2 * Descending-priority-sorted double-linked list
4 * (C) 2002-2003 Intel Corp
5 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
7 * 2001-2005 (c) MontaVista Software, Inc.
8 * Daniel Walker <dwalker@mvista.com>
10 * (C) 2005 Thomas Gleixner <tglx@linutronix.de>
12 * Simplifications of the original code by
13 * Oleg Nesterov <oleg@tv-sign.ru>
15 * Licensed under the FSF's GNU Public License v2 or later.
17 * Based on simple lists (include/linux/list.h).
19 * This is a priority-sorted list of nodes; each node has a
20 * priority from INT_MIN (highest) to INT_MAX (lowest).
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.
26 * This list is really a list of lists:
28 * - The tier 1 list is the prio_list, different priority nodes.
30 * - The tier 2 list is the node_list, serialized nodes.
32 * Simple ASCII art explanation:
34 * pl:prio_list (only for plist_node)
38 * ||------------------------------------|
39 * ||->|pl|<->|pl|<--------------->|pl|<-|
40 * | |10| |21| |21| |21| |40| (prio)
41 * | | | | | | | | | | |
42 * | | | | | | | | | | |
43 * |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
44 * |-------------------------------------------|
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.
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
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
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.
69 * INT_MIN is the highest priority, 0 is the medium highest, INT_MAX
72 * No locking is done, up to the caller.
75 #ifndef _LINUX_PLIST_H_
76 #define _LINUX_PLIST_H_
78 #include <linux/kernel.h>
79 #include <linux/list.h>
82 struct list_head node_list
;
87 struct list_head prio_list
;
88 struct list_head node_list
;
92 * PLIST_HEAD_INIT - static struct plist_head initializer
93 * @head: struct plist_head variable name
95 #define PLIST_HEAD_INIT(head) \
97 .node_list = LIST_HEAD_INIT((head).node_list) \
101 * PLIST_NODE_INIT - static struct plist_node initializer
102 * @node: struct plist_node variable name
103 * @__prio: initial node priority
105 #define PLIST_NODE_INIT(node, __prio) \
108 .prio_list = LIST_HEAD_INIT((node).prio_list), \
109 .node_list = LIST_HEAD_INIT((node).node_list), \
113 * plist_head_init - dynamic struct plist_head initializer
114 * @head: &struct plist_head pointer
117 plist_head_init(struct plist_head
*head
)
119 INIT_LIST_HEAD(&head
->node_list
);
123 * plist_node_init - Dynamic struct plist_node initializer
124 * @node: &struct plist_node pointer
125 * @prio: initial node priority
127 static inline void plist_node_init(struct plist_node
*node
, int prio
)
130 INIT_LIST_HEAD(&node
->prio_list
);
131 INIT_LIST_HEAD(&node
->node_list
);
134 extern void plist_add(struct plist_node
*node
, struct plist_head
*head
);
135 extern void plist_del(struct plist_node
*node
, struct plist_head
*head
);
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
142 #define plist_for_each(pos, head) \
143 list_for_each_entry(pos, &(head)->node_list, node_list)
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
151 * Iterate over a plist of given type, safe against removal of list entry.
153 #define plist_for_each_safe(pos, n, head) \
154 list_for_each_entry_safe(pos, n, &(head)->node_list, node_list)
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
162 #define plist_for_each_entry(pos, head, mem) \
163 list_for_each_entry(pos, &(head)->node_list, mem.node_list)
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
172 * Iterate over list of given type, safe against removal of list entry.
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)
178 * plist_head_empty - return !0 if a plist_head is empty
179 * @head: &struct plist_head pointer
181 static inline int plist_head_empty(const struct plist_head
*head
)
183 return list_empty(&head
->node_list
);
187 * plist_node_empty - return !0 if plist_node is not on a list
188 * @node: &struct plist_node pointer
190 static inline int plist_node_empty(const struct plist_node
*node
)
192 return list_empty(&node
->node_list
);
195 /* All functions below assume the plist_head is not empty. */
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
203 #ifdef CONFIG_DEBUG_PI_LIST
204 # define plist_first_entry(head, type, member) \
206 WARN_ON(plist_head_empty(head)); \
207 container_of(plist_first(head), type, member); \
210 # define plist_first_entry(head, type, member) \
211 container_of(plist_first(head), type, member)
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
220 #ifdef CONFIG_DEBUG_PI_LIST
221 # define plist_last_entry(head, type, member) \
223 WARN_ON(plist_head_empty(head)); \
224 container_of(plist_last(head), type, member); \
227 # define plist_last_entry(head, type, member) \
228 container_of(plist_last(head), type, member)
232 * plist_first - return the first node (and thus, highest priority)
233 * @head: the &struct plist_head pointer
235 * Assumes the plist is _not_ empty.
237 static inline struct plist_node
*plist_first(const struct plist_head
*head
)
239 return list_entry(head
->node_list
.next
,
240 struct plist_node
, node_list
);
244 * plist_last - return the last node (and thus, lowest priority)
245 * @head: the &struct plist_head pointer
247 * Assumes the plist is _not_ empty.
249 static inline struct plist_node
*plist_last(const struct plist_head
*head
)
251 return list_entry(head
->node_list
.prev
,
252 struct plist_node
, node_list
);
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