[dpdk-dev] doc: add thread-safety information about EFD library

diff --git a/doc/guides/prog_guide/efd_lib.rst b/doc/guides/prog_guide/efd_lib.rst
index 5b8e4e3..3f90fa9 100644
--- a/doc/guides/prog_guide/efd_lib.rst
+++ b/doc/guides/prog_guide/efd_lib.rst
@@ -270,6 +270,11 @@  failed to find a suitable perfect hash or the group was full). The function
 will return ``EFD_UPDATE_NO_CHANGE (3)`` if there is no change to the EFD
 table (i.e, same value already exists).
 
+.. Note::
+
+   This function is not multi-thread safe and should only be called
+   from one thread.
+
 EFD Lookup
 ~~~~~~~~~~
 
@@ -285,6 +290,11 @@  lookup function. ``rte_efd_lookup_bulk()`` is the bulk lookup function,
 that looks up num_keys simultaneously stored in the key_list and the
 corresponding return values will be returned in the value_list.
 
+.. Note::
+
+   This function is multi-thread safe, but there should not be other threads
+   writing in the EFD table, unless locks are used.
+
 EFD Delete
 ~~~~~~~~~~
 
@@ -295,6 +305,11 @@  use to lookup the existing value, which is ideally the caller's socket id.
 The previous value associated with this key will be returned
 in the prev_value argument.
 
+.. Note::
+
+   This function is not multi-thread safe and should only be called
+   from one thread.
+
 .. _Efd_internals:
 
 Library Internals
diff --git a/lib/librte_efd/rte_efd.h b/lib/librte_efd/rte_efd.h
index 1a1cb5b..6d31e18 100644
--- a/lib/librte_efd/rte_efd.h
+++ b/lib/librte_efd/rte_efd.h
@@ -198,6 +198,8 @@  rte_efd_find_existing(const char *name);
  * Computes an updated table entry for the supplied key/value pair.
  * The update is then immediately applied to the provided table and
  * all socket-local copies of the chunks are updated.
+ * This operation is not multi-thread safe
+ * and should only be called one from thread.
  *
  * @param table
  *   EFD table to reference
@@ -227,6 +229,8 @@  rte_efd_update(struct rte_efd_table *table, unsigned int socket_id,
 
 /**
  * Removes any value currently associated with the specified key from the table
+ * This operation is not multi-thread safe
+ * and should only be called from one thread.
  *
  * @param table
  *   EFD table to reference
@@ -247,6 +251,7 @@  rte_efd_delete(struct rte_efd_table *table, unsigned int socket_id,
 
 /**
  * Looks up the value associated with a key
+ * This operation is multi-thread safe.
  *
  * NOTE: Lookups will *always* succeed - this is a property of
  * using a perfect hash table.
@@ -270,6 +275,7 @@  rte_efd_lookup(const struct rte_efd_table *table, unsigned int socket_id,
 
 /**
  * Looks up the value associated with several keys.
+ * This operation is multi-thread safe.
  *
  * NOTE: Lookups will *always* succeed - this is a property of
  * using a perfect hash table.