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=-13.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 D38A2C4332E for ; Thu, 19 Mar 2020 21:43:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 94FFA20773 for ; Thu, 19 Mar 2020 21:43:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Okb9JBtL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727103AbgCSVnf (ORCPT ); Thu, 19 Mar 2020 17:43:35 -0400 Received: from mail-ot1-f67.google.com ([209.85.210.67]:43546 "EHLO mail-ot1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726930AbgCSVnf (ORCPT ); Thu, 19 Mar 2020 17:43:35 -0400 Received: by mail-ot1-f67.google.com with SMTP id a6so4007950otb.10 for ; Thu, 19 Mar 2020 14:43:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=PiU105LwR4CtW43tXMObNmMhkqu4rll7p1Rlw/fDhGQ=; b=Okb9JBtLix6HoE/n1OPWQyGcHGdyvGhMF5VDVjtJhupf/8TOqj5A2Tc/UPUs7A31Sd fVrixRhLUlniMsL/7tsy/kCBR83JuNMVD6kX5ECVMuxP0zQJSnIJGfq2mtpLK73uxny2 Xj+HrbKFe7UHqYJOCwqJ24I0r7mkCpDN9cjGeKy10zAyz0r0AC/IBUURV9ieWN6gMIMp /z/MZhjnFSdnQ+BHQzCbEeX6Xgo/+xcujxaNGqyA3SVby1zK0csZYD4R70gCMtrbMJll pmBwSe4J29xINTr84WYSnKZ/SPesCkE9xzwoSQ4mvQ/4v/iRif9SKSprStZlYn3pC4VX KpSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=PiU105LwR4CtW43tXMObNmMhkqu4rll7p1Rlw/fDhGQ=; b=U9ZJwFep2h0CpgDi/t7inhQvU68ZyVfEaff+rQ5gjigGrHqdarju/Xo5lbpkZwVpyx 3fHLYQnFAFLaugPU+rbIDpj1PVB53U0/jac4lyxcPHDOauIOglwXRZAlbraReus1S5Jg lzZaeGBisdu7XtBHhuqmlD+l68Srbt4V6ar3P6ei09m8+ORtpa5UcYO33gAZMJ3TN7O5 gEmpJL27KdnH57GBbwYF8G2maXKSbIECi3C8UpRdilk8UzOYEdj+4eoVr80k48xTp9ix 1bc5iCSaiurW4JJr7KFQ6LJBZs66vm2Y6NzoSenP5auzE+70A2r2SVCVegtL9MrZVB0F Ph1w== X-Gm-Message-State: ANhLgQ1RwlVDJCOza3Z/664J+g5yL5mQ3XUeZSfY01ALT5ab0o2AIXRT MgTyXKZYWxBiYv87ONEHiVc= X-Google-Smtp-Source: ADFU+vtvMwQ7ety0PRkbuZjX9+CuIAPrBtZgxesrF5R32AEbIB2ziIg2w0iTy1qA9/unV9/cH1rg9g== X-Received: by 2002:a9d:7750:: with SMTP id t16mr4049797otl.333.1584654214036; Thu, 19 Mar 2020 14:43:34 -0700 (PDT) Received: from ubuntu-m2-xlarge-x86 ([2604:1380:4111:8b00::1]) by smtp.gmail.com with ESMTPSA id v12sm1197807otp.75.2020.03.19.14.43.33 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 19 Mar 2020 14:43:33 -0700 (PDT) Date: Thu, 19 Mar 2020 14:43:31 -0700 From: Nathan Chancellor To: Jason Baron , Andrew Morton Cc: linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, Nick Desaulniers , Andrew Morton Subject: Re: [PATCH v2] dynamic_debug: Use address-of operator on section symbols Message-ID: <20200319214331.GA53874@ubuntu-m2-xlarge-x86> References: <20200220051320.10739-1-natechancellor@gmail.com> <20200319015909.GA8292@ubuntu-m2-xlarge-x86> <4b766edb-73e2-c295-22eb-b501405baa9f@akamai.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4b766edb-73e2-c295-22eb-b501405baa9f@akamai.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 19, 2020 at 04:03:39PM -0400, Jason Baron wrote: > > > On 3/18/20 9:59 PM, Nathan Chancellor wrote: > > On Wed, Feb 19, 2020 at 10:13:20PM -0700, Nathan Chancellor wrote: > >> Clang warns: > >> > >> ../lib/dynamic_debug.c:1034:24: warning: array comparison always > >> evaluates to false [-Wtautological-compare] > >> if (__start___verbose == __stop___verbose) { > >> ^ > >> 1 warning generated. > >> > >> These are not true arrays, they are linker defined symbols, which are > >> just addresses. Using the address of operator silences the warning and > >> does not change the resulting assembly with either clang/ld.lld or > >> gcc/ld (tested with diff + objdump -Dr). > >> > >> Link: https://github.com/ClangBuiltLinux/linux/issues/894 > >> Suggested-by: Nick Desaulniers > >> Signed-off-by: Nathan Chancellor > >> --- > >> v1 -> v2: https://lore.kernel.org/lkml/20200219045423.54190-5-natechancellor@gmail.com/ > >> > >> * No longer a series because there is no prerequisite patch. > >> * Use address-of operator instead of casting to unsigned long. > >> > >> lib/dynamic_debug.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c > >> index aae17d9522e5..8f199f403ab5 100644 > >> --- a/lib/dynamic_debug.c > >> +++ b/lib/dynamic_debug.c > >> @@ -1031,7 +1031,7 @@ static int __init dynamic_debug_init(void) > >> int n = 0, entries = 0, modct = 0; > >> int verbose_bytes = 0; > >> > >> - if (__start___verbose == __stop___verbose) { > >> + if (&__start___verbose == &__stop___verbose) { > >> pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n"); > >> return 1; > >> } > >> -- > >> 2.25.1 > >> > > > > Gentle ping for review/acceptance. > > > > Cheers, > > Nathan > > Works for me. > > Acked-by: Jason Baron Thank you! Andrew, I assume you'll pick this up? Cheers, Nathan