+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
+static inline int skb_clone_writable(struct sk_buff *skb, int len)
+{
+ return false;
+}
+#endif
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,31)
+static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
+{
+ return (struct dst_entry *)skb->dst;
+}
+
+static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
+{
+ skb->dst = dst;
+}
+
+static inline struct rtable *skb_rtable(const struct sk_buff *skb)
+{
+ return (struct rtable *)skb->dst;
+}
+#endif