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Date: Sat, 10 Feb 2024 18:22:54 +0100
From: Christian Brauner <brauner@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>, 
	"Eric W. Biederman" <ebiederm@xmission.com>, Tycho Andersen <tycho@tycho.pizza>, linux-api@vger.kernel.org, 
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] pidfd: change pidfd_send_signal() to respect
 PIDFD_THREAD
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In-Reply-To: <20240210165133.GD27557@redhat.com>

On Sat, Feb 10, 2024 at 05:51:33PM +0100, Oleg Nesterov wrote:
> On 02/10, Christian Brauner wrote:
> >
> > On Sat, Feb 10, 2024 at 02:15:18PM +0100, Oleg Nesterov wrote:
> > > On 02/10, Christian Brauner wrote:
> > > >
> > > > The question is what is more useful for userspace when they do:
> > > > pidfd_send_signal(1234, PIDFD_SEND_PROCESS_GROUP)?
> > > >
> > > > (1) They either mean to signal a process group that is headed by 1234.
> > >
> > > Yes, this is what I had in mind, see also another email from me.
> > > Simple, clear, and matches kill(-1234).
> >
> > I went for a walk and kept thinking about this and I agree with you.
> > It will require that 1234 will be a process group leader but I think
> > that this is ok to require that.
> 
> Yes... but I am starting to understand why you mentioned the new
> open PIDFD_PROCESS_GROUP flag... perhaps we can do something like
> this later, but this needs more thinking.
> 
> > +	if (type == PIDFD_SIGNAL_PROCESS_GROUP)
> > +		ret = kill_pgrp_info(sig, &kinfo, pid);
> 
> I guess you meant
> 
> 	if (type == PIDTYPE_PGID)
> 
> other than that,

Bahaa, yes of course.

> 
> Reviewed-by: Oleg Nesterov <oleg@redhat.com>

Thanks!