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=-0.5 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 08CCAC4361B for ; Sat, 12 Dec 2020 13:22:35 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C13DC22C7E for ; Sat, 12 Dec 2020 13:22:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C13DC22C7E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C8BD36E85A; Sat, 12 Dec 2020 13:22:32 +0000 (UTC) Received: from mail-pg1-x52d.google.com (mail-pg1-x52d.google.com [IPv6:2607:f8b0:4864:20::52d]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3EEAF6E844; Sat, 12 Dec 2020 13:22:31 +0000 (UTC) Received: by mail-pg1-x52d.google.com with SMTP id n1so6522827pge.8; Sat, 12 Dec 2020 05:22:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=VTZpp0n/Om/Jf11Mz+DqRKpiaIjN4mJ897+taVy59Ug=; b=gs+DafSa6tm6ZhcmtOMAV2zOpZsgVdlfnJO3Cc8h6uZ7zEIkJ//kiGJiG610YJYd9c hi7RAK/gnCn0RzWdwMYCDo5iWNdBQbtvJKYrsQI5ZcoVP15/FlhWsHbcStHoxRpLv5K2 7tZggztOJ5OrWHKSc7C0B5gdsPwG3Jh4XQNGDZzJ5uC91i9eb/FOwSgLNZwxuhvbJlm1 NZRNGWscN+BvdnS2hdE/2kf8TIOM+A9TYoTVx3z4X0kR366gEuSlj/jqKKPOYQFh4Kj3 5afdtXgK8N3xa39LgKIpCZwsKgk5qgska42v8wTbiGBbB+guXeCE2Frkke6P3b+dq3Ir zifA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VTZpp0n/Om/Jf11Mz+DqRKpiaIjN4mJ897+taVy59Ug=; b=elUe3EVxoJomd+L+OwDLpkyuXi1PY6lIaL+yX9OxDv7A9JqwXBtlpEVh3rvN81upo9 snBCsLUUAVdR5zMcBWrsUIlba6PMdvYrziakwIS9w3haj0tLdfqLci/AOr111dZBv5aP XLATsz34EgQ3RGMevWJy5PdITch4u5wSx7QPThz1BgJ6eOVdGpUNb9npIu5K92jJfRkr qEezTZH6OsyCXyPGZ4oJ+EbePsgEOpBGAjN0DNz7B9/z4b1oVwlhqBxThb6mH7e/oSXO HN4/GkUVRh+6QN/k5JXl4V4wjFAIhUVmBJKG9XNhzxFgnSf1767oPPPrT2G4Hd15ReMz +vvA== X-Gm-Message-State: AOAM5323CDiL3iB0zpWrbO20PJ8sZ2jRMrXN/7xNXQEOpSRnwMapSiFu 6YSwzM3LsZUs7qAd/CkoUCUO1BWziaHhRyQPJVw= X-Google-Smtp-Source: ABdhPJz6qkGZaIbcK80z8oNTbmCmaNucZ+fxbrx52JjiY59cFl32wS2FAI0NK0C4i2f9nCp4IxJVJq78J8uiblnFRTg= X-Received: by 2002:a05:6a00:170a:b029:19d:afca:4704 with SMTP id h10-20020a056a00170ab029019dafca4704mr15887538pfc.7.1607779350726; Sat, 12 Dec 2020 05:22:30 -0800 (PST) MIME-Version: 1.0 References: <20201210192536.118432146@linutronix.de> <20201210194042.860029489@linutronix.de> <87h7osgifc.fsf@nanos.tec.linutronix.de> <87360cgfol.fsf@nanos.tec.linutronix.de> In-Reply-To: <87360cgfol.fsf@nanos.tec.linutronix.de> From: Andy Shevchenko Date: Sat, 12 Dec 2020 15:22:14 +0200 Message-ID: Subject: Re: [patch 03/30] genirq: Move irq_set_lockdep_class() to core To: Thomas Gleixner X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Karthikeyan Mitran , Peter Zijlstra , Catalin Marinas , dri-devel , Chris Wilson , "James E.J. Bottomley" , Saeed Mahameed , netdev , Will Deacon , Michal Simek , linux-s390@vger.kernel.org, afzal mohammed , Lorenzo Pieralisi , Dave Jiang , xen-devel@lists.xenproject.org, Leon Romanovsky , "open list:HFI1 DRIVER" , Marc Zyngier , Helge Deller , Russell King , Christian Borntraeger , linux-pci , Jakub Kicinski , Heiko Carstens , Wambui Karuga , Allen Hubbe , Juergen Gross , David Airlie , "open list:GPIO SUBSYSTEM" , Stefano Stabellini , Rodrigo Vivi , Bjorn Helgaas , Lee Jones , linux-arm Mailing List , Boris Ostrovsky , Tvrtko Ursulin , linux-parisc@vger.kernel.org, Pankaj Bharadiya , Hou Zhiqiang , LKML , Tariq Toukan , Jon Mason , linux-ntb@googlegroups.com, intel-gfx , "David S. Miller" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Sat, Dec 12, 2020 at 12:07 AM Thomas Gleixner wrote: > > On Fri, Dec 11 2020 at 22:08, Thomas Gleixner wrote: > > > On Fri, Dec 11 2020 at 19:53, Andy Shevchenko wrote: > > > >> On Thu, Dec 10, 2020 at 10:14 PM Thomas Gleixner wrote: > >>> > >>> irq_set_lockdep_class() is used from modules and requires irq_to_desc() to > >>> be exported. Move it into the core code which lifts another requirement for > >>> the export. > >> > >> ... > >> > >>> + if (IS_ENABLED(CONFIG_LOCKDEP)) > >>> + __irq_set_lockdep_class(irq, lock_class, request_class); > > > > You are right. Let me fix that. > > No. I have to correct myself. You're wrong. > > The inline is evaluated in the compilation units which include that > header and because the function declaration is unconditional it is > happy. > > Now the optimizer stage makes the whole thing a NOOP if CONFIG_LOCKDEP=n > and thereby drops the reference to the function which makes it not > required for linking. > > So in the file where the function is implemented: > > #ifdef CONFIG_LOCKDEP > void __irq_set_lockdep_class(....) > { > } > #endif > > The whole block is either discarded because CONFIG_LOCKDEP is not > defined or compile if it is defined which makes it available for the > linker. > > And in the latter case the optimizer keeps the call in the inline (it > optimizes the condition away because it's always true). > > So in both cases the compiler and the linker are happy and everything > works as expected. > > It would fail if the header file had the following: > > #ifdef CONFIG_LOCKDEP > void __irq_set_lockdep_class(....); > #endif > > Because then it would complain about the missing function prototype when > it evaluates the inline. I understand that (that's why I put "if even no warning") and what I'm talking about is the purpose of IS_ENABLED(). It's usually good for compile testing !CONFIG_FOO cases. But here it seems inconsistent. The pattern I usually see in the cases like this is #ifdef CONFIG_LOCKDEP void __irq_set_lockdep_class(....); #else static inline void ... {} #endif and call it directly in the caller. It's not a big deal, so up to you. -- With Best Regards, Andy Shevchenko _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel