tipc: convert name table read-write lock to RCU

Convert tipc name table read-write lock to RCU. After this change,
a new spin lock is used to protect name table on write side while
RCU is applied on read side.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Tested-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 372ad5e..aa79b3c 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -542,6 +542,15 @@
 	     pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
 			typeof(*(pos)), member))
 
+/**
+ * hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point
+ * @pos:	the type * to use as a loop cursor.
+ * @member:	the name of the hlist_node within the struct.
+ */
+#define hlist_for_each_entry_from_rcu(pos, member)			\
+	for (; pos;							\
+	     pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
+			typeof(*(pos)), member))
 
 #endif	/* __KERNEL__ */
 #endif