inet: use xa_array iterator to implement inet_dump_ifaddr()

1) inet_dump_ifaddr() can 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.

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

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 2afe78dfc3c2f6c0394925f1c35532a2dfd26d71..4daa8124f247c256c4f8c1ff29ac621570af0755 100644 (file)
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1676,7 +1676,7 @@ static int put_cacheinfo(struct sk_buff *skb, unsigned long cstamp,
        return nla_put(skb, IFA_CACHEINFO, sizeof(ci), &ci);
 }
 
-static int inet_fill_ifaddr(struct sk_buff *skb, struct in_ifaddr *ifa,
+static int inet_fill_ifaddr(struct sk_buff *skb, const struct in_ifaddr *ifa,
                            struct inet_fill_args *args)
 {
        struct ifaddrmsg *ifm;
@@ -1805,15 +1805,15 @@ static int inet_valid_dump_ifaddr_req(const struct nlmsghdr *nlh,
 }
 
 static int in_dev_dump_addr(struct in_device *in_dev, struct sk_buff *skb,
-                           struct netlink_callback *cb, int s_ip_idx,
+                           struct netlink_callback *cb, int *s_ip_idx,
                            struct inet_fill_args *fillargs)
 {
        struct in_ifaddr *ifa;
        int ip_idx = 0;
        int err;
 
-       in_dev_for_each_ifa_rtnl(ifa, in_dev) {
-               if (ip_idx < s_ip_idx) {
+       in_dev_for_each_ifa_rcu(ifa, in_dev) {
+               if (ip_idx < *s_ip_idx) {
                        ip_idx++;
                        continue;
                }
@@ -1825,9 +1825,9 @@ static int in_dev_dump_addr(struct in_device *in_dev, struct sk_buff *skb,
                ip_idx++;
        }
        err = 0;
-
+       ip_idx = 0;
 done:
-       cb->args[2] = ip_idx;
+       *s_ip_idx = ip_idx;
 
        return err;
 }
@@ -1859,75 +1859,53 @@ static int inet_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
        };
        struct net *net = sock_net(skb->sk);
        struct net *tgt_net = net;
-       int h, s_h;
-       int idx, s_idx;
-       int s_ip_idx;
-       struct net_device *dev;
+       struct {
+               unsigned long ifindex;
+               int ip_idx;
+       } *ctx = (void *)cb->ctx;
        struct in_device *in_dev;
-       struct hlist_head *head;
+       struct net_device *dev;
        int err = 0;
 
-       s_h = cb->args[0];
-       s_idx = idx = cb->args[1];
-       s_ip_idx = cb->args[2];
-
+       rcu_read_lock();
        if (cb->strict_check) {
                err = inet_valid_dump_ifaddr_req(nlh, &fillargs, &tgt_net,
                                                 skb->sk, cb);
                if (err < 0)
-                       goto put_tgt_net;
+                       goto done;
 
-               err = 0;
                if (fillargs.ifindex) {
-                       dev = __dev_get_by_index(tgt_net, fillargs.ifindex);
-                       if (!dev) {
-                               err = -ENODEV;
-                               goto put_tgt_net;
-                       }
-
-                       in_dev = __in_dev_get_rtnl(dev);
-                       if (in_dev) {
-                               err = in_dev_dump_addr(in_dev, skb, cb, s_ip_idx,
-                                                      &fillargs);
-                       }
-                       goto put_tgt_net;
-               }
-       }
-
-       for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
-               idx = 0;
-               head = &tgt_net->dev_index_head[h];
-               rcu_read_lock();
-               cb->seq = inet_base_seq(tgt_net);
-               hlist_for_each_entry_rcu(dev, head, index_hlist) {
-                       if (idx < s_idx)
-                               goto cont;
-                       if (h > s_h || idx > s_idx)
-                               s_ip_idx = 0;
+                       err = -ENODEV;
+                       dev = dev_get_by_index_rcu(tgt_net, fillargs.ifindex);
+                       if (!dev)
+                               goto done;
                        in_dev = __in_dev_get_rcu(dev);
                        if (!in_dev)
-                               goto cont;
-
-                       err = in_dev_dump_addr(in_dev, skb, cb, s_ip_idx,
-                                              &fillargs);
-                       if (err < 0) {
-                               rcu_read_unlock();
                                goto done;
-                       }
-cont:
-                       idx++;
+                       err = in_dev_dump_addr(in_dev, skb, cb, &ctx->ip_idx,
+                                              &fillargs);
+                       goto done;
                }
-               rcu_read_unlock();
        }
 
+       cb->seq = inet_base_seq(tgt_net);
+
+       for_each_netdev_dump(net, dev, ctx->ifindex) {
+               in_dev = __in_dev_get_rcu(dev);
+               if (!in_dev)
+                       continue;
+               err = in_dev_dump_addr(in_dev, skb, cb, &ctx->ip_idx,
+                                      &fillargs);
+               if (err < 0)
+                       goto done;
+       }
 done:
-       cb->args[0] = h;
-       cb->args[1] = idx;
-put_tgt_net:
+       if (err < 0 && likely(skb->len))
+               err = skb->len;
        if (fillargs.netnsid >= 0)
                put_net(tgt_net);
-
-       return skb->len ? : err;
+       rcu_read_unlock();
+       return err;
 }
 
 static void rtmsg_ifa(int event, struct in_ifaddr *ifa, struct nlmsghdr *nlh,
@@ -2818,7 +2796,8 @@ void __init devinet_init(void)
 
        rtnl_register(PF_INET, RTM_NEWADDR, inet_rtm_newaddr, NULL, 0);
        rtnl_register(PF_INET, RTM_DELADDR, inet_rtm_deladdr, NULL, 0);
-       rtnl_register(PF_INET, RTM_GETADDR, NULL, inet_dump_ifaddr, 0);
+       rtnl_register(PF_INET, RTM_GETADDR, NULL, inet_dump_ifaddr,
+                     RTNL_FLAG_DUMP_UNLOCKED);
        rtnl_register(PF_INET, RTM_GETNETCONF, inet_netconf_get_devconf,
                      inet_netconf_dump_devconf,
                      RTNL_FLAG_DOIT_UNLOCKED | RTNL_FLAG_DUMP_UNLOCKED);