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ipv6: speedup inet6_dump_ifinfo()

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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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2009-11-09 12:11:28 +00:00 committed by David S. Miller
parent 13cfa97bef
commit 84d2697d96
1 changed files with 28 additions and 17 deletions
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45
net/ipv6/addrconf.c
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@ -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);
idx = 0;
for_each_netdev(net, dev) {
if (idx < s_idx)
goto cont;
if ((idev = in6_dev_get(dev)) == NULL)
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;
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;
head = &net->dev_index_head[h];
hlist_for_each_entry_rcu(dev, node, head, index_hlist) {
if (idx < s_idx)
goto cont;
idev = __in6_dev_get(dev);
if (!idev)
goto cont;
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++;
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;
}