datapath: simplify sample action implementation

[cascardo/ovs.git] / datapath / actions.c

diff --git a/datapath/actions.c b/datapath/actions.c
index a688f19..6c6088e 100644 (file)
--- a/datapath/actions.c
+++ b/datapath/actions.c
@@ -449,7 +449,6 @@ static int sample(struct datapath *dp, struct sk_buff *skb,
 {
        const struct nlattr *acts_list = NULL;
        const struct nlattr *a;
-       struct sk_buff *sample_skb;
        int rem;
 
        for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
@@ -469,28 +468,24 @@ static int sample(struct datapath *dp, struct sk_buff *skb,
        rem = nla_len(acts_list);
        a = nla_data(acts_list);
 
-       /* Actions list is either empty or only contains a single user-space
-        * action, the latter being a special case as it is the only known
-        * usage of the sample action.
-        * In these special cases don't clone the skb as there are no
-        * side-effects in the nested actions.
-        * Otherwise, clone in case the nested actions have side effects. */
-       if (likely(rem == 0 ||
-                  (nla_type(a) == OVS_ACTION_ATTR_USERSPACE &&
-                   last_action(a, rem)))) {
-               sample_skb = skb;
-               skb_get(skb);
-       } else {
-               sample_skb = skb_clone(skb, GFP_ATOMIC);
-       }
+       /* Actions list is empty, do nothing */
+       if (unlikely(!rem))
+               return 0;
+
+       /* The only known usage of sample action is having a single user-space
+        * action. Treat this usage as a special case.
+        * The output_userspace() should clone the skb to be sent to the
+        * user space. This skb will be consumed by its caller. */
+       if (likely(nla_type(a) == OVS_ACTION_ATTR_USERSPACE &&
+                  last_action(a, rem)))
+               return output_userspace(dp, skb, a);
+
+       skb = skb_clone(skb, GFP_ATOMIC);
+       if (!skb)
+               /* Skip the sample action when out of memory. */
+               return 0;
 
-       /* Note that do_execute_actions() never consumes skb.
-        * In the case where skb has been cloned above it is the clone that
-        * is consumed.  Otherwise the skb_get(skb) call prevents
-        * consumption by do_execute_actions(). Thus, it is safe to simply
-        * return the error code and let the caller (also
-        * do_execute_actions()) free skb on error. */
-       return do_execute_actions(dp, sample_skb, a, rem);
+       return do_execute_actions(dp, skb, a, rem);
 }
 
 static void execute_hash(struct sk_buff *skb, const struct nlattr *attr)