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Ingo Molnar77ba89c2006-06-27 02:54:51 -07001/*
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 * |HEAD |
35 * | |
36 * |prio_list.prev|<------------------------------------|
37 * |prio_list.next|<->|pl|<->|pl|<--------------->|pl|<-|
38 * |10 | |10| |21| |21| |21| |40| (prio)
39 * | | | | | | | | | | | |
40 * | | | | | | | | | | | |
41 * |node_list.next|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
42 * |node_list.prev|<------------------------------------|
43 *
44 * The nodes on the prio_list list are sorted by priority to simplify
45 * the insertion of new nodes. There are no nodes with duplicate
46 * priorites on the list.
47 *
48 * The nodes on the node_list is ordered by priority and can contain
49 * entries which have the same priority. Those entries are ordered
50 * FIFO
51 *
52 * Addition means: look for the prio_list node in the prio_list
53 * for the priority of the node and insert it before the node_list
54 * entry of the next prio_list node. If it is the first node of
55 * that priority, add it to the prio_list in the right position and
56 * insert it into the serialized node_list list
57 *
58 * Removal means remove it from the node_list and remove it from
59 * the prio_list if the node_list list_head is non empty. In case
60 * of removal from the prio_list it must be checked whether other
61 * entries of the same priority are on the list or not. If there
62 * is another entry of the same priority then this entry has to
63 * replace the removed entry on the prio_list. If the entry which
64 * is removed is the only entry of this priority then a simple
65 * remove from both list is sufficient.
66 *
67 * INT_MIN is the highest priority, 0 is the medium highest, INT_MAX
68 * is lowest priority.
69 *
70 * No locking is done, up to the caller.
71 *
72 */
73#ifndef _LINUX_PLIST_H_
74#define _LINUX_PLIST_H_
75
Thomas Gleixnerb4459792006-06-28 17:14:07 +020076#include <linux/kernel.h>
Ingo Molnar77ba89c2006-06-27 02:54:51 -070077#include <linux/list.h>
78#include <linux/spinlock_types.h>
79
80struct plist_head {
81 struct list_head prio_list;
82 struct list_head node_list;
83#ifdef CONFIG_DEBUG_PI_LIST
84 spinlock_t *lock;
85#endif
86};
87
88struct plist_node {
89 int prio;
90 struct plist_head plist;
91};
92
93#ifdef CONFIG_DEBUG_PI_LIST
94# define PLIST_HEAD_LOCK_INIT(_lock) .lock = _lock
95#else
96# define PLIST_HEAD_LOCK_INIT(_lock)
97#endif
98
Gregory Haskins40751342008-12-29 09:39:53 -050099#define _PLIST_HEAD_INIT(head) \
100 .prio_list = LIST_HEAD_INIT((head).prio_list), \
101 .node_list = LIST_HEAD_INIT((head).node_list)
102
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700103/**
Randy Dunlap11265422007-04-16 22:53:15 -0700104 * PLIST_HEAD_INIT - static struct plist_head initializer
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700105 * @head: struct plist_head variable name
Randy Dunlap11265422007-04-16 22:53:15 -0700106 * @_lock: lock to initialize for this list
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700107 */
108#define PLIST_HEAD_INIT(head, _lock) \
109{ \
Gregory Haskins40751342008-12-29 09:39:53 -0500110 _PLIST_HEAD_INIT(head), \
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700111 PLIST_HEAD_LOCK_INIT(&(_lock)) \
112}
113
114/**
Randy Dunlap11265422007-04-16 22:53:15 -0700115 * PLIST_NODE_INIT - static struct plist_node initializer
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700116 * @node: struct plist_node variable name
117 * @__prio: initial node priority
118 */
119#define PLIST_NODE_INIT(node, __prio) \
120{ \
121 .prio = (__prio), \
Gregory Haskins40751342008-12-29 09:39:53 -0500122 .plist = { _PLIST_HEAD_INIT((node).plist) }, \
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700123}
124
125/**
126 * plist_head_init - dynamic struct plist_head initializer
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700127 * @head: &struct plist_head pointer
Randy Dunlap11265422007-04-16 22:53:15 -0700128 * @lock: list spinlock, remembered for debugging
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700129 */
130static inline void
131plist_head_init(struct plist_head *head, spinlock_t *lock)
132{
133 INIT_LIST_HEAD(&head->prio_list);
134 INIT_LIST_HEAD(&head->node_list);
135#ifdef CONFIG_DEBUG_PI_LIST
136 head->lock = lock;
137#endif
138}
139
140/**
141 * plist_node_init - Dynamic struct plist_node initializer
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700142 * @node: &struct plist_node pointer
143 * @prio: initial node priority
144 */
145static inline void plist_node_init(struct plist_node *node, int prio)
146{
147 node->prio = prio;
148 plist_head_init(&node->plist, NULL);
149}
150
151extern void plist_add(struct plist_node *node, struct plist_head *head);
152extern void plist_del(struct plist_node *node, struct plist_head *head);
153
154/**
155 * plist_for_each - iterate over the plist
Randy Dunlap11265422007-04-16 22:53:15 -0700156 * @pos: the type * to use as a loop counter
157 * @head: the head for your list
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700158 */
159#define plist_for_each(pos, head) \
160 list_for_each_entry(pos, &(head)->node_list, plist.node_list)
161
162/**
Randy Dunlap11265422007-04-16 22:53:15 -0700163 * plist_for_each_safe - iterate safely over a plist of given type
164 * @pos: the type * to use as a loop counter
165 * @n: another type * to use as temporary storage
166 * @head: the head for your list
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700167 *
Randy Dunlap11265422007-04-16 22:53:15 -0700168 * Iterate over a plist of given type, safe against removal of list entry.
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700169 */
170#define plist_for_each_safe(pos, n, head) \
171 list_for_each_entry_safe(pos, n, &(head)->node_list, plist.node_list)
172
173/**
174 * plist_for_each_entry - iterate over list of given type
Randy Dunlap11265422007-04-16 22:53:15 -0700175 * @pos: the type * to use as a loop counter
176 * @head: the head for your list
177 * @mem: the name of the list_struct within the struct
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700178 */
179#define plist_for_each_entry(pos, head, mem) \
180 list_for_each_entry(pos, &(head)->node_list, mem.plist.node_list)
181
182/**
Randy Dunlap11265422007-04-16 22:53:15 -0700183 * plist_for_each_entry_safe - iterate safely over list of given type
184 * @pos: the type * to use as a loop counter
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700185 * @n: another type * to use as temporary storage
Randy Dunlap11265422007-04-16 22:53:15 -0700186 * @head: the head for your list
187 * @m: the name of the list_struct within the struct
188 *
189 * Iterate over list of given type, safe against removal of list entry.
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700190 */
191#define plist_for_each_entry_safe(pos, n, head, m) \
192 list_for_each_entry_safe(pos, n, &(head)->node_list, m.plist.node_list)
193
194/**
195 * plist_head_empty - return !0 if a plist_head is empty
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700196 * @head: &struct plist_head pointer
197 */
198static inline int plist_head_empty(const struct plist_head *head)
199{
200 return list_empty(&head->node_list);
201}
202
203/**
204 * plist_node_empty - return !0 if plist_node is not on a list
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700205 * @node: &struct plist_node pointer
206 */
207static inline int plist_node_empty(const struct plist_node *node)
208{
209 return plist_head_empty(&node->plist);
210}
211
212/* All functions below assume the plist_head is not empty. */
213
214/**
215 * plist_first_entry - get the struct for the first entry
Randy Dunlap11265422007-04-16 22:53:15 -0700216 * @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
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700219 */
220#ifdef CONFIG_DEBUG_PI_LIST
221# define plist_first_entry(head, type, member) \
222({ \
223 WARN_ON(plist_head_empty(head)); \
224 container_of(plist_first(head), type, member); \
225})
226#else
227# define plist_first_entry(head, type, member) \
228 container_of(plist_first(head), type, member)
229#endif
230
231/**
232 * plist_first - return the first node (and thus, highest priority)
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700233 * @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, plist.node_list);
241}
242
243#endif