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77ba89c5 IM |
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 | * | |
bf6a9b83 LJ |
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 | * |-------------------------------------------| | |
77ba89c5 IM |
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 | * | |
9ca94d7c | 50 | * The nodes on the node_list are ordered by priority and can contain |
77ba89c5 IM |
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 | ||
b4459790 | 78 | #include <linux/kernel.h> |
77ba89c5 | 79 | #include <linux/list.h> |
77ba89c5 IM |
80 | |
81 | struct plist_head { | |
77ba89c5 | 82 | struct list_head node_list; |
77ba89c5 IM |
83 | }; |
84 | ||
85 | struct plist_node { | |
86 | int prio; | |
bf6a9b83 LJ |
87 | struct list_head prio_list; |
88 | struct list_head node_list; | |
77ba89c5 IM |
89 | }; |
90 | ||
77ba89c5 | 91 | /** |
11265420 | 92 | * PLIST_HEAD_INIT - static struct plist_head initializer |
77ba89c5 | 93 | * @head: struct plist_head variable name |
a2672459 | 94 | */ |
732375c6 | 95 | #define PLIST_HEAD_INIT(head) \ |
a2672459 | 96 | { \ |
732375c6 | 97 | .node_list = LIST_HEAD_INIT((head).node_list) \ |
a2672459 TG |
98 | } |
99 | ||
77ba89c5 | 100 | /** |
11265420 | 101 | * PLIST_NODE_INIT - static struct plist_node initializer |
77ba89c5 IM |
102 | * @node: struct plist_node variable name |
103 | * @__prio: initial node priority | |
104 | */ | |
105 | #define PLIST_NODE_INIT(node, __prio) \ | |
106 | { \ | |
107 | .prio = (__prio), \ | |
bf6a9b83 LJ |
108 | .prio_list = LIST_HEAD_INIT((node).prio_list), \ |
109 | .node_list = LIST_HEAD_INIT((node).node_list), \ | |
77ba89c5 IM |
110 | } |
111 | ||
112 | /** | |
113 | * plist_head_init - dynamic struct plist_head initializer | |
77ba89c5 | 114 | * @head: &struct plist_head pointer |
a2672459 TG |
115 | */ |
116 | static inline void | |
732375c6 | 117 | plist_head_init(struct plist_head *head) |
a2672459 | 118 | { |
a2672459 | 119 | INIT_LIST_HEAD(&head->node_list); |
77ba89c5 IM |
120 | } |
121 | ||
122 | /** | |
123 | * plist_node_init - Dynamic struct plist_node initializer | |
77ba89c5 IM |
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; | |
bf6a9b83 LJ |
130 | INIT_LIST_HEAD(&node->prio_list); |
131 | INIT_LIST_HEAD(&node->node_list); | |
77ba89c5 IM |
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 | |
11265420 RD |
139 | * @pos: the type * to use as a loop counter |
140 | * @head: the head for your list | |
77ba89c5 IM |
141 | */ |
142 | #define plist_for_each(pos, head) \ | |
bf6a9b83 | 143 | list_for_each_entry(pos, &(head)->node_list, node_list) |
77ba89c5 IM |
144 | |
145 | /** | |
11265420 RD |
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 | |
77ba89c5 | 150 | * |
11265420 | 151 | * Iterate over a plist of given type, safe against removal of list entry. |
77ba89c5 IM |
152 | */ |
153 | #define plist_for_each_safe(pos, n, head) \ | |
bf6a9b83 | 154 | list_for_each_entry_safe(pos, n, &(head)->node_list, node_list) |
77ba89c5 IM |
155 | |
156 | /** | |
157 | * plist_for_each_entry - iterate over list of given type | |
11265420 RD |
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 | |
77ba89c5 IM |
161 | */ |
162 | #define plist_for_each_entry(pos, head, mem) \ | |
bf6a9b83 | 163 | list_for_each_entry(pos, &(head)->node_list, mem.node_list) |
77ba89c5 IM |
164 | |
165 | /** | |
11265420 RD |
166 | * plist_for_each_entry_safe - iterate safely over list of given type |
167 | * @pos: the type * to use as a loop counter | |
77ba89c5 | 168 | * @n: another type * to use as temporary storage |
11265420 RD |
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. | |
77ba89c5 IM |
173 | */ |
174 | #define plist_for_each_entry_safe(pos, n, head, m) \ | |
bf6a9b83 | 175 | list_for_each_entry_safe(pos, n, &(head)->node_list, m.node_list) |
77ba89c5 IM |
176 | |
177 | /** | |
178 | * plist_head_empty - return !0 if a plist_head is empty | |
77ba89c5 IM |
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 | |
77ba89c5 IM |
188 | * @node: &struct plist_node pointer |
189 | */ | |
190 | static inline int plist_node_empty(const struct plist_node *node) | |
191 | { | |
bf6a9b83 | 192 | return list_empty(&node->node_list); |
77ba89c5 IM |
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 | |
11265420 RD |
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 | |
77ba89c5 IM |
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 | ||
12e4d0cc JB |
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 | ||
77ba89c5 IM |
231 | /** |
232 | * plist_first - return the first node (and thus, highest priority) | |
77ba89c5 IM |
233 | * @head: the &struct plist_head pointer |
234 | * | |
235 | * Assumes the plist is _not_ empty. | |
236 | */ | |
9ca94d7c | 237 | static inline struct plist_node *plist_first(const struct plist_head *head) |
77ba89c5 IM |
238 | { |
239 | return list_entry(head->node_list.next, | |
bf6a9b83 | 240 | struct plist_node, node_list); |
77ba89c5 IM |
241 | } |
242 | ||
12e4d0cc JB |
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, | |
bf6a9b83 | 252 | struct plist_node, node_list); |
12e4d0cc JB |
253 | } |
254 | ||
77ba89c5 | 255 | #endif |