list: Split list_del() debug checking into separate function

[mirror_ubuntu-artful-kernel.git] / lib / list_debug.c

/*
 * Copyright 2006, Red Hat, Inc., Dave Jones
 * Released under the General Public License (GPL).
 *
 * This file contains the linked list validation for DEBUG_LIST.
 */

#include <linux/export.h>
#include <linux/list.h>
#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/rculist.h>

/*
 * Check that the data structures for the list manipulations are reasonably
 * valid. Failures here indicate memory corruption (and possibly an exploit
 * attempt).
 */

bool __list_add_valid(struct list_head *new, struct list_head *prev,
		      struct list_head *next)
{
	if (unlikely(next->prev != prev)) {
		WARN(1, "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
			prev, next->prev, next);
		return false;
	}
	if (unlikely(prev->next != next)) {
		WARN(1, "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
			next, prev->next, prev);
		return false;
	}
	if (unlikely(new == prev || new == next)) {
		WARN(1, "list_add double add: new=%p, prev=%p, next=%p.\n",
			new, prev, next);
		return false;
	}
	return true;
}
EXPORT_SYMBOL(__list_add_valid);

bool __list_del_entry_valid(struct list_head *entry)
{
	struct list_head *prev, *next;

	prev = entry->prev;
	next = entry->next;

	if (unlikely(next == LIST_POISON1)) {
		WARN(1, "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
			entry, LIST_POISON1);
		return false;
	}
	if (unlikely(prev == LIST_POISON2)) {
		WARN(1, "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
			entry, LIST_POISON2);
		return false;
	}
	if (unlikely(prev->next != entry)) {
		WARN(1, "list_del corruption. prev->next should be %p, but was %p\n",
			entry, prev->next);
		return false;
	}
	if (unlikely(next->prev != entry)) {
		WARN(1, "list_del corruption. next->prev should be %p, but was %p\n",
			entry, next->prev);
		return false;
	}
	return true;

}
EXPORT_SYMBOL(__list_del_entry_valid);