openvswitch: Simplify do_execute_actions().

do_execute_actions() implements a worthwhile optimization: in case
an output action is the last action in an action list, skb_clone()
can be avoided by outputing the current skb. However, the
implementation is more complicated than necessary.  This patch
simplify this logic.

Signed-off-by: Andy Zhou <azhou@ovn.org>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 514f7bcf7c63ce0f3148e42726df74ff77c0c8af..efa9a8858cc6a474022f7f210250f0743ac6cf8c 100644 (file)
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -1141,12 +1141,6 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
                              struct sw_flow_key *key,
                              const struct nlattr *attr, int len)
 {
-       /* Every output action needs a separate clone of 'skb', but the common
-        * case is just a single output action, so that doing a clone and
-        * then freeing the original skbuff is wasteful.  So the following code
-        * is slightly obscure just to avoid that.
-        */
-       int prev_port = -1;
        const struct nlattr *a;
        int rem;
 
@@ -1154,20 +1148,28 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
             a = nla_next(a, &rem)) {
                int err = 0;
 
-               if (unlikely(prev_port != -1)) {
-                       struct sk_buff *out_skb = skb_clone(skb, GFP_ATOMIC);
-
-                       if (out_skb)
-                               do_output(dp, out_skb, prev_port, key);
+               switch (nla_type(a)) {
+               case OVS_ACTION_ATTR_OUTPUT: {
+                       int port = nla_get_u32(a);
+                       struct sk_buff *clone;
+
+                       /* Every output action needs a separate clone
+                        * of 'skb', In case the output action is the
+                        * last action, cloning can be avoided.
+                        */
+                       if (nla_is_last(a, rem)) {
+                               do_output(dp, skb, port, key);
+                               /* 'skb' has been used for output.
+                                */
+                               return 0;
+                       }
 
+                       clone = skb_clone(skb, GFP_ATOMIC);
+                       if (clone)
+                               do_output(dp, clone, port, key);
                        OVS_CB(skb)->cutlen = 0;
-                       prev_port = -1;
-               }
-
-               switch (nla_type(a)) {
-               case OVS_ACTION_ATTR_OUTPUT:
-                       prev_port = nla_get_u32(a);
                        break;
+               }
 
                case OVS_ACTION_ATTR_TRUNC: {
                        struct ovs_action_trunc *trunc = nla_data(a);
@@ -1257,11 +1259,7 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
                }
        }
 
-       if (prev_port != -1)
-               do_output(dp, skb, prev_port, key);
-       else
-               consume_skb(skb);
-
+       consume_skb(skb);
        return 0;
 }