netlink: Use rhashtable walk interface in diag dump

This patch converts the diag dumping code to use the rhashtable
walk code instead of going through rhashtable by hand.  The lock
nl_table_lock is now only taken while we process the multicast
list as it's not needed for the rhashtable walk.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 73 insertions, 30 deletions

diff --git a/net/netlink/diag.c b/net/netlink/diag.c
index 8dd836a8dd60..3e3e2534478a 100644
--- a/net/netlink/diag.c
+++ b/net/netlink/diag.c
@@ -63,43 +63,75 @@ out_nlmsg_trim:
 static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
                                 int protocol, int s_num)
 {
+        struct rhashtable_iter *hti = (void *)cb->args[2];
         struct netlink_table *tbl = &nl_table[protocol];
-        struct rhashtable *ht = &tbl->hash;
-        const struct bucket_table *htbl = rht_dereference_rcu(ht->tbl, ht);
         struct net *net = sock_net(skb->sk);
         struct netlink_diag_req *req;
         struct netlink_sock *nlsk;
         struct sock *sk;
-        int ret = 0, num = 0, i;
+        int num = 2;
+        int ret = 0;
 
         req = nlmsg_data(cb->nlh);
 
-        for (i = 0; i < htbl->size; i++) {
-                struct rhash_head *pos;
+        if (s_num > 1)
+                goto mc_list;
 
-                rht_for_each_entry_rcu(nlsk, pos, htbl, i, node) {
-                        sk = (struct sock *)nlsk;
+        num--;
 
-                        if (!net_eq(sock_net(sk), net))
-                                continue;
-                        if (num < s_num) {
-                                num++;
+        if (!hti) {
+                hti = kmalloc(sizeof(*hti), GFP_KERNEL);
+                if (!hti)
+                        return -ENOMEM;
+
+                cb->args[2] = (long)hti;
+        }
+
+        if (!s_num)
+                rhashtable_walk_enter(&tbl->hash, hti);
+
+        ret = rhashtable_walk_start(hti);
+        if (ret == -EAGAIN)
+                ret = 0;
+        if (ret)
+                goto stop;
+
+        while ((nlsk = rhashtable_walk_next(hti))) {
+                if (IS_ERR(nlsk)) {
+                        ret = PTR_ERR(nlsk);
+                        if (ret == -EAGAIN) {
+                                ret = 0;
                                 continue;
                         }
+                        break;
+                }
 
-                        if (sk_diag_fill(sk, skb, req,
-                                         NETLINK_CB(cb->skb).portid,
-                                         cb->nlh->nlmsg_seq,
-                                         NLM_F_MULTI,
-                                         sock_i_ino(sk)) < 0) {
-                                ret = 1;
-                                goto done;
-                        }
+                sk = (struct sock *)nlsk;
 
-                        num++;
+                if (!net_eq(sock_net(sk), net))
+                        continue;
+
+                if (sk_diag_fill(sk, skb, req,
+                                 NETLINK_CB(cb->skb).portid,
+                                 cb->nlh->nlmsg_seq,
+                                 NLM_F_MULTI,
+                                 sock_i_ino(sk)) < 0) {
+                        ret = 1;
+                        break;
                 }
         }
 
+stop:
+        rhashtable_walk_stop(hti);
+        if (ret)
+                goto done;
+
+        rhashtable_walk_exit(hti);
+        cb->args[2] = 0;
+        num++;
+
+mc_list:
+        read_lock(&nl_table_lock);
         sk_for_each_bound(sk, &tbl->mc_list) {
                 if (sk_hashed(sk))
                         continue;
@@ -116,13 +148,14 @@ static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
                                  NLM_F_MULTI,
                                  sock_i_ino(sk)) < 0) {
                         ret = 1;
-                        goto done;
+                        break;
                 }
                 num++;
         }
+        read_unlock(&nl_table_lock);
+
 done:
         cb->args[0] = num;
-        cb->args[1] = protocol;
 
         return ret;
 }
@@ -131,20 +164,20 @@ static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
 {
         struct netlink_diag_req *req;
         int s_num = cb->args[0];
+        int err = 0;
 
         req = nlmsg_data(cb->nlh);
 
-        rcu_read_lock();
-        read_lock(&nl_table_lock);
-
         if (req->sdiag_protocol == NDIAG_PROTO_ALL) {
                 int i;
 
                 for (i = cb->args[1]; i < MAX_LINKS; i++) {
-                        if (__netlink_diag_dump(skb, cb, i, s_num))
+                        err = __netlink_diag_dump(skb, cb, i, s_num);
+                        if (err)
                                 break;
                         s_num = 0;
                 }
+                cb->args[1] = i;
         } else {
                 if (req->sdiag_protocol >= MAX_LINKS) {
                         read_unlock(&nl_table_lock);
@@ -152,13 +185,22 @@ static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
                         return -ENOENT;
                 }
 
-                __netlink_diag_dump(skb, cb, req->sdiag_protocol, s_num);
+                err = __netlink_diag_dump(skb, cb, req->sdiag_protocol, s_num);
         }
 
-        read_unlock(&nl_table_lock);
-        rcu_read_unlock();
+        return err < 0 ? err : skb->len;
+}
+
+static int netlink_diag_dump_done(struct netlink_callback *cb)
+{
+        struct rhashtable_iter *hti = (void *)cb->args[2];
+
+        if (cb->args[0] == 1)
+                rhashtable_walk_exit(hti);
 
-        return skb->len;
+        kfree(hti);
+
+        return 0;
 }
 
 static int netlink_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
@@ -172,6 +214,7 @@ static int netlink_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
         if (h->nlmsg_flags & NLM_F_DUMP) {
                 struct netlink_dump_control c = {
                         .dump = netlink_diag_dump,
+                        .done = netlink_diag_dump_done,
                 };
                 return netlink_dump_start(net->diag_nlsk, skb, h, &c);
         } else