Re: [PATCH 0/2] introduce __next_thread(), change next_thread()

[Linus Torvalds]

On Thu, 24 Aug 2023 at 07:32, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
>
> After document-while_each_thread-change-first_tid-to-use-for_each_thread.patch
> in mm tree + this series

Looking at your patch 2/2, I started looking at users ("Maybe we
*want* NULL for the end case, and make next_thread() and __next_thread
be the same?").

One of the main users is while_each_thread(), which certainly wants
that NULL case, both for an easier loop condition, but also because
the only user that uses the 't' pointer after the loop is
fs/proc/base.c, which wants it to be NULL.

And kernel/bpf/task_iter.c seems to *expect* NULL at the end?

End result: if you're changing next_thread() anyway, please just
change it to be a completely new thing that returns NULL at the end,
which is what everybody really seems to want, and don't add a new
__next_thread() helper. Ok?

              Linus