All of lore.kernel.org
 help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>,
	jan.kratochvil@redhat.com, linux-kernel@vger.kernel.org,
	torvalds@linux-foundation.org, akpm@linux-foundation.org,
	indan@nul.nu, bdonlan@gmail.com
Subject: Re: [PATCH 03/10] ptrace: implement PTRACE_SEIZE
Date: Thu, 26 May 2011 11:14:01 +0200	[thread overview]
Message-ID: <20110526091401.GD9715@htj.dyndns.org> (raw)
In-Reply-To: <20110525182919.GB16575@redhat.com>

Hello,

On Wed, May 25, 2011 at 08:29:19PM +0200, Oleg Nesterov wrote:
> > > And. Currently there is no way to detach a zombie leader. Perhaps we
> > > should change do_wait(), but it is not clear what should we do if the
> > > tracer is the real parent (we already discussed this a bit).
> >
> > Hmmm... maybe just allow detaching zombie leader?
> 
> Yes, I think we should do this.
> 
> If we change PTRACE_DETACH (or add the new request) to allow this, then
> I think it it should detach any zombie, leader or not.

I think we can just make PTRACE_DETACH to succeed for zombies.  No
reason to add a new request for this.

> Or we can change do_wait() to detach a zombie leader. In this case it
> is not clear what should we do if the debugger is the real parent.
> Perhaps do_wait() should do the same: detach a leader (but not reap).
> When the last thread does, the real parent will be notified again.
> IOW, wait(tgid) can succeed twice.

Just letting PTRACE_DETACH work for zombies sounds much simpler to me.

> > As it's guaranteed to be not running, we don't have problem with
> > ptrace_disable.
> 
> Agreed. In fact it can be running, but it can't return to the user-space,
> and I think this is enough.
> 
> ptrace_detach()->ptrace_disable() can race with SIGKILL anyway, this means
> it should safe to call it if the tracee is exiting/exited.

Yeap, unless userland gets to run again, I don't think there's any
problem.

Thanks.

-- 
tejun

  reply	other threads:[~2011-05-26  9:14 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-16 18:17 [PATCHSET ptrace] ptrace: implement PTRACE_SEIZE/INTERRUPT and group stop notification, take#2 Tejun Heo
2011-05-16 18:17 ` [PATCH 01/10] signal: remove three noop tracehooks Tejun Heo
2011-05-17 16:22   ` Christoph Hellwig
2011-05-17 16:27     ` Tejun Heo
2011-05-18 18:45   ` Oleg Nesterov
2011-05-19 12:11     ` Tejun Heo
2011-05-19 16:10       ` Oleg Nesterov
2011-05-16 18:17 ` [PATCH 02/10] job control: introduce JOBCTL_TRAP_STOP and use it for group stop trap Tejun Heo
2011-05-18 16:48   ` Oleg Nesterov
2011-05-18 16:57     ` Oleg Nesterov
2011-05-19 10:19     ` Tejun Heo
2011-05-19 16:19       ` Oleg Nesterov
2011-05-16 18:17 ` [PATCH 03/10] ptrace: implement PTRACE_SEIZE Tejun Heo
2011-05-18  0:40   ` Denys Vlasenko
2011-05-18  9:55     ` Tejun Heo
2011-05-18 10:44       ` Denys Vlasenko
2011-05-18 11:14         ` Tejun Heo
2011-05-19 14:17       ` Tejun Heo
2011-05-19 15:02         ` Tejun Heo
2011-05-19 19:31         ` Pedro Alves
2011-05-19 22:42           ` Denys Vlasenko
2011-05-19 23:00             ` Pedro Alves
2011-05-20  1:44               ` Denys Vlasenko
2011-05-20  8:56                 ` Pedro Alves
2011-05-20  9:12                   ` Tejun Heo
2011-05-20  9:07               ` Tejun Heo
2011-05-20  9:27                 ` Pedro Alves
2011-05-20  9:31                   ` Tejun Heo
2011-05-24  9:49                     ` Pedro Alves
2011-05-24 12:00                       ` Tejun Heo
2011-05-24 12:36                         ` Pedro Alves
2011-05-24 14:02                           ` Tejun Heo
2011-05-24 14:55                             ` Pedro Alves
2011-05-25 18:18                             ` Oleg Nesterov
2011-05-26  9:10                               ` Tejun Heo
2011-05-26 10:01                                 ` Pedro Alves
2011-05-26 10:11                                   ` Tejun Heo
2011-05-26 14:55                                 ` Oleg Nesterov
2011-05-23 13:09         ` Oleg Nesterov
2011-05-23 12:43       ` Oleg Nesterov
2011-05-24 10:28         ` Tejun Heo
2011-05-25 18:29           ` Oleg Nesterov
2011-05-26  9:14             ` Tejun Heo [this message]
2011-05-26 15:01               ` Oleg Nesterov
2011-05-27 18:21                 ` Tejun Heo
2011-05-30 19:22                   ` Oleg Nesterov
     [not found]                     ` <BANLkTimupSd774N-VBoswOj+Dza=5ofvWQ@mail.gmail.com>
2011-05-31 19:08                       ` Oleg Nesterov
2011-05-31 21:32                         ` Linus Torvalds
2011-06-01 20:04                           ` Oleg Nesterov
2011-06-01  5:34                         ` Tejun Heo
2011-06-01 20:08                           ` Oleg Nesterov
2011-06-02  5:01                             ` Tejun Heo
2011-05-18 18:17   ` Oleg Nesterov
2011-05-19 10:34     ` Tejun Heo
2011-05-16 18:17 ` [PATCH 04/10] ptrace: implement PTRACE_INTERRUPT Tejun Heo
2011-05-18 18:38   ` Oleg Nesterov
2011-05-19 12:07     ` Tejun Heo
2011-05-19 16:21       ` Oleg Nesterov
2011-05-16 18:17 ` [PATCH 05/10] ptrace: restructure ptrace_getsiginfo() Tejun Heo
2011-05-16 18:17 ` [PATCH 06/10] ptrace: add siginfo.si_pt_flags Tejun Heo
2011-05-16 18:17 ` [PATCH 07/10] ptrace: make group stop state visible via PTRACE_GETSIGINFO Tejun Heo
2011-05-19 16:27   ` Oleg Nesterov
2011-05-19 16:40     ` Tejun Heo
2011-05-16 18:17 ` [PATCH 08/10] ptrace: don't let PTRACE_SETSIGINFO override __SI_TRAP siginfo Tejun Heo
2011-05-16 18:17 ` [PATCH 09/10] ptrace: add JOBCTL_BLOCK_NOTIFY Tejun Heo
2011-05-19 16:32   ` Oleg Nesterov
2011-05-19 16:44     ` Tejun Heo
2011-05-19 16:48       ` Oleg Nesterov
2011-05-19 16:58         ` Tejun Heo
2011-05-16 18:17 ` [PATCH 10/10] ptrace: implement group stop notification for ptracer Tejun Heo
2011-05-19 16:32   ` Oleg Nesterov
2011-05-19 16:57     ` Tejun Heo
2011-05-19 17:13       ` Oleg Nesterov
2011-05-19 22:48         ` Denys Vlasenko
2011-05-20  8:59           ` Tejun Heo
2011-05-23 13:34             ` Oleg Nesterov
2011-05-20  8:46         ` Tejun Heo
2011-05-19 16:58     ` Oleg Nesterov
2011-05-23 11:45       ` Oleg Nesterov
2011-05-24 13:44         ` Tejun Heo
2011-05-24 15:44           ` Tejun Heo
2011-05-26 14:44           ` Oleg Nesterov
2011-05-28  7:32             ` Tejun Heo
2011-05-18 18:50 ` [PATCHSET ptrace] ptrace: implement PTRACE_SEIZE/INTERRUPT and group stop notification, take#2 Oleg Nesterov
2011-05-19 12:08   ` Tejun Heo
2011-05-19 15:04 ` Linus Torvalds
2011-05-19 15:19   ` Tejun Heo
2011-05-19 22:45   ` Denys Vlasenko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20110526091401.GD9715@htj.dyndns.org \
    --to=tj@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=bdonlan@gmail.com \
    --cc=indan@nul.nu \
    --cc=jan.kratochvil@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=oleg@redhat.com \
    --cc=torvalds@linux-foundation.org \
    --cc=vda.linux@googlemail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.