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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);
}
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