LIST_CREATE(9F) Kernel Functions for Drivers LIST_CREATE(9F)


list_create, list_destroy, list_insert_after, list_insert_before,
list_insert_head, list_insert_tail, list_remove, list_remove_head,
list_remove_tail, list_head, list_tail, list_next, list_prev,
list_is_empty, list_link_init, list_link_active, list_move_tail,
list_link_replace - list functions


#include <sys/list.h>

void list_create(list_t * list, size_t size, size_t offset);

void list_destroy(list_t * list);

void list_insert_after(list_t * list, void *reference_item,
void *new_item);

void list_insert_before(list_t * list, void *reference_item,
void *new_item);

void list_insert_head(list_t * list*, void *new_item);

void list_insert_tail(list_t * list, void *new_item);

void list_remove(list_t * list, void *item);

void *list_remove_head(list_t * list);

void *list_remove_tail(list_t * list);

void *list_head(list_t * list);

void *list_tail(list_t * list);

void *list_next(list_t * list, void *reference_item);

void *list_prev(list_t * list, void *reference_item);

int list_is_empty(list_t * list);

void list_link_init(list_node_t *node);

int list_link_active(list_node_t *node);

void list_move_tail(list_t *dst, list_t *src);

void list_link_replace(list_node_t *node1, list_node_t *node2);


These functions provide a generic doubly-linked list implementation. To
utilize it, simply embed a list_node_t field in the structures that will
constitute the linked list elements and pass the list_node_t field offset
to list_create() in the appropriate parameter (see below). A single
list_node_t field can only be used in a single list simultaneously, so to
add a structure to multiple lists, embed multiple list_node_t fields in
your user structure.

Please note that a list_node_t contains pointers back to its parent
list_t so you cannot copy the list_t around once it has been initialized.
In particular, this kind of construct won't work:

struct { list_t l; } a, b;
list_create(&a.l, ...);
b = a; <= This will break the list in `b', as the `l' element
in `a' got copied to a different memory address.

To do this you must move the list items to the new list using functions
such as list_move_tail().

The list_create() function initializes a new list. The driver supplies
the storage for the list handle, the size of an individual element, and
the offset of a list_node_t within the element to use for the links of
the list.

The list_destroy() function destroys the list handle, including freeing
any resources that may have been internally allocated for the list. The
list must be empty when this function is called.

The list_insert_after() and list_insert_before() functions insert
new_item into the linked list at a location after or before the reference
item, which must already be on the list.

The list_insert_head() and list_insert_tail() functions insert the
new_item on the list at either the head or tail of the list. (The head
is the first item, the tail is the last item).

The list_remove() function removes the item from the list.

The list_remove_head() and list_remove_tail() functions remove the head
(first) or tail (last) item from the list. The item removed is returned
to the caller. If the list is empty when these functions are called, then
no change is made and NULL is returned to the caller.

The list_head() and list_tail() functions simply return the head (first)
or tail (last) item on the list. NULL is returned if the list is empty.

The list_next() and list_prev() functions return the next or previous
item in the list, relative to the named reference item which must be
linked on the list.

The list_is_empty() function returns 0 if the list has items in it, or
non-zero otherwise.

The list_link_init() function initializes the list_node_t. It is
functionally equivalent to bzero(node, sizeof(*node));

The list_link_active() function returns non-zero if the node is on an
active list.

The list_move_tail() function is used to append the items on the src list
to the end of the dst list. It is mandatory that the two lists were
initialized using identical size and offset parameters. Upon completion,
the src list will be empty.

The list_link_replace() function swaps two items on a list. Note that
the items need not be on the same list, but extreme care must be used to
ensure that both lists are protected from concurrent accesses and that
the lists were initialized with identical size and offset parameters.


See attributes(5) for descriptions of the following attributes:

|Interface Stability | Committed |



September 17, 2009 LIST_CREATE(9F)