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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) static int inet6_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
{ {
struct net *net = sock_net(skb->sk); struct net *net = sock_net(skb->sk);
int idx, err; int h, s_h;
int s_idx = cb->args[0]; int idx = 0, err, s_idx;
struct net_device *dev; struct net_device *dev;
struct inet6_dev *idev; struct inet6_dev *idev;
struct hlist_head *head;
struct hlist_node *node;
read_lock(&dev_base_lock); s_h = cb->args[0];
idx = 0; s_idx = cb->args[1];
for_each_netdev(net, dev) {
if (idx < s_idx) rcu_read_lock();
goto cont; for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
if ((idev = in6_dev_get(dev)) == NULL) idx = 0;
goto cont; head = &net->dev_index_head[h];
err = inet6_fill_ifinfo(skb, idev, NETLINK_CB(cb->skb).pid, hlist_for_each_entry_rcu(dev, node, head, index_hlist) {
cb->nlh->nlmsg_seq, RTM_NEWLINK, NLM_F_MULTI); if (idx < s_idx)
in6_dev_put(idev); goto cont;
if (err <= 0) idev = __in6_dev_get(dev);
break; 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: cont:
idx++; idx++;
}
} }
read_unlock(&dev_base_lock); out:
cb->args[0] = idx; rcu_read_unlock();
cb->args[1] = idx;
cb->args[0] = h;
return skb->len; return skb->len;
} }