Re: [PATCH] Introduce ActivePid: in /proc/self/status (v2, wasVpid:)

[Oleg Nesterov]

On 06/15, Greg Kurz wrote:
>
> @@ -176,6 +177,17 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
>  		if (tracer)
>  			tpid = task_pid_nr_ns(tracer, ns);
>  	}
> +	actpid = 0;
> +	sighand = rcu_dereference(p->sighand);
> +	if (sighand) {
> +		struct pid_namespace *pid_ns;
> +		unsigned long flags;
> +		spin_lock_irqsave(&sighand->siglock, flags);

Well. This is not exactly right. We have lock_task_sighand() for this.

But. Why do you need ->siglock? Why rcu_read_lock() is not enough?

Hmm. You don't even need pid_ns afaics, you could simply look at
pid->numbers[pid->level].

Oleg.

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