linux-kernel - Re: [PATCH 10/10] ptrace: implement group stop notification for ptracer

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Message-ID: <20110524154432.GH10334@htj.dyndns.org>
Date:	Tue, 24 May 2011 17:44:32 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	jan.kratochvil@...hat.com, vda.linux@...glemail.com,
	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, indan@....nu, bdonlan@...il.com
Subject: Re: [PATCH 10/10] ptrace: implement group stop notification for
 ptracer

Hello, Oleg.

On Tue, May 24, 2011 at 03:44:11PM +0200, Tejun Heo wrote:
> > 2. ptrace_trap_notify() always sets JOBCTL_TRAP_NOTIFY. Even if the caller
> > is prepare_signal(SIGCONT) and there were no SIGSTOP in the past. This looks
> > a bit strange to me. I mean, perhaps it would be better to provoke the trap
> > only if this SIGCONT is going to change the jobctl state.
> 
> Sure.  It doesn't really matter tho and might even be better for
> weeding out invalid assumptions.

Hmmm... tried to change this but I think it's better as-is.  As an
optimization, it isn't whole lot meaningful, and, if I do it, I would
probably end up moving SIGNAL_STOP_STOPPED and group_stop_count test
above actual wake up and then skipping wake up if none was true - it
would make SIGCONT handling more fragile without much benefit.

Thanks.

-- 
tejun
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