linux-kernel - Re: [PATCH 1/8] job control: Don't set group_stop exit

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Date:	Wed, 23 Mar 2011 18:02:36 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	roland@...hat.com, jan.kratochvil@...hat.com,
	vda.linux@...glemail.com, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	indan@....nu
Subject: Re: [PATCH 1/8] job control: Don't set group_stop exit_code if
 re-entering job control stop

Hey,

On Wed, Mar 23, 2011 at 05:40:14PM +0100, Oleg Nesterov wrote:
> > Hmmm... There are two competing signals in that case - SIGTTIN sent by
> > the parent and SIGSTOP sent by someone else.
> 
> "someone else" can be PTRACE_CONT(SIGSTOP) from the debugger.

The debugger should be doing PTRACE_CONT(notified_signo).  Am I
missing something?  Anyways, this doesn't really matter.  I kinda like
just testing STOP_STOPPED both in stop initiation and notification
paths but well it's no biggie either way.

> > Okay, I see.  Maybe we should discern between traced for group stop
> > from other traps but then again given the group stop re-entering while
> > ptraced it can be considered a relatively consistent behavior.  Yeah,
> > but probably better to remove the double reporting.
> 
> Yes. I have a vague feeling a new GROUP_STOP_YES_I_AM_STOPPED can
> be useful anyway. It should be set by task_participate_group_stop()
> if the task participates. We will see.

Yeah, agreed.  Let's mark it and ensure that a task doesn't stop for
group stop back-to-back.

Thanks.

-- 
tejun
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