Messages in this thread Patch in this message | | | Subject | [PATCH RFC 1/3] list: Introduce list entry pop/peek operations | From | Konstantin Khlebnikov <> | Date | Thu, 8 Jul 2010 12:46:54 +0400 |
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Introduce macroses:
list_pop_entry list_pop_last_entry list_pop_init_entry list_pop_init_last_entry list_peek_entry list_peek_last_entry
as syntax sugar for widely used constructions like this:
while (!list_empty(&list_head)) { entry = list_first_entry(&list_head, struct entry, member); list_del(&entry->member); ... }
with this macro it become:
while (list_pop_entry(&entry, &list_head, member)) { ... }
All macros returns true if the list is not empty, otherwise they not change the output variable.
list_pop_init_* call list_del_init instead list_del. list_peek_* not remove entries from the list.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> --- include/linux/list.h | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 88 insertions(+), 0 deletions(-)
diff --git a/include/linux/list.h b/include/linux/list.h index 5d57a3a..6a6e9d3 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -360,6 +360,94 @@ static inline void list_splice_tail_init(struct list_head *list, list_entry((ptr)->next, type, member) /** + * list_peek_entry - check is list non-empty and return list first entry + * @ptr: the pointer to struct * to save first entry + * @head: the struct list_head pointer. + * @member: the name of the list_struct within the struct. + * + * Return true if list was not empty and @ptr is changed + */ +#define list_peek_entry(ptr, head, member) ({ \ + bool __empty = list_empty(head); \ + if (!__empty) \ + *(ptr) = list_first_entry(head, typeof(**(ptr)), member); \ + (!__empty); }) + +/** + * list_peek_last_entry - check is list non-empty and return list last entry + * @ptr: the pointer to struct * to save last entry + * @head: the struct list_head pointer. + * @member: the name of the list_struct within the struct. + * + * Return true if list was not empty and @ptr is changed + */ +#define list_peek_last_entry(ptr, head, member) ({ \ + bool __empty = list_empty(head); \ + if (!__empty) \ + *(ptr) = list_entry((head)->prev, typeof(**(ptr)), member); \ + (!__empty); }) + +/** + * list_pop_entry - delete and return list first entry + * @ptr: the pointer to struct * whereto save result + * @head: the struct list_head pointer. + * @member: the name of the list_struct within the struct. + * + * Return true if list was not empty and @ptr is changed + */ +#define list_pop_entry(ptr, head, member) ({ \ + bool __empty = list_empty(head); \ + if (!__empty) { \ + *(ptr) = list_first_entry(head, typeof(**(ptr)), member); \ + list_del(&(*(ptr))->member); \ + } (!__empty); }) + +/** + * list_pop_init_entry - delete, reinitialise and return list first entry + * @ptr: the pointer to struct * whereto save result + * @head: the struct list_head pointer. + * @member: the name of the list_struct within the struct. + * + * Return true if list was not empty and @ptr is changed + */ +#define list_pop_init_entry(ptr, head, member) ({ \ + bool __empty = list_empty(head); \ + if (!__empty) { \ + *(ptr) = list_first_entry(head, typeof(**(ptr)), member); \ + list_del_init(&(*(ptr))->member); \ + } (!__empty); }) + +/** + * list_pop_last_entry - delete and return list last entry + * @ptr: the pointer to struct * whereto save result + * @head: the struct list_head pointer. + * @member: the name of the list_struct within the struct. + * + * Return true if list was not empty and @ptr is changed + */ +#define list_pop_last_entry(ptr, head, member) ({ \ + bool __empty = list_empty(head); \ + if (!__empty) { \ + *(ptr) = list_entry((head)->prev, typeof(**(ptr)), member); \ + list_del(&(*(ptr))->member); \ + } (!__empty); }) + +/** + * list_pop_init_last_entry - delete, reinitialise and return list last entry + * @ptr: the pointer to struct * whereto save result + * @head: the struct list_head pointer. + * @member: the name of the list_struct within the struct. + * + * Return true if list was not empty and @ptr is changed + */ +#define list_pop_init_last_entry(ptr, head, member) ({ \ + bool __empty = list_empty(head); \ + if (!__empty) { \ + *(ptr) = list_entry((head)->prev, typeof(**(ptr)), member); \ + list_del_init(&(*(ptr))->member); \ + } (!__empty); }) + +/** * list_for_each - iterate over a list * @pos: the &struct list_head to use as a loop cursor. * @head: the head for your list.
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