net: dst: provide accessor function to dst->xfrm

[ Upstream commit e87b3998 ]

dst->xfrm is conditionally defined.  Provide accessor funtion that
is always available.
Signed-off-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

include/net/dst.h

@@ -286,11 +286,22 @@ static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 {
 	return 0;
 }
+static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
+{
+	return NULL;
+}
+
 #else
 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 		       struct flowi *fl, struct sock *sk, int flags);
 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 			 struct flowi *fl, struct sock *sk, int flags);
+
+/* skb attached with this dst needs transformation if dst->xfrm is valid */
+static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
+{
+	return dst->xfrm;
+}
 #endif
 #endif