Re: [PATCH 0/2] be more generous with ptrlist repacking

[Linus Torvalds <torvalds@linux-foundation.org>]

On Thu, Nov 17, 2016 at 9:25 AM, Luc Van Oostenryck
<luc.vanoostenryck@gmail.com> wrote:
> The macros that do the ptrlist walking don't handle empty blocks.

Actually, most of the_do_ handle empty blocks. In particular, the
normal FOR_EACH_PTR() case should handle it just fine.

The exception is, I think:

 - first_ptr_list/last_ptr_list

 - DO_PREPARE/DO_RESET

which just don't walk the pointer block list, they just end up blindly doing

        PTR_ENTRY(list, 0);

for the first entry, or

        list = list->prev;
        PTR_ENTRY(list, list->nr-1);

for the last one.

I suspect they should be fairly easy to update to just walk the list
until they hit a non-empty case (like DO_NEXT() already does, for
example).

              Linus