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

Upstream commit:
    commit 6b660c4177aaebdc73df7a3378f0e8b110aa4b51
    Author: Taehee Yoo <ap420073@gmail.com>
    Date:   Sat Jul 6 01:08:09 2019 +0900

    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>
Acked-by: Yi-Hung Wei <yihung.wei@gmail.com>
Signed-off-by: Greg Rose <gvrose8192@gmail.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 4c485c88aca34c9f6709077cc323073d6df4fe59..2879f24ef3fc4548b2829201f7d8331808b7d0aa 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -2072,10 +2072,9 @@ 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;
@@ -2089,10 +2088,19 @@ 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)
@@ -2103,6 +2111,7 @@ 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;
 
@@ -2165,8 +2174,10 @@ restart:
                                      OVS_VPORT_CMD_NEW);
        BUG_ON(err < 0);
 
-       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);
 
@@ -2235,11 +2246,12 @@ 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();
@@ -2265,13 +2277,17 @@ 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, &ovs_dp_vport_multicast_group, reply, info);