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Date:   Wed, 25 May 2022 16:28:46 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     "Eric W. Biederman" <ebiederm@xmission.com>
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Subject: Re: [PATCH 07/16] signal: Wake up the designated parent
Message-ID: <20220525142845.GA2687@redhat.com>
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 <20220524132553.GD14347@redhat.com>
 <20220524162808.GF14347@redhat.com>
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On 05/24, Oleg Nesterov wrote:
>
> On 05/24, Oleg Nesterov wrote:
> >
> > I fail to understand this patch...
> >
> > On 05/18, Eric W. Biederman wrote:
> > >
> > > Today if a process is ptraced only the ptracer will ever be woken up in
> > > wait
> >
> > and why is this wrong?
> >
> > > Fixes: 75b95953a569 ("job control: Add @for_ptrace to do_notify_parent_cldstop()")
> >
> > how does this change fix 75b95953a569?
>
> OK, I guess you mean the 2nd do_notify_parent_cldstop() in ptrace_stop(),
> the problematic case is current->ptrace == T. Right?
>
> I dislike this patch anyway, but let me think more about it.

OK, now that I understand the problem, the patch doesn't look bad to me,
although I'd ask to make the changelog more clear.

After this change __wake_up_parent() can't accept any "parent" from
p->parent thread group, but all callers look fine except ptrace_detach().

Oleg.