From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 760B6C2D0DB for ; Mon, 20 Jan 2020 14:42:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49D982253D for ; Mon, 20 Jan 2020 14:42:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DgjA4IL3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729225AbgATOmy (ORCPT ); Mon, 20 Jan 2020 09:42:54 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:36406 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726860AbgATOmx (ORCPT ); Mon, 20 Jan 2020 09:42:53 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579531373; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=BQYougp4+VHH4evwtllbxoi9axAUvWpVMA1ll1rXksg=; b=DgjA4IL3mTHXE0odCXNx/qcOmrNjBYdU5va5IShreWXJdwB20VTGRBTo0UtHs62dHaGHNy mBe/+Vk6Gnlsjd5IbOkUnKLB8V4By316s+T6FrtD3qxpN5Kw7CvbvThAU2tp6vZfl8A2Mz vlp/tG5ymaKrZr0IH5iIGlCR1jw0aAA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-377-akDV5IjlMuqHo6s4pqNGKg-1; Mon, 20 Jan 2020 09:42:49 -0500 X-MC-Unique: akDV5IjlMuqHo6s4pqNGKg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AEC7A107ACC9; Mon, 20 Jan 2020 14:42:47 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.70]) by smtp.corp.redhat.com (Postfix) with SMTP id D980C7C34A; Mon, 20 Jan 2020 14:42:45 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 20 Jan 2020 15:42:47 +0100 (CET) Date: Mon, 20 Jan 2020 15:42:45 +0100 From: Oleg Nesterov To: Christian Brauner Cc: linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo , Li Zefan , Johannes Weiner , cgroups@vger.kernel.org Subject: Re: [PATCH v4 1/6] cgroup: unify attach permission checking Message-ID: <20200120144244.GD30403@redhat.com> References: <20200117181219.14542-1-christian.brauner@ubuntu.com> <20200117181219.14542-2-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200117181219.14542-2-christian.brauner@ubuntu.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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.