1 files changed, 19 insertions, 7 deletions

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);