Commit 2fbdf45d authored by Ricardo Martinez's avatar Ricardo Martinez Committed by David S. Miller
Browse files

list: Add list_next_entry_circular() and list_prev_entry_circular() 



Add macros to get the next or previous entries and wraparound if
needed. For example, calling list_next_entry_circular() on the last
element should return the first element in the list.

Signed-off-by: default avatarRicardo Martinez <ricardo.martinez@linux.intel.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c908565e

include/linux/list.h

+26 −0
Original line number Diff line number Diff line
@@ -563,6 +563,19 @@ static inline void list_splice_tail_init(struct list_head *list, 
#define list_next_entry(pos, member) \

	list_entry((pos)->member.next, typeof(*(pos)), member)



/**

 * list_next_entry_circular - get the next element in list

 * @pos:	the type * to cursor.

 * @head:	the list head to take the element from.

 * @member:	the name of the list_head within the struct.

 *

 * Wraparound if pos is the last element (return the first element).

 * Note, that list is expected to be not empty.

 */

#define list_next_entry_circular(pos, head, member) \

	(list_is_last(&(pos)->member, head) ? \

	list_first_entry(head, typeof(*(pos)), member) : list_next_entry(pos, member))



/**

 * list_prev_entry - get the prev element in list

 * @pos:	the type * to cursor
@@ -571,6 +584,19 @@ static inline void list_splice_tail_init(struct list_head *list, 
#define list_prev_entry(pos, member) \

	list_entry((pos)->member.prev, typeof(*(pos)), member)



/**

 * list_prev_entry_circular - get the prev element in list

 * @pos:	the type * to cursor.

 * @head:	the list head to take the element from.

 * @member:	the name of the list_head within the struct.

 *

 * Wraparound if pos is the first element (return the last element).

 * Note, that list is expected to be not empty.

 */

#define list_prev_entry_circular(pos, head, member) \

	(list_is_first(&(pos)->member, head) ? \

	list_last_entry(head, typeof(*(pos)), member) : list_prev_entry(pos, member))



/**

 * list_for_each	-	iterate over a list

 * @pos:	the &struct list_head to use as a loop cursor.