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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: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andy Shevchenko 2022-01-19 18:08:56 -08:00 committed by Linus Torvalds
parent 70ac69928e
commit 0425473037
1 changed files with 22 additions and 14 deletions
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36
include/linux/list.h
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@ -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
@ -597,8 +604,9 @@ 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); \
pos = n, n = pos->next)
for (pos = (head)->next, n = pos->next; \
!list_is_head(pos, (head)); \
pos = n, n = pos->next)
/**
* list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
@ -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)
/**