root/lib/plist.c

DEFINITIONS

1. plist_check_prev_next
2. plist_check_list
3. plist_check_head
4. plist_add
5. plist_del

/*
 * 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);
}