From: Roland McGrath <roland@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: oleg@redhat.com, jan.kratochvil@redhat.com,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
akpm@linux-foundation.org
Subject: Re: [PATCH 08/10] ptrace: participate in group stop from ptrace_stop() iff the task is trapping for group stop
Date: Fri, 28 Jan 2011 13:30:09 -0800 (PST) [thread overview]
Message-ID: <20110128213009.340C7183C1E@magilla.sf.frob.com> (raw)
In-Reply-To: Tejun Heo's message of Friday, 28 January 2011 16:08:42 +0100 <1296227324-25295-9-git-send-email-tj@kernel.org>
> A visible behavior change is increased likelihood of delayed group
> stop completion if the thread group contains one or more ptraced
> tasks.
I object to that difference in behavior. As I've said before, I don't
think there should be any option to circumvent a group stop via ptrace.
If you think otherwise, you have a hard road to convince me of it.
It was always the intent that traced tasks should participate in the
group stop bookkeeping. I suspect the better line of fixes will be just
to tie up the loose ends of the ptrace interactions so that all ptrace
stops do the correct group_stop_count bookkeeping and notifications. If
there is a group stop in progress but not yet complete, then PTRACE_CONT
on a thread in the group should probably just move it from TASK_TRACED
to TASK_STOPPED without resuming it at all.
Once a group stop is complete, then probably the ideal is that
PTRACE_CONT would not resume a thread until a real SIGCONT cleared the
job control stop condition. But it's likely that existing ptrace users
have expectations contrary to that, so we'll have to see.
Thanks,
Roland
next prev parent reply other threads:[~2011-01-28 21:30 UTC|newest]
Thread overview: 161+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-28 15:08 [PATCHSET] ptrace,signal: group stop / ptrace updates Tejun Heo
2011-01-28 15:08 ` [PATCH 01/10] signal: fix SIGCONT notification code Tejun Heo
2011-01-28 15:08 ` [PATCH 02/10] ptrace: remove the extra wake_up_process() from ptrace_detach() Tejun Heo
2011-01-28 18:46 ` Roland McGrath
2011-01-31 10:38 ` Tejun Heo
2011-02-01 10:26 ` [PATCH] ptrace: use safer wake up on ptrace_detach() Tejun Heo
2011-02-01 13:40 ` Oleg Nesterov
2011-02-01 15:07 ` Tejun Heo
2011-02-01 19:17 ` Oleg Nesterov
2011-02-02 5:31 ` Roland McGrath
2011-02-02 10:35 ` Tejun Heo
2011-02-02 0:27 ` Andrew Morton
2011-02-02 5:33 ` Roland McGrath
2011-02-02 5:38 ` Andrew Morton
2011-02-02 10:34 ` Tejun Heo
2011-02-02 19:33 ` Andrew Morton
2011-02-02 20:01 ` Tejun Heo
2011-02-02 21:40 ` Oleg Nesterov
2011-02-02 5:29 ` Roland McGrath
2011-02-02 5:28 ` [PATCH 02/10] ptrace: remove the extra wake_up_process() from ptrace_detach() Roland McGrath
2011-01-28 15:08 ` [PATCH 03/10] signal: remove superflous try_to_freeze() loop in do_signal_stop() Tejun Heo
2011-01-28 18:46 ` Roland McGrath
2011-01-28 15:08 ` [PATCH 04/10] ptrace: kill tracehook_notify_jctl() Tejun Heo
2011-01-28 21:09 ` Roland McGrath
2011-01-28 15:08 ` [PATCH 05/10] ptrace: add @why to ptrace_stop() Tejun Heo
2011-01-28 18:48 ` Roland McGrath
2011-01-28 15:08 ` [PATCH 06/10] signal: fix premature completion of group stop when interfered by ptrace Tejun Heo
2011-01-28 21:22 ` Roland McGrath
2011-01-31 11:00 ` Tejun Heo
2011-02-02 5:44 ` Roland McGrath
2011-02-02 10:56 ` Tejun Heo
2011-01-28 15:08 ` [PATCH 07/10] signal: use GROUP_STOP_PENDING to stop once for a single group stop Tejun Heo
2011-01-28 15:08 ` [PATCH 08/10] ptrace: participate in group stop from ptrace_stop() iff the task is trapping for " Tejun Heo
2011-01-28 21:30 ` Roland McGrath [this message]
2011-01-31 11:26 ` Tejun Heo
2011-02-02 5:57 ` Roland McGrath
2011-02-02 10:53 ` Tejun Heo
2011-02-03 10:02 ` Tejun Heo
2011-02-01 19:36 ` Oleg Nesterov
2011-01-28 15:08 ` [PATCH 09/10] ptrace: make do_signal_stop() use ptrace_stop() if the task is being ptraced Tejun Heo
2011-01-28 15:08 ` [PATCH 10/10] ptrace: clean transitions between TASK_STOPPED and TRACED Tejun Heo
2011-02-03 20:41 ` [PATCH 0/1] (Was: ptrace: clean transitions between TASK_STOPPED and TRACED) Oleg Nesterov
2011-02-03 20:41 ` [PATCH 1/1] ptrace: make sure do_wait() won't hang after PTRACE_ATTACH Oleg Nesterov
2011-02-03 21:36 ` Roland McGrath
2011-02-03 21:44 ` Oleg Nesterov
2011-02-04 10:53 ` Tejun Heo
2011-02-04 13:04 ` Oleg Nesterov
2011-02-04 14:48 ` Tejun Heo
2011-02-04 17:06 ` Oleg Nesterov
2011-02-05 13:39 ` Tejun Heo
2011-02-07 13:42 ` Oleg Nesterov
2011-02-07 14:11 ` Tejun Heo
2011-02-07 15:37 ` Oleg Nesterov
2011-02-07 16:31 ` Tejun Heo
2011-02-07 17:48 ` Oleg Nesterov
2011-02-09 14:18 ` Tejun Heo
2011-02-09 14:21 ` Tejun Heo
2011-02-09 21:25 ` Oleg Nesterov
2011-02-13 23:01 ` Denys Vlasenko
2011-02-14 9:03 ` Jan Kratochvil
2011-02-14 11:39 ` Denys Vlasenko
2011-02-14 17:32 ` Oleg Nesterov
2011-02-14 16:01 ` Oleg Nesterov
2011-02-26 3:59 ` Pavel Machek
2011-02-14 15:51 ` Oleg Nesterov
2011-02-14 14:50 ` Tejun Heo
2011-02-14 18:53 ` Oleg Nesterov
2011-02-13 22:25 ` Denys Vlasenko
2011-02-14 15:13 ` Tejun Heo
2011-02-14 16:15 ` Oleg Nesterov
2011-02-14 16:33 ` Tejun Heo
2011-02-14 17:23 ` Oleg Nesterov
2011-02-14 17:20 ` Denys Vlasenko
2011-02-14 17:30 ` Tejun Heo
2011-02-14 17:45 ` Oleg Nesterov
2011-02-14 17:54 ` Denys Vlasenko
2011-02-21 15:16 ` Tejun Heo
2011-02-21 15:28 ` Oleg Nesterov
2011-02-21 16:11 ` [pseudo patch] ptrace should respect the group stop Oleg Nesterov
2011-02-22 16:24 ` [PATCH 1/1] ptrace: make sure do_wait() won't hang after PTRACE_ATTACH Tejun Heo
2011-02-24 21:08 ` Oleg Nesterov
2011-02-25 15:45 ` Tejun Heo
2011-02-25 17:42 ` Roland McGrath
2011-02-28 15:23 ` Oleg Nesterov
2011-02-14 17:51 ` Oleg Nesterov
2011-02-14 18:55 ` Denys Vlasenko
2011-02-14 19:01 ` Oleg Nesterov
2011-02-14 19:42 ` Denys Vlasenko
2011-02-14 20:01 ` Oleg Nesterov
2011-02-15 15:24 ` Tejun Heo
2011-02-15 15:58 ` Oleg Nesterov
2011-02-15 17:31 ` Roland McGrath
2011-02-15 20:27 ` Oleg Nesterov
2011-02-18 17:02 ` Tejun Heo
2011-02-18 19:37 ` Oleg Nesterov
2011-02-21 16:22 ` Tejun Heo
2011-02-21 16:49 ` Oleg Nesterov
2011-02-21 16:59 ` Tejun Heo
2011-02-23 19:31 ` Oleg Nesterov
2011-02-25 15:10 ` Tejun Heo
2011-02-24 20:29 ` Oleg Nesterov
2011-02-25 15:51 ` Tejun Heo
2011-02-26 2:48 ` Denys Vlasenko
2011-02-28 12:56 ` Tejun Heo
2011-02-28 13:16 ` Denys Vlasenko
2011-02-28 13:29 ` Tejun Heo
2011-02-28 13:41 ` Denys Vlasenko
2011-02-28 13:53 ` Tejun Heo
2011-02-28 14:25 ` Denys Vlasenko
2011-02-28 14:39 ` Tejun Heo
2011-02-28 16:48 ` Oleg Nesterov
2011-02-28 14:36 ` Oleg Nesterov
2011-02-16 21:51 ` Jan Kratochvil
2011-02-17 3:37 ` Denys Vlasenko
2011-02-17 19:19 ` Oleg Nesterov
2011-02-18 21:11 ` Jan Kratochvil
2011-02-19 20:16 ` Oleg Nesterov
2011-02-17 16:49 ` Oleg Nesterov
2011-02-17 18:58 ` Roland McGrath
2011-02-17 19:33 ` Oleg Nesterov
2011-02-18 21:34 ` Jan Kratochvil
2011-02-19 20:06 ` Oleg Nesterov
2011-02-20 9:40 ` Jan Kratochvil
2011-02-20 17:06 ` Denys Vlasenko
2011-02-20 17:48 ` Oleg Nesterov
2011-02-20 19:10 ` Jan Kratochvil
2011-02-20 19:16 ` Oleg Nesterov
2011-02-20 17:16 ` Oleg Nesterov
2011-02-20 18:52 ` Jan Kratochvil
2011-02-20 20:38 ` Oleg Nesterov
2011-02-20 21:06 ` `(T) stopped' preservation after _exit() [Re: [PATCH 1/1] ptrace: make sure do_wait() won't hang after PTRACE_ATTACH] Jan Kratochvil
2011-02-20 21:19 ` Oleg Nesterov
2011-02-20 21:20 ` [PATCH 1/1] ptrace: make sure do_wait() won't hang after PTRACE_ATTACH Jan Kratochvil
2011-02-21 14:23 ` Oleg Nesterov
2011-02-23 16:44 ` Jan Kratochvil
2011-02-14 15:31 ` Oleg Nesterov
2011-02-14 17:24 ` Denys Vlasenko
2011-02-14 17:39 ` Oleg Nesterov
2011-02-14 17:57 ` Denys Vlasenko
2011-02-14 18:00 ` Oleg Nesterov
2011-02-14 18:06 ` Oleg Nesterov
2011-02-14 18:59 ` Denys Vlasenko
2011-02-13 21:24 ` Denys Vlasenko
2011-02-14 15:06 ` Oleg Nesterov
2011-02-14 15:19 ` Tejun Heo
2011-02-14 16:20 ` Oleg Nesterov
2011-02-14 17:05 ` Denys Vlasenko
2011-02-14 17:18 ` Oleg Nesterov
2011-01-28 16:54 ` [PATCHSET] ptrace,signal: group stop / ptrace updates Ingo Molnar
2011-01-28 17:41 ` Thomas Gleixner
2011-01-28 18:04 ` Anca Emanuel
2011-01-28 18:36 ` Mathieu Desnoyers
2011-01-28 17:55 ` Oleg Nesterov
2011-01-28 18:29 ` Bash not reacting to Ctrl-C Ingo Molnar
2011-02-05 20:34 ` Oleg Nesterov
2011-02-07 13:08 ` Oleg Nesterov
2011-02-09 6:17 ` Michael Witten
2011-02-09 14:53 ` Ingo Molnar
2011-02-09 19:37 ` Michael Witten
2011-02-11 14:41 ` Pavel Machek
2011-03-05 10:36 [PATCHSET] ptrace,signal: group stop / ptrace updates, take#2 Tejun Heo
2011-03-05 10:37 ` [PATCH 08/10] ptrace: participate in group stop from ptrace_stop() iff the task is trapping for group stop Tejun Heo
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