netns xfrm: add struct xfrm_policy::xp_net

Again, to avoid complications with passing netns when not necessary.
Again, ->xp_net is set-once field, once set it never changes.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 0d4353c..1ab1756 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -475,6 +475,9 @@
 
 struct xfrm_policy
 {
+#ifdef CONFIG_NET_NS
+	struct net		*xp_net;
+#endif
 	struct hlist_node	bydst;
 	struct hlist_node	byidx;
 
@@ -499,6 +502,11 @@
 	struct xfrm_tmpl       	xfrm_vec[XFRM_MAX_DEPTH];
 };
 
+static inline struct net *xp_net(struct xfrm_policy *xp)
+{
+	return read_pnet(&xp->xp_net);
+}
+
 struct xfrm_kmaddress {
 	xfrm_address_t          local;
 	xfrm_address_t          remote;
@@ -1425,7 +1433,7 @@
 }
 #endif
 
-struct xfrm_policy *xfrm_policy_alloc(gfp_t gfp);
+struct xfrm_policy *xfrm_policy_alloc(struct net *net, gfp_t gfp);
 
 extern void xfrm_policy_walk_init(struct xfrm_policy_walk *walk, u8 type);
 extern int xfrm_policy_walk(struct xfrm_policy_walk *walk,