Re: [PATCH v2 0/5] pid: add pidfd_open()

[Linus Torvalds]

On Mon, Apr 1, 2019 at 9:07 AM Jonathan Kowalski <bl0pbl33p@xxxxxxxxx> wrote:
>
> With the POLLHUP model on a simple pidfd, you'd know when the process
> you were referring to is dead (and one can map POLLPRI to dead and
> POLLHUP to zombie, etc).

Adding ->poll() to the pidfd should be easy. Again, it would be
trivially be made to work for the directory fd you get from
/proc/<pid> too.

Yeah, yeah, pollable directories are odd, but the vfs layer doesn't
care about things like "is this a directory or not". It will just call
the f_op->poll() method.

              Linus