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/*

 * 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);

}