Re: [PATCH v2 2/2] proc: Ensure we see the exit of each process tid exactly

Linus Torvalds
2020-04-24T20:10:55Z

On Fri, Apr 24, 2020 at 12:54 PM Eric W. Biederman
<ebiederm@xmission.com> wrote:
>
> The problem with
>
> remove
> remove
> add
> add
> is:
>
> A lookup that hit between the remove and the add could return nothing.

Argh. Because that thing doesn't actually _search_ the list, it just
wants to pick any (first) entry. So it doesn't actually care what it
gets, just that it gets something.

Ok, I see.

> For PIDTYPE_PID and PIDTYPE_TGID these practically aren't lists but
> pointers to the appropriate task. Only for PIDTYPE_PGID and PIDTYPE_SID
> do these become lists in practice.

Yeah, that's what confused me. Ok, please add a comment about the
"single-entry list" issue, and I'm happy.

Linus