Linux内核链表剖析
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/*
* This file is part of the DTLib template project, http://www.dt4sw.com
*
* The MIT License (MIT)
*
* Copyright (c) 唐佐林 (Delphi Tang)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H
// #include <linux/types.h>
// #include <linux/stddef.h>
// #include <linux/poison.h>
// #include <linux/prefetch.h>
#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif
#ifndef container_of
#define container_of(ptr, type, member) ((type *)((char *)ptr - offsetof(type,member)))
#endif
#define prefetch(x) ((void)x)
#define LIST_POISON1 (NULL)
#define LIST_POISON2 (NULL)
struct list_head
struct list_head *next, *prev;
;
struct hlist_head
struct hlist_node *first;
;
struct hlist_node
struct hlist_node *next, **pprev;
;
/*
* Simple doubly linked list implementation.
*
* Some of the internal functions ("__xxx") are useful when
* manipulating whole lists rather than single entries, as
* sometimes we already know the next/prev entries and we can
* generate better code by using them directly rather than
* using the generic single-entry routines.
*/
#define LIST_HEAD_INIT(name) &(name), &(name)
#define LIST_HEAD(name) \\
struct list_head name = LIST_HEAD_INIT(name)
static void INIT_LIST_HEAD(struct list_head *list)
list->next = list;
list->prev = list;
/*
* Insert a new entry between two known consecutive entries.
*
* This is only for internal list manipulation where we know
* the prev/next entries already!
*/
#ifndef CONFIG_DEBUG_LIST
static void __list_add(struct list_head *node,
struct list_head *prev,
struct list_head *next)
next->prev = node;
node->next = next;
node->prev = prev;
prev->next = node;
#else
extern void __list_add(struct list_head *node,
struct list_head *prev,
struct list_head *next);
#endif
/**
* list_add - add a new entry
* @new: new entry to be added
* @head: list head to add it after
*
* Insert a new entry after the specified head.
* This is good for implementing stacks.
*/
static void list_add(struct list_head *node, struct list_head *head)
__list_add(node, head, head->next);
/**
* list_add_tail - add a new entry
* @new: new entry to be added
* @head: list head to add it before
*
* Insert a new entry before the specified head.
* This is useful for implementing queues.
*/
static void list_add_tail(struct list_head *node, struct list_head *head)
__list_add(node, head->prev, head);
/*
* Delete a list entry by making the prev/next entries
* point to each other.
*
* This is only for internal list manipulation where we know
* the prev/next entries already!
*/
static void __list_del(struct list_head * prev, struct list_head * next)
next->prev = prev;
prev->next = next;
/**
* list_del - deletes entry from list.
* @entry: the element to delete from the list.
* Note: list_empty() on entry does not return true after this, the entry is
* in an undefined state.
*/
#ifndef CONFIG_DEBUG_LIST
static void __list_del_entry(struct list_head *entry)
__list_del(entry->prev, entry->next);
static void list_del(struct list_head *entry)
__list_del(entry->prev, entry->next);
entry->next = LIST_POISON1;
entry->prev = LIST_POISON2;
#else
extern void __list_del_entry(struct list_head *entry);
extern void list_del(struct list_head *entry);
#endif
/**
* list_replace - replace old entry by new one
* @old : the element to be replaced
* @new : the new element to insert
*
* If @old was empty, it will be overwritten.
*/
static void list_replace(struct list_head *old,
struct list_head *node)
node->next = old->next;
node->next->prev = node;
node->prev = old->prev;
node->prev->next = node;
static void list_replace_init(struct list_head *old,
struct list_head *node)
list_replace(old, node);
INIT_LIST_HEAD(old);
/**
* list_del_init - deletes entry from list and reinitialize it.
* @entry: the element to delete from the list.
*/
static void list_del_init(struct list_head *entry)
__list_del_entry(entry);
INIT_LIST_HEAD(entry);
/**
* list_move - delete from one list and add as another's head
* @list: the entry to move
* @head: the head that will precede our entry
*/
static void list_move(struct list_head *list, struct list_head *head)
__list_del_entry(list);
list_add(list, head);
/**
* list_move_tail - delete from one list and add as another's tail
* @list: the entry to move
* @head: the head that will follow our entry
*/
static void list_move_tail(struct list_head *list,
struct list_head *head)
__list_del_entry(list);
list_add_tail(list, head);
/**
* list_is_last - tests whether @list is the last entry in list @head
* @list: the entry to test
* @head: the head of the list
*/
static int list_is_last(const struct list_head *list,
const struct list_head *head)
return list->next == head;
/**
* list_empty - tests whether a list is empty
* @head: the list to test.
*/
static int list_empty(const struct list_head *head)
return head->next == head;
/**
* list_empty_careful - tests whether a list is empty and not being modified
* @head: the list to test
*
* Description:
* tests whether a list is empty _and_ checks that no other CPU might be
* in the process of modifying either member (next or prev)
*
* NOTE: using list_empty_careful() without synchronization
* can only be safe if the only activity that can happen
* to the list entry is list_del_init(). Eg. it cannot be used
* if another CPU could re-list_add() it.
*/
static int list_empty_careful(const struct list_head *head)
struct list_head *next = head->next;
return (next == head) && (next == head->prev);
/**
* list_rotate_left - rotate the list to the left
* @head: the head of the list
*/
static void list_rotate_left(struct list_head *head)
struct list_head *first;
if (!list_empty(head))
first = head->next;
list_move_tail(first, head);
/**
* list_is_singular - tests whether a list has just one entry.
* @head: the list to test.
*/
static int list_is_singular(const struct list_head *head)
return !list_empty(head) && (head->next == head->prev);
static void __list_cut_position(struct list_head *list,
struct list_head *head, struct list_head *entry)
struct list_head *new_first = entry->next;
list->next = head->next;
list->next->prev = list;
list->prev = entry;
entry->next = list;
head->next = new_first;
new_first->prev = head;
/**
* list_cut_position - cut a list into two
* @list: a new list to add all removed entries
* @head: a list with entries
* @entry: an entry within head, could be the head itself
* and if so we won't cut the list
*
* This helper moves the initial part of @head, up to and
* including @entry, from @head to @list. You should
* pass on @entry an element you know is on @head. @list
* should be an empty list or a list you do not care about
* losing its data.
*
*/
static void list_cut_position(struct list_head *list,
struct list_head *head, struct list_head *entry)
if (list_empty(head))
return;
if (list_is_singular(head) &&
(head->next != entry && head != entry))
return;
if (entry == head)
INIT_LIST_HEAD(list);
else
__list_cut_position(list, head, entry);
static void __list_splice(const struct list_head *list,
struct list_head *prev,
struct list_head *next)
struct list_head *first = list->next;
struct list_head *last = list->prev;
first->prev = prev;
prev->next = first;
last->next = next;
next->prev = last;
/**
* list_splice - join two lists, this is designed for stacks
* @list: the new list to add.
* @head: the place to add it in the first list.
*/
static void list_splice(const struct list_head *list,
struct list_head *head)
if (!list_empty(list))
__list_splice(list, head, head->next);
/**
* list_splice_tail - join two lists, each list being a queue
* @list: the new list to add.
* @head: the place to add it in the first list.
*/
static void list_splice_tail(struct list_head *list,
struct list_head *head)
if (!list_empty(list))
__list_splice(list, head->prev, head);
/**
* list_splice_init - join two lists and reinitialise the emptied list.
* @list: the new list to add.
* @head: the place to add it in the first list.
*
* The list at @list is reinitialised
*/
static void list_splice_init(struct list_head *list,
struct list_head *head)
if (!list_empty(list))
__list_splice(list, head, head->next);
INIT_LIST_HEAD(list);
/**
* list_splice_tail_init - join two lists and reinitialise the emptied list
* @list: the new list to add.
* @head: the place to add it in the first list.
*
* Each of the lists is a queue.
* The list at @list is reinitialised
*/
static void list_splice_tail_init(struct list_head *list,
struct list_head *head)
if (!list_empty(list))
__list_splice(list, head->prev, head);
INIT_LIST_HEAD(list);
/**
* list_entry - get the struct for this entry
* @ptr: the &struct list_head pointer.
* @type: the type of the struct this is embedded in.
* @member: the name of the list_struct within the struct.
*/
#define list_entry(ptr, type, member) \\
container_of(ptr, type, member)
/**
* list_first_entry - get the first element from a list
* @ptr: the list head to take the element from.
* @type: the type of the struct this is embedded in.
* @member: the name of the list_struct within the struct.
*
* Note, that list is expected to be not empty.
*/
#define list_first_entry(ptr, type, member) \\
list_entry((ptr)->next, type, member)
/**
* list_for_each - iterate over a list
* @pos: the &struct list_head to use as a loop cursor.
* @head: the head for your list.
*/
#define list_for_each(pos, head) \\
for (pos = (head)->next; prefetch(pos->next), pos != (head); \\
pos = pos->next)
/**
* __list_for_each - iterate over a list
* @pos: the &struct list_head to use as a loop cursor.
* @head: the head for your list.
*
* This variant differs from list_for_each() in that it's the
* simplest possible list iteration code, no prefetching is done.
* Use this for code that knows the list to be very short (empty
* or 1 entry) most of the time.
*/
#define __list_for_each(pos, head) \\
for (pos = (head)->next; pos != (head); pos = pos->next)
/**
* list_for_each_prev - iterate over a list backwards
* @pos: the &struct list_head to use as a loop cursor.
* @head: the head for your list.
*/
#define list_for_each_prev(pos, head) \\
for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \\
pos = pos->prev)
/**
* list_for_each_safe - iterate over a list safe against removal of list entry
* @pos: the &struct list_head to use as a loop cursor.
* @n: another &struct list_head to use as temporary storage
* @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)
/**
* list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
* @pos: the &struct list_head to use as a loop cursor.
* @n: another &struct list_head to use as temporary storage
* @head: the head for your list.
*/
#define list_for_each_prev_safe(pos, n, head) \\
for (pos = (head)->prev, n = pos->prev; \\
prefetch(pos->prev), pos != (head); \\
pos = n, n = pos->prev)
/**
* list_for_each_entry - iterate over list of given type
* @pos: the type * to use as a loop cursor.
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry(pos, head, member) \\
for (pos = list_entry((head)->next, typeof(*pos), member); \\
prefetch(pos->member.next), &pos->member != (head); \\
pos = list_entry(pos->member.next, typeof(*pos), member))
/**
* list_for_each_entry_reverse - iterate backwards over list of given type.
* @pos: the type * to use as a loop cursor.
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry_reverse(pos, head, member) \\
for (pos = list_entry((head)->prev, typeof(*pos), member); \\
prefetch(pos->member.prev), &pos->member != (head); \\
pos = list_entry(pos->member.prev, typeof(*pos), member))
/**
* list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
* @pos: the type * to use as a start point
* @head: the head of the list
* @member: the name of the list_struct within the struct.
*
* Prepares a pos entry for use as a start point in list_for_each_entry_continue().
*/
#define list_prepare_entry(pos, head, member) \\
((pos) ? : list_entry(head, typeof(*pos), member))
/**
* list_for_each_entry_continue - continue iteration over list of given type
* @pos: the type * to use as a loop cursor.
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*
* Continue to iterate over list of given type, continuing after
* the current position.
*/
#define list_for_each_entry_continue(pos, head, member) \\
for (pos = list_entry(pos->member.next, typeof(*pos), member); \\
prefetch(pos->member.next), &pos->member != (head); \\
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