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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 | |
81 | struct plist_head { |
82 | struct list_head node_list; |
83 | }; |
84 | |
85 | struct 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 | */ |
116 | static inline void |
117 | plist_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 | */ |
127 | static 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 | |
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); |
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 | */ |
181 | static 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 | */ |
190 | static 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 | */ |
237 | static 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 | */ |
249 | static 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 |
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