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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 024bba3..f9f7fd6 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3823,28 +3823,39 @@
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;
}
