Date: Fri, 18 Feb 2011 22:11:40 +0100
From: Jan Kratochvil <jan.kratochvil@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>, Tejun Heo <tj@kernel.org>,
        Roland McGrath <roland@redhat.com>, linux-kernel@vger.kernel.org,
        torvalds@linux-foundation.org, akpm@linux-foundation.org
Subject: Re: [PATCH 1/1] ptrace: make sure do_wait() won't hang after
 PTRACE_ATTACH
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 <20110217191952.GA13611@redhat.com>
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On Thu, 17 Feb 2011 20:19:52 +0100, Oleg Nesterov wrote:
> > > That is after PTRACE_DETACH(0) the process should remain `T (stopped)'
> > > iff the process was `T (stopped)' before PTRACE_ATTACH.
> > >  - PTRACE_DETACH(0)       should preserve `T (stopped)'.
> >
> > I assume you are thinking about PTRACE_ATTACH + wait():SIGSTOP
> > + PTRACE_DETACH(0) sequence.
> 
> plus it should be stopped before attach, I assume. Otherwise this
> not true with the current code.

I did not talk about the current code.  I was making a proposal of new
behavior (which should not break existing software).

If PTRACE_ATTACH was done on process with `T (stopped)' then after
PTRACE_DETACH(0) again the process should be `T (stopped)'.


Regards,
Jan
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