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 80struct 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 89struct 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 */ 144static inline void 145plist_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 */ 160static inline void 161plist_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 */ 176static 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 182extern void plist_add(struct plist_node *node, struct plist_head *head); 183extern 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 */ 229static 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 */ 238static 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 */ 285static 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 */ 297static 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