Re: [PATCH v1 1/1] waitid: Add support for waiting for the current process group

[Oleg Nesterov]

On 08/14, christian.brauner@xxxxxxxxxx wrote:
>
>  	case P_PGID:
>  		type = PIDTYPE_PGID;
> -		if (upid <= 0)
> +		if (upid < 0)
>  			return -EINVAL;
> +
> +		if (upid == 0)
> +			pid = get_pid(task_pgrp(current));

this needs rcu lock or tasklist_lock, this can race with another thread
doing sys_setpgid/setsid (see change_pid(PIDTYPE_PGID)).

Oleg.