Commit b8b7ed1e authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Jakub Kicinski
Browse files

neighbour: Drop read_lock_bh(&tbl->lock) in pneigh_lookup(). 



Now, all callers of pneigh_lookup() are under RCU, and the read
lock there is no longer needed.

Let's drop the lock, inline __pneigh_lookup_1() to pneigh_lookup(),
and call it from pneigh_create().

The next patch will remove tbl->lock from pneigh_create().

Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250716221221.442239-14-kuniyu@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent dd103c9a

net/core/neighbour.c

+16 −27
Original line number Diff line number Diff line
@@ -720,23 +720,6 @@ static u32 pneigh_hash(const void *pkey, unsigned int key_len) 
	return hash_val;

}



static struct pneigh_entry *__pneigh_lookup_1(struct pneigh_entry *n,

					      struct net *net,

					      const void *pkey,

					      unsigned int key_len,

					      struct net_device *dev)

{

	while (n) {

		if (!memcmp(n->key, pkey, key_len) &&

		    net_eq(pneigh_net(n), net) &&

		    (n->dev == dev || !n->dev))

			return n;



		n = rcu_dereference_protected(n->next, 1);

	}

	return NULL;

}



struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl,

				   struct net *net, const void *pkey,

				   struct net_device *dev)
@@ -747,13 +730,19 @@ struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, 


	key_len = tbl->key_len;

	hash_val = pneigh_hash(pkey, key_len);

	n = rcu_dereference_check(tbl->phash_buckets[hash_val],

				  lockdep_is_held(&tbl->lock));



	read_lock_bh(&tbl->lock);

	n = __pneigh_lookup_1(rcu_dereference_protected(tbl->phash_buckets[hash_val], 1),

			      net, pkey, key_len, dev);

	read_unlock_bh(&tbl->lock);



	while (n) {

		if (!memcmp(n->key, pkey, key_len) &&

		    net_eq(pneigh_net(n), net) &&

		    (n->dev == dev || !n->dev))

			return n;



		n = rcu_dereference_check(n->next, lockdep_is_held(&tbl->lock));

	}



	return NULL;

}

EXPORT_IPV6_MOD(pneigh_lookup);
@@ -762,19 +751,18 @@ struct pneigh_entry *pneigh_create(struct neigh_table *tbl, 
				   struct net_device *dev)

{

	struct pneigh_entry *n;

	unsigned int key_len = tbl->key_len;

	u32 hash_val = pneigh_hash(pkey, key_len);

	unsigned int key_len;

	u32 hash_val;



	ASSERT_RTNL();



	read_lock_bh(&tbl->lock);

	n = __pneigh_lookup_1(rcu_dereference_protected(tbl->phash_buckets[hash_val], 1),

			      net, pkey, key_len, dev);

	n = pneigh_lookup(tbl, net, pkey, dev);

	read_unlock_bh(&tbl->lock);



	if (n)

		goto out;



	key_len = tbl->key_len;

	n = kzalloc(sizeof(*n) + key_len, GFP_KERNEL);

	if (!n)

		goto out;
@@ -791,6 +779,7 @@ struct pneigh_entry *pneigh_create(struct neigh_table *tbl, 
		goto out;

	}



	hash_val = pneigh_hash(pkey, key_len);

	write_lock_bh(&tbl->lock);

	n->next = tbl->phash_buckets[hash_val];

	rcu_assign_pointer(tbl->phash_buckets[hash_val], n);