Re: [PATCH v2 2/2] pidfd: change pidfd_send_signal() to respect PIDFD_THREAD

[Oleg Nesterov]

On 02/21, Christian Brauner wrote:
>
> On Tue, Feb 20, 2024 at 05:22:02PM +0100, Oleg Nesterov wrote:
> >
> > > > > +       /* Currently unused. */
> > > > > +       if (info)
> > > > > +               return -EINVAL;
> > > >
> > > > Well, to me this looks like the unnecessary restriction... And why?
> > >
> > > Because right now we aren't sure that it's used
> >
> > Yes, but...
> >
> > > and we aren't sure what use-cases are there.
> >
> > the same use-cases as for rt_sigqueueinfo() ?
>
> Specifically for pidfd_send_signal() I mean. To me it seems very
> unlikely that anyone would be opening a pidfd to itself

Ah, with this, I do agree. And that is why (I think) we can remove
the "task_pid(current) != pid" check in the "info != NULL" branch.

Oleg.