text: #ifndef _LINUX_LLIST_H
  #define _LINUX_LLIST_H
  
  #include <stddef.h>
  
  #ifndef inline
  #define inline __inline__
  #endif
  
  static inline void prefetch(__attribute__((unused)) const void *x) {;}
  
  /**
   * container_of - cast a member of a structure out to the containing structure
   *
   * @ptr:	the pointer to the member.
   * @type:	the type of the container struct this is embedded in.
   * @member:	the name of the member within the struct.
   *
   */
  #define container_of(ptr, type, member) ({			\
          const typeof( ((type *)0)->member ) *__mptr = (typeof( ((type *)0)->member ) *)(ptr);	\
          (type *)( (char *)__mptr - offsetof(type, member) );})
  
  
  /*
   * These are non-NULL pointers that will result in page faults
   * under normal circumstances, used to verify that nobody uses
   * non-initialized llist entries.
   */
  #define LLIST_POISON1  ((void *) 0x00100100)
  #define LLIST_POISON2  ((void *) 0x00200200)
  
  /*
   * Simple doubly linked llist implementation.
   *
   * Some of the internal functions ("__xxx") are useful when
   * manipulating whole llists 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.
   */
  
  struct llist_head {
  	struct llist_head *next, *prev;
  };
  
  #define LLIST_HEAD_INIT(name) { &(name), &(name) }
  
  #define LLIST_HEAD(name) \
  	struct llist_head name = LLIST_HEAD_INIT(name)
  
  #define INIT_LLIST_HEAD(ptr) do { \
  	(ptr)->next = (ptr); (ptr)->prev = (ptr); \
  } while (0)
  
  /*
   * Insert a new entry between two known consecutive entries.
   *
   * This is only for internal llist manipulation where we know
   * the prev/next entries already!
   */
  static inline void __llist_add(struct llist_head *_new,
  				 struct llist_head *prev,
  				 struct llist_head *next)
  {
  	next->prev = _new;
  	_new->next = next;
  	_new->prev = prev;
  	prev->next = _new;
  }
  
  /**
   * llist_add - add a new entry
   * @new: new entry to be added
   * @head: llist head to add it after
   *
   * Insert a new entry after the specified head.
   * This is good for implementing stacks.
   */
  static inline void llist_add(struct llist_head *_new, struct llist_head *head)
  {
  	__llist_add(_new, head, head->next);
  }
  
  /**
   * llist_add_tail - add a new entry
   * @new: new entry to be added
   * @head: llist head to add it before
   *
   * Insert a new entry before the specified head.
   * This is useful for implementing queues.
   */
  static inline void llist_add_tail(struct llist_head *_new, struct llist_head *head)
  {
  	__llist_add(_new, head->prev, head);
  }
  
  /*
   * Delete a llist entry by making the prev/next entries
   * point to each other.
   *
   * This is only for internal llist manipulation where we know
   * the prev/next entries already!
   */
  static inline void __llist_del(struct llist_head * prev, struct llist_head * next)
  {
  	next->prev = prev;
  	prev->next = next;
  }
  
  /**
   * llist_del - deletes entry from llist.
   * @entry: the element to delete from the llist.
   * Note: llist_empty on entry does not return true after this, the entry is
   * in an undefined state.
   */
  static inline void llist_del(struct llist_head *entry)
  {
  	__llist_del(entry->prev, entry->next);
  	entry->next = (struct llist_head *)LLIST_POISON1;
  	entry->prev = (struct llist_head *)LLIST_POISON2;
  }
  
  /**
   * llist_del_init - deletes entry from llist and reinitialize it.
   * @entry: the element to delete from the llist.
   */
  static inline void llist_del_init(struct llist_head *entry)
  {
  	__llist_del(entry->prev, entry->next);
  	INIT_LLIST_HEAD(entry);
  }
  
  /**
   * llist_move - delete from one llist and add as another's head
   * @llist: the entry to move
   * @head: the head that will precede our entry
   */
  static inline void llist_move(struct llist_head *llist, struct llist_head *head)
  {
          __llist_del(llist->prev, llist->next);
          llist_add(llist, head);
  }
  
  /**
   * llist_move_tail - delete from one llist and add as another's tail
   * @llist: the entry to move
   * @head: the head that will follow our entry
   */
  static inline void llist_move_tail(struct llist_head *llist,
  				  struct llist_head *head)
  {
          __llist_del(llist->prev, llist->next);
          llist_add_tail(llist, head);
  }
  
  /**
   * llist_empty - tests whether a llist is empty
   * @head: the llist to test.
   */
  static inline int llist_empty(const struct llist_head *head)
  {
  	return head->next == head;
  }
  
  static inline void __llist_splice(struct llist_head *llist,
  				 struct llist_head *head)
  {
  	struct llist_head *first = llist->next;
  	struct llist_head *last = llist->prev;
  	struct llist_head *at = head->next;
  
  	first->prev = head;
  	head->next = first;
  
  	last->next = at;
  	at->prev = last;
  }
  
  /**
   * llist_splice - join two llists
   * @llist: the new llist to add.
   * @head: the place to add it in the first llist.
   */
  static inline void llist_splice(struct llist_head *llist, struct llist_head *head)
  {
  	if (!llist_empty(llist))
  		__llist_splice(llist, head);
  }
  
  /**
   * llist_splice_init - join two llists and reinitialise the emptied llist.
   * @llist: the new llist to add.
   * @head: the place to add it in the first llist.
   *
   * The llist at @llist is reinitialised
   */
  static inline void llist_splice_init(struct llist_head *llist,
  				    struct llist_head *head)
  {
  	if (!llist_empty(llist)) {
  		__llist_splice(llist, head);
  		INIT_LLIST_HEAD(llist);
  	}
  }
  
  /**
   * llist_entry - get the struct for this entry
   * @ptr:	the &struct llist_head pointer.
   * @type:	the type of the struct this is embedded in.
   * @member:	the name of the llist_struct within the struct.
   */
  #define llist_entry(ptr, type, member) \
  	container_of(ptr, type, member)
  
  /**
   * llist_for_each	-	iterate over a llist
   * @pos:	the &struct llist_head to use as a loop counter.
   * @head:	the head for your llist.
   */
  #define llist_for_each(pos, head) \
  	for (pos = (head)->next, prefetch(pos->next); pos != (head); \
  		pos = pos->next, prefetch(pos->next))
  
  /**
   * __llist_for_each	-	iterate over a llist
   * @pos:	the &struct llist_head to use as a loop counter.
   * @head:	the head for your llist.
   *
   * This variant differs from llist_for_each() in that it's the
   * simplest possible llist iteration code, no prefetching is done.
   * Use this for code that knows the llist to be very short (empty
   * or 1 entry) most of the time.
   */
  #define __llist_for_each(pos, head) \
  	for (pos = (head)->next; pos != (head); pos = pos->next)
  
  /**
   * llist_for_each_prev	-	iterate over a llist backwards
   * @pos:	the &struct llist_head to use as a loop counter.
   * @head:	the head for your llist.
   */
  #define llist_for_each_prev(pos, head) \
  	for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
  		pos = pos->prev, prefetch(pos->prev))
  
  /**
   * llist_for_each_safe	-	iterate over a llist safe against removal of llist entry
   * @pos:	the &struct llist_head to use as a loop counter.
   * @n:		another &struct llist_head to use as temporary storage
   * @head:	the head for your llist.
   */
  #define llist_for_each_safe(pos, n, head) \
  	for (pos = (head)->next, n = pos->next; pos != (head); \
  		pos = n, n = pos->next)
  
  /**
   * llist_for_each_entry	-	iterate over llist of given type
   * @pos:	the type * to use as a loop counter.
   * @head:	the head for your llist.
   * @member:	the name of the llist_struct within the struct.
   */
  #define llist_for_each_entry(pos, head, member)				\
  	for (pos = llist_entry((head)->next, typeof(*pos), member),	\
  			prefetch(pos->member.next);			\
  		&pos->member != (head); 					\
  		pos = llist_entry(pos->member.next, typeof(*pos), member),	\
  			prefetch(pos->member.next))
  
  /**
   * llist_for_each_entry_reverse - iterate backwards over llist of given type.
   * @pos:	the type * to use as a loop counter.
   * @head:	the head for your llist.
   * @member:	the name of the llist_struct within the struct.
   */
  #define llist_for_each_entry_reverse(pos, head, member)			\
  	for (pos = llist_entry((head)->prev, typeof(*pos), member),	\
  			prefetch(pos->member.prev);			\
  		&pos->member != (head); 					\
  		pos = llist_entry(pos->member.prev, typeof(*pos), member),	\
  			prefetch(pos->member.prev))
  
  /**
   * llist_for_each_entry_continue -	iterate over llist of given type
   *			continuing after existing point
   * @pos:	the type * to use as a loop counter.
   * @head:	the head for your llist.
   * @member:	the name of the llist_struct within the struct.
   */
  #define llist_for_each_entry_continue(pos, head, member) 		\
  	for (pos = llist_entry(pos->member.next, typeof(*pos), member),	\
  			prefetch(pos->member.next);			\
  		&pos->member != (head);					\
  		pos = llist_entry(pos->member.next, typeof(*pos), member),	\
  			prefetch(pos->member.next))
  
  /**
   * llist_for_each_entry_safe - iterate over llist of given type safe against removal of llist entry
   * @pos:	the type * to use as a loop counter.
   * @n:		another type * to use as temporary storage
   * @head:	the head for your llist.
   * @member:	the name of the llist_struct within the struct.
   */
  #define llist_for_each_entry_safe(pos, n, head, member)			\
  	for (pos = llist_entry((head)->next, typeof(*pos), member),	\
  		n = llist_entry(pos->member.next, typeof(*pos), member);	\
  		&pos->member != (head); 					\
  		pos = n, n = llist_entry(n->member.next, typeof(*n), member))
  
  /**
   * llist_for_each_rcu	-	iterate over an rcu-protected llist
   * @pos:	the &struct llist_head to use as a loop counter.
   * @head:	the head for your llist.
   */
  #define llist_for_each_rcu(pos, head) \
  	for (pos = (head)->next, prefetch(pos->next); pos != (head); \
          	pos = pos->next, ({ smp_read_barrier_depends(); 0;}), prefetch(pos->next))
  
  #define __llist_for_each_rcu(pos, head) \
  	for (pos = (head)->next; pos != (head); \
          	pos = pos->next, ({ smp_read_barrier_depends(); 0;}))
  
  /**
   * llist_for_each_safe_rcu	-	iterate over an rcu-protected llist safe
   *					against removal of llist entry
   * @pos:	the &struct llist_head to use as a loop counter.
   * @n:		another &struct llist_head to use as temporary storage
   * @head:	the head for your llist.
   */
  #define llist_for_each_safe_rcu(pos, n, head) \
  	for (pos = (head)->next, n = pos->next; pos != (head); \
  		pos = n, ({ smp_read_barrier_depends(); 0;}), n = pos->next)
  
  /**
   * llist_for_each_entry_rcu	-	iterate over rcu llist of given type
   * @pos:	the type * to use as a loop counter.
   * @head:	the head for your llist.
   * @member:	the name of the llist_struct within the struct.
   */
  #define llist_for_each_entry_rcu(pos, head, member)			\
  	for (pos = llist_entry((head)->next, typeof(*pos), member),	\
  			prefetch(pos->member.next);			\
  		&pos->member != (head); 					\
  		pos = llist_entry(pos->member.next, typeof(*pos), member),	\
  			({ smp_read_barrier_depends(); 0;}),		\
  			prefetch(pos->member.next))
  
  
  /**
   * llist_for_each_continue_rcu	-	iterate over an rcu-protected llist
   *			continuing after existing point.
   * @pos:	the &struct llist_head to use as a loop counter.
   * @head:	the head for your llist.
   */
  #define llist_for_each_continue_rcu(pos, head) \
  	for ((pos) = (pos)->next, prefetch((pos)->next); (pos) != (head); \
          	(pos) = (pos)->next, ({ smp_read_barrier_depends(); 0;}), prefetch((pos)->next))
  
  
  #endif
  