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From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Pedro Alves <pedro@codesourcery.com>,
	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: Wed, 25 May 2011 20:18:56 +0200	[thread overview]
Message-ID: <20110525181856.GA16575@redhat.com> (raw)
In-Reply-To: <20110524140215.GF10334@htj.dyndns.org>

Sorry for delay again, I was a bit offline.

On 05/24, Tejun Heo wrote:
>
> Hello,
>
> On Tue, May 24, 2011 at 01:36:03PM +0100, Pedro Alves wrote:
> > On Tuesday 24 May 2011 13:00:13, Tejun Heo wrote:
> > > Hello,
> > >
> > > On Tue, May 24, 2011 at 10:49:58AM +0100, Pedro Alves wrote:
> > > > A couple interface questions that just crossed my mind:
> > > >
> > > >  - on a fork/vfork/clone, if PTRACE_EVENT_FORK|VFORK|CLONE have been
> > > >    enabled, will the tracer still see the new child stop with a
> > > >    SIGSTOP, or will it see a PTRACE_EVENT_INTERRUPT?
> > >
> > > This won't change, so SIGSTOP although we probably want to improve it
> > > such that this can be distinguished from SIGTRAP from userland.
> >
> > (I assume you meant SIGSTOP from userland.)  So that if a SIGSTOPs
> > from userland is sent before the tracer waits for the child, the
> > tracer sees a siginfo corresponding to the userland SIGSTOP?  Sounds
> > like it might work.
>
> Now that thinking more about it, TRAP_STOP (INTERRUPT trap) would
> probably be better.  I'll think more about it.  For fork, it doesn't
> really matter but deliverying SIGSTOP on CLONE isn't too good.  From
> user's POV, TRAP_STOP should work too, right?

I am a bit confused, sorry if I missed/misunderstood the context...

I thought, we already discussed this. Obviously, PT_SEIZED should be
inherited by the child during the auto-attach (and it is indeed copied
by ptrace_init_task). Why should we send SIGSTOP to the child then?
Even in the fork case, this leads to the same problems as the current
PTRACE_ATTACH has with the bogus SIGSTOP it sends. I think TRAP_STOP
is the only sane option, no?


Btw. Speaking of SEIZE->execvd->INTERRUPT which makes the tracee see
a SIGTRAP. Stupid question. Perhaps PTRACE_SEIZE should set
PT_TRACESYSGOOD | PT_TRACE_EXEC along with PT_SEIZED automatically?
PT_SEIZED implies the new behaviour anyway.

Oleg.


  parent reply	other threads:[~2011-05-25 18:21 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 [this message]
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
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

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