Re: [PATCH v2 5/7] clone4: Add a CLONE_AUTOREAP flag to automatically reap the child process

On Fri, Mar 20, 2015 at 08:09:14PM +0100, Oleg Nesterov wrote:

On 03/20, Thiago Macieira wrote:

quoted

On Friday 20 March 2015 19:14:04 Oleg Nesterov wrote:

quoted

Also. I forgot that the kernel always resets ->exit_signal to SIGCHLD on
exec or reparenting. Reparenting is probably fine. But what about exec?
Should it keep ->exit_signal == 0 if "autoreap" ? I think it should not, to
avoid the strange special case.

Not delivering any signal was the objective of this patch series, so yes
exit_signal == 0 should survive an exec and even re-exec.

OK, but then perhaps we should never send SIGCHLD (on exit) if "autoreap",
to make the logic simple.

And copy_process() should probably do

	if ((clone_flags & CSIGNAL) && (clone_flags && CLONE_AUTOREAP))
		return -EINVAL;

so that we still can change this behaviour later.

I'm fine with that, as it would handle the particular use case we care
about.

However, the reset-signal-on-reparent thing might still make sense,
particularly for the ptrace-reparent case (less so for the
reparent-to-child-reaper case).

- Josh Triplett