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Commit 3c18d4de authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2a324ce7

include/linux/list.h

+9 −3
Original line number Diff line number Diff line
@@ -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);

}

lib/list_debug.c

+26 −13
Original line number Diff line number Diff line
@@ -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;

}