Commit bed1be20 authored by Eric Dumazet's avatar Eric Dumazet Committed by Patrick McHardy
Browse files

netfilter: nfnetlink_log: RCU conversion 



- instances_lock becomes a spinlock
- lockless lookups

While nfnetlink_log probably not performance critical, using less
rwlocks in our code is always welcomed...

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
parent c463ac97

net/netfilter/nfnetlink_log.c

+27 −22
Original line number Diff line number Diff line
@@ -66,9 +66,10 @@ struct nfulnl_instance { 
	u_int16_t group_num;		/* number of this queue */

	u_int16_t flags;

	u_int8_t copy_mode;

	struct rcu_head rcu;

};



static DEFINE_RWLOCK(instances_lock);

static DEFINE_SPINLOCK(instances_lock);

static atomic_t global_seq;



#define INSTANCE_BUCKETS	16
@@ -88,7 +89,7 @@ __instance_lookup(u_int16_t group_num) 
	struct nfulnl_instance *inst;



	head = &instance_table[instance_hashfn(group_num)];

	hlist_for_each_entry(inst, pos, head, hlist) {

	hlist_for_each_entry_rcu(inst, pos, head, hlist) {

		if (inst->group_num == group_num)

			return inst;

	}
@@ -106,22 +107,26 @@ instance_lookup_get(u_int16_t group_num) 
{

	struct nfulnl_instance *inst;



	read_lock_bh(&instances_lock);

	rcu_read_lock_bh();

	inst = __instance_lookup(group_num);

	if (inst)

		instance_get(inst);

	read_unlock_bh(&instances_lock);

	rcu_read_unlock_bh();



	return inst;

}



static void

instance_put(struct nfulnl_instance *inst)

static void nfulnl_instance_free_rcu(struct rcu_head *head)

{

	if (inst && atomic_dec_and_test(&inst->use)) {

		kfree(inst);

	kfree(container_of(head, struct nfulnl_instance, rcu));

	module_put(THIS_MODULE);

}



static void

instance_put(struct nfulnl_instance *inst)

{

	if (inst && atomic_dec_and_test(&inst->use))

		call_rcu_bh(&inst->rcu, nfulnl_instance_free_rcu);

}



static void nfulnl_timer(unsigned long data);
@@ -132,7 +137,7 @@ instance_create(u_int16_t group_num, int pid) 
	struct nfulnl_instance *inst;

	int err;



	write_lock_bh(&instances_lock);

	spin_lock_bh(&instances_lock);

	if (__instance_lookup(group_num)) {

		err = -EEXIST;

		goto out_unlock;
@@ -169,12 +174,12 @@ instance_create(u_int16_t group_num, int pid) 
	hlist_add_head(&inst->hlist,

		       &instance_table[instance_hashfn(group_num)]);



	write_unlock_bh(&instances_lock);

	spin_unlock_bh(&instances_lock);



	return inst;



out_unlock:

	write_unlock_bh(&instances_lock);

	spin_unlock_bh(&instances_lock);

	return ERR_PTR(err);

}
@@ -200,9 +205,9 @@ __instance_destroy(struct nfulnl_instance *inst) 
static inline void

instance_destroy(struct nfulnl_instance *inst)

{

	write_lock_bh(&instances_lock);

	spin_lock_bh(&instances_lock);

	__instance_destroy(inst);

	write_unlock_bh(&instances_lock);

	spin_unlock_bh(&instances_lock);

}



static int
@@ -672,7 +677,7 @@ nfulnl_rcv_nl_event(struct notifier_block *this, 
		int i;



		/* destroy all instances for this pid */

		write_lock_bh(&instances_lock);

		spin_lock_bh(&instances_lock);

		for  (i = 0; i < INSTANCE_BUCKETS; i++) {

			struct hlist_node *tmp, *t2;

			struct nfulnl_instance *inst;
@@ -684,7 +689,7 @@ nfulnl_rcv_nl_event(struct notifier_block *this, 
					__instance_destroy(inst);

			}

		}

		write_unlock_bh(&instances_lock);

		spin_unlock_bh(&instances_lock);

	}

	return NOTIFY_DONE;

}
@@ -861,19 +866,19 @@ static struct hlist_node *get_first(struct iter_state *st) 


	for (st->bucket = 0; st->bucket < INSTANCE_BUCKETS; st->bucket++) {

		if (!hlist_empty(&instance_table[st->bucket]))

			return instance_table[st->bucket].first;

			return rcu_dereference_bh(instance_table[st->bucket].first);

	}

	return NULL;

}



static struct hlist_node *get_next(struct iter_state *st, struct hlist_node *h)

{

	h = h->next;

	h = rcu_dereference_bh(h->next);

	while (!h) {

		if (++st->bucket >= INSTANCE_BUCKETS)

			return NULL;



		h = instance_table[st->bucket].first;

		h = rcu_dereference_bh(instance_table[st->bucket].first);

	}

	return h;

}
@@ -890,9 +895,9 @@ static struct hlist_node *get_idx(struct iter_state *st, loff_t pos) 
}



static void *seq_start(struct seq_file *seq, loff_t *pos)

	__acquires(instances_lock)

	__acquires(rcu_bh)

{

	read_lock_bh(&instances_lock);

	rcu_read_lock_bh();

	return get_idx(seq->private, *pos);

}
@@ -903,9 +908,9 @@ static void *seq_next(struct seq_file *s, void *v, loff_t *pos) 
}



static void seq_stop(struct seq_file *s, void *v)

	__releases(instances_lock)

	__releases(rcu_bh)

{

	read_unlock_bh(&instances_lock);

	rcu_read_unlock_bh();

}



static int seq_show(struct seq_file *s, void *v)