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Date: Thu, 19 Jan 2012 15:10:51 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
        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
Message-ID: <20120119141051.GA9652@redhat.com>
References: <20120116153231.GF2998@moon> <4F15EA53.8030405@gmail.com> <20120118135809.GA10105@redhat.com> <20120118142156.GR1968@moon> <20120118143631.GA11776@redhat.com> <20120118182344.GD2889@moon> <20120118190725.GE2889@moon>
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On 01/18, Cyrill Gorcunov wrote:
>
> I suppose it might be something like below. I've updated comment and
> quoted your comment there just I wont forget this next time I'll be
> reading the source. Thanks!

I believe the patrch is correct.

But... Cyrill, I am wondering how much will you hate me if I make
yet another attempt to delay this patch.

> +static int children_seq_open(struct inode *inode, struct file *file)
> +{
> +	struct proc_pid_children_iter *iter = NULL;
> +	struct task_struct *task = NULL;
> +	int ret = 0;
> +
> +	task = get_proc_task(inode);
> +	if (!task) {
> +		ret = -ENOENT;
> +		goto err;
> +	}

For what??

> +	if (!ret) {
> +		struct seq_file *m = file->private_data;
> +		m->private = iter;
> +
> +		iter->pid_start = get_pid(task_pid(task));

This is what we need, right? So can't we remove this "task_struct *task"
and simply do

		iter->pid_start = get_ppid(proc_pid(inode));

?

And while this is absolutely cosmetic probably ->parent_pid is
a bit better name, but this is up to you.

Oleg.