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: 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 9ff8ab9..522bdc7 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3481,91 +3481,114 @@ enum addr_type_t
        ANYCAST_ADDR,
 };
 
+/* 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)
+{
+       struct inet6_ifaddr *ifa;
+       struct ifmcaddr6 *ifmca;
+       struct ifacaddr6 *ifaca;
+       int err = 1;
+       int ip_idx = *p_ip_idx;
+
+       read_lock_bh(&idev->lock);
+       switch (type) {
+       case UNICAST_ADDR:
+               /* unicast address incl. temp addr */
+               for (ifa = idev->addr_list; ifa;
+                    ifa = ifa->if_next, ip_idx++) {
+                       if (ip_idx < s_ip_idx)
+                               continue;
+                       err = inet6_fill_ifaddr(skb, ifa,
+                                               NETLINK_CB(cb->skb).pid,
+                                               cb->nlh->nlmsg_seq,
+                                               RTM_NEWADDR,
+                                               NLM_F_MULTI);
+                       if (err <= 0)
+                               break;
+               }
+               break;
+       case MULTICAST_ADDR:
+               /* multicast address */
+               for (ifmca = idev->mc_list; ifmca;
+                    ifmca = ifmca->next, ip_idx++) {
+                       if (ip_idx < s_ip_idx)
+                               continue;
+                       err = inet6_fill_ifmcaddr(skb, ifmca,
+                                                 NETLINK_CB(cb->skb).pid,
+                                                 cb->nlh->nlmsg_seq,
+                                                 RTM_GETMULTICAST,
+                                                 NLM_F_MULTI);
+                       if (err <= 0)
+                               break;
+               }
+               break;
+       case ANYCAST_ADDR:
+               /* anycast address */
+               for (ifaca = idev->ac_list; ifaca;
+                    ifaca = ifaca->aca_next, ip_idx++) {
+                       if (ip_idx < s_ip_idx)
+                               continue;
+                       err = inet6_fill_ifacaddr(skb, ifaca,
+                                                 NETLINK_CB(cb->skb).pid,
+                                                 cb->nlh->nlmsg_seq,
+                                                 RTM_GETANYCAST,
+                                                 NLM_F_MULTI);
+                       if (err <= 0)
+                               break;
+               }
+               break;
+       default:
+               break;
+       }
+       read_unlock_bh(&idev->lock);
+       *p_ip_idx = ip_idx;
+       return err;
+}
+
 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;
-       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);
+       struct inet6_dev *idev;
+       struct hlist_head *head;
+       struct hlist_node *node;
 
-       s_idx = cb->args[0];
-       s_ip_idx = ip_idx = cb->args[1];
+       s_h = cb->args[0];
+       s_idx = idx = cb->args[1];
+       s_ip_idx = ip_idx = cb->args[2];
 
-       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:
-                       /* unicast address incl. temp addr */
-                       for (ifa = idev->addr_list; ifa;
-                            ifa = ifa->if_next, ip_idx++) {
-                               if (ip_idx < s_ip_idx)
-                                       continue;
-                               err = inet6_fill_ifaddr(skb, ifa,
-                                                       NETLINK_CB(cb->skb).pid,
-                                                       cb->nlh->nlmsg_seq,
-                                                       RTM_NEWADDR,
-                                                       NLM_F_MULTI);
-                               if (err <= 0)
-                                       break;
-                       }
-                       break;
-               case MULTICAST_ADDR:
-                       /* multicast address */
-                       for (ifmca = idev->mc_list; ifmca;
-                            ifmca = ifmca->next, ip_idx++) {
-                               if (ip_idx < s_ip_idx)
-                                       continue;
-                               err = inet6_fill_ifmcaddr(skb, ifmca,
-                                                         NETLINK_CB(cb->skb).pid,
-                                                         cb->nlh->nlmsg_seq,
-                                                         RTM_GETMULTICAST,
-                                                         NLM_F_MULTI);
-                               if (err <= 0)
-                                       break;
-                       }
-                       break;
-               case ANYCAST_ADDR:
-                       /* anycast address */
-                       for (ifaca = idev->ac_list; ifaca;
-                            ifaca = ifaca->aca_next, ip_idx++) {
-                               if (ip_idx < s_ip_idx)
-                                       continue;
-                               err = inet6_fill_ifacaddr(skb, ifaca,
-                                                         NETLINK_CB(cb->skb).pid,
-                                                         cb->nlh->nlmsg_seq,
-                                                         RTM_GETANYCAST,
-                                                         NLM_F_MULTI);
-                               if (err <= 0)
-                                       break;
-                       }
-                       break;
-               default:
-                       break;
-               }
-               read_unlock_bh(&idev->lock);
-               in6_dev_put(idev);
+       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 (err <= 0)
-                       break;
+                       if (in6_dump_addrs(idev, skb, cb, type,
+                                          s_ip_idx, &ip_idx) <= 0)
+                               goto done;
 cont:
-               idx++;
+                       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;
 }