datapath: Directly use methods for protecting RCU/RTNL data.

We currently have a wrapper to protect the datapath ports array.
However, this can lead to confusion over exactly what lock is
protecting the access (either RTNL or RCU).  This removes the
wrapper in favor of directly accessing the data, which also has
the benefit of being less permissive about what lock we allow so
it can be restricted to the one that we expect.

Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 93947ee..a69461d 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -112,12 +112,6 @@ static struct datapath *get_dp(int dp_ifindex)
        return dp;
 }
 
-/* Must be called with rcu_read_lock or RTNL lock. */
-static struct vport *get_vport_protected(struct datapath *dp, u16 port_no)
-{
-       return rcu_dereference_rtnl(dp->ports[port_no]);
-}
-
 /* Must be called with rcu_read_lock or RTNL lock. */
 const char *dp_name(const struct datapath *dp)
 {
@@ -132,7 +126,7 @@ static int get_dpifindex(struct datapath *dp)
 
        rcu_read_lock();
 
-       local = get_vport_protected(dp, OVSP_LOCAL);
+       local = rcu_dereference(dp->ports[OVSP_LOCAL]);
        if (local)
                ifindex = local->ops->get_ifindex(local);
        else
@@ -1421,7 +1415,7 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
        return 0;
 
 err_destroy_local_port:
-       dp_detach_port(get_vport_protected(dp, OVSP_LOCAL));
+       dp_detach_port(rtnl_dereference(dp->ports[OVSP_LOCAL]));
 err_destroy_percpu:
        free_percpu(dp->stats_percpu);
 err_destroy_table:
@@ -1465,7 +1459,7 @@ static int ovs_dp_cmd_del(struct sk_buff *skb, struct genl_info *info)
 
        dp_sysfs_del_dp(dp);
        list_del(&dp->list_node);
-       dp_detach_port(get_vport_protected(dp, OVSP_LOCAL));
+       dp_detach_port(rtnl_dereference(dp->ports[OVSP_LOCAL]));
 
        /* rtnl_unlock() will wait until all the references to devices that
         * are pending unregistration have been dropped.  We do it here to
@@ -1696,7 +1690,7 @@ static struct vport *lookup_vport(struct ovs_header *ovs_header,
                if (!dp)
                        return ERR_PTR(-ENODEV);
 
-               vport = get_vport_protected(dp, port_no);
+               vport = rcu_dereference_rtnl(dp->ports[port_no]);
                if (!vport)
                        return ERR_PTR(-ENOENT);
                return vport;
@@ -1752,7 +1746,7 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
                if (port_no >= DP_MAX_PORTS)
                        goto exit_unlock;
 
-               vport = get_vport_protected(dp, port_no);
+               vport = rtnl_dereference(dp->ports[port_no]);
                err = -EBUSY;
                if (vport)
                        goto exit_unlock;
@@ -1762,7 +1756,7 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
                                err = -EFBIG;
                                goto exit_unlock;
                        }
-                       vport = get_vport_protected(dp, port_no);
+                       vport = rtnl_dereference(dp->ports[port_no]);
                        if (!vport)
                                break;
                }
@@ -1939,7 +1933,7 @@ static int ovs_vport_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
        for (port_no = cb->args[0]; port_no < DP_MAX_PORTS; port_no++) {
                struct vport *vport;
 
-               vport = get_vport_protected(dp, port_no);
+               vport = rcu_dereference(dp->ports[port_no]);
                if (!vport)
                        continue;