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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 8509FC10F0E for ; Thu, 18 Apr 2019 13:12:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60FE3208E4 for ; Thu, 18 Apr 2019 13:12:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389028AbfDRNMU (ORCPT ); Thu, 18 Apr 2019 09:12:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39754 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733205AbfDRNMT (ORCPT ); Thu, 18 Apr 2019 09:12:19 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B232E3099FD3; Thu, 18 Apr 2019 13:12:12 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.38]) by smtp.corp.redhat.com (Postfix) with SMTP id E8F4119C65; Thu, 18 Apr 2019 13:12:07 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 18 Apr 2019 15:12:12 +0200 (CEST) Date: Thu, 18 Apr 2019 15:12:07 +0200 From: Oleg Nesterov To: Christian Brauner Cc: torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, jannh@google.com, dhowells@redhat.com, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, serge@hallyn.com, luto@kernel.org, arnd@arndb.de, ebiederm@xmission.com, keescook@chromium.org, tglx@linutronix.de, mtk.manpages@gmail.com, akpm@linux-foundation.org, cyphar@cyphar.com, joel@joelfernandes.org, dancol@google.com Subject: Re: [PATCH v2 2/5] clone: add CLONE_PIDFD Message-ID: <20190418131206.GB13701@redhat.com> References: <20190418101841.4476-1-christian@brauner.io> <20190418101841.4476-3-christian@brauner.io> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190418101841.4476-3-christian@brauner.io> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Thu, 18 Apr 2019 13:12:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/18, Christian Brauner wrote: > > @@ -1674,13 +1729,14 @@ static __latent_entropy struct task_struct *copy_process( > unsigned long clone_flags, > unsigned long stack_start, > unsigned long stack_size, > + int __user *parent_tidptr, > int __user *child_tidptr, > struct pid *pid, > int trace, > unsigned long tls, > int node) > { > - int retval; > + int pidfd = -1, retval; it seems that initialization is unneeded, but this is cosmetic. I see no technical problems, feel free to add my reviewed-by. But let me ask a couple of questions... Why O_CLOEXEC? I am just curious, I do not really care. Should we allow CLONE_THREAD | CLONE_PIDFD ? Are you sure we will never need to extend this interface? If not, then perhaps it make sense to add something like if (CLONE_PIDFD) { unsigned long not_used_yet; if (get_user(not_used_yet, parent_tidptr) || not_used_yet != 0) return -EINVAL; } this way we can easily add more arguments in future or even turn CLONE_PIDFD into CLONE_MORE_ARGS_IN_PARENT_TIDPTR. Not that I think this is really good idea, sys_clone2() makes more sense, but still. Oleg.