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 9ED6DC4332F for ; Wed, 23 Nov 2022 19:06:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239600AbiKWTGZ (ORCPT ); Wed, 23 Nov 2022 14:06:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36268 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236590AbiKWTGY (ORCPT ); Wed, 23 Nov 2022 14:06:24 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC46F922D2; Wed, 23 Nov 2022 11:06:23 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 586E161EBE; Wed, 23 Nov 2022 19:06:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7968C433D6; Wed, 23 Nov 2022 19:06:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1669230382; bh=imibZHjJL9cpBpAGiGFcUllw5xFRNIsDuHu6Y+fwag4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=V2GZdWHPvr+u9NV42kW3apisS1jk4Cp6h19MZ6qfaWIUGIVJV5gV2ha39zpYgwqP7 WIt60wd9b8FvKniDUGYZZUiLCvZQFxPf+YdmrcSFnI46/b/EWX33zlFDz2TQxA125f 2aOS9p5Y/Iiz28acyMaujccSu8U/Ol2yQw6Symkw= Date: Wed, 23 Nov 2022 20:06:20 +0100 From: Greg Kroah-Hartman To: Jason Gunthorpe Cc: Matthew Wilcox , Maximilian Luz , Andy Shevchenko , linux-kernel@vger.kernel.org, Jens Axboe , "Rafael J. Wysocki" , Len Brown , Stefan Richter , Wolfram Sang , Alexandre Belloni , Dmitry Torokhov , Sean Young , Mauro Carvalho Chehab , Rob Herring , Frank Rowand , Hans de Goede , Mark Gross , Vinod Koul , Bard Liao , Pierre-Louis Bossart , Sanyog Kale , Andreas Noever , Michael Jamet , Mika Westerberg , Yehezkel Bernat , Jiri Slaby , Heikki Krogerus , "Martin K. Petersen" , Chaitanya Kulkarni , Ming Lei , Jilin Yuan , Alan Stern , Sakari Ailus , Thomas Gleixner , Ira Weiny , Dan Williams , Won Chung , alsa-devel@alsa-project.org, devicetree@vger.kernel.org, linux-acpi@vger.kernel.org, linux-block@vger.kernel.org, linux-i2c@vger.kernel.org, linux-i3c@lists.infradead.org, linux-input@vger.kernel.org, linux-media@vger.kernel.org, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, linux1394-devel@lists.sourceforge.net, platform-driver-x86@vger.kernel.org Subject: Re: [PATCH 3/5] driver core: make struct device_type.uevent() take a const * Message-ID: References: <97be39ed-3cea-d55a-caa6-c2652baef399@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Wed, Nov 23, 2022 at 02:25:59PM -0400, Jason Gunthorpe wrote: > On Wed, Nov 23, 2022 at 07:10:49PM +0100, Greg Kroah-Hartman wrote: > > On Wed, Nov 23, 2022 at 05:49:36PM +0000, Matthew Wilcox wrote: > > > On Wed, Nov 23, 2022 at 01:29:56PM -0400, Jason Gunthorpe wrote: > > > > #define generic_container_of(in_type, in, out_type, out_member) \ > > > > _Generic(in, \ > > > > const in_type *: ((const out_type *)container_of(in, out_type, out_member)), \ > > > > in_type *: ((out_type *)container_of(in, out_type, out_member)) \ > > > > ) > > > > > > There's a neat trick I found in seqlock.h: > > > > > > #define generic_container_of(in_t, in, out_t, m) \ > > > _Generic(*(in), \ > > > const in_t: ((const out_t *)container_of(in, out_t, m)), \ > > > in_t: ((out_t *)container_of(in, out_type, m)) \ > > > ) > > > > > > and now it fits in 80 columns ;-) > > > > Nice trick! Dropping the inline functions is a bit different, let me > > see if that still gives a sane error if we pass an incorrect type or > > mess with the const * the wrong way. I'll run some tests tomorrow > > afternoon... > > The errors in some cases are very verbose, but it is somewhat > understandable - the worst is when _Generic fails to match anything, > but also at least clang partially expanded container_of and it throws > other assertions too. > > I also wonder if this could just be rolled into the normal > container_of. I think we might be able to now, my previous attempts with inline functions prevented that. I'll beat on that tomorrow... > in_type would have to be derived like: > > in_type = typeof((out_type *)NULL)->out_member) > > But I don't know if you can use typeof in a generic type matching expression.. Maybe that is what threw me before, I can't remember. I do know we tried a number of different attempts, can't recall the failed ones... thanks, greg k-h