1 files changed, 16 insertions, 12 deletions

diff --git a/include/linux/list.h b/include/linux/list.h
index 8392884a2977..d167b5d7c0ac 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -1,6 +1,7 @@
 #ifndef _LINUX_LIST_H
 #define _LINUX_LIST_H
 
+#include <linux/types.h>
 #include <linux/stddef.h>
 #include <linux/poison.h>
 #include <linux/prefetch.h>
@@ -16,10 +17,6 @@
  * using the generic single-entry routines.
  */
 
-struct list_head {
-        struct list_head *next, *prev;
-};
-
 #define LIST_HEAD_INIT(name) { &(name), &(name) }
 
 #define LIST_HEAD(name) \
@@ -544,6 +541,21 @@ static inline void list_splice_tail_init(struct list_head *list,
              &pos->member != (head);                                    \
              pos = n, n = list_entry(n->member.prev, typeof(*n), member))
 
+/**
+ * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
+ * @pos:        the loop cursor used in the list_for_each_entry_safe loop
+ * @n:          temporary storage used in list_for_each_entry_safe
+ * @member:     the name of the list_struct within the struct.
+ *
+ * list_safe_reset_next is not safe to use in general if the list may be
+ * modified concurrently (eg. the lock is dropped in the loop body). An
+ * exception to this is if the cursor element (pos) is pinned in the list,
+ * and list_safe_reset_next is called after re-taking the lock and before
+ * completing the current iteration of the loop body.
+ */
+#define list_safe_reset_next(pos, n, member)                            \
+        n = list_entry(pos->member.next, typeof(*pos), member)
+
 /*
  * Double linked lists with a single pointer list head.
  * Mostly useful for hash tables where the two pointer list head is
@@ -551,14 +563,6 @@ static inline void list_splice_tail_init(struct list_head *list,
  * You lose the ability to access the tail in O(1).
  */
 
-struct hlist_head {
-        struct hlist_node *first;
-};
-
-struct hlist_node {
-        struct hlist_node *next, **pprev;
-};
-
 #define HLIST_HEAD_INIT { .first = NULL }
 #define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }
 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)