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

[Oleg Nesterov]

On 08/14, christian.brau...@ubuntu.com 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.