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netfilter: CLUSTERIP: RCU conversion

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- clusterip_lock becomes a spinlock
- lockless lookups
- kfree() deferred after RCU grace period
- rcu_barrier_bh() inserted in clusterip_tg_exit()

v2)
- As Patrick pointed out, we use atomic_inc_not_zero() in
clusterip_config_find_get().
- list_add_rcu() and list_del_rcu() variants are used.
- atomic_dec_and_lock() used in clusterip_config_entry_put()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Eric Dumazet 2010-06-15 13:08:51 +02:00 committed by Patrick McHardy
parent 0b041f8d1e
commit d73f33b168
1 changed files with 29 additions and 19 deletions
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48
net/ipv4/netfilter/ipt_CLUSTERIP.c
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@ -53,12 +53,13 @@ struct clusterip_config {
#endif
enum clusterip_hashmode hash_mode; /* which hashing mode */
u_int32_t hash_initval; /* hash initialization */
struct rcu_head rcu;
};
static LIST_HEAD(clusterip_configs);
/* clusterip_lock protects the clusterip_configs list */
static DEFINE_RWLOCK(clusterip_lock);
static DEFINE_SPINLOCK(clusterip_lock);
#ifdef CONFIG_PROC_FS
static const struct file_operations clusterip_proc_fops;
@ -71,11 +72,17 @@ clusterip_config_get(struct clusterip_config *c)
atomic_inc(&c->refcount);
}
static void clusterip_config_rcu_free(struct rcu_head *head)
{
kfree(container_of(head, struct clusterip_config, rcu));
}
static inline void
clusterip_config_put(struct clusterip_config *c)
{
if (atomic_dec_and_test(&c->refcount))
kfree(c);
call_rcu_bh(&c->rcu, clusterip_config_rcu_free);
}
/* decrease the count of entries using/referencing this config. If last
@ -84,10 +91,11 @@ clusterip_config_put(struct clusterip_config *c)
static inline void
clusterip_config_entry_put(struct clusterip_config *c)
{
write_lock_bh(&clusterip_lock);
if (atomic_dec_and_test(&c->entries)) {
list_del(&c->list);
write_unlock_bh(&clusterip_lock);
local_bh_disable();
if (atomic_dec_and_lock(&c->entries, &clusterip_lock)) {
list_del_rcu(&c->list);
spin_unlock(&clusterip_lock);
local_bh_enable();
dev_mc_del(c->dev, c->clustermac);
dev_put(c->dev);
@ -100,7 +108,7 @@ clusterip_config_entry_put(struct clusterip_config *c)
#endif
return;
}
write_unlock_bh(&clusterip_lock);
local_bh_enable();
}
static struct clusterip_config *
@ -108,7 +116,7 @@ __clusterip_config_find(__be32 clusterip)
{
struct clusterip_config *c;
list_for_each_entry(c, &clusterip_configs, list) {
list_for_each_entry_rcu(c, &clusterip_configs, list) {
if (c->clusterip == clusterip)
return c;
}
@ -121,16 +129,15 @@ clusterip_config_find_get(__be32 clusterip, int entry)
{
struct clusterip_config *c;
read_lock_bh(&clusterip_lock);
rcu_read_lock_bh();
c = __clusterip_config_find(clusterip);
if (!c) {
read_unlock_bh(&clusterip_lock);
return NULL;
if (c) {
if (unlikely(!atomic_inc_not_zero(&c->refcount)))
c = NULL;
else if (entry)
atomic_inc(&c->entries);
}
atomic_inc(&c->refcount);
if (entry)
atomic_inc(&c->entries);
read_unlock_bh(&clusterip_lock);
rcu_read_unlock_bh();
return c;
}
@ -181,9 +188,9 @@ clusterip_config_init(const struct ipt_clusterip_tgt_info *i, __be32 ip,
}
#endif
write_lock_bh(&clusterip_lock);
list_add(&c->list, &clusterip_configs);
write_unlock_bh(&clusterip_lock);
spin_lock_bh(&clusterip_lock);
list_add_rcu(&c->list, &clusterip_configs);
spin_unlock_bh(&clusterip_lock);
return c;
}
@ -733,6 +740,9 @@ static void __exit clusterip_tg_exit(void)
#endif
nf_unregister_hook(&cip_arp_ops);
xt_unregister_target(&clusterip_tg_reg);
/* Wait for completion of call_rcu_bh()'s (clusterip_config_rcu_free) */
rcu_barrier_bh();
}
module_init(clusterip_tg_init);