linux/include/linux/plist.h
<<
>>
Prefs
   1/*
   2 * Descending-priority-sorted double-linked list
   3 *
   4 * (C) 2002-2003 Intel Corp
   5 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
   6 *
   7 * 2001-2005 (c) MontaVista Software, Inc.
   8 * Daniel Walker <dwalker@mvista.com>
   9 *
  10 * (C) 2005 Thomas Gleixner <tglx@linutronix.de>
  11 *
  12 * Simplifications of the original code by
  13 * Oleg Nesterov <oleg@tv-sign.ru>
  14 *
  15 * Licensed under the FSF's GNU Public License v2 or later.
  16 *
  17 * Based on simple lists (include/linux/list.h).
  18 *
  19 * This is a priority-sorted list of nodes; each node has a
  20 * priority from INT_MIN (highest) to INT_MAX (lowest).
  21 *
  22 * Addition is O(K), removal is O(1), change of priority of a node is
  23 * O(K) and K is the number of RT priority levels used in the system.
  24 * (1 <= K <= 99)
  25 *
  26 * This list is really a list of lists:
  27 *
  28 *  - The tier 1 list is the prio_list, different priority nodes.
  29 *
  30 *  - The tier 2 list is the node_list, serialized nodes.
  31 *
  32 * Simple ASCII art explanation:
  33 *
  34 * pl:prio_list (only for plist_node)
  35 * nl:node_list
  36 *   HEAD|             NODE(S)
  37 *       |
  38 *       ||------------------------------------|
  39 *       ||->|pl|<->|pl|<--------------->|pl|<-|
  40 *       |   |10|   |21|   |21|   |21|   |40|   (prio)
  41 *       |   |  |   |  |   |  |   |  |   |  |
  42 *       |   |  |   |  |   |  |   |  |   |  |
  43 * |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
  44 * |-------------------------------------------|
  45 *
  46 * The nodes on the prio_list list are sorted by priority to simplify
  47 * the insertion of new nodes. There are no nodes with duplicate
  48 * priorites on the list.
  49 *
  50 * The nodes on the node_list are ordered by priority and can contain
  51 * entries which have the same priority. Those entries are ordered
  52 * FIFO
  53 *
  54 * Addition means: look for the prio_list node in the prio_list
  55 * for the priority of the node and insert it before the node_list
  56 * entry of the next prio_list node. If it is the first node of
  57 * that priority, add it to the prio_list in the right position and
  58 * insert it into the serialized node_list list
  59 *
  60 * Removal means remove it from the node_list and remove it from
  61 * the prio_list if the node_list list_head is non empty. In case
  62 * of removal from the prio_list it must be checked whether other
  63 * entries of the same priority are on the list or not. If there
  64 * is another entry of the same priority then this entry has to
  65 * replace the removed entry on the prio_list. If the entry which
  66 * is removed is the only entry of this priority then a simple
  67 * remove from both list is sufficient.
  68 *
  69 * INT_MIN is the highest priority, 0 is the medium highest, INT_MAX
  70 * is lowest priority.
  71 *
  72 * No locking is done, up to the caller.
  73 *
  74 */
  75#ifndef _LINUX_PLIST_H_
  76#define _LINUX_PLIST_H_
  77
  78#include <linux/kernel.h>
  79#include <linux/list.h>
  80
  81struct plist_head {
  82        struct list_head node_list;
  83};
  84
  85struct plist_node {
  86        int                     prio;
  87        struct list_head        prio_list;
  88        struct list_head        node_list;
  89};
  90
  91/**
  92 * PLIST_HEAD_INIT - static struct plist_head initializer
  93 * @head:       struct plist_head variable name
  94 */
  95#define PLIST_HEAD_INIT(head)                           \
  96{                                                       \
  97        .node_list = LIST_HEAD_INIT((head).node_list)   \
  98}
  99
 100/**
 101 * PLIST_NODE_INIT - static struct plist_node initializer
 102 * @node:       struct plist_node variable name
 103 * @__prio:     initial node priority
 104 */
 105#define PLIST_NODE_INIT(node, __prio)                   \
 106{                                                       \
 107        .prio  = (__prio),                              \
 108        .prio_list = LIST_HEAD_INIT((node).prio_list),  \
 109        .node_list = LIST_HEAD_INIT((node).node_list),  \
 110}
 111
 112/**
 113 * plist_head_init - dynamic struct plist_head initializer
 114 * @head:       &struct plist_head pointer
 115 */
 116static inline void
 117plist_head_init(struct plist_head *head)
 118{
 119        INIT_LIST_HEAD(&head->node_list);
 120}
 121
 122/**
 123 * plist_node_init - Dynamic struct plist_node initializer
 124 * @node:       &struct plist_node pointer
 125 * @prio:       initial node priority
 126 */
 127static inline void plist_node_init(struct plist_node *node, int prio)
 128{
 129        node->prio = prio;
 130        INIT_LIST_HEAD(&node->prio_list);
 131        INIT_LIST_HEAD(&node->node_list);
 132}
 133
 134extern void plist_add(struct plist_node *node, struct plist_head *head);
 135extern void plist_del(struct plist_node *node, struct plist_head *head);
 136
 137/**
 138 * plist_for_each - iterate over the plist
 139 * @pos:        the type * to use as a loop counter
 140 * @head:       the head for your list
 141 */
 142#define plist_for_each(pos, head)       \
 143         list_for_each_entry(pos, &(head)->node_list, node_list)
 144
 145/**
 146 * plist_for_each_safe - iterate safely over a plist of given type
 147 * @pos:        the type * to use as a loop counter
 148 * @n:  another type * to use as temporary storage
 149 * @head:       the head for your list
 150 *
 151 * Iterate over a plist of given type, safe against removal of list entry.
 152 */
 153#define plist_for_each_safe(pos, n, head)       \
 154         list_for_each_entry_safe(pos, n, &(head)->node_list, node_list)
 155
 156/**
 157 * plist_for_each_entry - iterate over list of given type
 158 * @pos:        the type * to use as a loop counter
 159 * @head:       the head for your list
 160 * @mem:        the name of the list_struct within the struct
 161 */
 162#define plist_for_each_entry(pos, head, mem)    \
 163         list_for_each_entry(pos, &(head)->node_list, mem.node_list)
 164
 165/**
 166 * plist_for_each_entry_safe - iterate safely over list of given type
 167 * @pos:        the type * to use as a loop counter
 168 * @n:          another type * to use as temporary storage
 169 * @head:       the head for your list
 170 * @m:          the name of the list_struct within the struct
 171 *
 172 * Iterate over list of given type, safe against removal of list entry.
 173 */
 174#define plist_for_each_entry_safe(pos, n, head, m)      \
 175        list_for_each_entry_safe(pos, n, &(head)->node_list, m.node_list)
 176
 177/**
 178 * plist_head_empty - return !0 if a plist_head is empty
 179 * @head:       &struct plist_head pointer
 180 */
 181static inline int plist_head_empty(const struct plist_head *head)
 182{
 183        return list_empty(&head->node_list);
 184}
 185
 186/**
 187 * plist_node_empty - return !0 if plist_node is not on a list
 188 * @node:       &struct plist_node pointer
 189 */
 190static inline int plist_node_empty(const struct plist_node *node)
 191{
 192        return list_empty(&node->node_list);
 193}
 194
 195/* All functions below assume the plist_head is not empty. */
 196
 197/**
 198 * plist_first_entry - get the struct for the first entry
 199 * @head:       the &struct plist_head pointer
 200 * @type:       the type of the struct this is embedded in
 201 * @member:     the name of the list_struct within the struct
 202 */
 203#ifdef CONFIG_DEBUG_PI_LIST
 204# define plist_first_entry(head, type, member)  \
 205({ \
 206        WARN_ON(plist_head_empty(head)); \
 207        container_of(plist_first(head), type, member); \
 208})
 209#else
 210# define plist_first_entry(head, type, member)  \
 211        container_of(plist_first(head), type, member)
 212#endif
 213
 214/**
 215 * plist_last_entry - get the struct for the last entry
 216 * @head:       the &struct plist_head pointer
 217 * @type:       the type of the struct this is embedded in
 218 * @member:     the name of the list_struct within the struct
 219 */
 220#ifdef CONFIG_DEBUG_PI_LIST
 221# define plist_last_entry(head, type, member)   \
 222({ \
 223        WARN_ON(plist_head_empty(head)); \
 224        container_of(plist_last(head), type, member); \
 225})
 226#else
 227# define plist_last_entry(head, type, member)   \
 228        container_of(plist_last(head), type, member)
 229#endif
 230
 231/**
 232 * plist_first - return the first node (and thus, highest priority)
 233 * @head:       the &struct plist_head pointer
 234 *
 235 * Assumes the plist is _not_ empty.
 236 */
 237static inline struct plist_node *plist_first(const struct plist_head *head)
 238{
 239        return list_entry(head->node_list.next,
 240                          struct plist_node, node_list);
 241}
 242
 243/**
 244 * plist_last - return the last node (and thus, lowest priority)
 245 * @head:       the &struct plist_head pointer
 246 *
 247 * Assumes the plist is _not_ empty.
 248 */
 249static inline struct plist_node *plist_last(const struct plist_head *head)
 250{
 251        return list_entry(head->node_list.prev,
 252                          struct plist_node, node_list);
 253}
 254
 255#endif
 256
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.