ipv6: use xa_array iterator to implement inet6_netconf_dump_devconf()

1) inet6_netconf_dump_devconf() can run under RCU protection
   instead of RTNL.

2) properly return 0 at the end of a dump, avoiding an
   an extra recvmsg() system call.

3) Do not use inet6_base_seq() anymore, for_each_netdev_dump()
   has nice properties. Restarting a GETDEVCONF dump if a device has
   been added/removed or if net->ipv6.dev_addr_genid has changed is moot.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 436d9a6e6a82e1a0b99e190aa54255460706c565..2f84e6ecf19f48602cadb47bc378c9b5a1cdbf65 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -727,17 +727,18 @@ static u32 inet6_base_seq(const struct net *net)
        return res;
 }
 
-
 static int inet6_netconf_dump_devconf(struct sk_buff *skb,
                                      struct netlink_callback *cb)
 {
        const struct nlmsghdr *nlh = cb->nlh;
        struct net *net = sock_net(skb->sk);
-       int h, s_h;
-       int idx, s_idx;
+       struct {
+               unsigned long ifindex;
+               unsigned int all_default;
+       } *ctx = (void *)cb->ctx;
        struct net_device *dev;
        struct inet6_dev *idev;
-       struct hlist_head *head;
+       int err = 0;
 
        if (cb->strict_check) {
                struct netlink_ext_ack *extack = cb->extack;
@@ -754,64 +755,48 @@ static int inet6_netconf_dump_devconf(struct sk_buff *skb,
                }
        }
 
-       s_h = cb->args[0];
-       s_idx = idx = cb->args[1];
-
-       for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
-               idx = 0;
-               head = &net->dev_index_head[h];
-               rcu_read_lock();
-               cb->seq = inet6_base_seq(net);
-               hlist_for_each_entry_rcu(dev, head, index_hlist) {
-                       if (idx < s_idx)
-                               goto cont;
-                       idev = __in6_dev_get(dev);
-                       if (!idev)
-                               goto cont;
-
-                       if (inet6_netconf_fill_devconf(skb, dev->ifindex,
-                                                      &idev->cnf,
-                                                      NETLINK_CB(cb->skb).portid,
-                                                      nlh->nlmsg_seq,
-                                                      RTM_NEWNETCONF,
-                                                      NLM_F_MULTI,
-                                                      NETCONFA_ALL) < 0) {
-                               rcu_read_unlock();
-                               goto done;
-                       }
-                       nl_dump_check_consistent(cb, nlmsg_hdr(skb));
-cont:
-                       idx++;
-               }
-               rcu_read_unlock();
+       rcu_read_lock();
+       for_each_netdev_dump(net, dev, ctx->ifindex) {
+               idev = __in6_dev_get(dev);
+               if (!idev)
+                       continue;
+               err = inet6_netconf_fill_devconf(skb, dev->ifindex,
+                                                &idev->cnf,
+                                                NETLINK_CB(cb->skb).portid,
+                                                nlh->nlmsg_seq,
+                                                RTM_NEWNETCONF,
+                                                NLM_F_MULTI,
+                                                NETCONFA_ALL);
+               if (err < 0)
+                       goto done;
        }
-       if (h == NETDEV_HASHENTRIES) {
-               if (inet6_netconf_fill_devconf(skb, NETCONFA_IFINDEX_ALL,
-                                              net->ipv6.devconf_all,
-                                              NETLINK_CB(cb->skb).portid,
-                                              nlh->nlmsg_seq,
-                                              RTM_NEWNETCONF, NLM_F_MULTI,
-                                              NETCONFA_ALL) < 0)
+       if (ctx->all_default == 0) {
+               err = inet6_netconf_fill_devconf(skb, NETCONFA_IFINDEX_ALL,
+                                                net->ipv6.devconf_all,
+                                                NETLINK_CB(cb->skb).portid,
+                                                nlh->nlmsg_seq,
+                                                RTM_NEWNETCONF, NLM_F_MULTI,
+                                                NETCONFA_ALL);
+               if (err < 0)
                        goto done;
-               else
-                       h++;
-       }
-       if (h == NETDEV_HASHENTRIES + 1) {
-               if (inet6_netconf_fill_devconf(skb, NETCONFA_IFINDEX_DEFAULT,
-                                              net->ipv6.devconf_dflt,
-                                              NETLINK_CB(cb->skb).portid,
-                                              nlh->nlmsg_seq,
-                                              RTM_NEWNETCONF, NLM_F_MULTI,
-                                              NETCONFA_ALL) < 0)
+               ctx->all_default++;
+       }
+       if (ctx->all_default == 1) {
+               err = inet6_netconf_fill_devconf(skb, NETCONFA_IFINDEX_DEFAULT,
+                                                net->ipv6.devconf_dflt,
+                                                NETLINK_CB(cb->skb).portid,
+                                                nlh->nlmsg_seq,
+                                                RTM_NEWNETCONF, NLM_F_MULTI,
+                                                NETCONFA_ALL);
+               if (err < 0)
                        goto done;
-               else
-                       h++;
+               ctx->all_default++;
        }
 done:
-       cb->args[0] = h;
-       cb->args[1] = idx;
-
-       return skb->len;
+       if (err < 0 && likely(skb->len))
+               err = skb->len;
+       rcu_read_unlock();
+       return err;
 }
 
 #ifdef CONFIG_SYSCTL
@@ -7503,7 +7488,8 @@ int __init addrconf_init(void)
        err = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETNETCONF,
                                   inet6_netconf_get_devconf,
                                   inet6_netconf_dump_devconf,
-                                  RTNL_FLAG_DOIT_UNLOCKED);
+                                  RTNL_FLAG_DOIT_UNLOCKED |
+                                  RTNL_FLAG_DUMP_UNLOCKED);
        if (err < 0)
                goto errout;
        err = ipv6_addr_label_rtnl_register();