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Date: Thu, 5 Sep 2002 18:52:57 -0400
From: Daniel Jacobowitz <dan@debian.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>,
       Linus Torvalds <torvalds@transmeta.com>, linux-kernel@vger.kernel.org
Subject: Re: [patch] ptrace-fix-2.5.33-A1
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On Fri, Sep 06, 2002 at 12:25:32AM +0200, Ingo Molnar wrote:
> > > this splitup of the lists makes it possible for the debugger to do a wait4
> > > that will get events from the debugged task, and for the debugged task to
> > > also be available to the real parent.
> > 
> > Great.  I'm not exactly sure on how this works right now: sys_wait4 only
> > iterates over ->children, with the exception of the special code in
> > TASK_ZOMBIE.  I'm not quite sure when events from a traced process get
> > to the normal parent of that process, or when they're supposed to.
> 
> i'm not sure about this either. What happens if an (untraced) parent has
> traced and untraced children, and does a wait4. Would it confuse the
> debugger if the parent could get one of the traced tasks as a result in
> wait4? And how does the debugger solve this problem?

Not a problem.  The parent never gets an event that is not first
reported to the debugger, via the hook in sys_wait4... A debugger that
runs other processes has to play some games with wait loops in order to
manage its children and its debugees, but that's old news.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer
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