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Expand CONFIG_DEBUG_LIST to several other list operations 

When list debugging is enabled, we aim to readably show list corruption
errors, and the basic list_add/list_del operations end up having extra
debugging code in them to do some basic validation of the list entries.

However, "list_del_init()" and "list_move[_tail]()" ended up avoiding
the debug code due to how they were written. This fixes that.

So the _next_ time we have list_move() problems with stale list entries,
we'll hopefully have an easier time finding them..

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2011-02-18 11:32:28 -08:00
parent 2a324ce7b7
commit 3c18d4de86
2 changed files with 35 additions and 16 deletions
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12
include/linux/list.h
View File

@ -96,6 +96,11 @@ static inline void __list_del(struct list_head * prev, struct list_head * next)
* in an undefined state.
*/
#ifndef CONFIG_DEBUG_LIST
static inline void __list_del_entry(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
}
static inline void list_del(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
@ -103,6 +108,7 @@ static inline void list_del(struct list_head *entry)
entry->prev = LIST_POISON2;
}
#else
extern void __list_del_entry(struct list_head *entry);
extern void list_del(struct list_head *entry);
#endif
@ -135,7 +141,7 @@ static inline void list_replace_init(struct list_head *old,
*/
static inline void list_del_init(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
__list_del_entry(entry);
INIT_LIST_HEAD(entry);
}
@ -146,7 +152,7 @@ static inline void list_del_init(struct list_head *entry)
*/
static inline void list_move(struct list_head *list, struct list_head *head)
{
__list_del(list->prev, list->next);
__list_del_entry(list);
list_add(list, head);
}
@ -158,7 +164,7 @@ static inline void list_move(struct list_head *list, struct list_head *head)
static inline void list_move_tail(struct list_head *list,
struct list_head *head)
{
__list_del(list->prev, list->next);
__list_del_entry(list);
list_add_tail(list, head);
}

39
lib/list_debug.c
View File

@ -35,6 +35,31 @@ void __list_add(struct list_head *new,
}
EXPORT_SYMBOL(__list_add);
void __list_del_entry(struct list_head *entry)
{
struct list_head *prev, *next;
prev = entry->prev;
next = entry->next;
if (WARN(next == LIST_POISON1,
"list_del corruption, %p->next is LIST_POISON1 (%p)\n",
entry, LIST_POISON1) ||
WARN(prev == LIST_POISON2,
"list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
entry, LIST_POISON2) ||
WARN(prev->next != entry,
"list_del corruption. prev->next should be %p, "
"but was %p\n", entry, prev->next) ||
WARN(next->prev != entry,
"list_del corruption. next->prev should be %p, "
"but was %p\n", entry, next->prev))
return;
__list_del(prev, next);
}
EXPORT_SYMBOL(__list_del_entry);
/**
* list_del - deletes entry from list.
* @entry: the element to delete from the list.
@ -43,19 +68,7 @@ EXPORT_SYMBOL(__list_add);
*/
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);
__list_del_entry(entry);
entry->next = LIST_POISON1;
entry->prev = LIST_POISON2;
}