net: openvswitch: do not update max_headroom if new headroom is equal to old headroom

When a vport is deleted, the maximum headroom size would be changed.
If the vport which has the largest headroom is deleted,
the new max_headroom would be set.
But, if the new headroom size is equal to the old headroom size,
updating routine is unnecessary.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Tested-by: Greg Rose <gvrose8192@gmail.com>
Reviewed-by: Greg Rose <gvrose8192@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 28 insertions, 11 deletions

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 33b388103741..892287d06c17 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1958,10 +1958,9 @@ static struct vport *lookup_vport(struct net *net,
 
 }
 
-/* Called with ovs_mutex */
-static void update_headroom(struct datapath *dp)
+static unsigned int ovs_get_max_headroom(struct datapath *dp)
 {
-        unsigned dev_headroom, max_headroom = 0;
+        unsigned int dev_headroom, max_headroom = 0;
         struct net_device *dev;
         struct vport *vport;
         int i;
@@ -1975,10 +1974,19 @@ static void update_headroom(struct datapath *dp)
                 }
         }
 
-        dp->max_headroom = max_headroom;
+        return max_headroom;
+}
+
+/* Called with ovs_mutex */
+static void ovs_update_headroom(struct datapath *dp, unsigned int new_headroom)
+{
+        struct vport *vport;
+        int i;
+
+        dp->max_headroom = new_headroom;
         for (i = 0; i < DP_VPORT_HASH_BUCKETS; i++)
                 hlist_for_each_entry_rcu(vport, &dp->ports[i], dp_hash_node)
-                        netdev_set_rx_headroom(vport->dev, max_headroom);
+                        netdev_set_rx_headroom(vport->dev, new_headroom);
 }
 
 static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
@@ -1989,6 +1997,7 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
         struct sk_buff *reply;
         struct vport *vport;
         struct datapath *dp;
+        unsigned int new_headroom;
         u32 port_no;
         int err;
 
@@ -2050,8 +2059,10 @@ restart:
                                       info->snd_portid, info->snd_seq, 0,
                                       OVS_VPORT_CMD_NEW);
 
-        if (netdev_get_fwd_headroom(vport->dev) > dp->max_headroom)
-                update_headroom(dp);
+        new_headroom = netdev_get_fwd_headroom(vport->dev);
+
+        if (new_headroom > dp->max_headroom)
+                ovs_update_headroom(dp, new_headroom);
         else
                 netdev_set_rx_headroom(vport->dev, dp->max_headroom);
 
@@ -2122,11 +2133,12 @@ exit_unlock_free:
 
 static int ovs_vport_cmd_del(struct sk_buff *skb, struct genl_info *info)
 {
-        bool must_update_headroom = false;
+        bool update_headroom = false;
         struct nlattr **a = info->attrs;
         struct sk_buff *reply;
         struct datapath *dp;
         struct vport *vport;
+        unsigned int new_headroom;
         int err;
 
         reply = ovs_vport_cmd_alloc_info();
@@ -2152,12 +2164,17 @@ static int ovs_vport_cmd_del(struct sk_buff *skb, struct genl_info *info)
         /* the vport deletion may trigger dp headroom update */
         dp = vport->dp;
         if (netdev_get_fwd_headroom(vport->dev) == dp->max_headroom)
-                must_update_headroom = true;
+                update_headroom = true;
+
         netdev_reset_rx_headroom(vport->dev);
         ovs_dp_detach_port(vport);
 
-        if (must_update_headroom)
-                update_headroom(dp);
+        if (update_headroom) {
+                new_headroom = ovs_get_max_headroom(dp);
+
+                if (new_headroom < dp->max_headroom)
+                        ovs_update_headroom(dp, new_headroom);
+        }
         ovs_unlock();
 
         ovs_notify(&dp_vport_genl_family, reply, info);