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Commit 84d2697d authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv6: speedup inet6_dump_ifinfo() 



When handling large number of netdevice, inet6_dump_ifinfo()
is very slow because it has O(N^2) complexity.

Instead of scanning one single list, we can use the 256 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 13cfa97b

net/ipv6/addrconf.c

+28 −17
Original line number Diff line number Diff line
@@ -3823,28 +3823,39 @@ nla_put_failure: 
static int inet6_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)

{

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

	int idx, err;

	int s_idx = cb->args[0];

	int h, s_h;

	int idx = 0, err, s_idx;

	struct net_device *dev;

	struct inet6_dev *idev;

	struct hlist_head *head;

	struct hlist_node *node;



	read_lock(&dev_base_lock);

	s_h = cb->args[0];

	s_idx = cb->args[1];



	rcu_read_lock();

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

		idx = 0;

	for_each_netdev(net, dev) {

		head = &net->dev_index_head[h];

		hlist_for_each_entry_rcu(dev, node, head, index_hlist) {

			if (idx < s_idx)

				goto cont;

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

			idev = __in6_dev_get(dev);

			if (!idev)

				goto cont;

		err = inet6_fill_ifinfo(skb, idev, NETLINK_CB(cb->skb).pid,

				cb->nlh->nlmsg_seq, RTM_NEWLINK, NLM_F_MULTI);

		in6_dev_put(idev);

		if (err <= 0)

			break;

			if (inet6_fill_ifinfo(skb, idev,

					      NETLINK_CB(cb->skb).pid,

					      cb->nlh->nlmsg_seq,

					      RTM_NEWLINK, NLM_F_MULTI) <= 0)

				goto out;

cont:

			idx++;

		}

	read_unlock(&dev_base_lock);

	cb->args[0] = idx;

	}

out:

	rcu_read_unlock();

	cb->args[1] = idx;

	cb->args[0] = h;



	return skb->len;

}