lkml.org 
[lkml]   [2019]   [Jan]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.19 12/99] netfilter: nf_conncount: speculative garbage collection on empty lists
Date
4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pablo Neira Ayuso <pablo@netfilter.org>

commit c80f10bc973af2ace6b1414724eeff61eaa71837 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/net/netfilter/nf_conntrack_count.h | 1
net/netfilter/nf_conncount.c | 47 +++++++++--------------------
2 files changed, 15 insertions(+), 33 deletions(-)

--- a/include/net/netfilter/nf_conntrack_count.h
+++ b/include/net/netfilter/nf_conntrack_count.h
@@ -9,7 +9,6 @@ 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,
--- a/net/netfilter/nf_conncount.c
+++ b/net/netfilter/nf_conncount.c
@@ -81,27 +81,20 @@ static int key_diff(const u32 *a, const
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
*/
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
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_co
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 *ne
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 *ne
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 *ne
* 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 *ne
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
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_ro
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)

\
 
 \ /
  Last update: 2019-01-21 15:09    [W:0.317 / U:46.924 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site