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Diffstat (limited to 'kernel/include/linux/plist.h')
| -rw-r--r-- | kernel/include/linux/plist.h | 300 |
1 files changed, 300 insertions, 0 deletions
diff --git a/kernel/include/linux/plist.h b/kernel/include/linux/plist.h new file mode 100644 index 000000000..97883604a --- /dev/null +++ b/kernel/include/linux/plist.h @@ -0,0 +1,300 @@ +/* + * 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> + * + * Licensed under the FSF's GNU Public License v2 or later. + * + * 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_PI_LIST +# 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_PI_LIST +# 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 |