3 files changed, 34 insertions, 12 deletions

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index c10036e7a463..89cb047ab314 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -782,11 +782,15 @@ skip_listen_ht:
                 struct sock *sk;
                 struct hlist_node *node;
 
+                num = 0;
+
+                if (hlist_empty(&head->chain) && hlist_empty(&head->twchain))
+                        continue;
+
                 if (i > s_i)
                         s_num = 0;
 
                 read_lock_bh(lock);
-                num = 0;
                 sk_for_each(sk, node, &head->chain) {
                         struct inet_sock *inet = inet_sk(sk);
 
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index cca921ea8550..71598f64c113 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -282,6 +282,8 @@ static struct rtable *rt_cache_get_first(struct seq_file *seq)
         struct rtable *r = NULL;
 
         for (st->bucket = rt_hash_mask; st->bucket >= 0; --st->bucket) {
+                if (!rt_hash_table[st->bucket].chain)
+                        continue;
                 rcu_read_lock_bh();
                 r = rcu_dereference(rt_hash_table[st->bucket].chain);
                 while (r) {
@@ -299,11 +301,14 @@ static struct rtable *__rt_cache_get_next(struct seq_file *seq,
                                           struct rtable *r)
 {
         struct rt_cache_iter_state *st = seq->private;
+
         r = r->u.dst.rt_next;
         while (!r) {
                 rcu_read_unlock_bh();
-                if (--st->bucket < 0)
-                        break;
+                do {
+                        if (--st->bucket < 0)
+                                return NULL;
+                } while (!rt_hash_table[st->bucket].chain);
                 rcu_read_lock_bh();
                 r = rt_hash_table[st->bucket].chain;
         }
@@ -2840,7 +2845,9 @@ int ip_rt_dump(struct sk_buff *skb,  struct netlink_callback *cb)
         if (s_h < 0)
                 s_h = 0;
         s_idx = idx = cb->args[1];
-        for (h = s_h; h <= rt_hash_mask; h++) {
+        for (h = s_h; h <= rt_hash_mask; h++, s_idx = 0) {
+                if (!rt_hash_table[h].chain)
+                        continue;
                 rcu_read_lock_bh();
                 for (rt = rcu_dereference(rt_hash_table[h].chain), idx = 0; rt;
                      rt = rcu_dereference(rt->u.dst.rt_next), idx++) {
@@ -2859,7 +2866,6 @@ int ip_rt_dump(struct sk_buff *skb,  struct netlink_callback *cb)
                         dst_release(xchg(&skb->dst, NULL));
                 }
                 rcu_read_unlock_bh();
-                s_idx = 0;
         }
 
 done:
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 44c1e934824b..37ca3843c40b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1946,6 +1946,12 @@ static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
         return rc;
 }
 
+static inline int empty_bucket(struct tcp_iter_state *st)
+{
+        return hlist_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
+                hlist_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
+}
+
 static void *established_get_first(struct seq_file *seq)
 {
         struct tcp_iter_state* st = seq->private;
@@ -1958,6 +1964,10 @@ static void *established_get_first(struct seq_file *seq)
                 struct inet_timewait_sock *tw;
                 rwlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
 
+                /* Lockless fast path for the common case of empty buckets */
+                if (empty_bucket(st))
+                        continue;
+
                 read_lock_bh(lock);
                 sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
                         if (sk->sk_family != st->family ||
@@ -2008,13 +2018,15 @@ get_tw:
                 read_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
                 st->state = TCP_SEQ_STATE_ESTABLISHED;
 
-                if (++st->bucket < tcp_hashinfo.ehash_size) {
-                        read_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
-                        sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain);
-                } else {
-                        cur = NULL;
-                        goto out;
-                }
+                /* Look for next non empty bucket */
+                while (++st->bucket < tcp_hashinfo.ehash_size &&
+                                empty_bucket(st))
+                        ;
+                if (st->bucket >= tcp_hashinfo.ehash_size)
+                        return NULL;
+
+                read_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
+                sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain);
         } else
                 sk = sk_next(sk);