Re: [PATCH 7/7] pid: get pid_t ppid of task in init_pid_ns

[Oleg Nesterov <oleg@redhat.com>]

On 01/23, Richard Guy Briggs wrote:
>
> Added the functions task_ppid_nr_ns() and task_ppid_nr() to abstract the lookup
> of the PPID (real_parent's pid_t) of a process, including rcu locking, in the
> arbitrary and init_pid_ns.
> This provides an alternative to sys_getppid(), which is relative to the child
> process' pid namespace.

I agree, this makes sense.


imho it would be better to send this patch along with sys_getppid()
conversions, but I won't argue.

> +static int pid_alive(const struct task_struct *p);
> +static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct pid_namespace *ns)
> +{
> +	pid_t pid = 0;
> +
> +	rcu_read_lock();
> +	if (pid_alive(tsk))
> +		pid = task_tgid_nr_ns(rcu_dereference(tsk->real_parent), ns);
> +	rcu_read_unlock();
> +
> +	return pid;
> +}

Perhaps it should be named task_ptgid_nr_ns() or even parent_tgid_nr_ns().
Since it returns tgid, not pid (== tid).

But this is cosmetic, I won't insist.

Oleg.