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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 | * |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 are 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 | |
76 | #include <linux/kernel.h> |
77 | #include <linux/list.h> |
78 | #include <linux/spinlock_types.h> |
79 | |
80 | struct plist_head { |
81 | struct list_head prio_list; |
82 | struct list_head node_list; |
83 | #ifdef CONFIG_DEBUG_PI_LIST |
84 | raw_spinlock_t *rawlock; |
85 | spinlock_t *spinlock; |
86 | #endif |
87 | }; |
88 | |
89 | struct plist_node { |
90 | int prio; |
91 | struct plist_head plist; |
92 | }; |
93 | |
94 | #ifdef CONFIG_DEBUG_PI_LIST |
95 | # define PLIST_HEAD_LOCK_INIT(_lock) .spinlock = _lock |
96 | # define PLIST_HEAD_LOCK_INIT_RAW(_lock) .rawlock = _lock |
97 | #else |
98 | # define PLIST_HEAD_LOCK_INIT(_lock) |
99 | # define PLIST_HEAD_LOCK_INIT_RAW(_lock) |
100 | #endif |
101 | |
102 | #define _PLIST_HEAD_INIT(head) \ |
103 | .prio_list = LIST_HEAD_INIT((head).prio_list), \ |
104 | .node_list = LIST_HEAD_INIT((head).node_list) |
105 | |
106 | /** |
107 | * PLIST_HEAD_INIT - static struct plist_head initializer |
108 | * @head: struct plist_head variable name |
109 | * @_lock: lock to initialize for this list |
110 | */ |
111 | #define PLIST_HEAD_INIT(head, _lock) \ |
112 | { \ |
113 | _PLIST_HEAD_INIT(head), \ |
114 | PLIST_HEAD_LOCK_INIT(&(_lock)) \ |
115 | } |
116 | |
117 | /** |
118 | * 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 | /** |
129 | * PLIST_NODE_INIT - static struct plist_node initializer |
130 | * @node: struct plist_node variable name |
131 | * @__prio: initial node priority |
132 | */ |
133 | #define PLIST_NODE_INIT(node, __prio) \ |
134 | { \ |
135 | .prio = (__prio), \ |
136 | .plist = { _PLIST_HEAD_INIT((node).plist) }, \ |
137 | } |
138 | |
139 | /** |
140 | * plist_head_init - dynamic struct plist_head initializer |
141 | * @head: &struct plist_head pointer |
142 | * @lock: spinlock protecting the list (debugging) |
143 | */ |
144 | static inline void |
145 | plist_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 |
150 | 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 | */ |
160 | static inline void |
161 | plist_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; |
168 | #endif |
169 | } |
170 | |
171 | /** |
172 | * plist_node_init - Dynamic struct plist_node initializer |
173 | * @node: &struct plist_node pointer |
174 | * @prio: initial node priority |
175 | */ |
176 | static 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 | |
182 | extern void plist_add(struct plist_node *node, struct plist_head *head); |
183 | extern void plist_del(struct plist_node *node, struct plist_head *head); |
184 | |
185 | /** |
186 | * plist_for_each - iterate over the plist |
187 | * @pos: the type * to use as a loop counter |
188 | * @head: the head for your list |
189 | */ |
190 | #define plist_for_each(pos, head) \ |
191 | list_for_each_entry(pos, &(head)->node_list, plist.node_list) |
192 | |
193 | /** |
194 | * 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 |
198 | * |
199 | * Iterate over a plist of given type, safe against removal of list entry. |
200 | */ |
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 |
206 | * @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 |
209 | */ |
210 | #define plist_for_each_entry(pos, head, mem) \ |
211 | list_for_each_entry(pos, &(head)->node_list, mem.plist.node_list) |
212 | |
213 | /** |
214 | * plist_for_each_entry_safe - iterate safely over list of given type |
215 | * @pos: the type * to use as a loop counter |
216 | * @n: another type * to use as temporary storage |
217 | * @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. |
221 | */ |
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 |
227 | * @head: &struct plist_head pointer |
228 | */ |
229 | static 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 |
236 | * @node: &struct plist_node pointer |
237 | */ |
238 | static 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 |
247 | * @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 |
250 | */ |
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_last_entry - get the struct for the last entry |
264 | * @head: the &struct plist_head pointer |
265 | * @type: the type of the struct this is embedded in |
266 | * @member: the name of the list_struct within the struct |
267 | */ |
268 | #ifdef CONFIG_DEBUG_PI_LIST |
269 | # define plist_last_entry(head, type, member) \ |
270 | ({ \ |
271 | WARN_ON(plist_head_empty(head)); \ |
272 | container_of(plist_last(head), type, member); \ |
273 | }) |
274 | #else |
275 | # define plist_last_entry(head, type, member) \ |
276 | container_of(plist_last(head), type, member) |
277 | #endif |
278 | |
279 | /** |
280 | * plist_first - return the first node (and thus, highest priority) |
281 | * @head: the &struct plist_head pointer |
282 | * |
283 | * Assumes the plist is _not_ empty. |
284 | */ |
285 | static inline struct plist_node *plist_first(const struct plist_head *head) |
286 | { |
287 | return list_entry(head->node_list.next, |
288 | struct plist_node, plist.node_list); |
289 | } |
290 | |
291 | /** |
292 | * plist_last - return the last node (and thus, lowest priority) |
293 | * @head: the &struct plist_head pointer |
294 | * |
295 | * Assumes the plist is _not_ empty. |
296 | */ |
297 | static inline struct plist_node *plist_last(const struct plist_head *head) |
298 | { |
299 | return list_entry(head->node_list.prev, |
300 | struct plist_node, plist.node_list); |
301 | } |
302 | |
303 | #endif |
304 |
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