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Subject[PATCH 3/4] list: introduce list_last_entry(), use list_{first,last}_entry()
We alredy have list_first_entry(), it makes sense to also add
list_last_entry() for consistency. And we use both helpers in
in list_for_each_*().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
include/linux/list.h | 19 +++++++++++++++----
1 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/include/linux/list.h b/include/linux/list.h
index c88a591..ef95941 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -362,6 +362,17 @@ static inline void list_splice_tail_init(struct list_head *list,
list_entry((ptr)->next, type, member)

/**
+ * list_last_entry - get the last element from a list
+ * @ptr: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_last_entry(ptr, type, member) \
+ list_entry((ptr)->prev, type, member)
+
+/**
* list_first_entry_or_null - get the first element from a list
* @ptr: the list head to take the element from.
* @type: the type of the struct this is embedded in.
@@ -432,7 +443,7 @@ static inline void list_splice_tail_init(struct list_head *list,
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry(pos, head, member) \
- for (pos = list_entry((head)->next, typeof(*pos), member); \
+ for (pos = list_first_entry(head, typeof(*pos), member); \
&pos->member != (head); \
pos = list_next_entry(pos, member))

@@ -443,7 +454,7 @@ static inline void list_splice_tail_init(struct list_head *list,
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry_reverse(pos, head, member) \
- for (pos = list_entry((head)->prev, typeof(*pos), member); \
+ for (pos = list_last_entry(head, typeof(*pos), member); \
&pos->member != (head); \
pos = list_prev_entry(pos, member))

@@ -506,7 +517,7 @@ static inline void list_splice_tail_init(struct list_head *list,
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry_safe(pos, n, head, member) \
- for (pos = list_entry((head)->next, typeof(*pos), member), \
+ for (pos = list_first_entry(head, typeof(*pos), member), \
n = list_next_entry(pos, member); \
&pos->member != (head); \
pos = n, n = list_next_entry(n, member))
@@ -553,7 +564,7 @@ static inline void list_splice_tail_init(struct list_head *list,
* of list entry.
*/
#define list_for_each_entry_safe_reverse(pos, n, head, member) \
- for (pos = list_entry((head)->prev, typeof(*pos), member), \
+ for (pos = list_last_entry(head, typeof(*pos), member), \
n = list_prev_entry(pos, member); \
&pos->member != (head); \
pos = n, n = list_prev_entry(n, member))
--
1.5.5.1


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