mirror of https://gerrit.osmocom.org/libosmocore
402 lines
13 KiB
C
402 lines
13 KiB
C
/*! \file linuxlist.h
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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 llists 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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#pragma once
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/*! \defgroup linuxlist Simple doubly linked list implementation
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* @{
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* \file linuxlist.h */
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#include <stddef.h>
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#ifndef inline
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#define inline __inline__
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#endif
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static inline void prefetch(const void *x) {;}
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/*! cast a member of a structure out to the containing structure
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*
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* \param[in] ptr the pointer to the member.
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* \param[in] type the type of the container struct this is embedded in.
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* \param[in] member the name of the member within the struct.
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*/
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#define container_of(ptr, type, member) ({ \
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const typeof( ((type *)0)->member ) *__mptr = (ptr); \
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(type *)( (char *)__mptr - offsetof(type, member) );})
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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 llist entries.
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*/
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#define LLIST_POISON1 ((void *) 0x00100100)
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#define LLIST_POISON2 ((void *) 0x00200200)
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/*! (double) linked list header structure */
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struct llist_head {
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/*! Pointer to next and previous item */
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struct llist_head *next, *prev;
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};
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#define LLIST_HEAD_INIT(name) { &(name), &(name) }
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/*! define a statically-initialized \ref llist_head
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* \param[in] name Variable name
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*
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* This is a helper macro that will define a named variable of type
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* \ref llist_head and initialize it */
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#define LLIST_HEAD(name) \
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struct llist_head name = LLIST_HEAD_INIT(name)
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/*! initialize a \ref llist_head to point back to self */
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#define INIT_LLIST_HEAD(ptr) do { \
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(ptr)->next = (ptr); (ptr)->prev = (ptr); \
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} while (0)
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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 llist manipulation where we know
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* the prev/next entries already!
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*/
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static inline void __llist_add(struct llist_head *_new,
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struct llist_head *prev,
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struct llist_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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/*! add a new entry into a linked list (at head)
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* \param _new New entry to be added
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* \param head \ref llist_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 llist_add(struct llist_head *_new, struct llist_head *head)
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{
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__llist_add(_new, head, head->next);
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}
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/*! add a new entry into a linked list (at tail)
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* \param _new New entry to be added
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* \param head Head of linked list to whose tail we shall add \a _new
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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 llist_add_tail(struct llist_head *_new, struct llist_head *head)
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{
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__llist_add(_new, head->prev, head);
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}
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/*
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* Delete a llist 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 llist manipulation where we know
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* the prev/next entries already!
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*/
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static inline void __llist_del(struct llist_head * prev, struct llist_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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/*! Delete entry from linked list
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* \param entry The element to delete from the llist
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*
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* Note: llist_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 llist_del(struct llist_head *entry)
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{
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__llist_del(entry->prev, entry->next);
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entry->next = (struct llist_head *)LLIST_POISON1;
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entry->prev = (struct llist_head *)LLIST_POISON2;
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}
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/*! Delete entry from linked list and reinitialize it
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* \param entry The element to delete from the list
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*/
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static inline void llist_del_init(struct llist_head *entry)
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{
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__llist_del(entry->prev, entry->next);
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INIT_LLIST_HEAD(entry);
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}
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/*! Delete from one llist and add as another's head
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* \param llist The entry to move
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* \param head The head that will precede our entry
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*/
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static inline void llist_move(struct llist_head *llist, struct llist_head *head)
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{
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__llist_del(llist->prev, llist->next);
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llist_add(llist, head);
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}
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/*! Delete from one llist and add as another's tail
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* \param llist The entry to move
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* \param head The head that will follow our entry
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*/
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static inline void llist_move_tail(struct llist_head *llist,
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struct llist_head *head)
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{
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__llist_del(llist->prev, llist->next);
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llist_add_tail(llist, head);
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}
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/*! Test whether a linked list is empty
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* \param[in] head The llist to test.
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* \returns 1 if the list is empty, 0 otherwise
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*/
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static inline int llist_empty(const struct llist_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 __llist_splice(struct llist_head *llist,
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struct llist_head *head)
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{
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struct llist_head *first = llist->next;
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struct llist_head *last = llist->prev;
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struct llist_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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/*! Join two llists
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* \param llist The new linked list to add
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* \param head The place to add \a llist in the other list
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*/
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static inline void llist_splice(struct llist_head *llist, struct llist_head *head)
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{
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if (!llist_empty(llist))
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__llist_splice(llist, head);
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}
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/*! join two llists and reinitialise the emptied llist.
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* \param llist The new linked list to add.
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* \param head The place to add it in the first llist.
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*
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* The llist at @llist is reinitialised
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*/
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static inline void llist_splice_init(struct llist_head *llist,
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struct llist_head *head)
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{
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if (!llist_empty(llist)) {
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__llist_splice(llist, head);
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INIT_LLIST_HEAD(llist);
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}
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}
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/*! Get the struct containing this list entry
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* \param ptr The \ref llist_head pointer
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* \param type The type of the struct this is embedded in
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* \param @member The name of the \ref llist_head within the struct
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*/
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#define llist_entry(ptr, type, member) \
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container_of(ptr, type, member)
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/*! Get the first element from a list
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* \param ptr the list head to take the element from.
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* \param type the type of the struct this is embedded in.
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* \param member the name of the list_head within the struct.
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*
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* Note, that list is expected to be not empty.
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*/
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#define llist_first_entry(ptr, type, member) \
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llist_entry((ptr)->next, type, member)
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/*! Get the last element from a list
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* \param ptr the list head to take the element from.
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* \param type the type of the struct this is embedded in.
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* \param member the name of the llist_head within the struct.
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*
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* Note, that list is expected to be not empty.
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*/
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#define llist_last_entry(ptr, type, member) \
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llist_entry((ptr)->prev, type, member)
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/*! Get the first element from a list, or NULL
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* \param ptr the list head to take the element from.
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* \param type the type of the struct this is embedded in.
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* \param member the name of the list_head within the struct.
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*
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* Note that if the list is empty, it returns NULL.
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*/
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#define llist_first_entry_or_null(ptr, type, member) \
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(!llist_empty(ptr) ? llist_first_entry(ptr, type, member) : NULL)
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/*! Iterate over a linked list
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* \param pos The \ref llist_head to use as a loop counter
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* \param head The head of the list over which to iterate
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*/
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#define llist_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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/*! Iterate over a llist (no prefetch)
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* \param pos The \ref llist_head to use as a loop counter
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* \param head The head of the list over which to iterate
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*
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* This variant differs from llist_for_each() in that it's the
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* simplest possible llist iteration code, no prefetching is done.
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* Use this for code that knows the llist 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 __llist_for_each(pos, head) \
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for (pos = (head)->next; pos != (head); pos = pos->next)
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/*! Iterate over a llist backwards
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* \param pos The \ref llist_head to use as a loop counter
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* \param head The head of the list over which to iterate
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*/
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#define llist_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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/*! Iterate over a list; safe against removal of llist entry
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* \param pos The \ref llist_head to use as a loop counter
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* \param n Another \ref llist_head to use as temporary storage
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* \param head The head of the list over which to iterate
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*/
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#define llist_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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/*! Iterate over llist of given type
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* \param pos The 'type *' to use as a loop counter
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* \param head The head of the list over which to iterate
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* \param member The name of the \ref llist_head within struct \a pos
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*/
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#define llist_for_each_entry(pos, head, member) \
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for (pos = llist_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 = llist_entry(pos->member.next, typeof(*pos), member), \
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prefetch(pos->member.next))
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/*! Iterate backwards over llist of given type.
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* \param pos The 'type *' to use as a loop counter
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* \param head The head of the list over which to iterate
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* \param member The name of the \ref llist_head within struct \a pos
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*/
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#define llist_for_each_entry_reverse(pos, head, member) \
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for (pos = llist_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 = llist_entry(pos->member.prev, typeof(*pos), member), \
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prefetch(pos->member.prev))
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/*! iterate over llist of given type continuing after existing
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* point
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* \param pos The 'type *' to use as a loop counter
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* \param head The head of the list over which to iterate
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* \param member The name of the \ref llist_head within struct \a pos
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*/
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#define llist_for_each_entry_continue(pos, head, member) \
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for (pos = llist_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 = llist_entry(pos->member.next, typeof(*pos), member), \
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prefetch(pos->member.next))
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/*! iterate over llist of given type, safe against removal of
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* non-consecutive(!) llist entries
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* \param pos The 'type *' to use as a loop counter
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* \param n Another type * to use as temporary storage
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* \param head The head of the list over which to iterate
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* \param member The name of the \ref llist_head within struct \a pos
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*/
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#define llist_for_each_entry_safe(pos, n, head, member) \
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for (pos = llist_entry((head)->next, typeof(*pos), member), \
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n = llist_entry(pos->member.next, typeof(*pos), member); \
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&pos->member != (head); \
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pos = n, n = llist_entry(n->member.next, typeof(*n), member))
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/**
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* llist_for_each_rcu - iterate over an rcu-protected llist
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* @pos: the &struct llist_head to use as a loop counter.
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* @head: the head for your llist.
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*/
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#define llist_for_each_rcu(pos, head) \
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for (pos = (head)->next, prefetch(pos->next); pos != (head); \
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pos = pos->next, ({ smp_read_barrier_depends(); 0;}), prefetch(pos->next))
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#define __llist_for_each_rcu(pos, head) \
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for (pos = (head)->next; pos != (head); \
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pos = pos->next, ({ smp_read_barrier_depends(); 0;}))
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/**
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* llist_for_each_safe_rcu - iterate over an rcu-protected llist safe
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* against removal of llist entry
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* @pos: the &struct llist_head to use as a loop counter.
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* @n: another &struct llist_head to use as temporary storage
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* @head: the head for your llist.
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*/
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#define llist_for_each_safe_rcu(pos, n, head) \
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for (pos = (head)->next, n = pos->next; pos != (head); \
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pos = n, ({ smp_read_barrier_depends(); 0;}), n = pos->next)
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/**
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* llist_for_each_entry_rcu - iterate over rcu llist 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 llist.
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* @member: the name of the llist_struct within the struct.
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*/
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#define llist_for_each_entry_rcu(pos, head, member) \
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for (pos = llist_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 = llist_entry(pos->member.next, typeof(*pos), member), \
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({ smp_read_barrier_depends(); 0;}), \
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prefetch(pos->member.next))
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/**
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* llist_for_each_continue_rcu - iterate over an rcu-protected llist
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* continuing after existing point.
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* @pos: the &struct llist_head to use as a loop counter.
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* @head: the head for your llist.
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*/
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#define llist_for_each_continue_rcu(pos, head) \
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for ((pos) = (pos)->next, prefetch((pos)->next); (pos) != (head); \
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(pos) = (pos)->next, ({ smp_read_barrier_depends(); 0;}), prefetch((pos)->next))
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/*! count nr of llist items by iterating.
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* \param head The llist head to count items of.
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* \returns Number of items.
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*
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* This function is not efficient, mostly useful for small lists and non time
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* critical cases like unit tests.
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*/
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static inline unsigned int llist_count(struct llist_head *head)
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{
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struct llist_head *entry;
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unsigned int i = 0;
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llist_for_each(entry, head)
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i++;
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return i;
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}
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/*!
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* }@
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*/
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