[linux.git] / lib / plist.c

/*
 * lib/plist.c
 *
 * 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]>
 *
 * 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);
}
Commit	Line	Data
77ba89c5 IM	1	/*
	2	* lib/plist.c
	3	*
	4	* Descending-priority-sorted double-linked list
	5	*
	6	* (C) 2002-2003 Intel Corp
	7	* Inaky Perez-Gonzalez <[email protected]>.
	8	*
	9	* 2001-2005 (c) MontaVista Software, Inc.
	10	* Daniel Walker <[email protected]>
	11	*
	12	* (C) 2005 Thomas Gleixner <[email protected]>
	13	*
	14	* Simplifications of the original code by
	15	* Oleg Nesterov <[email protected]>
	16	*
	17	* Licensed under the FSF's GNU Public License v2 or later.
	18	*
	19	* Based on simple lists (include/linux/list.h).
	20	*
	21	* This file contains the add / del functions which are considered to
	22	* be too large to inline. See include/linux/plist.h for further
	23	* information.
	24	*/
	25
	26	#include <linux/plist.h>
	27	#include <linux/spinlock.h>
	28
	29	#ifdef CONFIG_DEBUG_PI_LIST
	30
	31	static void plist_check_prev_next(struct list_head t, struct list_head p,
	32	struct list_head *n)
	33	{
	34	if (n->prev != p \|\| p->next != n) {
	35	printk("top: %p, n: %p, p: %p\n", t, t->next, t->prev);
	36	printk("prev: %p, n: %p, p: %p\n", p, p->next, p->prev);
	37	printk("next: %p, n: %p, p: %p\n", n, n->next, n->prev);
	38	WARN_ON(1);
	39	}
	40	}
	41
	42	static void plist_check_list(struct list_head *top)
	43	{
	44	struct list_head prev = top, next = top->next;
	45
	46	plist_check_prev_next(top, prev, next);
	47	while (next != top) {
	48	prev = next;
	49	next = prev->next;
	50	plist_check_prev_next(top, prev, next);
	51	}
	52	}
	53
	54	static void plist_check_head(struct plist_head *head)
	55	{
	56	WARN_ON(!head->lock);
	57	if (head->lock)
	58	WARN_ON_SMP(!spin_is_locked(head->lock));
	59	plist_check_list(&head->prio_list);
	60	plist_check_list(&head->node_list);
	61	}
	62
	63	#else
	64	# define plist_check_head(h) do { } while (0)
65	#endif
66
67	/**
68	* plist_add - add @node to @head
69	*
70	* @node: &struct plist_node pointer
71	* @head: &struct plist_head pointer
72	*/
73	void plist_add(struct plist_node node, struct plist_head head)
74	{
75	struct plist_node *iter;
76
77	plist_check_head(head);
78	WARN_ON(!plist_node_empty(node));
79
80	list_for_each_entry(iter, &head->prio_list, plist.prio_list) {
81	if (node->prio < iter->prio)
82	goto lt_prio;
83	else if (node->prio == iter->prio) {
84	iter = list_entry(iter->plist.prio_list.next,
85	struct plist_node, plist.prio_list);
86	goto eq_prio;
87	}
88	}
89
90	lt_prio:
91	list_add_tail(&node->plist.prio_list, &iter->plist.prio_list);
92	eq_prio:
93	list_add_tail(&node->plist.node_list, &iter->plist.node_list);
94
95	plist_check_head(head);
96	}
97
98	/**
99	* plist_del - Remove a @node from plist.
100	*
101	* @node: &struct plist_node pointer - entry to be removed
102	* @head: &struct plist_head pointer - list head
103	*/
104	void plist_del(struct plist_node node, struct plist_head head)
105	{
106	plist_check_head(head);
107
108	if (!list_empty(&node->plist.prio_list)) {
109	struct plist_node *next = plist_first(&node->plist);
110
111	list_move_tail(&next->plist.prio_list, &node->plist.prio_list);
112	list_del_init(&node->plist.prio_list);
113	}
114
115	list_del_init(&node->plist.node_list);
116
117	plist_check_head(head);
118	}