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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
Thomas Gleixnera2672452009-11-17 14:46:14 +010084 raw_spinlock_t *rawlock;
85 spinlock_t *spinlock;
Ingo Molnar77ba89c2006-06-27 02:54:51 -070086#endif
87};
88
89struct plist_node {
90 int prio;
91 struct plist_head plist;
92};
93
94#ifdef CONFIG_DEBUG_PI_LIST
Thomas Gleixnera2672452009-11-17 14:46:14 +010095# define PLIST_HEAD_LOCK_INIT(_lock) .spinlock = _lock
96# define PLIST_HEAD_LOCK_INIT_RAW(_lock) .rawlock = _lock
Ingo Molnar77ba89c2006-06-27 02:54:51 -070097#else
98# define PLIST_HEAD_LOCK_INIT(_lock)
Thomas Gleixnera2672452009-11-17 14:46:14 +010099# define PLIST_HEAD_LOCK_INIT_RAW(_lock)
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700100#endif
101
Gregory Haskins40751342008-12-29 09:39:53 -0500102#define _PLIST_HEAD_INIT(head) \
103 .prio_list = LIST_HEAD_INIT((head).prio_list), \
104 .node_list = LIST_HEAD_INIT((head).node_list)
105
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700106/**
Randy Dunlap11265422007-04-16 22:53:15 -0700107 * PLIST_HEAD_INIT - static struct plist_head initializer
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700108 * @head: struct plist_head variable name
Randy Dunlap11265422007-04-16 22:53:15 -0700109 * @_lock: lock to initialize for this list
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700110 */
111#define PLIST_HEAD_INIT(head, _lock) \
112{ \
Thomas Gleixnera2672452009-11-17 14:46:14 +0100113 _PLIST_HEAD_INIT(head), \
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700114 PLIST_HEAD_LOCK_INIT(&(_lock)) \
115}
116
117/**
Thomas Gleixnera2672452009-11-17 14:46:14 +0100118 * PLIST_HEAD_INIT_RAW - static struct plist_head initializer
119 * @head: struct plist_head variable name
120 * @_lock: lock to initialize for this list
121 */
122#define PLIST_HEAD_INIT_RAW(head, _lock) \
123{ \
124 _PLIST_HEAD_INIT(head), \
125 PLIST_HEAD_LOCK_INIT_RAW(&(_lock)) \
126}
127
128/**
Randy Dunlap11265422007-04-16 22:53:15 -0700129 * PLIST_NODE_INIT - static struct plist_node initializer
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700130 * @node: struct plist_node variable name
131 * @__prio: initial node priority
132 */
133#define PLIST_NODE_INIT(node, __prio) \
134{ \
135 .prio = (__prio), \
Thomas Gleixnera2672452009-11-17 14:46:14 +0100136 .plist = { _PLIST_HEAD_INIT((node).plist) }, \
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700137}
138
139/**
140 * plist_head_init - dynamic struct plist_head initializer
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700141 * @head: &struct plist_head pointer
Thomas Gleixnera2672452009-11-17 14:46:14 +0100142 * @lock: spinlock protecting the list (debugging)
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700143 */
144static inline void
145plist_head_init(struct plist_head *head, spinlock_t *lock)
146{
147 INIT_LIST_HEAD(&head->prio_list);
148 INIT_LIST_HEAD(&head->node_list);
149#ifdef CONFIG_DEBUG_PI_LIST
Thomas Gleixnera2672452009-11-17 14:46:14 +0100150 head->spinlock = lock;
151 head->rawlock = NULL;
152#endif
153}
154
155/**
156 * plist_head_init_raw - dynamic struct plist_head initializer
157 * @head: &struct plist_head pointer
158 * @lock: raw_spinlock protecting the list (debugging)
159 */
160static inline void
161plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock)
162{
163 INIT_LIST_HEAD(&head->prio_list);
164 INIT_LIST_HEAD(&head->node_list);
165#ifdef CONFIG_DEBUG_PI_LIST
166 head->rawlock = lock;
167 head->spinlock = NULL;
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700168#endif
169}
170
171/**
172 * plist_node_init - Dynamic struct plist_node initializer
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700173 * @node: &struct plist_node pointer
174 * @prio: initial node priority
175 */
176static inline void plist_node_init(struct plist_node *node, int prio)
177{
178 node->prio = prio;
179 plist_head_init(&node->plist, NULL);
180}
181
182extern void plist_add(struct plist_node *node, struct plist_head *head);
183extern void plist_del(struct plist_node *node, struct plist_head *head);
184
185/**
186 * plist_for_each - iterate over the plist
Randy Dunlap11265422007-04-16 22:53:15 -0700187 * @pos: the type * to use as a loop counter
188 * @head: the head for your list
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700189 */
190#define plist_for_each(pos, head) \
191 list_for_each_entry(pos, &(head)->node_list, plist.node_list)
192
193/**
Randy Dunlap11265422007-04-16 22:53:15 -0700194 * plist_for_each_safe - iterate safely over a plist of given type
195 * @pos: the type * to use as a loop counter
196 * @n: another type * to use as temporary storage
197 * @head: the head for your list
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700198 *
Randy Dunlap11265422007-04-16 22:53:15 -0700199 * Iterate over a plist of given type, safe against removal of list entry.
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700200 */
201#define plist_for_each_safe(pos, n, head) \
202 list_for_each_entry_safe(pos, n, &(head)->node_list, plist.node_list)
203
204/**
205 * plist_for_each_entry - iterate over list of given type
Randy Dunlap11265422007-04-16 22:53:15 -0700206 * @pos: the type * to use as a loop counter
207 * @head: the head for your list
208 * @mem: the name of the list_struct within the struct
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700209 */
210#define plist_for_each_entry(pos, head, mem) \
211 list_for_each_entry(pos, &(head)->node_list, mem.plist.node_list)
212
213/**
Randy Dunlap11265422007-04-16 22:53:15 -0700214 * plist_for_each_entry_safe - iterate safely over list of given type
215 * @pos: the type * to use as a loop counter
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700216 * @n: another type * to use as temporary storage
Randy Dunlap11265422007-04-16 22:53:15 -0700217 * @head: the head for your list
218 * @m: the name of the list_struct within the struct
219 *
220 * Iterate over list of given type, safe against removal of list entry.
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700221 */
222#define plist_for_each_entry_safe(pos, n, head, m) \
223 list_for_each_entry_safe(pos, n, &(head)->node_list, m.plist.node_list)
224
225/**
226 * plist_head_empty - return !0 if a plist_head is empty
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700227 * @head: &struct plist_head pointer
228 */
229static inline int plist_head_empty(const struct plist_head *head)
230{
231 return list_empty(&head->node_list);
232}
233
234/**
235 * plist_node_empty - return !0 if plist_node is not on a list
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700236 * @node: &struct plist_node pointer
237 */
238static inline int plist_node_empty(const struct plist_node *node)
239{
240 return plist_head_empty(&node->plist);
241}
242
243/* All functions below assume the plist_head is not empty. */
244
245/**
246 * plist_first_entry - get the struct for the first entry
Randy Dunlap11265422007-04-16 22:53:15 -0700247 * @head: the &struct plist_head pointer
248 * @type: the type of the struct this is embedded in
249 * @member: the name of the list_struct within the struct
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700250 */
251#ifdef CONFIG_DEBUG_PI_LIST
252# define plist_first_entry(head, type, member) \
253({ \
254 WARN_ON(plist_head_empty(head)); \
255 container_of(plist_first(head), type, member); \
256})
257#else
258# define plist_first_entry(head, type, member) \
259 container_of(plist_first(head), type, member)
260#endif
261
262/**
263 * plist_first - return the first node (and thus, highest priority)
Ingo Molnar77ba89c2006-06-27 02:54:51 -0700264 * @head: the &struct plist_head pointer
265 *
266 * Assumes the plist is _not_ empty.
267 */
268static inline struct plist_node* plist_first(const struct plist_head *head)
269{
270 return list_entry(head->node_list.next,
271 struct plist_node, plist.node_list);
272}
273
274#endif