From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: roland@redhat.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
"rjw@sisk.plpavel"@ucw.cz,
Jan Kratochvil <jan.kratochvil@redhat.com>
Subject: Re: [PATCH 08/14] ptrace: make do_signal_stop() use ptrace_stop() if the task is being ptraced
Date: Sun, 28 Nov 2010 20:54:42 +0100 [thread overview]
Message-ID: <20101128195442.GB12896@redhat.com> (raw)
In-Reply-To: <1290768569-16224-9-git-send-email-tj@kernel.org>
On 11/26, Tejun Heo wrote:
>
> A ptraced task would still stop at do_signal_stop() when it's stopping
> for stop signals and do_signal_stop() behaves the same whether the
> task is ptraced or not. However, in addition to stopping,
> ptrace_stop() also does ptrace specific stuff like calling
> architecture specific callbacks, so this behavior makes the code more
> fragile and difficult to understand.
OK. This patch adds the obviously user-visible change. It looks
very minor, but I never know when it comes to ptrace.
To simplify, suppose that we have a single-thread tracee, and
debugger "acks" SIGSTOP, say, it does ptrace(PTRACE_CONT, SIGSTOP).
Before this patch, the tracee stops in TASK_STOPPED, now it calls
ptrace_stop() and goes to TASK_TRACED state.
Add Jan. I hope this is OK, but this might break the tracer if
it looks into fs/proc (probably only test-cases do this).
At least, with or without this patch ->last_siginfo is NULL, good.
The check in do_signal_stop() looks racy though, see the next
email.
Oleg.
next prev parent reply other threads:[~2010-11-28 20:01 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-26 10:49 [PATCHSET RFC] ptrace,signal: sane interaction between ptrace and job control signals Tejun Heo
2010-11-26 10:49 ` [PATCH 01/14] signal: fix SIGCONT notification code Tejun Heo
2010-11-26 13:49 ` Oleg Nesterov
2010-12-01 1:43 ` Roland McGrath
2010-11-26 10:49 ` [PATCH 02/14] freezer: fix a race during freezing of TASK_STOPPED tasks Tejun Heo
2010-11-26 19:40 ` Rafael J. Wysocki
2010-11-26 19:59 ` Tejun Heo
2010-11-26 10:49 ` [PATCH 03/14] freezer: remove superflous try_to_freeze() loop in do_signal_stop() Tejun Heo
2010-11-26 19:42 ` Rafael J. Wysocki
2010-11-26 10:49 ` [PATCH 04/14] signal: don't notify parent if not stopping after tracehook_notify_jctl() " Tejun Heo
2010-11-26 14:46 ` Oleg Nesterov
2010-11-26 15:04 ` Tejun Heo
2010-11-26 10:49 ` [PATCH 05/14] signal: fix premature completion of group stop when interfered by ptrace Tejun Heo
2010-11-26 15:40 ` Oleg Nesterov
2010-11-26 16:03 ` Tejun Heo
2010-11-26 10:49 ` [PATCH 06/14] signal: use GROUP_STOP_PENDING to avoid stopping multiple times for a single group stop Tejun Heo
2010-11-26 17:59 ` Oleg Nesterov
2010-11-26 18:39 ` Tejun Heo
2010-11-27 11:40 ` [PATCH UPDATED " Tejun Heo
2010-11-28 19:07 ` Oleg Nesterov
2010-11-29 13:38 ` Tejun Heo
2010-11-26 10:49 ` [PATCH 07/14] ptrace: add @why to ptrace_stop() Tejun Heo
2010-11-26 10:49 ` [PATCH 08/14] ptrace: make do_signal_stop() use ptrace_stop() if the task is being ptraced Tejun Heo
2010-11-28 19:54 ` Oleg Nesterov [this message]
2010-11-28 20:22 ` Jan Kratochvil
2010-11-28 20:53 ` Oleg Nesterov
2010-11-26 10:49 ` [PATCH 09/14] ptrace: clean transitions between TASK_STOPPED and TRACED Tejun Heo
2010-11-28 20:25 ` Oleg Nesterov
2010-11-28 20:51 ` Jan Kratochvil
2010-11-29 13:48 ` Tejun Heo
2010-11-26 10:49 ` [PATCH 10/14] ptrace: don't consume group count from ptrace_stop() Tejun Heo
2010-11-26 10:49 ` [PATCH 11/14] ptrace: make group stop notification reliable against ptrace Tejun Heo
2010-11-28 20:30 ` Oleg Nesterov
2010-11-29 13:52 ` Tejun Heo
2010-11-26 10:49 ` [PATCH 12/14] ptrace: reorganize __ptrace_unlink() and ptrace_untrace() Tejun Heo
2010-11-26 10:49 ` [PATCH 13/14] ptrace: make SIGCONT notification reliable against ptrace Tejun Heo
2010-11-26 10:49 ` [PATCH 14/14] ptrace: remove the extra wake_up_process() from ptrace_detach() Tejun Heo
2010-11-28 20:44 ` Oleg Nesterov
2010-11-29 13:55 ` Tejun Heo
2010-11-26 10:55 ` [PATCHSET RFC] ptrace,signal: sane interaction between ptrace and job control signals Tejun Heo
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