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Commit d73f33b1 authored by Eric Dumazet's avatar Eric Dumazet Committed by Patrick McHardy
Browse files

netfilter: CLUSTERIP: RCU conversion 



- 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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
parent 0b041f8d

net/ipv4/netfilter/ipt_CLUSTERIP.c

+29 −19
Original line number Diff line number Diff line
@@ -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;

	}

	atomic_inc(&c->refcount);

	if (entry)

	if (c) {

		if (unlikely(!atomic_inc_not_zero(&c->refcount)))

			c = NULL;

		else 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);