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 DC7C0C433EF for ; Tue, 18 Jan 2022 14:21:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244808AbiAROVB (ORCPT ); Tue, 18 Jan 2022 09:21:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54890 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244543AbiAROUw (ORCPT ); Tue, 18 Jan 2022 09:20:52 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E59EFC061574 for ; Tue, 18 Jan 2022 06:20:49 -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 sin.source.kernel.org (Postfix) with ESMTPS id 46353CE19F2 for ; Tue, 18 Jan 2022 14:20:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60690C00446; Tue, 18 Jan 2022 14:20:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642515646; bh=LQnVNXXFkBGvBwIEYlzUC8mACRKwyF7PmpnrofVDnmE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=khXMs8nOsMDKs5MbBbUOYqR0A/rLczE6TVnUebuvjd1p/2kox9EI8UHHK3/EjV30Z ohxTVi74dxt8DMuc247yuDL7XlpUTU0Zx8h9nonZxWsId6kYqmpHC0XIVOLA3xeXAW eLxJcJWMsST1k9ztnKqcMMcgjxgmKJ1NGTpgYlI8lE/i+uFAOa1rMuu5RoDEDEz6wo SSUb1DBt8Hrs4qjX8iLFIZWLnncgw7TBwix/+xt7cI42bgjDT8OXg7e7JtRjocepJ3 oxCpVtpas1q4P4rbAkfT+tu3MbIqUJlCCTdjPERSM3/oTW+JZf6DSlaAj1WDwvVpDO ZU5KAaVkdPuvw== Date: Tue, 18 Jan 2022 22:13:03 +0800 From: Jisheng Zhang To: Baoquan He Cc: Russell King , Catalin Marinas , Will Deacon , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, hpa@zytor.com, Eric Biederman , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, kexec@lists.infradead.org, Alexandre ghiti Subject: Re: [PATCH v2 0/5] kexec: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef Message-ID: References: <20211206160514.2000-1-jszhang@kernel.org> <20220116133847.GE2388@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220116133847.GE2388@MiWiFi-R3L-srv> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 16, 2022 at 09:38:47PM +0800, Baoquan He wrote: > Hi Jisheng, Hi Baoquan, > > On 12/07/21 at 12:05am, Jisheng Zhang wrote: > > Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE" > > by a check for "IS_ENABLED(CONFIG_KEXEC_CORE)", to simplify the code > > and increase compile coverage. > > I go through this patchset, You mention the benefits it brings are > 1) simplity the code; > 2) increase compile coverage; > > For benefit 1), it mainly removes the dummy function in x86, arm and > arm64, right? Another benefit: remove those #ifdef #else #endif usage. Recently, I fixed a bug due to lots of "#ifdefs": http://lists.infradead.org/pipermail/linux-riscv/2021-December/010607.html > > For benefit 2), increasing compile coverage, could you tell more how it > achieves and why it matters? What if people disables CONFIG_KEXEC_CORE in > purpose? Please forgive my poor compiling knowledge. Just my humble opinion, let's compare the code:: #ifdef CONFIG_KEXEC_CORE code block A; #endif If KEXEC_CORE is disabled, code block A won't be compiled at all, the preprocessor will remove code block A; If we convert the code to: if (IS_ENABLED(CONFIG_KEXEC_CORE)) { code block A; } Even if KEXEC_CORE is disabled, code block A is still compiled. Thanks