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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 #endif
enum clusterip_hashmode hash_mode; /* which hashing mode */ enum clusterip_hashmode hash_mode; /* which hashing mode */
u_int32_t hash_initval; /* hash initialization */ u_int32_t hash_initval; /* hash initialization */
struct rcu_head rcu;
}; };
static LIST_HEAD(clusterip_configs); static LIST_HEAD(clusterip_configs);
/* clusterip_lock protects the clusterip_configs list */ /* clusterip_lock protects the clusterip_configs list */
static DEFINE_RWLOCK(clusterip_lock); static DEFINE_SPINLOCK(clusterip_lock);
#ifdef CONFIG_PROC_FS #ifdef CONFIG_PROC_FS
static const struct file_operations clusterip_proc_fops; static const struct file_operations clusterip_proc_fops;
@ -71,11 +72,17 @@ clusterip_config_get(struct clusterip_config *c)
atomic_inc(&c->refcount); 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 static inline void
clusterip_config_put(struct clusterip_config *c) clusterip_config_put(struct clusterip_config *c)
{ {
if (atomic_dec_and_test(&c->refcount)) 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 /* 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 static inline void
clusterip_config_entry_put(struct clusterip_config *c) clusterip_config_entry_put(struct clusterip_config *c)
{ {
write_lock_bh(&clusterip_lock); local_bh_disable();
if (atomic_dec_and_test(&c->entries)) { if (atomic_dec_and_lock(&c->entries, &clusterip_lock)) {
list_del(&c->list); list_del_rcu(&c->list);
write_unlock_bh(&clusterip_lock); spin_unlock(&clusterip_lock);
local_bh_enable();
dev_mc_del(c->dev, c->clustermac); dev_mc_del(c->dev, c->clustermac);
dev_put(c->dev); dev_put(c->dev);
@ -100,7 +108,7 @@ clusterip_config_entry_put(struct clusterip_config *c)
#endif #endif
return; return;
} }
write_unlock_bh(&clusterip_lock); local_bh_enable();
} }
static struct clusterip_config * static struct clusterip_config *
@ -108,7 +116,7 @@ __clusterip_config_find(__be32 clusterip)
{ {
struct clusterip_config *c; 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) if (c->clusterip == clusterip)
return c; return c;
} }
@ -121,16 +129,15 @@ clusterip_config_find_get(__be32 clusterip, int entry)
{ {
struct clusterip_config *c; struct clusterip_config *c;
read_lock_bh(&clusterip_lock); rcu_read_lock_bh();
c = __clusterip_config_find(clusterip); c = __clusterip_config_find(clusterip);
if (!c) { if (c) {
read_unlock_bh(&clusterip_lock); if (unlikely(!atomic_inc_not_zero(&c->refcount)))
return NULL; c = NULL;
else if (entry)
atomic_inc(&c->entries);
} }
atomic_inc(&c->refcount); rcu_read_unlock_bh();
if (entry)
atomic_inc(&c->entries);
read_unlock_bh(&clusterip_lock);
return c; return c;
} }
@ -181,9 +188,9 @@ clusterip_config_init(const struct ipt_clusterip_tgt_info *i, __be32 ip,
} }
#endif #endif
write_lock_bh(&clusterip_lock); spin_lock_bh(&clusterip_lock);
list_add(&c->list, &clusterip_configs); list_add_rcu(&c->list, &clusterip_configs);
write_unlock_bh(&clusterip_lock); spin_unlock_bh(&clusterip_lock);
return c; return c;
} }
@ -733,6 +740,9 @@ static void __exit clusterip_tg_exit(void)
#endif #endif
nf_unregister_hook(&cip_arp_ops); nf_unregister_hook(&cip_arp_ops);
xt_unregister_target(&clusterip_tg_reg); 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); module_init(clusterip_tg_init);