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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 | * | |
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 is 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 | ||
b4459790 | 76 | #include <linux/kernel.h> |
77ba89c5 IM |
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 | |
a2672459 TG |
84 | raw_spinlock_t *rawlock; |
85 | spinlock_t *spinlock; | |
77ba89c5 IM |
86 | #endif |
87 | }; | |
88 | ||
89 | struct plist_node { | |
90 | int prio; | |
91 | struct plist_head plist; | |
92 | }; | |
93 | ||
94 | #ifdef CONFIG_DEBUG_PI_LIST | |
a2672459 TG |
95 | # define PLIST_HEAD_LOCK_INIT(_lock) .spinlock = _lock |
96 | # define PLIST_HEAD_LOCK_INIT_RAW(_lock) .rawlock = _lock | |
77ba89c5 IM |
97 | #else |
98 | # define PLIST_HEAD_LOCK_INIT(_lock) | |
a2672459 | 99 | # define PLIST_HEAD_LOCK_INIT_RAW(_lock) |
77ba89c5 IM |
100 | #endif |
101 | ||
4075134e GH |
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 | ||
77ba89c5 | 106 | /** |
11265420 | 107 | * PLIST_HEAD_INIT - static struct plist_head initializer |
77ba89c5 | 108 | * @head: struct plist_head variable name |
11265420 | 109 | * @_lock: lock to initialize for this list |
77ba89c5 IM |
110 | */ |
111 | #define PLIST_HEAD_INIT(head, _lock) \ | |
112 | { \ | |
a2672459 | 113 | _PLIST_HEAD_INIT(head), \ |
77ba89c5 IM |
114 | PLIST_HEAD_LOCK_INIT(&(_lock)) \ |
115 | } | |
116 | ||
a2672459 TG |
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 | ||
77ba89c5 | 128 | /** |
11265420 | 129 | * PLIST_NODE_INIT - static struct plist_node initializer |
77ba89c5 IM |
130 | * @node: struct plist_node variable name |
131 | * @__prio: initial node priority | |
132 | */ | |
133 | #define PLIST_NODE_INIT(node, __prio) \ | |
134 | { \ | |
135 | .prio = (__prio), \ | |
a2672459 | 136 | .plist = { _PLIST_HEAD_INIT((node).plist) }, \ |
77ba89c5 IM |
137 | } |
138 | ||
139 | /** | |
140 | * plist_head_init - dynamic struct plist_head initializer | |
77ba89c5 | 141 | * @head: &struct plist_head pointer |
a2672459 | 142 | * @lock: spinlock protecting the list (debugging) |
77ba89c5 IM |
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 | |
a2672459 TG |
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; | |
77ba89c5 IM |
168 | #endif |
169 | } | |
170 | ||
171 | /** | |
172 | * plist_node_init - Dynamic struct plist_node initializer | |
77ba89c5 IM |
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 | |
11265420 RD |
187 | * @pos: the type * to use as a loop counter |
188 | * @head: the head for your list | |
77ba89c5 IM |
189 | */ |
190 | #define plist_for_each(pos, head) \ | |
191 | list_for_each_entry(pos, &(head)->node_list, plist.node_list) | |
192 | ||
193 | /** | |
11265420 RD |
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 | |
77ba89c5 | 198 | * |
11265420 | 199 | * Iterate over a plist of given type, safe against removal of list entry. |
77ba89c5 IM |
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 | |
11265420 RD |
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 | |
77ba89c5 IM |
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 | /** | |
11265420 RD |
214 | * plist_for_each_entry_safe - iterate safely over list of given type |
215 | * @pos: the type * to use as a loop counter | |
77ba89c5 | 216 | * @n: another type * to use as temporary storage |
11265420 RD |
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. | |
77ba89c5 IM |
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 | |
77ba89c5 IM |
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 | |
77ba89c5 IM |
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 | |
11265420 RD |
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 | |
77ba89c5 IM |
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_first - return the first node (and thus, highest priority) | |
77ba89c5 IM |
264 | * @head: the &struct plist_head pointer |
265 | * | |
266 | * Assumes the plist is _not_ empty. | |
267 | */ | |
268 | static inline struct plist_node* plist_first(const struct plist_head *head) | |
269 | { | |
270 | return list_entry(head->node_list.next, | |
271 | struct plist_node, plist.node_list); | |
272 | } | |
273 | ||
274 | #endif |