openvswitch: Use RCU lock for dp dump operation.

RCUfy dp-dump operation which is already read-only. This
makes all ovs dump operations lockless.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index e6fb866e4ed4..9d97ef3c9830 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -951,9 +951,10 @@ static struct genl_ops dp_packet_genl_ops[] = {
 
 static void get_dp_stats(struct datapath *dp, struct ovs_dp_stats *stats)
 {
+        struct flow_table *table;
         int i;
-        struct flow_table *table = ovsl_dereference(dp->table);
 
+        table = rcu_dereference_check(dp->table, lockdep_ovsl_is_held());
         stats->n_flows = ovs_flow_tbl_count(table);
 
         stats->n_hit = stats->n_missed = stats->n_lost = 0;
@@ -1665,7 +1666,7 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
                 goto err_destroy_local_port;
 
         ovs_net = net_generic(ovs_dp_get_net(dp), ovs_net_id);
-        list_add_tail(&dp->list_node, &ovs_net->dps);
+        list_add_tail_rcu(&dp->list_node, &ovs_net->dps);
 
         ovs_unlock();
 
@@ -1703,7 +1704,7 @@ static void __dp_destroy(struct datapath *dp)
                                 ovs_dp_detach_port(vport);
         }
 
-        list_del(&dp->list_node);
+        list_del_rcu(&dp->list_node);
 
         /* OVSP_LOCAL is datapath internal port. We need to make sure that
          * all port in datapath are destroyed first before freeing datapath.
@@ -1808,8 +1809,8 @@ static int ovs_dp_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
         int skip = cb->args[0];
         int i = 0;
 
-        ovs_lock();
-        list_for_each_entry(dp, &ovs_net->dps, list_node) {
+        rcu_read_lock();
+        list_for_each_entry_rcu(dp, &ovs_net->dps, list_node) {
                 if (i >= skip &&
                     ovs_dp_cmd_fill_info(dp, skb, NETLINK_CB(cb->skb).portid,
                                          cb->nlh->nlmsg_seq, NLM_F_MULTI,
@@ -1817,7 +1818,7 @@ static int ovs_dp_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
                         break;
                 i++;
         }
-        ovs_unlock();
+        rcu_read_unlock();
 
         cb->args[0] = i;