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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/bug.h>
#include <linux/plist.h>
#include <linux/spinlock.h>

#ifdef CONFIG_DEBUG_PI_LIST

static struct plist_head test_head;

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)
{
if (!plist_head_empty(head))
plist_check_list(&plist_first(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 *first, *iter, *prev = NULL;
struct list_head *node_next = &head->node_list;

plist_check_head(head);
WARN_ON(!plist_node_empty(node));
WARN_ON(!list_empty(&node->prio_list));

if (plist_head_empty(head))
goto ins_node;

first = iter = plist_first(head);

do {
if (node->prio < iter->prio) {
node_next = &iter->node_list;
break;
}

prev = iter;
iter = list_entry(iter->prio_list.next,
struct plist_node, prio_list);
} while (iter != first);

if (!prev || prev->prio != node->prio)
list_add_tail(&node->prio_list, &iter->prio_list);
ins_node:
list_add_tail(&node->node_list, node_next);

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->prio_list)) {
if (node->node_list.next != &head->node_list) {
struct plist_node *next;

next = list_entry(node->node_list.next,
struct plist_node, node_list);

/* add the next plist_node into prio_list */
if (list_empty(&next->prio_list))
list_add(&next->prio_list, &node->prio_list);
}
list_del_init(&node->prio_list);
}

list_del_init(&node->node_list);

plist_check_head(head);
}

#ifdef CONFIG_DEBUG_PI_LIST
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/init.h>

static struct plist_node __initdata test_node[241];

static void __init plist_test_check(int nr_expect)
{
struct plist_node *first, *prio_pos, *node_pos;

if (plist_head_empty(&test_head)) {
BUG_ON(nr_expect != 0);
return;
}

prio_pos = first = plist_first(&test_head);
plist_for_each(node_pos, &test_head) {
if (nr_expect-- < 0)
break;
if (node_pos == first)
continue;
if (node_pos->prio == prio_pos->prio) {
BUG_ON(!list_empty(&node_pos->prio_list));
continue;
}

BUG_ON(prio_pos->prio > node_pos->prio);
BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list);
prio_pos = node_pos;
}

BUG_ON(nr_expect != 0);
BUG_ON(prio_pos->prio_list.next != &first->prio_list);
}

static int __init plist_test(void)
{
int nr_expect = 0, i, loop;
unsigned int r = local_clock();

printk(KERN_INFO "start plist test\n");
plist_head_init(&test_head);
for (i = 0; i < ARRAY_SIZE(test_node); i++)
plist_node_init(test_node + i, 0);

for (loop = 0; loop < 1000; loop++) {
r = r * 193939 % 47629;
i = r % ARRAY_SIZE(test_node);
if (plist_node_empty(test_node + i)) {
r = r * 193939 % 47629;
test_node[i].prio = r % 99;
plist_add(test_node + i, &test_head);
nr_expect++;
} else {
plist_del(test_node + i, &test_head);
nr_expect--;
}
plist_test_check(nr_expect);
}

for (i = 0; i < ARRAY_SIZE(test_node); i++) {
if (plist_node_empty(test_node + i))
continue;
plist_del(test_node + i, &test_head);
nr_expect--;
plist_test_check(nr_expect);
}

printk(KERN_INFO "end plist test\n");
return 0;
}

module_init(plist_test);

#endif
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