Re: [PATCH v4 1/6] cgroup: unify attach permission checking

[Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

I guess I am totally confused, but...

On 01/17, Christian Brauner wrote:
>
> +static inline bool cgroup_same_domain(const struct cgroup *src_cgrp,
> +				      const struct cgroup *dst_cgrp)
> +{
> +	return src_cgrp->dom_cgrp == dst_cgrp->dom_cgrp;
> +}
> +
> +static int cgroup_attach_permissions(struct cgroup *src_cgrp,
> +				     struct cgroup *dst_cgrp,
> +				     struct super_block *sb, bool thread)
> +{
> +	int ret = 0;
> +
> +	ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp, sb);
> +	if (ret)
> +		return ret;
> +
> +	ret = cgroup_migrate_vet_dst(dst_cgrp);
> +	if (ret)
> +		return ret;
> +
> +	if (thread &&
> +	    !cgroup_same_domain(src_cgrp->dom_cgrp, dst_cgrp->dom_cgrp))
                                        ^^^^^^^^^^          ^^^^^^^^^^

             cgroup_same_domain(src_cgrp, dst_cgrp)

no?

And given that cgroup_same_domain() has no other users, perhaps it can
simply check

	     src_cgrp->dom_cgrp != dst_cgrp->dom_cgrp

?

Oleg.