From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Pavel Emelyanov <xemul@parallels.com>,
Serge Hallyn <serge.hallyn@canonical.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Tejun Heo <tj@kernel.org>, Andrew Vagin <avagin@openvz.org>,
Vasiliy Kulikov <segoon@openwall.com>
Subject: Re: [RFC] fs, proc: Introduce /proc/<pid>/task/<tid>/children entry v6
Date: Mon, 16 Jan 2012 20:20:21 +0400 [thread overview]
Message-ID: <20120116162021.GH2998@moon> (raw)
In-Reply-To: <20120116161114.GA17727@redhat.com>
On Mon, Jan 16, 2012 at 05:11:14PM +0100, Oleg Nesterov wrote:
> On 01/16, Cyrill Gorcunov wrote:
> >
> > +get_children_pid(struct proc_pid_children_iter *iter, struct pid *pid_prev, loff_t pos)
> > +{
> > + struct task_struct *start, *task;
> > + struct pid *pid = NULL;
> > +
> > + read_lock(&tasklist_lock);
> > +
> > + start = pid_task(iter->pid_start, PIDTYPE_PID);
> > + if (!start)
> > + goto out;
> > +
> > + /*
> > + * Lets try to continue searching first, this gives
> > + * us significant speedup on children-rich processes.
> > + */
> > + if (pid_prev) {
> > + task = pid_task(pid_prev, PIDTYPE_PID);
> > + if (task && task->real_parent == start &&
> > + !(list_empty(&task->sibling))) {
>
> Damn. No, this is wrong.
>
> Damn! Yes, it was we who told you to check list_empty(sibling) ;)
>
> But this is not enough. exit_ptrace() can do list_move() without
> changing ->real_parent.
>
> I'll try to think. At first glance we can rely on EXIT_DEAD, but
> I'd like to avoid this, I think EXIT_DEAD should die.
>
Ouch! Thanks for catching this Oleg. I'll try to come with something
to show as well.
Cyrill
next prev parent reply other threads:[~2012-01-16 16:20 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-16 15:32 [RFC] fs, proc: Introduce /proc/<pid>/task/<tid>/children entry v6 Cyrill Gorcunov
2012-01-16 16:11 ` Oleg Nesterov
2012-01-16 16:20 ` Cyrill Gorcunov [this message]
2012-01-17 17:40 ` Oleg Nesterov
2012-01-17 17:57 ` Cyrill Gorcunov
2012-01-17 18:14 ` Oleg Nesterov
2012-01-17 18:30 ` Cyrill Gorcunov
2012-01-17 21:38 ` KOSAKI Motohiro
2012-01-18 9:43 ` Cyrill Gorcunov
2012-01-18 13:58 ` Oleg Nesterov
2012-01-18 14:21 ` Cyrill Gorcunov
2012-01-18 14:36 ` Oleg Nesterov
2012-01-18 18:23 ` Cyrill Gorcunov
2012-01-18 19:07 ` Cyrill Gorcunov
2012-01-19 14:10 ` Oleg Nesterov
2012-01-19 14:47 ` Cyrill Gorcunov
2012-01-19 15:55 ` Oleg Nesterov
2012-01-19 16:27 ` Cyrill Gorcunov
2012-01-19 16:44 ` Oleg Nesterov
2012-01-19 17:07 ` Cyrill Gorcunov
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