Re: [PATCH 0/6] improve list_sort test

Don Mullis
2010-08-08T20:07:52Z

On Sun, Aug 8, 2010 at 12:31 PM, Don Mullis <don.mullis@gmail.com> wrote:
> Artem Bityutskiy <dedekind1@gmail.com> writes:
>> Actually, your 'list_sort()' version does have a problem. I found out
>> that it calls 'cmp(priv, a, b)' with 'a = b' sometimes, and in these
>> cases 'a' and 'b' can point to something which is not a valid element of
>> the original list. Probably a senitel or something like that.

Looks like if the original list is a POT in length, the first callback
from line 73 will pass a==b both pointing to the original list_head.
Would you be able to test this fix?

--- linux-2.6.orig/lib/list_sort.c
+++ linux-2.6/lib/list_sort.c
@@ -70,7 +70,7 @@ static void merge_and_restore_back_links
* element comparison is needed, so the client's cmp()
* routine can invoke cond_resched() periodically.
*/
- (*cmp)(priv, tail, tail);
+ (*cmp)(priv, tail->next, tail->next);

tail->next->prev = tail;
tail = tail->next;