/*
   * Copyright 2006, Red Hat, Inc., Dave Jones
   * Released under the General Public License (GPL).
   *
   * This file contains the linked list implementations for
   * DEBUG_LIST.
   */
  
  #include <linux/module.h>
  #include <linux/list.h>
  
  /*
   * Insert a new entry between two known consecutive entries.
   *
   * This is only for internal list manipulation where we know
   * the prev/next entries already!
   */
  
  void __list_add(struct list_head *new,
  			      struct list_head *prev,
  			      struct list_head *next)
  {
  	if (unlikely(next->prev != prev)) {

  		printk(KERN_ERR "list_add corruption. next->prev should be "
  			"prev (%p), but was %p. (next=%p).
  ",
  			prev, next->prev, next);

  		BUG();
  	}
  	if (unlikely(prev->next != next)) {

  		printk(KERN_ERR "list_add corruption. prev->next should be "
  			"next (%p), but was %p. (prev=%p).
  ",
  			next, prev->next, prev);

  		BUG();
  	}
  	next->prev = new;
  	new->next = next;
  	new->prev = prev;
  	prev->next = new;
  }
  EXPORT_SYMBOL(__list_add);
  
  /**
   * list_add - add a new entry
   * @new: new entry to be added
   * @head: list head to add it after
   *
   * Insert a new entry after the specified head.
   * This is good for implementing stacks.
   */
  void list_add(struct list_head *new, struct list_head *head)
  {
  	__list_add(new, head, head->next);
  }
  EXPORT_SYMBOL(list_add);
  
  /**
   * list_del - deletes entry from list.
   * @entry: the element to delete from the list.
   * Note: list_empty on entry does not return true after this, the entry is
   * in an undefined state.
   */
  void list_del(struct list_head *entry)
  {
  	if (unlikely(entry->prev->next != entry)) {

  		printk(KERN_ERR "list_del corruption. prev->next should be %p, "
  				"but was %p
  ", entry, entry->prev->next);

  		BUG();
  	}
  	if (unlikely(entry->next->prev != entry)) {

  		printk(KERN_ERR "list_del corruption. next->prev should be %p, "
  				"but was %p
  ", entry, entry->next->prev);

  		BUG();
  	}
  	__list_del(entry->prev, entry->next);
  	entry->next = LIST_POISON1;
  	entry->prev = LIST_POISON2;
  }
  EXPORT_SYMBOL(list_del);