[IPV6]: remove ifdef in route6 for xfrm6

The following patch create the usual static inline functions to disable
the xfrm6_init and xfrm6_fini function when XFRM is off.
That's allow to remove some ifdef and make the code a little more clear.
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/xfrm.h

@@ -842,7 +842,6 @@ xfrm_state_addr_cmp(struct xfrm_tmpl *tmpl, struct xfrm_state *x, unsigned short
 }
 
 #ifdef CONFIG_XFRM
-
 extern int __xfrm_policy_check(struct sock *, int dir, struct sk_buff *skb, unsigned short family);
 
 static inline int xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb, unsigned short family)
@@ -1066,12 +1065,23 @@ struct xfrm6_tunnel {
 
 extern void xfrm_init(void);
 extern void xfrm4_init(void);
-extern int xfrm6_init(void);
-extern void xfrm6_fini(void);
 extern void xfrm_state_init(void);
 extern void xfrm4_state_init(void);
+#ifdef CONFIG_XFRM
+extern int xfrm6_init(void);
+extern void xfrm6_fini(void);
 extern int xfrm6_state_init(void);
 extern void xfrm6_state_fini(void);
+#else
+static inline int xfrm6_init(void)
+{
+	return 0;
+}
+static inline void xfrm6_fini(void)
+{
+	;
+}
+#endif
 
 extern int xfrm_state_walk(u8 proto, int (*func)(struct xfrm_state *, int, void*), void *);
 extern struct xfrm_state *xfrm_state_alloc(void);

net/ipv6/route.c

@@ -2522,11 +2522,10 @@ int __init ip6_route_init(void)
 	if (ret)
 		goto out_fib6_init;
 
-#ifdef CONFIG_XFRM
 	ret = xfrm6_init();
 	if (ret)
 		goto out_proc_init;
-#endif
+
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 	ret = fib6_rules_init();
 	if (ret)
@@ -2547,9 +2546,7 @@ int __init ip6_route_init(void)
 	fib6_rules_cleanup();
 xfrm6_init:
 #endif
-#ifdef CONFIG_XFRM
 	xfrm6_fini();
-#endif
 out_proc_init:
 	ipv6_route_proc_fini(&init_net);
 out_fib6_init:
@@ -2566,9 +2563,7 @@ void ip6_route_cleanup(void)
 	fib6_rules_cleanup();
 #endif
 	ipv6_route_proc_fini(&init_net);
-#ifdef CONFIG_XFRM
 	xfrm6_fini();
-#endif
 	rt6_ifdown(NULL);
 	fib6_gc_cleanup();
 	kmem_cache_destroy(ip6_dst_ops.kmem_cachep);