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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A36ACC4332F for ; Sun, 5 Nov 2023 07:04:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229759AbjKEG76 (ORCPT ); Sun, 5 Nov 2023 01:59:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229455AbjKEG74 (ORCPT ); Sun, 5 Nov 2023 01:59:56 -0500 Received: from 1wt.eu (ded1.1wt.eu [163.172.96.212]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id AF532D3 for ; Sat, 4 Nov 2023 23:59:52 -0700 (PDT) Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 3A56xgHk020716; Sun, 5 Nov 2023 07:59:42 +0100 Date: Sun, 5 Nov 2023 07:59:42 +0100 From: Willy Tarreau To: Thomas =?iso-8859-1?Q?Wei=DFschuh?= Cc: Greg Kroah-Hartman , Arnd Bergmann , linux-kernel@vger.kernel.org, Zhangjin Wu , Yuan Tan Subject: Re: [PATCH RFC] misc/pvpanic: add support for normal shutdowns Message-ID: <20231105065942.GB20673@1wt.eu> References: <20231104-pvpanic-shutdown-v1-1-5ee7c9b3e301@weissschuh.net> <2023110407-unselect-uptight-b96d@gregkh> <365bbe1f-5ee8-40fe-bec0-53d9e7395c18@t-8ch.de> <2023110431-pacemaker-pruning-0e4c@gregkh> <59ed7f70-2953-443e-9fa5-d46c566e4a08@t-8ch.de> <2023110418-unreached-smith-5625@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Nov 04, 2023 at 06:32:57PM +0100, Thomas Weißschuh wrote: > On 2023-11-04 18:07:21+0100, Greg Kroah-Hartman wrote: > > On Sat, Nov 04, 2023 at 02:56:34PM +0100, Willy Tarreau wrote: > > > On Sat, Nov 04, 2023 at 02:53:37PM +0100, Thomas Weißschuh wrote: > > > > > > The real reason probably doesn't matter today as the header propably > > > > > > can't be dropped from Linux anyways for compatibility reasons. > > > > > > > > > > > > > And if they need to be here, why not use the proper BIT() macro for it? > > > > > > > > > > > > This was for uniformity with the existing code. > > > > > > I can send a (standalone?) patch to fix it up. > > > > > > > > > > If we keep it, sure, that would be nice. But let's try to drop it if > > > > > possible :) > > > > > > > > It will break the mentioned scripts/update-linux-headers.sh from qemu. > > > > > > > > > > > > Note: > > > > > > > > BIT() is part of include/vdso/bits.h which is not part of the > > > > uapi. How is it supposed to work? > > > > Some other uapi header also use BIT() but that seems to work by accident > > > > as the users have the macro defined themselves. > > > > > > Be careful here, we don't want to expose this kernel macro to userland, > > > it would break programs that define their own (possibly different) BIT > > > macro. BIT() is used in kernel headers but we should not presume that > > > it is available from userland. > > > > It's already there :( > > > > I thought we had a uapi-safe version somewhere, but I can't seem to find > > it anymore, so I don't remember what it is called. > > It seems to be _BITUL() and _BITULL() from include/uapi/linux/const.h. > > But first we'd need to figure out if we he can drop the pvpanic.h uapi > header. I hoped you could give a definitive answer for that. > Personally I'd hate to break stuff for qemu. Agreed, and I tend as well to be careful not to change uapi stuff in ways that can break, as it can take time to flow to applications and cause subtle breakage much later :-/ Willy