xfrm: state: don't use lock anymore unless acquire operation is needed

push the lock down, after earlier patches we can rely on rcu to
make sure state struct won't go away.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index 24cd394..1ab51d1 100644
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -38,9 +38,9 @@
 	 * mode. Also, it can be used by ah/esp icmp error handler to find
 	 * offending SA.
 	 */
-	struct hlist_head	*state_bydst;
-	struct hlist_head	*state_bysrc;
-	struct hlist_head	*state_byspi;
+	struct hlist_head	__rcu *state_bydst;
+	struct hlist_head	__rcu *state_bysrc;
+	struct hlist_head	__rcu *state_byspi;
 	unsigned int		state_hmask;
 	unsigned int		state_num;
 	struct work_struct	state_hash_work;