From: Roland McGrath <roland@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>,
jan.kratochvil@redhat.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org
Subject: Re: [PATCH 1/1] ptrace: make sure do_wait() won't hang after PTRACE_ATTACH
Date: Thu, 3 Feb 2011 13:36:39 -0800 (PST) [thread overview]
Message-ID: <20110203213640.1F516180995@magilla.sf.frob.com> (raw)
In-Reply-To: Oleg Nesterov's message of Thursday, 3 February 2011 21:41:54 +0100 <20110203204154.GB26371@redhat.com>
IMHO this sort of band-aid does not really help the overall situation.
It takes something that is intricate and fiddly and just fiddles it a
bit more. Userland will still have to handle older kernels where this
behavior is not there. If userland does anything that relies on this
new behavior, then it will have to try somehow to figure out which
kernel versions have which behavior and adapt, etc.
When the old behaviors are unhelpful like this, I think it is really
better to add new mechanisms instead. We can make new mechanisms more
clear and straightforward for userland to work with from the beginning.
Then the compatibility picture for userland is simply to try a new call
or new ptrace request or new option bit or whatever it is. When the
kernel supports the new thing, things are easy. When it doesn't, then
they cope with life as they have been coping before on old kernels.
I have some ideas about new things to add for this problem area. But
we have to think those through carefully and discuss all the details
thoroughly with Jan and other folks working on userland debuggers
before we write the kernel side.
Thanks,
Roland
next prev parent reply other threads:[~2011-02-03 21:36 UTC|newest]
Thread overview: 160+ 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
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 [this message]
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
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