linux-kernel - Re: [PATCH 1/1] ptrace: do_notify_parent_cldstop: fix the wrong ->nsproxy usage

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Message-ID: <20090527232425.GC10032@redhat.com>
Date:	Thu, 28 May 2009 01:24:25 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Roland McGrath <roland@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Hellwig <hch@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Pavel Emelyanov <xemul@...nvz.org>,
	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] ptrace: do_notify_parent_cldstop: fix the wrong
	->nsproxy usage

On 05/26, Roland McGrath wrote:
>
> > While this change is correct in any case (I hope), I wonder whether
> > we need another one:
> [...]
> > If the sub-thread is not traced, but ->group_leader is, perhaps it makes
> > more sense to notify the leader's tracer, not parent?
>
> I don't think so.

Agreed.

> > Not that I think this is really important. Just curious about what was
> > the intent.
>
> Here is how I would describe the intent (admittedly this logic is
> retrospective, not necessarily articulated as such when the code was
> written).  If the the triggering task is ptrace'd, this report is "for
> ptrace purposes"--even if it's the CLD_STOPPED case.  Otherwise, what's
> being reported is "the whole POSIX process is now stopped as per POSIX
> definitions".  The latter properly goes to the parent of the process,
> which is the group_leader->real_parent.

Yes. And I forgot that in this case the traced group_leader has already
reported CLD_STOPPED to tracer.

Oleg.

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