From patchwork Mon Aug 19 10:51:38 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 11100651 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 1456C1399 for ; Mon, 19 Aug 2019 10:53:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 036B0286C4 for ; Mon, 19 Aug 2019 10:53:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EB30C286D5; Mon, 19 Aug 2019 10:53:01 +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=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F35FD286C4 for ; Mon, 19 Aug 2019 10:52:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727319AbfHSKw6 (ORCPT ); Mon, 19 Aug 2019 06:52:58 -0400 Received: from conuserg-08.nifty.com ([210.131.2.75]:19333 "EHLO conuserg-08.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726477AbfHSKw5 (ORCPT ); Mon, 19 Aug 2019 06:52:57 -0400 Received: from localhost.localdomain (p14092-ipngnfx01kyoto.kyoto.ocn.ne.jp [153.142.97.92]) (authenticated) by conuserg-08.nifty.com with ESMTP id x7JAps3U023174; Mon, 19 Aug 2019 19:51:54 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-08.nifty.com x7JAps3U023174 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1566211915; bh=uAr7g3dUlNXQ7fN/nZvH1d8U2EQBEBFwzuJnQ8Wz3oU=; h=From:To:Cc:Subject:Date:From; b=ff7Ixy/f25QXv5KncFABS/pABvuk1I/MIXIBj5f3+90JOltA+Ka/pTfOyhKT5yKoV Mu/xzkLxYMMrRYrRAqiiuabc68TyAwnZjYNReWf3K6jMTIW+I4C7W5L9K4wup0nTtt 7rMlL/yLEPOw4RfoFvNNleN5Cj0CGXAQ+o1ZrJnaTaQEhPq111lGn/KoCC4JAy4ddt 7gc18oO7AKpJpJfCtM18M2sOPt8bUWkSR96jMAupet7jkJrOVrriuC3eBmRUbniH0n 82cQJf5M5Yz6+IratFRHqwKoudYON59/Fydi5XgDuOnsOipXGMl005tAVlF6o6SCQo 4gIBlM0StSuCw== X-Nifty-SrcIP: [153.142.97.92] From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: Nick Desaulniers , Nathan Chancellor , Miguel Ojeda , Masahiro Yamada , Borislav Petkov , Kees Cook , Luc Van Oostenryck , Michal Marek , Paul Burton , Xiaozhou Liu , clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org Subject: [PATCH] kbuild: enable unused-function warnings for W= build with Clang Date: Mon, 19 Aug 2019 19:51:38 +0900 Message-Id: <20190819105138.5053-1-yamada.masahiro@socionext.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP GCC and Clang have different policy for -Wunused-function; GCC does not report unused-function warnings at all for the functions marked as 'static inline'. Clang does report unused-function warnings if they are defined in source files instead of headers. We could use Clang for detecting unused functions, but it has been suppressed since commit abb2ea7dfd82 ("compiler, clang: suppress warning for unused static inline functions"). So, we never notice left-over code if functions in .c files are marked as inline. Let's remove __maybe_unused from the inline macro. As always, it is not a good idea to sprinkle warnings for the normal build. So, these warnings will be shown for the W= build. If you contribute to code clean-up, please run "make CC=clang W=1" and check -Wunused-function warnings. You will find lots of unused functions. Some of them are false-positives because the call-sites are disabled by #ifdef. I do not like to abuse the inline keyword for suppressing unused-function warnings because it might affect the compiler's optimization. When I need to fix unused-functions warnings, I prefer adding #ifdef or __maybe_unused to function definitions. Signed-off-by: Masahiro Yamada Reviewed-by: Kees Cook --- include/linux/compiler_types.h | 10 ++-------- scripts/Makefile.extrawarn | 1 + 2 files changed, 3 insertions(+), 8 deletions(-) diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 599c27b56c29..14de8d0162fb 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -130,10 +130,6 @@ struct ftrace_likely_data { /* * Force always-inline if the user requests it so via the .config. - * GCC does not warn about unused static inline functions for - * -Wunused-function. This turns out to avoid the need for complex #ifdef - * directives. Suppress the warning in clang as well by using "unused" - * function attribute, which is redundant but not harmful for gcc. * Prefer gnu_inline, so that extern inline functions do not emit an * externally visible function. This makes extern inline behave as per gnu89 * semantics rather than c99. This prevents multiple symbol definition errors @@ -143,11 +139,9 @@ struct ftrace_likely_data { * (which would break users of __always_inline). */ #if !defined(CONFIG_OPTIMIZE_INLINING) -#define inline inline __attribute__((__always_inline__)) __gnu_inline \ - __maybe_unused notrace +#define inline inline __attribute__((__always_inline__)) __gnu_inline notrace #else -#define inline inline __gnu_inline \ - __maybe_unused notrace +#define inline inline __gnu_inline notrace #endif #define __inline__ inline diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index a74ce2e3c33e..92f542797e03 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -70,5 +70,6 @@ KBUILD_CFLAGS += -Wno-initializer-overrides KBUILD_CFLAGS += -Wno-format KBUILD_CFLAGS += -Wno-sign-compare KBUILD_CFLAGS += -Wno-format-zero-length +KBUILD_CFLAGS += -Wno-unused-function endif endif