[linux-block.git] / lib / plist.c

/*
 * 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)
{
	WARN(n->prev != p || p->next != n,
			"top: %p, n: %p, p: %p\n"
			"prev: %p, n: %p, p: %p\n"
			"next: %p, n: %p, p: %p\n",
			 t, t->next, t->prev,
			p, p->next, p->prev,
			n, n->next, n->prev);
}

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 <inaky.perez-gonzalez@intel.com>.
	8	*
	9	* 2001-2005 (c) MontaVista Software, Inc.
	10	* Daniel Walker <dwalker@mvista.com>
	11	*
	12	* (C) 2005 Thomas Gleixner <tglx@linutronix.de>
	13	*
	14	* Simplifications of the original code by
	15	* Oleg Nesterov <oleg@tv-sign.ru>
	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	{
5cd2b459 AV	34	WARN(n->prev != p \|\| p->next != n,
	35	"top: %p, n: %p, p: %p\n"
	36	"prev: %p, n: %p, p: %p\n"
	37	"next: %p, n: %p, p: %p\n",
	38	t, t->next, t->prev,
	39	p, p->next, p->prev,
	40	n, n->next, n->prev);
77ba89c5 IM	41	}
	42
	43	static void plist_check_list(struct list_head *top)
	44	{
	45	struct list_head prev = top, next = top->next;
	46
	47	plist_check_prev_next(top, prev, next);
	48	while (next != top) {
	49	prev = next;
	50	next = prev->next;
	51	plist_check_prev_next(top, prev, next);
	52	}
	53	}
	54
	55	static void plist_check_head(struct plist_head *head)
	56	{
	57	WARN_ON(!head->lock);
	58	if (head->lock)
	59	WARN_ON_SMP(!spin_is_locked(head->lock));
	60	plist_check_list(&head->prio_list);
	61	plist_check_list(&head->node_list);
	62	}
	63
	64	#else
	65	# define plist_check_head(h) do { } while (0)
	66	#endif
	67
	68	/**
	69	* plist_add - add @node to @head
	70	*
	71	* @node: &struct plist_node pointer
	72	* @head: &struct plist_head pointer
	73	*/
	74	void plist_add(struct plist_node node, struct plist_head head)
	75	{
	76	struct plist_node *iter;
	77
	78	plist_check_head(head);
	79	WARN_ON(!plist_node_empty(node));
	80
	81	list_for_each_entry(iter, &head->prio_list, plist.prio_list) {
	82	if (node->prio < iter->prio)
	83	goto lt_prio;
	84	else if (node->prio == iter->prio) {
	85	iter = list_entry(iter->plist.prio_list.next,
	86	struct plist_node, plist.prio_list);
	87	goto eq_prio;
	88	}
	89	}
	90
	91	lt_prio:
	92	list_add_tail(&node->plist.prio_list, &iter->plist.prio_list);
	93	eq_prio:
	94	list_add_tail(&node->plist.node_list, &iter->plist.node_list);
	95
	96	plist_check_head(head);
	97	}
	98
	99	/**
	100	* plist_del - Remove a @node from plist.
	101	*
	102	* @node: &struct plist_node pointer - entry to be removed
	103	* @head: &struct plist_head pointer - list head
	104	*/
105	void plist_del(struct plist_node node, struct plist_head head)
106	{
107	plist_check_head(head);
108
109	if (!list_empty(&node->plist.prio_list)) {
110	struct plist_node *next = plist_first(&node->plist);
111
112	list_move_tail(&next->plist.prio_list, &node->plist.prio_list);
113	list_del_init(&node->plist.prio_list);
114	}
115
116	list_del_init(&node->plist.node_list);
117
118	plist_check_head(head);
119	}