From patchwork Fri Jan 18 16:00:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Murray X-Patchwork-Id: 10770757 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F24FA6C5 for ; Fri, 18 Jan 2019 16:01:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E10242EAA0 for ; Fri, 18 Jan 2019 16:01:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D579A2F31B; Fri, 18 Jan 2019 16:01:41 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 58C462F36D for ; Fri, 18 Jan 2019 16:01:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=gGF5W685pMMYuxBrfKlM+d4owd88EL2NZHhePXjAA/s=; b=i1BO8Wm4g0hlgKUnCyAQBFhXmW YLtfNHEaq/HAMDDJpkDxErTYNJrgOG9D+PmnrpnrRRrNpoGc6uWvixK6NByZ6BE2Dm4SMqNnEUDnm 1cCV+uJxhv5dZMipybku20uqGxPVXjptylBlC1xFJHpM37KJ27emsT22yl2ylbWkSgiX9hGd+Po4r WaFFFNLTkGziSPGW5lh7fvIzqM5Ml+ckemaNOksfXZSjhSB96LQSpi0Z6sYRJgCXvgQQrulZoxHdv JtWBXV2dsVD6M3nrdSks+dA+dUdYoLuT4GuDmD87h3BeF0ej0d7O0m6ruFYFK1MD4qtJY0d7yjNQY vUS36IBg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gkWaO-0006bF-6Z; Fri, 18 Jan 2019 16:01:36 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gkWZW-0006PV-Gg for linux-arm-kernel@lists.infradead.org; Fri, 18 Jan 2019 16:00:43 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1E4F41596; Fri, 18 Jan 2019 08:00:42 -0800 (PST) Received: from e119886-lin.cambridge.arm.com (unknown [10.37.6.11]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AACE33F557; Fri, 18 Jan 2019 08:00:39 -0800 (PST) From: Andrew Murray To: Masahiro Yamada , Arnd Bergmann , Kees Cook , Andrew Morton Subject: [PATCH 1/3] kconfig.h: abstract empty functions with STUB_UNLESS macro Date: Fri, 18 Jan 2019 16:00:28 +0000 Message-Id: <1547827230-55132-2-git-send-email-andrew.murray@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1547827230-55132-1-git-send-email-andrew.murray@arm.com> References: <1547827230-55132-1-git-send-email-andrew.murray@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190118_080042_555172_4F9DB94C X-CRM114-Status: GOOD ( 13.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: rjw@rjwysocki.net, Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Steven Price , Grant Likely , Dave P Martin , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP A common pattern found in header files is a function declaration dependent on a CONFIG_ option being enabled, followed by an empty function for when that option isn't enabled. This can often take up a lot of space and impact code readability. Let's introduce the following STUB_UNLESS macro: STUB_UNLESS(CONFIG_FOO, [body], prototype) This evaluates to 'prototype' prepended with 'extern' if CONFIG_FOO is set to 'y'. Otherwise it will evaluate to 'prototype' prepended with 'static inline' followed by an empty function body. Where optional argument 'body' then 'body' will be used as the function body, intended to allow for simple return statements. Signed-off-by: Andrew Murray Reviewed-by: Steven Price --- include/linux/kconfig.h | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h index cc8fa10..216a27f 100644 --- a/include/linux/kconfig.h +++ b/include/linux/kconfig.h @@ -12,6 +12,7 @@ #define __ARG_PLACEHOLDER_1 0, #define __take_second_arg(__ignored, val, ...) val +#define __take_fourth_arg(__ignored, __ignored2, __ignored3, val, ...) val /* * The use of "&&" / "||" is limited in certain expressions. @@ -70,4 +71,34 @@ */ #define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option)) + + +/* + * Allow for __stub to be overloaded by making the second argument optional + */ +#define __stub_overload(...) __take_fourth_arg(__VA_ARGS__, \ + __stub_body, __stub_void)(__VA_ARGS__) +#define __stub_body(option, body, ptype) __stub(option, body, ptype) +#define __stub_void(option, ptype) __stub(option, , ptype) + +/* + * Using the same trick as __defined we use the config option to conditionally + * expand to an extern function declaration or a static stub function. + */ +#define __stub(option, body, ptype) ___stub( \ + __ARG_PLACEHOLDER_##option, body, ptype) +#define ___stub(arg1_or_junk, body, ptype) __take_second_arg( \ + arg1_or_junk __extern_ptype(ptype), __static_ptype(body, ptype)) +#define __static_ptype(body, ptype) static inline ptype { body; } +#define __extern_ptype(ptype) extern ptype + +/* + * STUB_UNLESS(CONFIG_FOO, [body], prototype) evaluates to 'prototype' prepended + * with 'extern' if CONFIG_FOO is set to 'y'. Otherwise it will evaluate to + * 'prototype' prepended with 'static inline' followed by an empty function + * body. Where optional argument 'body' is present then 'body' will be used + * as the function body, intended to allow for simple return statements. + */ +#define STUB_UNLESS(...) __stub_overload(__VA_ARGS__) + #endif /* __LINUX_KCONFIG_H */