netlink: Move mutex_is_held under PROVE_LOCKING

The rhashtable function mutex_is_held is only used when PROVE_LOCKING
is enabled.  This patch modifies netlink so that we can rhashtable.h
itself can later make mutex_is_held optional depending on PROVE_LOCKING.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netlink/af_netlink.c

@@ -114,14 +114,14 @@ static atomic_t nl_table_users = ATOMIC_INIT(0);
 DEFINE_MUTEX(nl_sk_hash_lock);
 EXPORT_SYMBOL_GPL(nl_sk_hash_lock);
 
+#ifdef CONFIG_PROVE_LOCKING
 static int lockdep_nl_sk_hash_is_held(void)
 {
-#ifdef CONFIG_LOCKDEP
 	if (debug_locks)
 		return lockdep_is_held(&nl_sk_hash_lock) || lockdep_is_held(&nl_table_lock);
-#endif
 	return 1;
 }
+#endif
 
 static ATOMIC_NOTIFIER_HEAD(netlink_chain);
 
@@ -3133,7 +3133,9 @@ static int __init netlink_proto_init(void)
 		.max_shift = 16, /* 64K */
 		.grow_decision = rht_grow_above_75,
 		.shrink_decision = rht_shrink_below_30,
+#ifdef CONFIG_PROVE_LOCKING
 		.mutex_is_held = lockdep_nl_sk_hash_is_held,
+#endif
 	};
 
 	if (err != 0)