From: Tejun Heo <tj@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: roland@redhat.com, jan.kratochvil@redhat.com,
vda.linux@googlemail.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
indan@nul.nu
Subject: Re: [PATCH 7/8] job control: Notify the real parent of job control events regardless of ptrace
Date: Wed, 23 Mar 2011 18:20:25 +0100 [thread overview]
Message-ID: <20110323172025.GG12003@htj.dyndns.org> (raw)
In-Reply-To: <20110323170708.GA24304@redhat.com>
Hello,
On Wed, Mar 23, 2011 at 06:07:08PM +0100, Oleg Nesterov wrote:
> On 03/23, Tejun Heo wrote:
> > On Wed, Mar 23, 2011 at 05:46:57PM +0100, Oleg Nesterov wrote:
> > > > Ooh, on a related note, we probably want to change
> > > > do_notify_parent_cldstop() too. tsk->group_leader->real_parent is
> > > > used as the delivery target when !@for_ptracer. This is the same with
> > > > tsk->real_parent and the code has been like this for a long time but
> > > > is a bit confusing.
> > >
> > > Yes, although in this case we do
> > >
> > > tsk = tsk->group_leader;
> > > parent = tsk->real_parent;
> > >
> > > We need to change tsk to report the correct si_pid. But we could do
> > >
> > > parent = tsk->real_parent;
> > > tsk = tsk->group_leader;
> > >
> > > not sure this looks less confusing.
> >
> > They themselves are about the same but the inconsistency with the
> > is_real_parent() test is a bit confusing, I think. If we're testing
> > for duplicates by testing ->real_parent against ->parent then the
> > actual delivery should be also be using ->real_parent and ->parent,
> > so...
>
> Hmm. So I misunderstood you. And still can't understand...
>
> Could you explain how should we change do_notify_parent_cldstop()?
> I am just curious.
As you suggested above. :-) The inconsistency I'm concernced about is
the following.
/*
* Test whether the target task of the usual cldstop notification - the
* real_parent of @child - is in the same group as the ptracer.
*/
static bool real_parent_is_ptracer(struct task_struct *child)
{
return same_thread_group(child->parent, child->real_parent);
}
So, here, we're saying that if child->parent and child->real_parent
are in the same thread group, they're gonna be duplicates, but in
do_notify_parent_cldstop(), we target tsk->group_leader->real_parent,
which should be the same as tsk->real_parent but confusing
nonetheless. That's actually the reason why I used
child->group_leader->real_parent in the first place.
Thanks.
--
tejun
next prev parent reply other threads:[~2011-03-23 17:20 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-08 19:56 [RFC PATCHSET] ptrace,signal: Fix notifications to the real parent while ptraced Tejun Heo
2011-03-08 19:56 ` [PATCH 1/8] job control: Don't set group_stop exit_code if re-entering job control stop Tejun Heo
2011-03-21 13:20 ` Oleg Nesterov
2011-03-21 15:52 ` Tejun Heo
2011-03-22 18:44 ` Oleg Nesterov
2011-03-23 8:44 ` Tejun Heo
2011-03-23 16:40 ` Oleg Nesterov
2011-03-23 17:02 ` Tejun Heo
2011-03-23 17:09 ` Oleg Nesterov
2011-03-23 17:22 ` Tejun Heo
2011-03-08 19:56 ` [PATCH 2/8] job control: Small reorganization of wait_consider_task() Tejun Heo
2011-03-08 19:56 ` [PATCH 3/8] job control: Fix ptracer wait(2) hang and explain notask_error clearing Tejun Heo
2011-03-21 15:19 ` Oleg Nesterov
2011-03-21 16:09 ` Oleg Nesterov
2011-03-21 16:12 ` Tejun Heo
2011-03-22 19:08 ` Oleg Nesterov
2011-03-22 10:51 ` [PATCH UPDATED " Tejun Heo
2011-03-08 19:56 ` [PATCH 4/8] job control: Allow access to job control events through ptracees Tejun Heo
2011-03-21 16:39 ` Oleg Nesterov
2011-03-21 17:20 ` Tejun Heo
2011-03-22 11:10 ` [PATCH UPDATED " Tejun Heo
2011-03-08 19:56 ` [PATCH 5/8] job control: Add @for_ptrace to do_notify_parent_cldstop() Tejun Heo
2011-03-08 19:56 ` [PATCH 6/8] job control: Job control stop notifications should always go to the real parent Tejun Heo
2011-03-21 17:12 ` Oleg Nesterov
2011-03-08 19:56 ` [PATCH 7/8] job control: Notify the real parent of job control events regardless of ptrace Tejun Heo
2011-03-21 17:43 ` Oleg Nesterov
2011-03-22 8:04 ` Tejun Heo
2011-03-22 19:44 ` Oleg Nesterov
2011-03-23 9:17 ` Tejun Heo
2011-03-23 9:24 ` Tejun Heo
2011-03-23 16:46 ` Oleg Nesterov
2011-03-23 16:59 ` Tejun Heo
2011-03-23 17:07 ` Oleg Nesterov
2011-03-23 17:20 ` Tejun Heo [this message]
2011-03-23 17:17 ` Oleg Nesterov
2011-03-22 11:30 ` [PATCH UPDATED " Tejun Heo
2011-03-08 19:56 ` [PATCH 8/8] job control: Don't send duplicate job control stop notification while ptraced Tejun Heo
2011-03-21 17:48 ` Oleg Nesterov
2011-03-08 20:01 ` [RFC PATCHSET] ptrace,signal: Fix notifications to the real parent " Linus Torvalds
2011-03-09 16:50 ` Oleg Nesterov
2011-03-22 10:20 ` [PATCH 0.1/8] ptrace: Collapse ptrace_untrace() into __ptrace_unlink() Tejun Heo
2011-03-22 10:20 ` [PATCH 0.2/8] ptrace: Always put ptracee into appropriate execution state Tejun Heo
2011-03-22 20:33 ` Oleg Nesterov
2011-03-23 8:00 ` Tejun Heo
2011-03-22 13:11 ` [RFC PATCHSET] ptrace,signal: Fix notifications to the real parent while ptraced Tejun Heo
2011-03-22 20:59 ` Oleg Nesterov
2011-03-23 8:48 ` Tejun Heo
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