datapath: 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>
Acked-by: Jesse Gross <jesse@nicira.com>

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 2f02f71..eb07a89 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -972,9 +972,10 @@ 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;
@@ -1747,7 +1748,7 @@ 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();
 
@@ -1785,7 +1786,7 @@ 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.
@@ -1902,8 +1903,8 @@ 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,
@@ -1911,7 +1912,7 @@ 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;