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348
list.h
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348
list.h
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/*
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* Stolen from Linux 2.6.7
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; version 2 of the
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* License.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef CMUS_LIST_H
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#define CMUS_LIST_H
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#include "compiler.h" /* container_of */
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static inline void prefetch(const void *x)
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{
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}
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/*
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* These are non-NULL pointers that will result in page faults
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* under normal circumstances, used to verify that nobody uses
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* non-initialized list entries.
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*/
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#define LIST_POISON1 ((void *) 0x00100100)
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#define LIST_POISON2 ((void *) 0x00200200)
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/*
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* Simple doubly linked list implementation.
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*
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* Some of the internal functions ("_xxx") are useful when
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* manipulating whole lists rather than single entries, as
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* sometimes we already know the next/prev entries and we can
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* generate better code by using them directly rather than
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* using the generic single-entry routines.
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*/
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struct list_head {
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struct list_head *next, *prev;
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};
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#define LIST_HEAD_INIT(name) { &(name), &(name) }
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#define LIST_HEAD(name) \
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struct list_head name = LIST_HEAD_INIT(name)
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static inline void list_init(struct list_head *head)
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{
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head->next = head;
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head->prev = head;
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}
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/*
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* Insert a new entry between two known consecutive entries.
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*
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* This is only for internal list manipulation where we know
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* the prev/next entries already!
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*/
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static inline void _list_add(struct list_head *new,
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struct list_head *prev,
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struct list_head *next)
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{
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next->prev = new;
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new->next = next;
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new->prev = prev;
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prev->next = new;
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}
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static inline struct list_head *list_prev(struct list_head *list)
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{
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return list->prev;
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}
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static inline struct list_head *list_next(struct list_head *list)
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{
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return list->next;
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}
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/**
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* list_add - add a new entry
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* @new: new entry to be added
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* @head: list head to add it after
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*
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* Insert a new entry after the specified head.
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* This is good for implementing stacks.
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*/
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static inline void list_add(struct list_head *new, struct list_head *head)
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{
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_list_add(new, head, head->next);
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}
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/**
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* list_add_tail - add a new entry
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* @new: new entry to be added
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* @head: list head to add it before
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*
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* Insert a new entry before the specified head.
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* This is useful for implementing queues.
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*/
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static inline void list_add_tail(struct list_head *new, struct list_head *head)
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{
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_list_add(new, head->prev, head);
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}
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/*
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* Delete a list entry by making the prev/next entries
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* point to each other.
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*
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* This is only for internal list manipulation where we know
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* the prev/next entries already!
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*/
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static inline void _list_del(struct list_head *prev, struct list_head *next)
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{
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next->prev = prev;
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prev->next = next;
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}
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/**
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* list_del - deletes entry from list.
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* @entry: the element to delete from the list.
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* Note: list_empty on entry does not return true after this, the entry is
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* in an undefined state.
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*/
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static inline void list_del(struct list_head *entry)
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{
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_list_del(entry->prev, entry->next);
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entry->next = LIST_POISON1;
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entry->prev = LIST_POISON2;
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}
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/**
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* list_del_init - deletes entry from list and reinitialize it.
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* @entry: the element to delete from the list.
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*/
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static inline void list_del_init(struct list_head *entry)
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{
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_list_del(entry->prev, entry->next);
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list_init(entry);
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}
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/**
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* list_move - delete from one list and add as another one's head
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* @list: the entry to move
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* @head: the head that will precede our entry
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*/
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static inline void list_move(struct list_head *list, struct list_head *head)
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{
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_list_del(list->prev, list->next);
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list_add(list, head);
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}
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/**
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* list_move_tail - delete from one list and add as another one's tail
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* @list: the entry to move
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* @head: the head that will follow our entry
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*/
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static inline void list_move_tail(struct list_head *list,
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struct list_head *head)
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{
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_list_del(list->prev, list->next);
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list_add_tail(list, head);
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}
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/**
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* list_empty - tests whether a list is empty
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* @head: the list to test.
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*/
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static inline int list_empty(const struct list_head *head)
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{
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return head->next == head;
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}
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static inline void _list_splice(struct list_head *list,
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struct list_head *head)
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{
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struct list_head *first = list->next;
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struct list_head *last = list->prev;
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struct list_head *at = head->next;
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first->prev = head;
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head->next = first;
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last->next = at;
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at->prev = last;
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}
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/**
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* list_splice - join two lists
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* @list: the new list to add.
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* @head: the place to add it in the first list.
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*/
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static inline void list_splice(struct list_head *list, struct list_head *head)
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{
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if (!list_empty(list))
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_list_splice(list, head);
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}
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/**
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* list_splice_init - join two lists and reinitialize the emptied list.
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* @list: the new list to add.
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* @head: the place to add it in the first list.
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*
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* The list at @list is reinitialized
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*/
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static inline void list_splice_init(struct list_head *list,
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struct list_head *head)
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{
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if (!list_empty(list)) {
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_list_splice(list, head);
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list_init(list);
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}
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}
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/**
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* list_entry - get the struct for this entry
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* @ptr: the &struct list_head pointer.
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* @type: the type of the struct this is embedded in.
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* @member: the name of the list_struct within the struct.
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*/
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#define list_entry(ptr, type, member) \
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container_of(ptr, type, member)
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/**
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* list_for_each - iterate over a list
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* @pos: the &struct list_head to use as a loop counter.
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* @head: the head for your list.
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*/
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#define list_for_each(pos, head) \
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for (pos = (head)->next, prefetch(pos->next); pos != (head); \
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pos = pos->next, prefetch(pos->next))
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/**
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* _list_for_each - iterate over a list
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* @pos: the &struct list_head to use as a loop counter.
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* @head: the head for your list.
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*
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* This variant differs from list_for_each() in that it's the
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* simplest possible list iteration code, no prefetching is done.
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* Use this for code that knows the list to be very short (empty
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* or 1 entry) most of the time.
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*/
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#define _list_for_each(pos, head) \
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for (pos = (head)->next; pos != (head); pos = pos->next)
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/**
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* list_for_each_prev - iterate over a list backwards
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* @pos: the &struct list_head to use as a loop counter.
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* @head: the head for your list.
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*/
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#define list_for_each_prev(pos, head) \
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for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
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pos = pos->prev, prefetch(pos->prev))
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/**
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* list_for_each_safe - iterate over a list safe against removal of list entry
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* @pos: the &struct list_head to use as a loop counter.
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* @n: another &struct list_head to use as temporary storage
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* @head: the head for your list.
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*/
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#define list_for_each_safe(pos, n, head) \
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for (pos = (head)->next, n = pos->next; pos != (head); \
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pos = n, n = pos->next)
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/**
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* list_for_each_entry - iterate over list of given type
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* @pos: the type * to use as a loop counter.
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* @head: the head for your list.
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* @member: the name of the list_struct within the struct.
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*/
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#define list_for_each_entry(pos, head, member) \
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for (pos = list_entry((head)->next, __typeof__(*pos), member), \
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prefetch(pos->member.next); \
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&pos->member != (head); \
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pos = list_entry(pos->member.next, __typeof__(*pos), member), \
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prefetch(pos->member.next))
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/**
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* list_for_each_entry_reverse - iterate backwards over list of given type.
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* @pos: the type * to use as a loop counter.
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* @head: the head for your list.
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* @member: the name of the list_struct within the struct.
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*/
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#define list_for_each_entry_reverse(pos, head, member) \
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for (pos = list_entry((head)->prev, __typeof__(*pos), member), \
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prefetch(pos->member.prev); \
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&pos->member != (head); \
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pos = list_entry(pos->member.prev, __typeof__(*pos), member), \
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prefetch(pos->member.prev))
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/**
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* list_prepare_entry - prepare a pos entry for use as a start point in
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* list_for_each_entry_continue
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* @pos: the type * to use as a start point
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* @head: the head of the list
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* @member: the name of the list_struct within the struct.
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*/
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#define list_prepare_entry(pos, head, member) \
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((pos) ? : list_entry(head, __typeof__(*pos), member))
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/**
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* list_for_each_entry_continue - iterate over list of given type
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* continuing after existing point
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* @pos: the type * to use as a loop counter.
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* @head: the head for your list.
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* @member: the name of the list_struct within the struct.
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*/
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#define list_for_each_entry_continue(pos, head, member) \
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for (pos = list_entry(pos->member.next, __typeof__(*pos), member), \
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prefetch(pos->member.next); \
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&pos->member != (head); \
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pos = list_entry(pos->member.next, __typeof__(*pos), member), \
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prefetch(pos->member.next))
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/**
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* list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
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* @pos: the type * to use as a loop counter.
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* @n: another type * to use as temporary storage
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* @head: the head for your list.
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* @member: the name of the list_struct within the struct.
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*/
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#define list_for_each_entry_safe(pos, n, head, member) \
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for (pos = list_entry((head)->next, __typeof__(*pos), member), \
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n = list_entry(pos->member.next, __typeof__(*pos), member); \
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&pos->member != (head); \
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pos = n, n = list_entry(n->member.next, __typeof__(*n), member))
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/**
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* list_len - get the length of a list
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* @list: the list to measure
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*/
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static inline size_t list_len(struct list_head *list)
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{
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size_t len = 0;
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struct list_head *pos;
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list_for_each(pos, list)
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len++;
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return len;
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}
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#endif
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