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Date: Thu, 5 Sep 2002 19:02:50 -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 12:35:22AM +0200, Ingo Molnar wrote:
> 
> there are two kinds of wait4 calls, one that gets the WIFSTOPPED event
> from the debugged task, for this the traced task has to be in the
> debugger's ->children list.
> 
> Another one is when a debugged task exits and its parent wants the exit
> event. But in this case the task is untraced already, so it gets back into
> the parent's ->children list.
> 
> ie. wait4 should only look at the ->children list - zombies (or traced
> tasks debugged by this task) can only be there.
> 
> The only addition is that in the wait4 non-blocking case we need to look
> at the traced list as well - since a non-blocking wait4 is a 'could there
> be any children exiting' kind of query.

OK.  I think that the !list_empty (ptrace_children) isn't really enough
- since there can be things on our children list that we will not wait
for - should we be iterating over it making the same checks we do
above?

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer
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