/*
   * Descending-priority-sorted double-linked list
   *
   * (C) 2002-2003 Intel Corp
   * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
   *
   * 2001-2005 (c) MontaVista Software, Inc.
   * Daniel Walker <dwalker@mvista.com>
   *
   * (C) 2005 Thomas Gleixner <tglx@linutronix.de>
   *
   * Simplifications of the original code by
   * Oleg Nesterov <oleg@tv-sign.ru>
   *
   * Licensed under the FSF's GNU Public License v2 or later.
   *
   * Based on simple lists (include/linux/list.h).
   *
   * This is a priority-sorted list of nodes; each node has a
   * priority from INT_MIN (highest) to INT_MAX (lowest).
   *
   * Addition is O(K), removal is O(1), change of priority of a node is
   * O(K) and K is the number of RT priority levels used in the system.
   * (1 <= K <= 99)
   *
   * This list is really a list of lists:
   *
   *  - The tier 1 list is the prio_list, different priority nodes.
   *
   *  - The tier 2 list is the node_list, serialized nodes.
   *
   * Simple ASCII art explanation:
   *

   * pl:prio_list (only for plist_node)
   * nl:node_list
   *   HEAD|             NODE(S)
   *       |
   *       ||------------------------------------|
   *       ||->|pl|<->|pl|<--------------->|pl|<-|
   *       |   |10|   |21|   |21|   |21|   |40|   (prio)
   *       |   |  |   |  |   |  |   |  |   |  |
   *       |   |  |   |  |   |  |   |  |   |  |
   * |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
   * |-------------------------------------------|

   *
   * The nodes on the prio_list list are sorted by priority to simplify
   * the insertion of new nodes. There are no nodes with duplicate
   * priorites on the list.
   *

   * The nodes on the node_list are ordered by priority and can contain

   * entries which have the same priority. Those entries are ordered
   * FIFO
   *
   * Addition means: look for the prio_list node in the prio_list
   * for the priority of the node and insert it before the node_list
   * entry of the next prio_list node. If it is the first node of
   * that priority, add it to the prio_list in the right position and
   * insert it into the serialized node_list list
   *
   * Removal means remove it from the node_list and remove it from
   * the prio_list if the node_list list_head is non empty. In case
   * of removal from the prio_list it must be checked whether other
   * entries of the same priority are on the list or not. If there
   * is another entry of the same priority then this entry has to
   * replace the removed entry on the prio_list. If the entry which
   * is removed is the only entry of this priority then a simple
   * remove from both list is sufficient.
   *
   * INT_MIN is the highest priority, 0 is the medium highest, INT_MAX
   * is lowest priority.
   *
   * No locking is done, up to the caller.
   *
   */
  #ifndef _LINUX_PLIST_H_
  #define _LINUX_PLIST_H_

  #include <linux/kernel.h>

  #include <linux/list.h>

  
  struct plist_head {

  	struct list_head node_list;

  };
  
  struct plist_node {
  	int			prio;

  	struct list_head	prio_list;
  	struct list_head	node_list;

  };

  /**

   * PLIST_HEAD_INIT - static struct plist_head initializer

   * @head:	struct plist_head variable name

   */

  #define PLIST_HEAD_INIT(head)				\

  {							\

  	.node_list = LIST_HEAD_INIT((head).node_list)	\

  }
  
  /**

   * PLIST_NODE_INIT - static struct plist_node initializer

   * @node:	struct plist_node variable name
   * @__prio:	initial node priority
   */
  #define PLIST_NODE_INIT(node, __prio)			\
  {							\
  	.prio  = (__prio),				\

  	.prio_list = LIST_HEAD_INIT((node).prio_list),	\
  	.node_list = LIST_HEAD_INIT((node).node_list),	\

  }
  
  /**
   * plist_head_init - dynamic struct plist_head initializer

   * @head:	&struct plist_head pointer

   */
  static inline void

  plist_head_init(struct plist_head *head)

  {

  	INIT_LIST_HEAD(&head->node_list);

  }
  
  /**
   * plist_node_init - Dynamic struct plist_node initializer

   * @node:	&struct plist_node pointer
   * @prio:	initial node priority
   */
  static inline void plist_node_init(struct plist_node *node, int prio)
  {
  	node->prio = prio;

  	INIT_LIST_HEAD(&node->prio_list);
  	INIT_LIST_HEAD(&node->node_list);

  }
  
  extern void plist_add(struct plist_node *node, struct plist_head *head);
  extern void plist_del(struct plist_node *node, struct plist_head *head);
  
  /**
   * plist_for_each - iterate over the plist

   * @pos:	the type * to use as a loop counter
   * @head:	the head for your list

   */
  #define plist_for_each(pos, head)	\

  	 list_for_each_entry(pos, &(head)->node_list, node_list)

  
  /**

   * plist_for_each_safe - iterate safely over a plist of given type
   * @pos:	the type * to use as a loop counter
   * @n:	another type * to use as temporary storage
   * @head:	the head for your list

   *

   * Iterate over a plist of given type, safe against removal of list entry.

   */
  #define plist_for_each_safe(pos, n, head)	\

  	 list_for_each_entry_safe(pos, n, &(head)->node_list, node_list)

  
  /**
   * plist_for_each_entry	- iterate over list of given type

   * @pos:	the type * to use as a loop counter
   * @head:	the head for your list
   * @mem:	the name of the list_struct within the struct

   */
  #define plist_for_each_entry(pos, head, mem)	\

  	 list_for_each_entry(pos, &(head)->node_list, mem.node_list)

  
  /**

   * plist_for_each_entry_safe - iterate safely over list of given type
   * @pos:	the type * to use as a loop counter

   * @n:		another type * to use as temporary storage

   * @head:	the head for your list
   * @m:		the name of the list_struct within the struct
   *
   * Iterate over list of given type, safe against removal of list entry.

   */
  #define plist_for_each_entry_safe(pos, n, head, m)	\

  	list_for_each_entry_safe(pos, n, &(head)->node_list, m.node_list)

  
  /**
   * plist_head_empty - return !0 if a plist_head is empty

   * @head:	&struct plist_head pointer
   */
  static inline int plist_head_empty(const struct plist_head *head)
  {
  	return list_empty(&head->node_list);
  }
  
  /**
   * plist_node_empty - return !0 if plist_node is not on a list

   * @node:	&struct plist_node pointer
   */
  static inline int plist_node_empty(const struct plist_node *node)
  {

  	return list_empty(&node->node_list);

  }
  
  /* All functions below assume the plist_head is not empty. */
  
  /**
   * plist_first_entry - get the struct for the first entry

   * @head:	the &struct plist_head pointer
   * @type:	the type of the struct this is embedded in
   * @member:	the name of the list_struct within the struct

   */
  #ifdef CONFIG_DEBUG_PI_LIST
  # define plist_first_entry(head, type, member)	\
  ({ \
  	WARN_ON(plist_head_empty(head)); \
  	container_of(plist_first(head), type, member); \
  })
  #else
  # define plist_first_entry(head, type, member)	\
  	container_of(plist_first(head), type, member)
  #endif
  
  /**

   * plist_last_entry - get the struct for the last entry
   * @head:	the &struct plist_head pointer
   * @type:	the type of the struct this is embedded in
   * @member:	the name of the list_struct within the struct
   */
  #ifdef CONFIG_DEBUG_PI_LIST
  # define plist_last_entry(head, type, member)	\
  ({ \
  	WARN_ON(plist_head_empty(head)); \
  	container_of(plist_last(head), type, member); \
  })
  #else
  # define plist_last_entry(head, type, member)	\
  	container_of(plist_last(head), type, member)
  #endif
  
  /**

   * plist_first - return the first node (and thus, highest priority)

   * @head:	the &struct plist_head pointer
   *
   * Assumes the plist is _not_ empty.
   */

  static inline struct plist_node *plist_first(const struct plist_head *head)

  {
  	return list_entry(head->node_list.next,

  			  struct plist_node, node_list);

  }

  /**
   * plist_last - return the last node (and thus, lowest priority)
   * @head:	the &struct plist_head pointer
   *
   * Assumes the plist is _not_ empty.
   */
  static inline struct plist_node *plist_last(const struct plist_head *head)
  {
  	return list_entry(head->node_list.prev,

  			  struct plist_node, node_list);

  }

  #endif