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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 A1269C433E1 for ; Tue, 18 Aug 2020 17:57:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88E5420786 for ; Tue, 18 Aug 2020 17:57:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726691AbgHRR56 (ORCPT ); Tue, 18 Aug 2020 13:57:58 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:53273 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726552AbgHRR55 (ORCPT ); Tue, 18 Aug 2020 13:57:57 -0400 Received: from ip5f5af70b.dynamic.kabel-deutschland.de ([95.90.247.11] helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1k85rt-0005EW-F5; Tue, 18 Aug 2020 17:57:53 +0000 Date: Tue, 18 Aug 2020 19:57:51 +0200 From: Christian Brauner To: Matthew Wilcox Cc: Christoph Hewllig , linux-kernel@vger.kernel.org, Linus Torvalds , linux-arch@vger.kernel.org, Jonathan Corbet , Yoshinori Sato , Tony Luck , Fenghua Yu , Geert Uytterhoeven , Ley Foon Tan , "David S. Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, Arnd Bergmann , Steven Rostedt , Stafford Horne , Peter Zijlstra , Kars de Jong , Kees Cook , Greentime Hu , "Eric W. Biederman" , Mauro Carvalho Chehab , Alexandre Chartre , Masami Hiramatsu , Tom Zanussi , Xiao Yang , linux-doc@vger.kernel.org, uclinux-h8-devel@lists.sourceforge.jp, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, sparclinux@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net, linux-kselftest@vger.kernel.org Subject: Re: [PATCH 00/11] Introduce kernel_clone(), kill _do_fork() Message-ID: <20200818175751.xg726hgyirbt354d@wittgenstein> References: <20200818173411.404104-1-christian.brauner@ubuntu.com> <20200818174447.GV17456@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200818174447.GV17456@casper.infradead.org> Sender: linux-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Tue, Aug 18, 2020 at 06:44:47PM +0100, Matthew Wilcox wrote: > On Tue, Aug 18, 2020 at 07:34:00PM +0200, Christian Brauner wrote: > > The only remaining function callable outside of kernel/fork.c is > > _do_fork(). It doesn't really follow the naming of kernel-internal > > syscall helpers as Christoph righly pointed out. Switch all callers and > > references to kernel_clone() and remove _do_fork() once and for all. > > My only concern is around return type. long, int, pid_t ... can we > choose one and stick to it? pid_t is probably the right return type > within the kernel, despite the return type of clone3(). It'll save us > some work if we ever go through the hassle of growing pid_t beyond 31-bit. It should be safe to switch kernel_clone() to return pid_t. (Afair, the syscall wrappers all have "long" as return type. (I think Linus provided some more details on that in another mail. Also see include/linux/syscalls.h. So the return type for clone3() is really somewhat a userspace thing, I think.) I wonder whether I should take the opportunity and switch the advertised flag arguments for the legacy clone() syscalls and kernel_thread() from unsigned long to unsigned int so we can get rid of the lower .flags = (lower_32_bits(clone_flags) & ~CSIGNAL), calls I added to fix sign extension issues glibc ran into... Christian