@@ -96,7 +96,14 @@ other flavors of rcu_dereference().  On the other hand, it is illegal
 to use rcu_dereference_protected() if either the RCU-protected pointer
 or the RCU-protected data that it points to can change concurrently.
 
-There are currently only "universal" versions of the rcu_assign_pointer()
-and RCU list-/tree-traversal primitives, which do not (yet) check for
-being in an RCU read-side critical section.  In the future, separate
-versions of these primitives might be created.
+Similar to rcu_dereference_protected, The RCU list and hlist traversal
+primitives also check for whether there are called from within a reader
+section. However, an optional lockdep expression can be passed to them as
+the last argument in case they are called under other non-RCU protection.
+
+For example, the workqueue for_each_pwq() macro is implemented as follows.
+It is safe to call for_each_pwq() outside a reader section but under protection
+of wq->mutex:
+#define for_each_pwq(pwq, wq)
+	list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node,
+				lock_is_held(&(wq->mutex).dep_map))

@@ -290,7 +290,7 @@ rcu_dereference()
 	at any time, including immediately after the rcu_dereference().
 	And, again like rcu_assign_pointer(), rcu_dereference() is
 	typically used indirectly, via the _rcu list-manipulation
-	primitives, such as list_for_each_entry_rcu().
+	primitives, such as list_for_each_entry_rcu() [2].
 
 	[1] The variant rcu_dereference_protected() can be used outside
 	of an RCU read-side critical section as long as the usage is

@@ -305,6 +305,13 @@ rcu_dereference()
 	a lockdep splat is emitted.  See RCU/Design/Requirements/Requirements.html
 	and the API's code comments for more details and example usage.
 
+	[2] In case the list_for_each_entry_rcu() primitive is intended
+	to be used outside of an RCU reader section such as when
+	protected by a lock, then an additional lockdep expression can be
+	passed as the last argument to it so that RCU lockdep checking code
+	knows that the dereference of the list pointers are safe. If the
+	indicated protection is not provided, a lockdep splat is emitted.
+
 The following diagram shows how each API communicates among the
 reader, updater, and reclaimer.