| /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| /* |
| * Descending-priority-sorted double-linked list |
| * |
| * (C) 2002-2003 Intel Corp |
| * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>. |
| * |
| * 2001-2005 (c) MontaVista Software, Inc. |
| * Daniel Walker <dwalker@mvista.com> |
| * |
| * (C) 2005 Thomas Gleixner <tglx@linutronix.de> |
| * |
| * Simplifications of the original code by |
| * Oleg Nesterov <oleg@tv-sign.ru> |
| * |
| * 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/kernel.h> |
| #include <linux/list.h> |
| |
| struct plist_head { |
| struct list_head node_list; |
| }; |
| |
| struct plist_node { |
| int prio; |
| struct list_head prio_list; |
| struct list_head node_list; |
| }; |
| |
| /** |
| * PLIST_HEAD_INIT - static struct plist_head initializer |
| * @head: struct plist_head variable name |
| */ |
| #define PLIST_HEAD_INIT(head) \ |
| { \ |
| .node_list = LIST_HEAD_INIT((head).node_list) \ |
| } |
| |
| /** |
| * PLIST_HEAD - declare and init plist_head |
| * @head: name for struct plist_head variable |
| */ |
| #define PLIST_HEAD(head) \ |
| struct plist_head head = PLIST_HEAD_INIT(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) \ |
| { \ |
| .prio = (__prio), \ |
| .prio_list = LIST_HEAD_INIT((node).prio_list), \ |
| .node_list = LIST_HEAD_INIT((node).node_list), \ |
| } |
| |
| /** |
| * plist_head_init - dynamic struct plist_head initializer |
| * @head: &struct plist_head pointer |
| */ |
| static inline void |
| plist_head_init(struct plist_head *head) |
| { |
| INIT_LIST_HEAD(&head->node_list); |
| } |
| |
| /** |
| * 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) |
| { |
| node->prio = prio; |
| INIT_LIST_HEAD(&node->prio_list); |
| INIT_LIST_HEAD(&node->node_list); |
| } |
| |
| 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) \ |
| list_for_each_entry(pos, &(head)->node_list, node_list) |
| |
| /** |
| * 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) \ |
| list_for_each_entry_continue(pos, &(head)->node_list, node_list) |
| |
| /** |
| * 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) \ |
| list_for_each_entry_safe(pos, n, &(head)->node_list, node_list) |
| |
| /** |
| * 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) \ |
| list_for_each_entry(pos, &(head)->node_list, mem.node_list) |
| |
| /** |
| * 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) \ |
| list_for_each_entry_continue(pos, &(head)->node_list, m.node_list) |
| |
| /** |
| * 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) \ |
| list_for_each_entry_safe(pos, n, &(head)->node_list, m.node_list) |
| |
| /** |
| * 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) |
| { |
| return list_empty(&head->node_list); |
| } |
| |
| /** |
| * 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) |
| { |
| return list_empty(&node->node_list); |
| } |
| |
| /* 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) \ |
| ({ \ |
| WARN_ON(plist_head_empty(head)); \ |
| container_of(plist_first(head), type, member); \ |
| }) |
| #else |
| # define plist_first_entry(head, type, member) \ |
| container_of(plist_first(head), type, member) |
| #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) \ |
| ({ \ |
| WARN_ON(plist_head_empty(head)); \ |
| container_of(plist_last(head), type, member); \ |
| }) |
| #else |
| # define plist_last_entry(head, type, member) \ |
| container_of(plist_last(head), type, member) |
| #endif |
| |
| /** |
| * plist_next - get the next entry in list |
| * @pos: the type * to cursor |
| */ |
| #define plist_next(pos) \ |
| list_next_entry(pos, node_list) |
| |
| /** |
| * plist_prev - get the prev entry in list |
| * @pos: the type * to cursor |
| */ |
| #define plist_prev(pos) \ |
| list_prev_entry(pos, node_list) |
| |
| /** |
| * 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) |
| { |
| return list_entry(head->node_list.next, |
| struct plist_node, node_list); |
| } |
| |
| /** |
| * 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) |
| { |
| return list_entry(head->node_list.prev, |
| struct plist_node, node_list); |
| } |
| |
| #endif |