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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C6072FA372A for ; Wed, 16 Oct 2019 16:23:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A442C21835 for ; Wed, 16 Oct 2019 16:23:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406154AbfJPQXL (ORCPT ); Wed, 16 Oct 2019 12:23:11 -0400 Received: from mga17.intel.com ([192.55.52.151]:52798 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727138AbfJPQXL (ORCPT ); Wed, 16 Oct 2019 12:23:11 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Oct 2019 09:23:10 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,304,1566889200"; d="scan'208";a="220832260" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by fmsmga004.fm.intel.com with ESMTP; 16 Oct 2019 09:23:08 -0700 Received: from andy by smile with local (Exim 4.92.2) (envelope-from ) id 1iKm4q-0005d4-0w; Wed, 16 Oct 2019 19:23:08 +0300 Date: Wed, 16 Oct 2019 19:23:08 +0300 From: Andy Shevchenko To: Dmitry Torokhov Cc: "Rafael J. Wysocki" , Heikki Krogerus , Mika Westerberg , Linus Walleij , Ard Biesheuvel , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org Subject: Re: [PATCH v5 11/14] software node: move small properties inline when copying Message-ID: <20191016162308.GY32742@smile.fi.intel.com> References: <20191011230721.206646-1-dmitry.torokhov@gmail.com> <20191011230721.206646-12-dmitry.torokhov@gmail.com> <20191015122028.GI32742@smile.fi.intel.com> <20191015182553.GG105649@dtor-ws> <20191016074857.GN32742@smile.fi.intel.com> <20191016160126.GB35946@dtor-ws> <20191016161845.GX32742@smile.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191016161845.GX32742@smile.fi.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 16, 2019 at 07:18:45PM +0300, Andy Shevchenko wrote: > On Wed, Oct 16, 2019 at 09:01:26AM -0700, Dmitry Torokhov wrote: > > On Wed, Oct 16, 2019 at 10:48:57AM +0300, Andy Shevchenko wrote: > > > On Tue, Oct 15, 2019 at 11:25:53AM -0700, Dmitry Torokhov wrote: > > > > You store a value as union, but going to read as a member of union? > > > I'm pretty sure it breaks standard rules. > > > > No, I move the values _in place_ of the union, and the data is always > > fetched via void pointers. And copying data via char * or memcpy() is > > allowed even in C99 and C11. > > > > But I am wondering why are we actually worrying about all of this? The > > kernel is gnu89 and I think is going to stay this way because we use > > initializers with a cast in a lot of places: > > > > #define __RAW_SPIN_LOCK_UNLOCKED(lockname) \ > > (raw_spinlock_t) __RAW_SPIN_LOCK_INITIALIZER(lockname) > > > > and C99 and gnu99 do not allow this. See > > https://lore.kernel.org/lkml/20141019231031.GB9319@node.dhcp.inet.fi/ > > This is simple not a cast. 4.62 Compound literals in C99 ISO C99 supports compound literals. A compound literal looks like a cast followed by an initializer. Its value is an object of the type specified in the cast, containing the elements specified in the initializer. It is an lvalue. -- With Best Regards, Andy Shevchenko