Re: [PATCH 1/5] pid: get pid_t ppid of task in init_pid_ns

[Oleg Nesterov <oleg@redhat.com>]

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.