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Commit 234b27c3 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv6: speedup inet6_dump_addr() 



When handling large number of netdevices, inet6_dump_addr()
is very slow because it has O(N^2) complexity.

Instead of scanning one single list, we can use the NETDEV_HASHENTRIES
sub lists of the dev_index hash table, and RCU lookups.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5256f2ef

net/ipv6/addrconf.c

+97 −74
Original line number Diff line number Diff line
@@ -3481,31 +3481,17 @@ enum addr_type_t 
	ANYCAST_ADDR,

};



static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb,

			   enum addr_type_t type)

/* called with rcu_read_lock() */

static int in6_dump_addrs(struct inet6_dev *idev, struct sk_buff *skb,

			  struct netlink_callback *cb, enum addr_type_t type,

			  int s_ip_idx, int *p_ip_idx)

{

	int idx, ip_idx;

	int s_idx, s_ip_idx;

	int err = 1;

	struct net_device *dev;

	struct inet6_dev *idev = NULL;

	struct inet6_ifaddr *ifa;

	struct ifmcaddr6 *ifmca;

	struct ifacaddr6 *ifaca;

	struct net *net = sock_net(skb->sk);



	s_idx = cb->args[0];

	s_ip_idx = ip_idx = cb->args[1];

	int err = 1;

	int ip_idx = *p_ip_idx;



	idx = 0;

	for_each_netdev(net, dev) {

		if (idx < s_idx)

			goto cont;

		if (idx > s_idx)

			s_ip_idx = 0;

		ip_idx = 0;

		if ((idev = in6_dev_get(dev)) == NULL)

			goto cont;

	read_lock_bh(&idev->lock);

	switch (type) {

	case UNICAST_ADDR:
@@ -3557,15 +3543,52 @@ static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb, 
		break;

	}

	read_unlock_bh(&idev->lock);

		in6_dev_put(idev);

	*p_ip_idx = ip_idx;

	return err;

}



		if (err <= 0)

			break;

static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb,

			   enum addr_type_t type)

{

	struct net *net = sock_net(skb->sk);

	int h, s_h;

	int idx, ip_idx;

	int s_idx, s_ip_idx;

	struct net_device *dev;

	struct inet6_dev *idev;

	struct hlist_head *head;

	struct hlist_node *node;



	s_h = cb->args[0];

	s_idx = idx = cb->args[1];

	s_ip_idx = ip_idx = cb->args[2];



	rcu_read_lock();

	for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {

		idx = 0;

		head = &net->dev_index_head[h];

		hlist_for_each_entry_rcu(dev, node, head, index_hlist) {

			if (idx < s_idx)

				goto cont;

			if (idx > s_idx)

				s_ip_idx = 0;

			ip_idx = 0;

			if ((idev = __in6_dev_get(dev)) == NULL)

				goto cont;



			if (in6_dump_addrs(idev, skb, cb, type,

					   s_ip_idx, &ip_idx) <= 0)

				goto done;

cont:

			idx++;

		}

	cb->args[0] = idx;

	cb->args[1] = ip_idx;

	}

done:

	rcu_read_unlock();

	cb->args[0] = h;

	cb->args[1] = idx;

	cb->args[2] = ip_idx;



	return skb->len;

}