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linux-next/lib/list_debug.c
Baruch Siach e3f76e3386 list debugging: warn when deleting a deleted entry
Use the magic LIST_POISON* values to detect an incorrect use of list_del
on a deleted entry.  This DEBUG_LIST specific warning is easier to
understand than the generic Oops message caused by LIST_POISON
dereference.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-09 20:45:08 -07:00

63 lines
1.7 KiB
C

/*
* 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)
{
WARN(next->prev != prev,
"list_add corruption. next->prev should be "
"prev (%p), but was %p. (next=%p).\n",
prev, next->prev, next);
WARN(prev->next != next,
"list_add corruption. prev->next should be "
"next (%p), but was %p. (prev=%p).\n",
next, prev->next, prev);
next->prev = new;
new->next = next;
new->prev = prev;
prev->next = new;
}
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)
{
WARN(entry->next == LIST_POISON1,
"list_del corruption, next is LIST_POISON1 (%p)\n",
LIST_POISON1);
WARN(entry->next != LIST_POISON1 && entry->prev == LIST_POISON2,
"list_del corruption, prev is LIST_POISON2 (%p)\n",
LIST_POISON2);
WARN(entry->prev->next != entry,
"list_del corruption. prev->next should be %p, "
"but was %p\n", entry, entry->prev->next);
WARN(entry->next->prev != entry,
"list_del corruption. next->prev should be %p, "
"but was %p\n", entry, entry->next->prev);
__list_del(entry->prev, entry->next);
entry->next = LIST_POISON1;
entry->prev = LIST_POISON2;
}
EXPORT_SYMBOL(list_del);