[NETFILTER]: nf_conntrack_expect: use RCU for expectation hash

Use RCU for expectation hash. This doesn't buy much for conntrack
runtime performance, but allows to reduce the use of nf_conntrack_lock
for /proc and nf_netlink_conntrack.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 6 deletions

diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
index 543c02b74c9..2fdcd9233a0 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
@@ -191,10 +191,12 @@ struct ct_expect_iter_state {
 static struct hlist_node *ct_expect_get_first(struct seq_file *seq)
 {
         struct ct_expect_iter_state *st = seq->private;
+        struct hlist_node *n;
 
         for (st->bucket = 0; st->bucket < nf_ct_expect_hsize; st->bucket++) {
-                if (!hlist_empty(&nf_ct_expect_hash[st->bucket]))
-                        return nf_ct_expect_hash[st->bucket].first;
+                n = rcu_dereference(nf_ct_expect_hash[st->bucket].first);
+                if (n)
+                        return n;
         }
         return NULL;
 }
@@ -204,11 +206,11 @@ static struct hlist_node *ct_expect_get_next(struct seq_file *seq,
 {
         struct ct_expect_iter_state *st = seq->private;
 
-        head = head->next;
+        head = rcu_dereference(head->next);
         while (head == NULL) {
                 if (++st->bucket >= nf_ct_expect_hsize)
                         return NULL;
-                head = nf_ct_expect_hash[st->bucket].first;
+                head = rcu_dereference(nf_ct_expect_hash[st->bucket].first);
         }
         return head;
 }
@@ -225,7 +227,7 @@ static struct hlist_node *ct_expect_get_idx(struct seq_file *seq, loff_t pos)
 
 static void *exp_seq_start(struct seq_file *seq, loff_t *pos)
 {
-        read_lock_bh(&nf_conntrack_lock);
+        rcu_read_lock();
         return ct_expect_get_idx(seq, *pos);
 }
 
@@ -237,7 +239,7 @@ static void *exp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 
 static void exp_seq_stop(struct seq_file *seq, void *v)
 {
-        read_unlock_bh(&nf_conntrack_lock);
+        rcu_read_unlock();
 }
 
 static int exp_seq_show(struct seq_file *s, void *v)