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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 DB903C47080 for ; Tue, 1 Jun 2021 21:31:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9E5361159 for ; Tue, 1 Jun 2021 21:31:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234740AbhFAVdb (ORCPT ); Tue, 1 Jun 2021 17:33:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:54072 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234513AbhFAVda (ORCPT ); Tue, 1 Jun 2021 17:33:30 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9105F60FE3; Tue, 1 Jun 2021 21:31:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622583108; bh=kvGZ/iThdsHX6lx/mK//0fCXDu5p9x4gQqJ8bXxQPCc=; h=From:To:Cc:Subject:Date:From; b=UYejXAk2vgPs1tJWdtNdXHMidre/gIvpL8bXkx8+f7ZLKSLtmZ/mKb9mN08h/klQL YxsBeYf+VW3IjpKS842i6d3/yRfroBKDrfOeNjh1Q5zM7KUVqrW8L94DRav73uQE1l RdvmGrQ2wj4h8P9k31xxkaIYCu4i/VfjS7wKZlElp/59MDjuG/fr04yH1kb4WRl2pN 5vvC8AvbhSwn5WXCuZjlv0clBKrj+jbtb6tZwJidKvikVSq0Sby478S2g6C7gCkoyk orNy+FWHr5wb3mT+CfXgNG8U5/w+4p5IG3nuz08bmRMXq6/53dKQDr/olpv1l7jHOQ XTPmsvtDrGq5A== From: Bjorn Helgaas To: linux-kernel@vger.kernel.org Cc: Masahiro Yamada , Kees Cook , Linus Walleij , Arnd Bergmann , Paul Cercueil , =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , Bjorn Helgaas Subject: [PATCH] kconfig.h: explain IS_MODULE(), IS_ENABLED() Date: Tue, 1 Jun 2021 16:31:43 -0500 Message-Id: <20210601213143.1973770-1-helgaas@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Bjorn Helgaas Extend IS_MODULE() and IS_ENABLED comments to explain why one might use "#if IS_ENABLED(CONFIG_FOO)" instead of "#ifdef CONFIG_FOO". To wit, "#ifdef CONFIG_FOO" is true only for CONFIG_FOO=y, while "#if IS_ENABLED(CONFIG_FOO)" is true for both CONFIG_FOO=y and CONFIG_FOO=m. This is because "CONFIG_FOO=m" in .config does not result in "CONFIG_FOO" being defined. The actual definitions are in autoconf.h, where: CONFIG_FOO=y results in #define CONFIG_FOO 1 CONFIG_FOO=m results in #define CONFIG_FOO_MODULE 1 Signed-off-by: Bjorn Helgaas --- include/linux/kconfig.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h index cc8fa109cfa3..20d1079e92b4 100644 --- a/include/linux/kconfig.h +++ b/include/linux/kconfig.h @@ -51,7 +51,8 @@ /* * IS_MODULE(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'm', 0 - * otherwise. + * otherwise. CONFIG_FOO=m results in "#define CONFIG_FOO_MODULE 1" in + * autoconf.h. */ #define IS_MODULE(option) __is_defined(option##_MODULE) @@ -66,7 +67,8 @@ /* * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or 'm', - * 0 otherwise. + * 0 otherwise. Note that CONFIG_FOO=y results in "#define CONFIG_FOO 1" in + * autoconf.h, while CONFIG_FOO=m results in "#define CONFIG_FOO_MODULE 1". */ #define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option)) -- 2.25.1