rculist: move list_for_each_rcu() to where it belongs

The list_for_each_rcu() relies on the rcu_dereference() API which is not
provided by the list.h. At the same time list.h is a low-level basic header
that must not have dependencies like RCU, besides the fact of the potential
circular dependencies in some cases. With all that said, move RCU related
API to the rculist.h where it belongs.

Signed-off-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Simona Vetter <[e-mail]>
Reviewed-by: "Paul E. McKenney" <[e-mail]>
Signed-off-by: Neeraj Upadhyay (AMD) <[e-mail]>
Signed-off-by: "Paul E. McKenney" <[e-mail]>

include/linux/list.h

···
 	for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)
 
 /**
- * list_for_each_rcu - Iterate over a list in an RCU-safe fashion
- * @pos:	the &struct list_head to use as a loop cursor.
- * @head:	the head for your list.
- */
-#define list_for_each_rcu(pos, head)		  \
-	for (pos = rcu_dereference((head)->next); \
-	     !list_is_head(pos, (head)); \
-	     pos = rcu_dereference(pos->next))
-
-/**
  * list_for_each_continue - continue iteration over a list
  * @pos:	the &struct list_head to use as a loop cursor.
  * @head:	the head for your list.

include/linux/rculist.h

···
 #define list_bidir_prev_rcu(list) (*((struct list_head __rcu **)(&(list)->prev)))
 
 /**
+ * list_for_each_rcu - Iterate over a list in an RCU-safe fashion
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each_rcu(pos, head)		  \
+	for (pos = rcu_dereference((head)->next); \
+	     !list_is_head(pos, (head)); \
+	     pos = rcu_dereference(pos->next))
+
+/**
  * list_tail_rcu - returns the prev pointer of the head of the list
  * @head: the head of the list
  *

kernel/cgroup/dmem.c

···
 #include <linux/mutex.h>
 #include <linux/page_counter.h>
 #include <linux/parser.h>
+#include <linux/rculist.h>
 #include <linux/slab.h>
 
 struct dmem_cgroup_region {