Commit 04254730 authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Linus Torvalds
Browse files

list: introduce list_is_head() helper and re-use it in list.h 

Introduce list_is_head() in the similar (*) way as it's done for
list_entry_is_head().  Make use of it in the list.h.

*) it's done as inliner and not a macro to be aligned with other
   list_is_*() APIs; while at it, make all three to have the same
   style.

Link: https://lkml.kernel.org/r/20211201141824.81400-1-andriy.shevchenko@linux.intel.com


Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 70ac6992

include/linux/list.h

+22 −14
Original line number Diff line number Diff line
@@ -258,8 +258,7 @@ static inline void list_bulk_move_tail(struct list_head *head, 
 * @list: the entry to test

 * @head: the head of the list

 */

static inline int list_is_first(const struct list_head *list,

					const struct list_head *head)

static inline int list_is_first(const struct list_head *list, const struct list_head *head)

{

	return list->prev == head;

}
@@ -269,12 +268,21 @@ static inline int list_is_first(const struct list_head *list, 
 * @list: the entry to test

 * @head: the head of the list

 */

static inline int list_is_last(const struct list_head *list,

				const struct list_head *head)

static inline int list_is_last(const struct list_head *list, const struct list_head *head)

{

	return list->next == head;

}



/**

 * list_is_head - tests whether @list is the list @head

 * @list: the entry to test

 * @head: the head of the list

 */

static inline int list_is_head(const struct list_head *list, const struct list_head *head)

{

	return list == head;

}



/**

 * list_empty - tests whether a list is empty

 * @head: the list to test.
@@ -318,7 +326,7 @@ static inline void list_del_init_careful(struct list_head *entry) 
static inline int list_empty_careful(const struct list_head *head)

{

	struct list_head *next = smp_load_acquire(&head->next);

	return (next == head) && (next == head->prev);

	return list_is_head(next, head) && (next == head->prev);

}



/**
@@ -393,10 +401,9 @@ static inline void list_cut_position(struct list_head *list, 
{

	if (list_empty(head))

		return;

	if (list_is_singular(head) &&

		(head->next != entry && head != entry))

	if (list_is_singular(head) && !list_is_head(entry, head) && (entry != head->next))

		return;

	if (entry == head)

	if (list_is_head(entry, head))

		INIT_LIST_HEAD(list);

	else

		__list_cut_position(list, head, entry);
@@ -570,7 +577,7 @@ static inline void list_splice_tail_init(struct list_head *list, 
 * @head:	the head for your list.

 */

#define list_for_each(pos, head) \

	for (pos = (head)->next; pos != (head); pos = pos->next)

	for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)



/**

 * list_for_each_continue - continue iteration over a list
@@ -580,7 +587,7 @@ static inline void list_splice_tail_init(struct list_head *list, 
 * Continue to iterate over a list, continuing after the current position.

 */

#define list_for_each_continue(pos, head) \

	for (pos = pos->next; pos != (head); pos = pos->next)

	for (pos = pos->next; !list_is_head(pos, (head)); pos = pos->next)



/**

 * list_for_each_prev	-	iterate over a list backwards
@@ -588,7 +595,7 @@ static inline void list_splice_tail_init(struct list_head *list, 
 * @head:	the head for your list.

 */

#define list_for_each_prev(pos, head) \

	for (pos = (head)->prev; pos != (head); pos = pos->prev)

	for (pos = (head)->prev; !list_is_head(pos, (head)); pos = pos->prev)



/**

 * list_for_each_safe - iterate over a list safe against removal of list entry
@@ -597,7 +604,8 @@ static inline void list_splice_tail_init(struct list_head *list, 
 * @head:	the head for your list.

 */

#define list_for_each_safe(pos, n, head) \

	for (pos = (head)->next, n = pos->next; pos != (head); \

	for (pos = (head)->next, n = pos->next; \

	     !list_is_head(pos, (head)); \

	     pos = n, n = pos->next)



/**
@@ -608,7 +616,7 @@ static inline void list_splice_tail_init(struct list_head *list, 
 */

#define list_for_each_prev_safe(pos, n, head) \

	for (pos = (head)->prev, n = pos->prev; \

	     pos != (head); \

	     !list_is_head(pos, (head)); \

	     pos = n, n = pos->prev)



/**