From: Tejun Heo <tj@kernel.org>
To: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: oleg@redhat.com, vda.linux@googlemail.com,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
akpm@linux-foundation.org, indan@nul.nu
Subject: Re: PTRACE_SEIZE should not stop [Re: [PATCH 02/11] ptrace: implement PTRACE_SEIZE]
Date: Mon, 16 May 2011 15:45:10 +0200 [thread overview]
Message-ID: <20110516134510.GA23665@htj.dyndns.org> (raw)
In-Reply-To: <20110516132123.GA13544@host1.jankratochvil.net>
Hello, Jan.
On Mon, May 16, 2011 at 03:21:23PM +0200, Jan Kratochvil wrote:
> Currently that waitpid will report SIGUSR1 first and then the INTERRUPT trap.
Yes, it would.
> I suggest - if possible - that tracer will get that INTERRUPT trap first.
>
> But you made the optimization that the INTERRUPT gets suppressed in such case.
> Which improves performance for the cost of more complicated debuggers.
INTERRUPT is suppressed if group stop is pending not signal. That was
more about duplicity between INTERRUPT trap and group stop, which made
the whole thing uglier. I merged the two together so there's no such
distinction anymore.
> I guess after PTRACE_SEIZE if the first signal/event is not INTERRUPT there
> will not be any INTERRUPT later, as you said.
I replied in another message too but now SEIZE and INTERRUPT behave
identically. Any trap clears the condition.
I don't think INTERRUPT can be prioritized like that above existing
trap conditions. Traps are taken sometimes deep in the kernel
(e.g. fork/exec) and often after modifying states irrevocably
(e.g. signal is already dequeued on signal trap). I don't think how
it would be possible to rewind the state changes and replay it later.
FWIW, if INTERRUPT exists while signal is pending, INTERRUPT will be
taken first but that doesn't mean all that much as we can't roll back
from traps which already have happened and tracee might be in any trap
by the time PTRACE_INTERRUPT is issued.
Thank you.
--
tejun
next prev parent reply other threads:[~2011-05-16 13:45 UTC|newest]
Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-08 15:48 [PATCHSET ptrace] ptrace: implement PTRACE_SEIZE/INTERRUPT and group stop notification Tejun Heo
2011-05-08 15:48 ` [PATCH 01/11] job control: rename signal->group_stop and flags to jobctl and rearrange flags Tejun Heo
2011-05-08 15:48 ` [PATCH 02/11] ptrace: implement PTRACE_SEIZE Tejun Heo
2011-05-09 16:18 ` Oleg Nesterov
2011-05-10 9:46 ` Tejun Heo
2011-05-10 13:20 ` Oleg Nesterov
2011-05-10 13:47 ` Tejun Heo
2011-05-10 18:19 ` Oleg Nesterov
2011-05-15 15:56 ` PTRACE_SEIZE should not stop [Re: [PATCH 02/11] ptrace: implement PTRACE_SEIZE] Jan Kratochvil
2011-05-15 16:26 ` Tejun Heo
2011-05-15 17:15 ` Jan Kratochvil
2011-05-15 17:25 ` Tejun Heo
2011-05-15 19:48 ` Jan Kratochvil
2011-05-16 8:31 ` Tejun Heo
2011-05-16 12:26 ` Jan Kratochvil
2011-05-16 12:42 ` Tejun Heo
2011-05-16 13:03 ` Jan Kratochvil
2011-05-16 13:51 ` Tejun Heo
2011-05-16 13:21 ` Jan Kratochvil
2011-05-16 13:45 ` Tejun Heo [this message]
2011-05-16 13:48 ` Jan Kratochvil
2011-05-16 13:54 ` Tejun Heo
2011-05-08 15:48 ` [PATCH 03/11] ptrace: ptrace_check_attach(): rename @kill to @ignore_state and add comments Tejun Heo
2011-05-08 15:48 ` [PATCH 04/11] ptrace: implement PTRACE_INTERRUPT Tejun Heo
2011-05-08 21:58 ` Denys Vlasenko
2011-05-09 10:09 ` Tejun Heo
2011-05-09 10:55 ` Denys Vlasenko
2011-05-09 16:58 ` Oleg Nesterov
2011-05-10 9:50 ` Tejun Heo
2011-05-10 14:06 ` Oleg Nesterov
2011-05-10 14:20 ` Tejun Heo
2011-05-10 18:08 ` Oleg Nesterov
2011-05-11 8:29 ` Tejun Heo
2011-05-12 17:06 ` Oleg Nesterov
2011-05-12 17:21 ` Tejun Heo
2011-05-10 21:59 ` Denys Vlasenko
2011-05-11 9:19 ` Tejun Heo
2011-05-11 12:23 ` Denys Vlasenko
2011-05-11 13:22 ` Tejun Heo
2011-05-11 16:20 ` Bryan Donlan
2011-05-11 19:24 ` Tejun Heo
2011-05-15 16:10 ` PTRACE_DETACH without stop [Re: [PATCH 04/11] ptrace: implement PTRACE_INTERRUPT] Jan Kratochvil
2011-05-15 16:35 ` Tejun Heo
2011-05-15 17:39 ` Jan Kratochvil
2011-05-16 9:01 ` Tejun Heo
2011-05-16 12:08 ` Jan Kratochvil
2011-05-16 12:24 ` Tejun Heo
2011-05-08 15:48 ` [PATCH 05/11] ptrace: restructure ptrace_getsiginfo() Tejun Heo
2011-05-08 15:49 ` [PATCH 06/11] ptrace: make group stop state visible via PTRACE_GETSIGINFO Tejun Heo
2011-05-10 16:55 ` Oleg Nesterov
2011-05-10 17:11 ` Oleg Nesterov
2011-05-11 8:08 ` Tejun Heo
2011-05-12 16:47 ` Oleg Nesterov
2011-05-12 17:15 ` Tejun Heo
2011-05-08 15:49 ` [PATCH 07/11] ptrace: add JOBCTL_TRAPPED Tejun Heo
2011-05-08 15:49 ` [PATCH 08/11] ptrace: move fallback JOBCTL_TRAPPING clearing to get_signal_to_deliver() Tejun Heo
2011-05-11 15:48 ` Oleg Nesterov
2011-05-11 19:17 ` Tejun Heo
2011-05-12 15:40 ` Oleg Nesterov
2011-05-08 15:49 ` [PATCH 09/11] job control: reorganize wait_task_stopped() Tejun Heo
2011-05-11 15:48 ` Oleg Nesterov
2011-05-11 19:29 ` Tejun Heo
2011-05-12 15:42 ` Oleg Nesterov
2011-05-12 16:02 ` Tejun Heo
2011-05-12 17:25 ` Oleg Nesterov
2011-05-12 17:32 ` Tejun Heo
2011-05-12 17:33 ` Tejun Heo
2011-05-12 18:33 ` Oleg Nesterov
2011-05-13 8:46 ` Tejun Heo
2011-05-13 17:21 ` Oleg Nesterov
2011-05-14 10:56 ` Tejun Heo
2011-05-15 14:40 ` waitpid(WNOHANG) should report SIGCHLD-notified signals [Re: [PATCH 09/11] job control: reorganize wait_task_stopped()] Jan Kratochvil
2011-05-15 16:47 ` Tejun Heo
2011-05-15 17:01 ` Tejun Heo
2011-05-15 17:47 ` Jan Kratochvil
2011-05-16 9:13 ` Tejun Heo
2011-05-16 12:11 ` Jan Kratochvil
2011-05-16 12:27 ` Tejun Heo
2011-05-16 12:39 ` Jan Kratochvil
2011-05-16 12:46 ` Tejun Heo
2011-05-08 15:49 ` [PATCH 10/11] ptrace: move JOBCTL_TRAPPING wait to wait(2) and ptrace_check_attach() Tejun Heo
2011-05-11 16:49 ` Oleg Nesterov
2011-05-11 17:00 ` Oleg Nesterov
2011-05-11 19:45 ` Tejun Heo
2011-05-11 19:53 ` Tejun Heo
2011-05-12 10:23 ` Tejun Heo
2011-05-12 16:06 ` Oleg Nesterov
2011-05-12 15:59 ` Oleg Nesterov
2011-05-12 16:07 ` Tejun Heo
2011-05-12 18:20 ` Oleg Nesterov
2011-05-13 9:13 ` Tejun Heo
2011-05-13 18:34 ` Oleg Nesterov
2011-05-08 15:49 ` [PATCH 11/11] ptrace: implement group stop notification for ptracer Tejun Heo
2011-05-08 22:42 ` Denys Vlasenko
2011-05-09 10:10 ` Tejun Heo
2011-05-10 22:37 ` Denys Vlasenko
2011-05-11 9:05 ` Tejun Heo
2011-05-11 12:01 ` Denys Vlasenko
2011-05-11 13:13 ` Tejun Heo
2011-05-11 19:58 ` Oleg Nesterov
2011-05-11 20:18 ` Tejun Heo
2011-05-11 20:21 ` Tejun Heo
2011-05-12 10:24 ` Tejun Heo
2011-05-15 14:02 ` getter PTRACE_GETSIGINFO should not modify anything [Re: [PATCH 11/11] ptrace: implement group stop notification for ptracer] Jan Kratochvil
2011-05-15 14:28 ` Tejun Heo
2011-05-15 17:17 ` Jan Kratochvil
2011-05-15 17:28 ` Tejun Heo
2011-05-15 20:06 ` Jan Kratochvil
2011-05-16 8:43 ` Tejun Heo
2011-05-16 12:17 ` Jan Kratochvil
2011-05-16 12:56 ` Tejun Heo
2011-05-16 13:00 ` Ingo Molnar
2011-05-08 22:27 ` [PATCHSET ptrace] ptrace: implement PTRACE_SEIZE/INTERRUPT and group stop notification Denys Vlasenko
2011-05-09 9:48 ` Tejun Heo
2011-05-15 13:55 ` ptrace-testsuite status [Re: [PATCHSET ptrace] ptrace: implement PTRACE_SEIZE/INTERRUPT and group stop notification] Jan Kratochvil
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