linux-kernel - Re: [PATCH 1/5] pid: get pid_t ppid of task in init_pid

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Message-ID: <20131230170431.GA2457@redhat.com>
Date:	Mon, 30 Dec 2013 18:04:31 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Richard Guy Briggs <rgb@...hat.com>
Cc:	linux-audit@...hat.com, linux-kernel@...r.kernel.org,
	Eric Paris <eparis@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>, stable@...r.kernel.org
Subject: Re: [PATCH 1/5] pid: get pid_t ppid of task in init_pid_ns

On 12/23, Richard Guy Briggs wrote:
>
> +static inline pid_t task_ppid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
> +{
> +	pid_t pid;
> +
> +	rcu_read_lock();
> +	pid = pid_alive(tsk) ?
> +		task_pid_nr_ns(rcu_dereference(tsk->real_parent), ns) : 0;
> +	rcu_read_unlock();
> +
> +	return pid;
> +}

I do not really mind, but perhaps

	pid_t pid = 0;

	rcu_read_lock();
	if (pid_alive(task))
		pid = task_pid_nr_ns(rcu_dereference(tsk->real_parent);
	rcu_read_unlock();

	return pid;

looks a bit cleaner.

> +static inline pid_t task_ppid_nr(struct task_struct *tsk)
> +{
> +	pid_t pid;
> +
> +	rcu_read_lock();
> +	pid = pid_alive(tsk) ?
> +		task_pid_nr(rcu_dereference(tsk->real_parent)) : 0;
> +	rcu_read_unlock();
> +
> +	return pid;
> +}

It could simply do

	return task_ppid_nr_ns(tsk, init_pid_ns);

but again, I won't argue.

Oleg.

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