/* SPDX-License-Identifier: GPL-2.0-or-later */ /* * Descending-priority-sorted double-linked list * * (C) 2002-2003 Intel Corp * Inaky Perez-Gonzalez <[email protected]>. * * 2001-2005 (c) MontaVista Software, Inc. * Daniel Walker <[email protected]> * * (C) 2005 Thomas Gleixner <[email protected]> * * Simplifications of the original code by * Oleg Nesterov <[email protected]> * * Based on simple lists (include/linux/list.h). * * This is a priority-sorted list of nodes; each node has a * priority from INT_MIN (highest) to INT_MAX (lowest). * * Addition is O(K), removal is O(1), change of priority of a node is * O(K) and K is the number of RT priority levels used in the system. * (1 <= K <= 99) * * This list is really a list of lists: * * - The tier 1 list is the prio_list, different priority nodes. * * - The tier 2 list is the node_list, serialized nodes. * * Simple ASCII art explanation: * * pl:prio_list (only for plist_node) * nl:node_list * HEAD| NODE(S) * | * ||------------------------------------| * ||->|pl|<->|pl|<--------------->|pl|<-| * | |10| |21| |21| |21| |40| (prio) * | | | | | | | | | | | * | | | | | | | | | | | * |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-| * |-------------------------------------------| * * The nodes on the prio_list list are sorted by priority to simplify * the insertion of new nodes. There are no nodes with duplicate * priorites on the list. * * The nodes on the node_list are ordered by priority and can contain * entries which have the same priority. Those entries are ordered * FIFO * * Addition means: look for the prio_list node in the prio_list * for the priority of the node and insert it before the node_list * entry of the next prio_list node. If it is the first node of * that priority, add it to the prio_list in the right position and * insert it into the serialized node_list list * * Removal means remove it from the node_list and remove it from * the prio_list if the node_list list_head is non empty. In case * of removal from the prio_list it must be checked whether other * entries of the same priority are on the list or not. If there * is another entry of the same priority then this entry has to * replace the removed entry on the prio_list. If the entry which * is removed is the only entry of this priority then a simple * remove from both list is sufficient. * * INT_MIN is the highest priority, 0 is the medium highest, INT_MAX * is lowest priority. * * No locking is done, up to the caller. */ #ifndef _LINUX_PLIST_H_ #define _LINUX_PLIST_H_ #include <linux/container_of.h> #include <linux/list.h> #include <linux/plist_types.h> #include <asm/bug.h> /** * PLIST_HEAD_INIT - static struct plist_head initializer * @head: struct plist_head variable name */ #define PLIST_HEAD_INIT(head) … /** * PLIST_HEAD - declare and init plist_head * @head: name for struct plist_head variable */ #define PLIST_HEAD(head) … /** * PLIST_NODE_INIT - static struct plist_node initializer * @node: struct plist_node variable name * @__prio: initial node priority */ #define PLIST_NODE_INIT(node, __prio) … /** * plist_head_init - dynamic struct plist_head initializer * @head: &struct plist_head pointer */ static inline void plist_head_init(struct plist_head *head) { … } /** * plist_node_init - Dynamic struct plist_node initializer * @node: &struct plist_node pointer * @prio: initial node priority */ static inline void plist_node_init(struct plist_node *node, int prio) { … } extern void plist_add(struct plist_node *node, struct plist_head *head); extern void plist_del(struct plist_node *node, struct plist_head *head); extern void plist_requeue(struct plist_node *node, struct plist_head *head); /** * plist_for_each - iterate over the plist * @pos: the type * to use as a loop counter * @head: the head for your list */ #define plist_for_each(pos, head) … /** * plist_for_each_continue - continue iteration over the plist * @pos: the type * to use as a loop cursor * @head: the head for your list * * Continue to iterate over plist, continuing after the current position. */ #define plist_for_each_continue(pos, head) … /** * plist_for_each_safe - iterate safely over a plist of given type * @pos: the type * to use as a loop counter * @n: another type * to use as temporary storage * @head: the head for your list * * Iterate over a plist of given type, safe against removal of list entry. */ #define plist_for_each_safe(pos, n, head) … /** * plist_for_each_entry - iterate over list of given type * @pos: the type * to use as a loop counter * @head: the head for your list * @mem: the name of the list_head within the struct */ #define plist_for_each_entry(pos, head, mem) … /** * plist_for_each_entry_continue - continue iteration over list of given type * @pos: the type * to use as a loop cursor * @head: the head for your list * @m: the name of the list_head within the struct * * Continue to iterate over list of given type, continuing after * the current position. */ #define plist_for_each_entry_continue(pos, head, m) … /** * plist_for_each_entry_safe - iterate safely over list of given type * @pos: the type * to use as a loop counter * @n: another type * to use as temporary storage * @head: the head for your list * @m: the name of the list_head within the struct * * Iterate over list of given type, safe against removal of list entry. */ #define plist_for_each_entry_safe(pos, n, head, m) … /** * plist_head_empty - return !0 if a plist_head is empty * @head: &struct plist_head pointer */ static inline int plist_head_empty(const struct plist_head *head) { … } /** * plist_node_empty - return !0 if plist_node is not on a list * @node: &struct plist_node pointer */ static inline int plist_node_empty(const struct plist_node *node) { … } /* All functions below assume the plist_head is not empty. */ /** * plist_first_entry - get the struct for the first entry * @head: the &struct plist_head pointer * @type: the type of the struct this is embedded in * @member: the name of the list_head within the struct */ #ifdef CONFIG_DEBUG_PLIST #define plist_first_entry(head, type, member) … #else #define plist_first_entry … #endif /** * plist_last_entry - get the struct for the last entry * @head: the &struct plist_head pointer * @type: the type of the struct this is embedded in * @member: the name of the list_head within the struct */ #ifdef CONFIG_DEBUG_PLIST #define plist_last_entry(head, type, member) … #else #define plist_last_entry … #endif /** * plist_next - get the next entry in list * @pos: the type * to cursor */ #define plist_next(pos) … /** * plist_prev - get the prev entry in list * @pos: the type * to cursor */ #define plist_prev(pos) … /** * plist_first - return the first node (and thus, highest priority) * @head: the &struct plist_head pointer * * Assumes the plist is _not_ empty. */ static inline struct plist_node *plist_first(const struct plist_head *head) { … } /** * plist_last - return the last node (and thus, lowest priority) * @head: the &struct plist_head pointer * * Assumes the plist is _not_ empty. */ static inline struct plist_node *plist_last(const struct plist_head *head) { … } #endif
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