From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: roland@redhat.com, jan.kratochvil@redhat.com,
vda.linux@googlemail.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
indan@nul.nu
Subject: Re: [PATCH 0.2/8] ptrace: Always put ptracee into appropriate execution state
Date: Tue, 22 Mar 2011 21:33:22 +0100 [thread overview]
Message-ID: <20110322203322.GD28038@redhat.com> (raw)
In-Reply-To: <20110322102046.GO12003@htj.dyndns.org>
On 03/22, Tejun Heo wrote:
>
> This patch updates __ptrace_unlink() such that GROUP_STOP_PENDING is
> reinstated regardless of the ptracee's current state as long as it's
> alive and makes sure that signal_wake_up() is called if execution
> state transition is necessary.
Looks correct (and the previous one too).
But I don't understand the PF_EXITING check,
> + /*
> + * Reinstate GROUP_STOP_PENDING if group stop is in effect and
> + * @child isn't dead.
> + */
> + if (!(child->flags & PF_EXITING) &&
> + (child->signal->flags & SIGNAL_STOP_STOPPED ||
> + child->signal->group_stop_count))
> + child->group_stop |= GROUP_STOP_PENDING;
Why do we need to filter out PF_EXITING tasks? This doesn't look
strictly necessary. And note that exit_signals() doesn't always
take ->siglock, we can race anyway.
> + * Note that @resume should be used iff @child
> + * is in TASK_TRACED; otherwise, we might unduly disrupt
> + * TASK_KILLABLE sleeps.
Yes. but, just in case,
> + */
> + if (child->group_stop & GROUP_STOP_PENDING || task_is_traced(child))
> + signal_wake_up(child, task_is_traced(child));
signal_wake_up() is not needed if task_is_traced(). Even if we added
GROUP_STOP_PENDING, ptrace_stop() does recalc_sigpending_tsk() anyway
before return.
So we could do
if (SIGNAL_STOP_STOPPED || group_stop_count) {
child->group_stop |= GROUP_STOP_PENDING;
signal_wake_up(child, 0);
}
if (task_is_traced(child))
wake_up_state(TASK_TRACED);
But probably a single wakeup looks more simple/clean, so I agree.
Oleg.
next prev parent reply other threads:[~2011-03-22 20:42 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-08 19:56 [RFC PATCHSET] ptrace,signal: Fix notifications to the real parent while ptraced Tejun Heo
2011-03-08 19:56 ` [PATCH 1/8] job control: Don't set group_stop exit_code if re-entering job control stop Tejun Heo
2011-03-21 13:20 ` Oleg Nesterov
2011-03-21 15:52 ` Tejun Heo
2011-03-22 18:44 ` Oleg Nesterov
2011-03-23 8:44 ` Tejun Heo
2011-03-23 16:40 ` Oleg Nesterov
2011-03-23 17:02 ` Tejun Heo
2011-03-23 17:09 ` Oleg Nesterov
2011-03-23 17:22 ` Tejun Heo
2011-03-08 19:56 ` [PATCH 2/8] job control: Small reorganization of wait_consider_task() Tejun Heo
2011-03-08 19:56 ` [PATCH 3/8] job control: Fix ptracer wait(2) hang and explain notask_error clearing Tejun Heo
2011-03-21 15:19 ` Oleg Nesterov
2011-03-21 16:09 ` Oleg Nesterov
2011-03-21 16:12 ` Tejun Heo
2011-03-22 19:08 ` Oleg Nesterov
2011-03-22 10:51 ` [PATCH UPDATED " Tejun Heo
2011-03-08 19:56 ` [PATCH 4/8] job control: Allow access to job control events through ptracees Tejun Heo
2011-03-21 16:39 ` Oleg Nesterov
2011-03-21 17:20 ` Tejun Heo
2011-03-22 11:10 ` [PATCH UPDATED " Tejun Heo
2011-03-08 19:56 ` [PATCH 5/8] job control: Add @for_ptrace to do_notify_parent_cldstop() Tejun Heo
2011-03-08 19:56 ` [PATCH 6/8] job control: Job control stop notifications should always go to the real parent Tejun Heo
2011-03-21 17:12 ` Oleg Nesterov
2011-03-08 19:56 ` [PATCH 7/8] job control: Notify the real parent of job control events regardless of ptrace Tejun Heo
2011-03-21 17:43 ` Oleg Nesterov
2011-03-22 8:04 ` Tejun Heo
2011-03-22 19:44 ` Oleg Nesterov
2011-03-23 9:17 ` Tejun Heo
2011-03-23 9:24 ` Tejun Heo
2011-03-23 16:46 ` Oleg Nesterov
2011-03-23 16:59 ` Tejun Heo
2011-03-23 17:07 ` Oleg Nesterov
2011-03-23 17:20 ` Tejun Heo
2011-03-23 17:17 ` Oleg Nesterov
2011-03-22 11:30 ` [PATCH UPDATED " Tejun Heo
2011-03-08 19:56 ` [PATCH 8/8] job control: Don't send duplicate job control stop notification while ptraced Tejun Heo
2011-03-21 17:48 ` Oleg Nesterov
2011-03-08 20:01 ` [RFC PATCHSET] ptrace,signal: Fix notifications to the real parent " Linus Torvalds
2011-03-09 16:50 ` Oleg Nesterov
2011-03-22 10:20 ` [PATCH 0.1/8] ptrace: Collapse ptrace_untrace() into __ptrace_unlink() Tejun Heo
2011-03-22 10:20 ` [PATCH 0.2/8] ptrace: Always put ptracee into appropriate execution state Tejun Heo
2011-03-22 20:33 ` Oleg Nesterov [this message]
2011-03-23 8:00 ` Tejun Heo
2011-03-22 13:11 ` [RFC PATCHSET] ptrace,signal: Fix notifications to the real parent while ptraced Tejun Heo
2011-03-22 20:59 ` Oleg Nesterov
2011-03-23 8:48 ` Tejun Heo
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