[Devel] [PATCH rh7] ve: cgroups -- Allow to attach non-self into ve cgroups, v2

[Vladimir Davydov]

On Mon, May 18, 2015 at 03:52:35PM +0300, Cyrill Gorcunov wrote:
> --- linux-pcs7.git.orig/kernel/ve/ve.c
> +++ linux-pcs7.git/kernel/ve/ve.c
> @@ -750,24 +750,31 @@ static void ve_destroy(struct cgroup *cg
>  static int ve_can_attach(struct cgroup *cg, struct cgroup_taskset *tset)
>  {
>  	struct ve_struct *ve = cgroup_ve(cg);
> -	struct task_struct *task = current;
> -
> -	if (cgroup_taskset_size(tset) != 1 ||
> -	    cgroup_taskset_first(tset) != task ||
> -	    !thread_group_leader(task) ||
> -	    !thread_group_empty(task))
> -		return -EINVAL;
> +	struct task_struct *task;
>  
>  	if (ve->is_locked)
>  		return -EBUSY;
>  
>  	/*
> +	 * We either moving the whole group of threads,
> +	 * either a single thread process.
> +	 */
> +	if (cgroup_taskset_size(tset) == 1) {

!= ?

> +		task = cgroup_taskset_first(tset);
> +		if (!thread_group_leader(task) && !thread_group_empty(task))
> +			return -EINVAL;
> +	}
> +
> +	/*
>  	 * Forbid userspace tasks to enter during starting or stopping.
> -	 * Permit attaching kernel threads and init task for this containers.
> +	 * Permit attaching kernel threads for this containers.
>  	 */
> -	if (!ve->is_running && (ve->ve_ns || nr_threads_ve(ve)) &&
> -			!(task->flags & PF_KTHREAD))
> -		return -EPIPE;
> +	if (!ve->is_running && (ve->ve_ns || nr_threads_ve(ve))) {
> +		cgroup_taskset_for_each(task, cg, tset) {
> +			if (!(task->flags & PF_KTHREAD))
> +				return -EPIPE;
> +		}
> +	}
>  
>  	return 0;
>  }