ipv6: use xa_array iterator to implement inet6_dump_addr()

inet6_dump_addr() can use the new xa_array iterator
for better scalability.

Make it ready for RCU-only protection.
RTNL use is removed in the following patch.

Also properly return 0 at the end of a dump to avoid
and extra recvmsg() to get NLMSG_DONE.

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

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index c662972..4359e49 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -717,7 +717,7 @@ errout:
 static u32 inet6_base_seq(const struct net *net)
 {
        u32 res = atomic_read(&net->ipv6.dev_addr_genid) +
-                 net->dev_base_seq;
+                 READ_ONCE(net->dev_base_seq);
 
        /* Must not return 0 (see nl_dump_check_consistent()).
         * Chose a value far away from 0.
@@ -5272,13 +5272,13 @@ static int inet6_fill_ifacaddr(struct sk_buff *skb,
 
 /* called with rcu_read_lock() */
 static int in6_dump_addrs(const struct inet6_dev *idev, struct sk_buff *skb,
-                         struct netlink_callback *cb, int s_ip_idx,
+                         struct netlink_callback *cb, int *s_ip_idx,
                          struct inet6_fill_args *fillargs)
 {
        const struct ifmcaddr6 *ifmca;
        const struct ifacaddr6 *ifaca;
        int ip_idx = 0;
-       int err = 1;
+       int err = 0;
 
        switch (fillargs->type) {
        case UNICAST_ADDR: {
@@ -5287,7 +5287,7 @@ static int in6_dump_addrs(const struct inet6_dev *idev, struct sk_buff *skb,
 
                /* unicast address incl. temp addr */
                list_for_each_entry_rcu(ifa, &idev->addr_list, if_list) {
-                       if (ip_idx < s_ip_idx)
+                       if (ip_idx < *s_ip_idx)
                                goto next;
                        err = inet6_fill_ifaddr(skb, ifa, fillargs);
                        if (err < 0)
@@ -5305,7 +5305,7 @@ next:
                for (ifmca = rcu_dereference(idev->mc_list);
                     ifmca;
                     ifmca = rcu_dereference(ifmca->next), ip_idx++) {
-                       if (ip_idx < s_ip_idx)
+                       if (ip_idx < *s_ip_idx)
                                continue;
                        err = inet6_fill_ifmcaddr(skb, ifmca, fillargs);
                        if (err < 0)
@@ -5317,7 +5317,7 @@ next:
                /* anycast address */
                for (ifaca = rcu_dereference(idev->ac_list); ifaca;
                     ifaca = rcu_dereference(ifaca->aca_next), ip_idx++) {
-                       if (ip_idx < s_ip_idx)
+                       if (ip_idx < *s_ip_idx)
                                continue;
                        err = inet6_fill_ifacaddr(skb, ifaca, fillargs);
                        if (err < 0)
@@ -5327,7 +5327,7 @@ next:
        default:
                break;
        }
-       cb->args[2] = ip_idx;
+       *s_ip_idx = err ? ip_idx : 0;
        return err;
 }
 
@@ -5390,6 +5390,7 @@ static int inet6_valid_dump_ifaddr_req(const struct nlmsghdr *nlh,
 static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb,
                           enum addr_type_t type)
 {
+       struct net *tgt_net = sock_net(skb->sk);
        const struct nlmsghdr *nlh = cb->nlh;
        struct inet6_fill_args fillargs = {
                .portid = NETLINK_CB(cb->skb).portid,
@@ -5398,72 +5399,52 @@ static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb,
                .netnsid = -1,
                .type = type,
        };
-       struct net *tgt_net = sock_net(skb->sk);
-       int idx, s_idx, s_ip_idx;
-       int h, s_h;
+       struct {
+               unsigned long ifindex;
+               int ip_idx;
+       } *ctx = (void *)cb->ctx;
        struct net_device *dev;
        struct inet6_dev *idev;
-       struct hlist_head *head;
        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 = inet6_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;
-                       }
+                       err = -ENODEV;
+                       dev = dev_get_by_index_rcu(tgt_net, fillargs.ifindex);
+                       if (!dev)
+                               goto done;
                        idev = __in6_dev_get(dev);
-                       if (idev) {
-                               err = in6_dump_addrs(idev, skb, cb, s_ip_idx,
+                       if (idev)
+                               err = in6_dump_addrs(idev, skb, cb,
+                                                    &ctx->ip_idx,
                                                     &fillargs);
-                               if (err > 0)
-                                       err = 0;
-                       }
-                       goto put_tgt_net;
+                       goto done;
                }
        }
 
        cb->seq = inet6_base_seq(tgt_net);
-       for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
-               idx = 0;
-               head = &tgt_net->dev_index_head[h];
-               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;
-                       idev = __in6_dev_get(dev);
-                       if (!idev)
-                               goto cont;
-
-                       if (in6_dump_addrs(idev, skb, cb, s_ip_idx,
-                                          &fillargs) < 0)
-                               goto done;
-cont:
-                       idx++;
-               }
+       for_each_netdev_dump(tgt_net, dev, ctx->ifindex) {
+               idev = __in6_dev_get(dev);
+               if (!idev)
+                       continue;
+               err = in6_dump_addrs(idev, skb, cb, &ctx->ip_idx,
+                                    &fillargs);
+               if (err < 0)
+                       goto done;
        }
 done:
-       cb->args[0] = h;
-       cb->args[1] = idx;
-put_tgt_net:
        rcu_read_unlock();
        if (fillargs.netnsid >= 0)
                put_net(tgt_net);
 
-       return skb->len ? : err;
+       return err;
 }
 
 static int inet6_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)