Re: [PATCH v3 1/3] pidfd: allow pidfd_open() on non-thread-group leaders

On 01/25, Tycho Andersen wrote:

One of the things I don't like about PIDFD_THREAD is that it's hard to
tell whether an arbitrary thread is a leader or not. Right now we do
it by parsing /proc/pid/status, which shows all the stuff from
do_task_stat() that we don't care about but which is quite expensive
to compute. (Maybe there's a better way?)

With PIDFD_THREAD we could could do it twice, once with the flag, get
EINVAL, and then do it again. But ideally we wouldn't have to.

Too late for me, most probably I misunderstood.

If you want the PIDFD_THREAD behaviour, you can always use this flag
without any check...

Could you spell?

Oleg.