openvswitch: Clarify locking.

Remove unnecessary locking from functions that are always called with
appropriate locking.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Signed-off-by: Thomas Graf <tgraf@redhat.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>

2 files changed, 9 insertions, 7 deletions

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 90a1e5e66287..138ea0c9e1b3 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -173,6 +173,7 @@ static struct hlist_head *vport_hash_bucket(const struct datapath *dp,
         return &dp->ports[port_no & (DP_VPORT_HASH_BUCKETS - 1)];
 }
 
+/* Called with ovs_mutex or RCU read lock. */
 struct vport *ovs_lookup_vport(const struct datapath *dp, u16 port_no)
 {
         struct vport *vport;
@@ -652,7 +653,7 @@ static size_t ovs_flow_cmd_msg_size(const struct sw_flow_actions *acts)
                 + nla_total_size(acts->actions_len); /* OVS_FLOW_ATTR_ACTIONS */
 }
 
-/* Called with ovs_mutex. */
+/* Called with ovs_mutex or RCU read lock. */
 static int ovs_flow_cmd_fill_info(struct sw_flow *flow, struct datapath *dp,
                                   struct sk_buff *skb, u32 portid,
                                   u32 seq, u32 flags, u8 cmd)
@@ -743,6 +744,7 @@ error:
         return err;
 }
 
+/* Must be called with ovs_mutex. */
 static struct sk_buff *ovs_flow_cmd_alloc_info(struct sw_flow *flow,
                                                struct genl_info *info)
 {
@@ -753,6 +755,7 @@ static struct sk_buff *ovs_flow_cmd_alloc_info(struct sw_flow *flow,
         return genlmsg_new_unicast(len, info, GFP_KERNEL);
 }
 
+/* Must be called with ovs_mutex. */
 static struct sk_buff *ovs_flow_cmd_build_info(struct sw_flow *flow,
                                                struct datapath *dp,
                                                struct genl_info *info,
@@ -1094,6 +1097,7 @@ static size_t ovs_dp_cmd_msg_size(void)
         return msgsize;
 }
 
+/* Called with ovs_mutex or RCU read lock. */
 static int ovs_dp_cmd_fill_info(struct datapath *dp, struct sk_buff *skb,
                                 u32 portid, u32 seq, u32 flags, u8 cmd)
 {
@@ -1109,9 +1113,7 @@ static int ovs_dp_cmd_fill_info(struct datapath *dp, struct sk_buff *skb,
 
         ovs_header->dp_ifindex = get_dpifindex(dp);
 
-        rcu_read_lock();
         err = nla_put_string(skb, OVS_DP_ATTR_NAME, ovs_dp_name(dp));
-        rcu_read_unlock();
         if (err)
                 goto nla_put_failure;
 
@@ -1136,6 +1138,7 @@ error:
         return -EMSGSIZE;
 }
 
+/* Must be called with ovs_mutex. */
 static struct sk_buff *ovs_dp_cmd_build_info(struct datapath *dp,
                                              struct genl_info *info, u8 cmd)
 {
@@ -1154,7 +1157,7 @@ static struct sk_buff *ovs_dp_cmd_build_info(struct datapath *dp,
         return skb;
 }
 
-/* Called with ovs_mutex. */
+/* Called with rcu_read_lock or ovs_mutex. */
 static struct datapath *lookup_datapath(struct net *net,
                                         struct ovs_header *ovs_header,
                                         struct nlattr *a[OVS_DP_ATTR_MAX + 1])
@@ -1166,10 +1169,8 @@ static struct datapath *lookup_datapath(struct net *net,
         else {
                 struct vport *vport;
 
-                rcu_read_lock();
                 vport = ovs_vport_locate(net, nla_data(a[OVS_DP_ATTR_NAME]));
                 dp = vport && vport->port_no == OVSP_LOCAL ? vport->dp : NULL;
-                rcu_read_unlock();
         }
         return dp ? dp : ERR_PTR(-ENODEV);
 }
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index 6d8d2da0a8ec..1019fc1db06e 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -122,6 +122,7 @@ unlock:
         spin_unlock(&stats->lock);
 }
 
+/* Called with ovs_mutex. */
 void ovs_flow_stats_get(struct sw_flow *flow, struct ovs_flow_stats *ovs_stats,
                         unsigned long *used, __be16 *tcp_flags)
 {
@@ -132,7 +133,7 @@ void ovs_flow_stats_get(struct sw_flow *flow, struct ovs_flow_stats *ovs_stats,
         memset(ovs_stats, 0, sizeof(*ovs_stats));
 
         for_each_node(node) {
-                struct flow_stats *stats = rcu_dereference(flow->stats[node]);
+                struct flow_stats *stats = ovsl_dereference(flow->stats[node]);
 
                 if (stats) {
                         /* Local CPU may write on non-local stats, so we must