diff options
| -rw-r--r-- | include/linux/plist.h | 247 | ||||
| -rw-r--r-- | lib/Kconfig | 6 | ||||
| -rw-r--r-- | lib/Makefile | 1 | ||||
| -rw-r--r-- | lib/plist.c | 118 |
4 files changed, 372 insertions, 0 deletions
diff --git a/include/linux/plist.h b/include/linux/plist.h new file mode 100644 index 000000000000..3404faef542c --- /dev/null +++ b/include/linux/plist.h @@ -0,0 +1,247 @@ +/* + * 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: + * + * |HEAD | + * | | + * |prio_list.prev|<------------------------------------| + * |prio_list.next|<->|pl|<->|pl|<--------------->|pl|<-| + * |10 | |10| |21| |21| |21| |40| (prio) + * | | | | | | | | | | | | + * | | | | | | | | | | | | + * |node_list.next|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-| + * |node_list.prev|<------------------------------------| + * + * 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 is 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/list.h> +#include <linux/spinlock_types.h> + +struct plist_head { + struct list_head prio_list; + struct list_head node_list; +#ifdef CONFIG_DEBUG_PI_LIST + spinlock_t *lock; +#endif +}; + +struct plist_node { + int prio; + struct plist_head plist; +}; + +#ifdef CONFIG_DEBUG_PI_LIST +# define PLIST_HEAD_LOCK_INIT(_lock) .lock = _lock +#else +# define PLIST_HEAD_LOCK_INIT(_lock) +#endif + +/** + * #PLIST_HEAD_INIT - static struct plist_head initializer + * + * @head: struct plist_head variable name + */ +#define PLIST_HEAD_INIT(head, _lock) \ +{ \ + .prio_list = LIST_HEAD_INIT((head).prio_list), \ + .node_list = LIST_HEAD_INIT((head).node_list), \ + PLIST_HEAD_LOCK_INIT(&(_lock)) \ +} + +/** + * #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), \ + .plist = PLIST_HEAD_INIT((node).plist, NULL), \ +} + +/** + * plist_head_init - dynamic struct plist_head initializer + * + * @head: &struct plist_head pointer + */ +static inline void +plist_head_init(struct plist_head *head, spinlock_t *lock) +{ + INIT_LIST_HEAD(&head->prio_list); + INIT_LIST_HEAD(&head->node_list); +#ifdef CONFIG_DEBUG_PI_LIST + head->lock = lock; +#endif +} + +/** + * 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; + plist_head_init(&node->plist, NULL); +} + +extern void plist_add(struct plist_node *node, struct plist_head *head); +extern void plist_del(struct plist_node *node, struct plist_head *head); + +/** + * plist_for_each - iterate over the plist + * + * @pos1: 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, plist.node_list) + +/** + * plist_for_each_entry_safe - iterate over a plist of given type safe + * against removal of list entry + * + * @pos1: the type * to use as a loop counter. + * @n1: another type * to use as temporary storage + * @head: the head for your list. + */ +#define plist_for_each_safe(pos, n, head) \ + list_for_each_entry_safe(pos, n, &(head)->node_list, plist.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. + * @member: the name of the list_struct within the struct. + */ +#define plist_for_each_entry(pos, head, mem) \ + list_for_each_entry(pos, &(head)->node_list, mem.plist.node_list) + +/** + * plist_for_each_entry_safe - iterate over list of given type safe against + * removal of list entry + * + * @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_struct within the struct. + */ +#define plist_for_each_entry_safe(pos, n, head, m) \ + list_for_each_entry_safe(pos, n, &(head)->node_list, m.plist.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 plist_head_empty(&node->plist); +} + +/* All functions below assume the plist_head is not empty. */ + +/** + * plist_first_entry - get the struct for the first entry + * + * @ptr: the &struct plist_head pointer. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_struct 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_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, plist.node_list); +} + +#endif diff --git a/lib/Kconfig b/lib/Kconfig index 3de93357f5ab..f6299342b882 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -86,4 +86,10 @@ config TEXTSEARCH_BM config TEXTSEARCH_FSM tristate +# +# plist support is select#ed if needed +# +config PLIST + boolean + endmenu diff --git a/lib/Makefile b/lib/Makefile index 79358ad1f113..10c13c9d7824 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -25,6 +25,7 @@ lib-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o lib-$(CONFIG_GENERIC_HWEIGHT) += hweight.o obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o +obj-$(CONFIG_PLIST) += plist.o obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o ifneq ($(CONFIG_HAVE_DEC_LOCK),y) diff --git a/lib/plist.c b/lib/plist.c new file mode 100644 index 000000000000..3074a02272f3 --- /dev/null +++ b/lib/plist.c @@ -0,0 +1,118 @@ +/* + * lib/plist.c + * + * 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 file contains the add / del functions which are considered to + * be too large to inline. See include/linux/plist.h for further + * information. + */ + +#include <linux/plist.h> +#include <linux/spinlock.h> + +#ifdef CONFIG_DEBUG_PI_LIST + +static void plist_check_prev_next(struct list_head *t, struct list_head *p, + struct list_head *n) +{ + if (n->prev != p || p->next != n) { + printk("top: %p, n: %p, p: %p\n", t, t->next, t->prev); + printk("prev: %p, n: %p, p: %p\n", p, p->next, p->prev); + printk("next: %p, n: %p, p: %p\n", n, n->next, n->prev); + WARN_ON(1); + } +} + +static void plist_check_list(struct list_head *top) +{ + struct list_head *prev = top, *next = top->next; + + plist_check_prev_next(top, prev, next); + while (next != top) { + prev = next; + next = prev->next; + plist_check_prev_next(top, prev, next); + } +} + +static void plist_check_head(struct plist_head *head) +{ + WARN_ON(!head->lock); + if (head->lock) + WARN_ON_SMP(!spin_is_locked(head->lock)); + plist_check_list(&head->prio_list); + plist_check_list(&head->node_list); +} + +#else +# define plist_check_head(h) do { } while (0) +#endif + +/** + * plist_add - add @node to @head + * + * @node: &struct plist_node pointer + * @head: &struct plist_head pointer + */ +void plist_add(struct plist_node *node, struct plist_head *head) +{ + struct plist_node *iter; + + plist_check_head(head); + WARN_ON(!plist_node_empty(node)); + + list_for_each_entry(iter, &head->prio_list, plist.prio_list) { + if (node->prio < iter->prio) + goto lt_prio; + else if (node->prio == iter->prio) { + iter = list_entry(iter->plist.prio_list.next, + struct plist_node, plist.prio_list); + goto eq_prio; + } + } + +lt_prio: + list_add_tail(&node->plist.prio_list, &iter->plist.prio_list); +eq_prio: + list_add_tail(&node->plist.node_list, &iter->plist.node_list); + + plist_check_head(head); +} + +/** + * plist_del - Remove a @node from plist. + * + * @node: &struct plist_node pointer - entry to be removed + * @head: &struct plist_head pointer - list head + */ +void plist_del(struct plist_node *node, struct plist_head *head) +{ + plist_check_head(head); + + if (!list_empty(&node->plist.prio_list)) { + struct plist_node *next = plist_first(&node->plist); + + list_move_tail(&next->plist.prio_list, &node->plist.prio_list); + list_del_init(&node->plist.prio_list); + } + + list_del_init(&node->plist.node_list); + + plist_check_head(head); +} |