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 810F7ECAAA1 for ; Tue, 30 Aug 2022 08:49:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231676AbiH3Itr (ORCPT ); Tue, 30 Aug 2022 04:49:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231672AbiH3Itl (ORCPT ); Tue, 30 Aug 2022 04:49:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECF98B99D2; Tue, 30 Aug 2022 01:49:39 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id A77CFB81887; Tue, 30 Aug 2022 08:49:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C9BBC433D7; Tue, 30 Aug 2022 08:49:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661849377; bh=y+1MMFa8GkCF5J8xOBa4wpAmNDUFKU7en8TBxW//a4E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Bf1YtPs307mo8lMrBvPJ8JYzsN4hPwgTGnjeruF2ZT+1HYnd27ANo4lCmBvYw6VuQ 2XxLEk1UupnJaBo6WfhMPaUkQ7okqnaaO9IlK6tMeOhVGHNOJT8Nvn6H+iLkIHrqoI YzbnTxjGWzGZRSZHOSZBz4hrQkidgYl3DUpQ/ghA= Date: Tue, 30 Aug 2022 10:49:34 +0200 From: Greg Kroah-Hartman To: Ilpo =?iso-8859-1?Q?J=E4rvinen?= Cc: Jiri Slaby , linux-serial@vger.kernel.org, Andy Shevchenko , Jonathan Corbet , Vladimir Zapolskiy , Russell King , Richard Genoud , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Maxime Coquelin , Alexandre Torgue , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, Lino Sanfilippo Subject: Re: [PATCH v2 4/4] serial: Add kserial_rs485 to avoid wasted space due to .padding Message-ID: References: <20220830072956.3630-1-ilpo.jarvinen@linux.intel.com> <20220830072956.3630-5-ilpo.jarvinen@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220830072956.3630-5-ilpo.jarvinen@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 30, 2022 at 10:29:56AM +0300, Ilpo Järvinen wrote: > The struct serial_rs485 has a .padding field to make uapi updates > easier. It wastes space, however. Create struct kserial_rs485 which is > a kerner counterpart w/o padding. "kernel"? And what is the size difference now? > +/** > + * struct kserial_rs485 - kernel-side struct for controlling RS485 settings. > + * @flags: RS485 feature flags > + * @delay_rts_before_send: Delay before send (milliseconds) > + * @delay_rts_after_send: Delay after send (milliseconds) > + * @addr_recv: Receive filter for RS485 addressing mode > + * (used only when %SER_RS485_ADDR_RECV is set). > + * @addr_dest: Destination address for RS485 addressing mode > + * (used only when %SER_RS485_ADDR_DEST is set). > + * > + * Must match with struct serial_rs485 in include/uapi/linux/serial.h excluding > + * the padding. Why must this match? And how is that going to be enforced? > + */ > +struct kserial_rs485 { > + __u32 flags; > + __u32 delay_rts_before_send; > + __u32 delay_rts_after_send; > + struct { > + __u8 addr_recv; > + __u8 addr_dest; > + }; As this is an in-kernel structure, this should be "u32" and "u8" now. thanks, greg k-h