From mboxrd@z Thu Jan  1 00:00:00 1970
From: josh@joshtriplett.org
Subject: Re: [PATCH v2 0/7] CLONE_FD: Task exit notification via file
 descriptor
Date: Mon, 23 Mar 2015 08:03:29 -0700
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Cc: Thiago Macieira <thiago.macieira@intel.com>,
	Kees Cook <keescook@chromium.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Oleg Nesterov <oleg@redhat.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Rik van Riel <riel@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>
To: David Drysdale <drysdale@google.com>
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On Mon, Mar 23, 2015 at 02:12:34PM +0000, David Drysdale wrote:
> On Mon, Mar 16, 2015 at 11:29 PM,  <josh@joshtriplett.org> wrote:
> > On Mon, Mar 16, 2015 at 03:14:14PM -0700, Thiago Macieira wrote:
> >> On Monday 16 March 2015 14:44:20 Kees Cook wrote:
> >> > >               O_CLOEXEC
> >> > >                      Set  the  close-on-exec  flag on the new file
> >> > >descriptor. See the description of the O_CLOEXEC flag in open(2)  for
> >> > >reasons why this may be useful.
> >> >
> >> > This begs the question: what happens when all CLONE_FD fds for a
> >> > process are closed? Will the parent get SIGCHLD instead, will it
> >> > auto-reap, or will it be un-wait-able (I assume not this...)
> >>
> >> Depends on CLONE_AUTOREAP. If it's on, then no one gets SIGCHLD, no one can
> >> wait() on it and the process autoreaps itself.
> >
> > Minor nit: CLONE_AUTOREAP makes the process autoreap and nobody can wait
> > on it, but if you pass SIGCHLD or some other exit signal to clone then
> > you'll still get that signal.
> 
> Quick query: does CLONE_AUTOREAP also affect waiting for non-exit
> events (i.e. WUNTRACED / WCONTINUED), by original parent and/or ptracer?

It shouldn't, no.  You can't wait on the process to exit (you'll get
-ECHLD after it wakes up), but you can wait on it to continue or
similar; none of the autoreap changes should affect that.

- Josh Triplett