datapath: 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>

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 71792de..93f8e36 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -175,6 +175,7 @@ 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;
@@ -653,7 +654,7 @@ 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)
@@ -744,6 +745,7 @@ 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)
 {
@@ -754,6 +756,7 @@ 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,
@@ -1095,6 +1098,7 @@ 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)
 {
@@ -1110,9 +1114,7 @@ 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;
 
@@ -1137,6 +1139,7 @@ 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)
 {
@@ -1155,7 +1158,7 @@ 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])
@@ -1167,10 +1170,8 @@ 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/datapath/flow.c b/datapath/flow.c
index 4e9c4c7..5d1d2f2 100644 (file)
--- a/datapath/flow.c
+++ b/datapath/flow.c
@@ -123,6 +123,7 @@ 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)
 {
@@ -133,7 +134,7 @@ 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