From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
xt_hashlimit uses a central lock per hash table and suffers from
contention on some workloads. (Multiqueue NIC or if RPS is enabled)
After RCU conversion, central lock is only used when a writer wants to
add or delete an entry.
For 'readers', updating an existing entry, they use an individual lock
per entry.
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
net/netfilter/xt_hashlimit.c | 70 ++++++++++++++++++++++++++++--------------
1 files changed, 47 insertions(+), 23 deletions(-)
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index 5470bb0..453178d 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -81,12 +81,14 @@ struct dsthash_ent {
struct dsthash_dst dst;
/* modified structure members in the end */
+ spinlock_t lock;
unsigned long expires; /* precalculated expiry time */
struct {
unsigned long prev; /* last modification */
u_int32_t credit;
u_int32_t credit_cap, cost;
} rateinfo;
+ struct rcu_head rcu;
};
struct xt_hashlimit_htable {
@@ -143,9 +145,11 @@ dsthash_find(const struct xt_hashlimit_htable *ht,
u_int32_t hash = hash_dst(ht, dst);
if (!hlist_empty(&ht->hash[hash])) {
- hlist_for_each_entry(ent, pos, &ht->hash[hash], node)
- if (dst_cmp(ent, dst))
+ hlist_for_each_entry_rcu(ent, pos, &ht->hash[hash], node)
+ if (dst_cmp(ent, dst)) {
+ spin_lock(&ent->lock);
return ent;
+ }
}
return NULL;
}
@@ -157,9 +161,10 @@ dsthash_alloc_init(struct xt_hashlimit_htable *ht,
{
struct dsthash_ent *ent;
+ spin_lock(&ht->lock);
/* initialize hash with random val at the time we allocate
* the first hashtable entry */
- if (!ht->rnd_initialized) {
+ if (unlikely(!ht->rnd_initialized)) {
get_random_bytes(&ht->rnd, sizeof(ht->rnd));
ht->rnd_initialized = true;
}
@@ -168,27 +173,36 @@ dsthash_alloc_init(struct xt_hashlimit_htable *ht,
/* FIXME: do something. question is what.. */
if (net_ratelimit())
pr_err("max count of %u reached\n", ht->cfg.max);
- return NULL;
- }
-
- ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
+ ent = NULL;
+ } else
+ ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
if (!ent) {
if (net_ratelimit())
pr_err("cannot allocate dsthash_ent\n");
- return NULL;
- }
- memcpy(&ent->dst, dst, sizeof(ent->dst));
+ } else {
+ memcpy(&ent->dst, dst, sizeof(ent->dst));
+ spin_lock_init(&ent->lock);
- hlist_add_head(&ent->node, &ht->hash[hash_dst(ht, dst)]);
- ht->count++;
+ spin_lock(&ent->lock);
+ hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
+ ht->count++;
+ }
+ spin_unlock(&ht->lock);
return ent;
}
+static void dsthash_free_rcu(struct rcu_head *head)
+{
+ struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
+
+ kmem_cache_free(hashlimit_cachep, ent);
+}
+
static inline void
dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
{
- hlist_del(&ent->node);
- kmem_cache_free(hashlimit_cachep, ent);
+ hlist_del_rcu(&ent->node);
+ call_rcu_bh(&ent->rcu, dsthash_free_rcu);
ht->count--;
}
static void htable_gc(unsigned long htlong);
@@ -512,15 +526,14 @@ hashlimit_mt(const struct sk_buff *skb, const struct xt_match_param *par)
if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
goto hotdrop;
- spin_lock_bh(&hinfo->lock);
+ rcu_read_lock_bh();
dh = dsthash_find(hinfo, &dst);
if (dh == NULL) {
dh = dsthash_alloc_init(hinfo, &dst);
if (dh == NULL) {
- spin_unlock_bh(&hinfo->lock);
+ rcu_read_unlock_bh();
goto hotdrop;
}
-
dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
dh->rateinfo.prev = jiffies;
dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
@@ -537,11 +550,13 @@ hashlimit_mt(const struct sk_buff *skb, const struct xt_match_param *par)
if (dh->rateinfo.credit >= dh->rateinfo.cost) {
/* below the limit */
dh->rateinfo.credit -= dh->rateinfo.cost;
- spin_unlock_bh(&hinfo->lock);
+ spin_unlock(&dh->lock);
+ rcu_read_unlock_bh();
return !(info->cfg.mode & XT_HASHLIMIT_INVERT);
}
- spin_unlock_bh(&hinfo->lock);
+ spin_unlock(&dh->lock);
+ rcu_read_unlock_bh();
/* default match is underlimit - so over the limit, we need to invert */
return info->cfg.mode & XT_HASHLIMIT_INVERT;
@@ -666,12 +681,15 @@ static void dl_seq_stop(struct seq_file *s, void *v)
static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
struct seq_file *s)
{
+ int res;
+
+ spin_lock(&ent->lock);
/* recalculate to show accurate numbers */
rateinfo_recalc(ent, jiffies);
switch (family) {
case NFPROTO_IPV4:
- return seq_printf(s, "%ld %pI4:%u->%pI4:%u %u %u %u\n",
+ res = seq_printf(s, "%ld %pI4:%u->%pI4:%u %u %u %u\n",
(long)(ent->expires - jiffies)/HZ,
&ent->dst.ip.src,
ntohs(ent->dst.src_port),
@@ -679,9 +697,10 @@ static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
ntohs(ent->dst.dst_port),
ent->rateinfo.credit, ent->rateinfo.credit_cap,
ent->rateinfo.cost);
+ break;
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
case NFPROTO_IPV6:
- return seq_printf(s, "%ld %pI6:%u->%pI6:%u %u %u %u\n",
+ res = seq_printf(s, "%ld %pI6:%u->%pI6:%u %u %u %u\n",
(long)(ent->expires - jiffies)/HZ,
&ent->dst.ip6.src,
ntohs(ent->dst.src_port),
@@ -689,11 +708,14 @@ static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
ntohs(ent->dst.dst_port),
ent->rateinfo.credit, ent->rateinfo.credit_cap,
ent->rateinfo.cost);
+ break;
#endif
default:
BUG();
- return 0;
+ res = 0;
}
+ spin_unlock(&ent->lock);
+ return res;
}
static int dl_seq_show(struct seq_file *s, void *v)
@@ -817,9 +839,11 @@ err1:
static void __exit hashlimit_mt_exit(void)
{
- kmem_cache_destroy(hashlimit_cachep);
xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
unregister_pernet_subsys(&hashlimit_net_ops);
+
+ rcu_barrier_bh();
+ kmem_cache_destroy(hashlimit_cachep);
}
module_init(hashlimit_mt_init);
--
1.7.0.4
--
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