {
/* Not found, but might be about to be confirmed */
if (PTR_ERR(found) == -EAGAIN) {
@@ -221,7 +213,6 @@ void nf_conncount_list_init(struct nf_conncount_list *list)
spin_lock_init(&list->list_lock);
INIT_LIST_HEAD(&list->head);
list->count = 0;
- list->dead = false;
}
EXPORT_SYMBOL_GPL(nf_conncount_list_init);
@@ -233,7 +224,6 @@ bool nf_conncount_gc_list(struct net *net,
struct nf_conncount_tuple *conn, *conn_n;
struct nf_conn *found_ct;
unsigned int collected = 0;
- bool free_entry = false;
bool ret = false;
/* don't bother if other cpu is already doing GC */
@@ -241,15 +231,10 @@ bool nf_conncount_gc_list(struct net *net,
return false;
list_for_each_entry_safe(conn, conn_n, &list->head, node) {
- found = find_or_evict(net, list, conn, &free_entry);
+ found = find_or_evict(net, list, conn);
if (IS_ERR(found)) {
- if (PTR_ERR(found) == -ENOENT) {
- if (free_entry) {
- spin_unlock(&list->list_lock);
- return true;
- }
+ if (PTR_ERR(found) == -ENOENT)
collected++;
- }
continue;
}
@@ -260,10 +245,7 @@ bool nf_conncount_gc_list(struct net *net,
* closed already -> ditch it
*/
nf_ct_put(found_ct);
- if (conn_free(list, conn)) {
- spin_unlock(&list->list_lock);
- return true;
- }
+ conn_free(list, conn);
collected++;
continue;
}
@@ -273,10 +255,8 @@ bool nf_conncount_gc_list(struct net *net,
break;
}
- if (!list->count) {
- list->dead = true;
+ if (!list->count)
ret = true;
- }
spin_unlock(&list->list_lock);
return ret;
@@ -291,6 +271,7 @@ static void __tree_nodes_free(struct rcu_head *h)
kmem_cache_free(conncount_rb_cachep, rbconn);
}
+/* caller must hold tree nf_conncount_locks[] lock */
static void tree_nodes_free(struct rb_root *root,
struct nf_conncount_rb *gc_nodes[],
unsigned int gc_count)
@@ -300,8 +281,10 @@ static void tree_nodes_free(struct rb_root *root,
while (gc_count) {
rbconn = gc_nodes[--gc_count];
spin_lock(&rbconn->list.list_lock);
- rb_erase(&rbconn->node, root);
- call_rcu(&rbconn->rcu_head, __tree_nodes_free);
+ if (!rbconn->list.count) {
+ rb_erase(&rbconn->node, root);
+ call_rcu(&rbconn->rcu_head, __tree_nodes_free);
+ }
spin_unlock(&rbconn->list.list_lock);
}
}
@@ -318,7 +301,6 @@ insert_tree(struct net *net,
struct rb_root *root,
unsigned int hash,
const u32 *key,
- u8 keylen,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone)
{
@@ -327,6 +309,7 @@ insert_tree(struct net *net,
struct nf_conncount_rb *rbconn;
struct nf_conncount_tuple *conn;
unsigned int count = 0, gc_count = 0;
+ u8 keylen = data->keylen;
bool do_gc = true;
spin_lock_bh(&nf_conncount_locks[hash]);
@@ -454,7 +437,7 @@ count_tree(struct net *net,
if (!tuple)
return 0;
- return insert_tree(net, data, root, hash, key, keylen, tuple, zone);
+ return insert_tree(net, data, root, hash, key, tuple, zone);
}
static void tree_gc_worker(struct work_struct *work)

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