aboutsummaryrefslogtreecommitdiffstats
path: root/include/linux/plist.h
blob: 8b6c970cff6c45b8805a30bfe2d0ad0f3600a0d9 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
/*
 * 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_HEAD - declare and init plist_head
 * @head:	name for struct plist_head variable
 */
#define PLIST_HEAD(head) \
	struct plist_head head = PLIST_HEAD_INIT(head)

/**
 * 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);

extern void plist_requeue(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_continue - continue iteration over the plist
 * @pos:	the type * to use as a loop cursor
 * @head:	the head for your list
 *
 * Continue to iterate over plist, continuing after the current position.
 */
#define plist_for_each_continue(pos, head)	\
	 list_for_each_entry_continue(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_continue - continue iteration over list of given type
 * @pos:	the type * to use as a loop cursor
 * @head:	the head for your list
 * @m:		the name of the list_struct within the struct
 *
 * Continue to iterate over list of given type, continuing after
 * the current position.
 */
#define plist_for_each_entry_continue(pos, head, m)	\
	list_for_each_entry_continue(pos, &(head)->node_list, m.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_next - get the next entry in list
 * @pos:	the type * to cursor
 */
#define plist_next(pos) \
	list_next_entry(pos, node_list)

/**
 * plist_prev - get the prev entry in list
 * @pos:	the type * to cursor
 */
#define plist_prev(pos) \
	list_prev_entry(pos, node_list)

/**
 * 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